Meter reading device, meter reading program, and meter reading method

Abstract

To provide a meter reading device capable of preventing a decrease in reading accuracy even when environmental conditions for photographing a meter change.SOLUTION: A meter reading device includes: an image acquisition unit (1) configured to acquire a captured image; an indication needle detection unit (4) configured to detect an indication position indicated by an indication needle on the captured image by comparing the captured image acquired by the image acquisition unit (1) with a reference image that shows the indication needle and serves as a reference for detecting, on a meter, the indication position indicated by the indication needle, and create an indication needle detection result based on the comparison result of the reference image and the captured image captured when the indication position is detected; and a reference image updating unit (7) configured to re-create a reference image based on the indication needle detection result created when comparing the captured image with the reference image by the indication needle detection unit (4), and update a reference image by using an update reference image which is the re-created reference image.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a meter reading device, a meter reading program, and a meter reading method. [Background technology]

[0002] There is a technology that automatically reads the indicated value, which is the numerical value indicated by the meter needle, from an image of the meter, instead of a human being checking the meter visually. For example, Patent Document 1 discloses a technique for reading the pointer of an analog meter, which involves creating a scanned image of the scale and a scanned image of the pointer based on previously stored information indicating the shape of the pointer from an image of the scale of the meter, calculating a distribution of likelihoods indicating the likelihood that the pointer is captured in the scanned image of the scale by comparing the scanned image of the scale and the scanned image of the pointer, and identifying the numerical value indicated by the pointer of the meter based on the distribution of the calculated likelihoods in a direction perpendicular to the scale. More specifically, the information indicating the shape of the pointer includes information on the outline of the pointer and the needle color. The scanned image of the pointer is created by drawing a background image that is sufficiently larger than the length and width of the pointer stored in advance in the color of the scale stored in advance, drawing the outline of the pointer corresponding to the length and width based on the outline information in the center of the background image, and drawing the inside of the outline in the previously stored needle color, and scanning the image of the pointer in a direction perpendicular to the scale of the captured image. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-038188 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional technology, the scanned image of the pointer used to identify the position of the pointer of the meter is created from pre-stored information on the outline of the pointer and the shape of the pointer, including the needle color. Therefore, when the environmental conditions under which the meter is imaged, such as lighting, change and a difference occurs between the appearance of the pointer in the image of the meter dial and the appearance of the pointer based on the pre-stored information on the shape of the pointer, there is a possibility that the accuracy of reading the indicated value of the meter may decrease.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a meter reading device that is capable of preventing a decrease in reading accuracy even when the environmental conditions in which the meter is photographed change. [Means for solving the problem]

[0006] The meter reading device of the present disclosure is a meter reading device that calculates an indication value, which is a numerical value indicated by the pointer, from the indication position of the pointer on an image detected based on an image in which at least the scale of the meter is imaged, and is equipped with an image acquisition unit that acquires the image, a pointer detection unit that detects the indication position of the pointer on the image by comparing the image acquired by the image acquisition unit with a reference image showing the pointer that serves as a standard for detecting the indication position of the pointer on the meter, and creates a pointer detection result based on the comparison result between the image acquired by the pointer detection unit when the indication position is detected and the reference image, and a reference image update unit that recreates the reference image based on the pointer detection result created by the pointer detection unit when comparing the image acquired with the reference image, and updates the reference image with the recreated reference image, which is an update reference image. Effect of the Invention

[0007] According to the meter reading device of the present invention, even if the environmental conditions under which the meter is photographed change, it is possible to prevent a decrease in reading accuracy. [Brief description of the drawings]

[0008] [Figure 1]1 is a diagram showing a configuration example of a meter reading device according to a first embodiment and a meter reading system including the meter reading device; [Diagram 2] 4 is a diagram showing an example of the configuration of a main part of a reference image updating unit in the meter reading device according to the first embodiment; FIG. [Diagram 3] FIG. 3 is a diagram showing an example of a meter image in the first embodiment. [Figure 4] FIG. 4 is a diagram showing an example of setting information input by a user in the first embodiment. [Diagram 5] FIG. 2 is a diagram showing an example of a polar coordinate system meter image in the first embodiment. [Figure 6] FIG. 2 is a diagram showing an example of a reference image in the first embodiment. [Figure 7] FIG. 4 is a diagram for explaining an example of template scanning in template matching performed by the pointer detection unit in the first embodiment. [Figure 8] 10 is a diagram for explaining an example of a needle imaging region cut out on a polar coordinate system meter image by an initial reference image creating unit in the first embodiment. FIG. [Figure 9] 4 is a flowchart for explaining the operation of the meter reading device according to the first embodiment in an "initial setting process." [Figure 10] 4 is a flowchart for explaining the operation of the meter reading device according to the first embodiment in a "reading process." [Figure 11] 11A and 11B are diagrams illustrating an example of a hardware configuration of the meter reading device according to the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In order to describe the present disclosure in more detail, embodiments of the present disclosure will be described below with reference to the accompanying drawings.

[0010] Embodiment 1 The meter reading device according to the first embodiment calculates a numerical value (hereinafter referred to as "indicated value") indicated by the pointer of the meter to be read from the indicated position of the pointer of the meter on the captured image detected based on an image of at least the dial of the meter. In this way, the meter reading device reads the indicated value indicated by the meter pointer. Hereinafter, the meter pointer is also simply referred to as the "pointer pointer." In the first embodiment, the meter is assumed to be an analog meter in which a pointer (that is, an indicator needle) is used to read the graduations on a dial. The meter may be, for example, a power meter for measuring power consumption, a temperature meter for measuring temperature, or a pressure meter for measuring air or liquid pressure, which are installed in a factory. Note that this is merely an example, and the meter may be a general analog meter, at least the scale of which can be imaged at a fixed angle. In the following first embodiment, as an example, the meter is a rotary analog meter that indicates a numerical value by the movement of a rotating pointer.

[0011] FIG. 1 is a diagram showing an example of the configuration of a meter reading device 100 according to the first embodiment and a meter reading system 1000 including the meter reading device 100. As shown in FIG. As shown in FIG. 1, the meter reading system 1000 includes an imaging device 300, a meter reading device 100, and an external device 200. The imaging device 300 is an image capturing device.

[0012] The imaging device 300 is provided so as to be able to capture an image of at least the dial of a meter (not shown), and captures an image of the meter. The position and angle of view of the imaging device 300 relative to the meter are fixed, and the imaging device 300 captures an image of the meter at a predetermined angle. In the first embodiment, as an example, the imaging device 300 captures an image of the meter from the front side of the meter.

[0013] The meter reading device 100 is provided, for example, in a meter. The meter reading device 100 acquires an image of the meter captured by the imaging device 300, detects the indicated position of the indicator needle on the acquired image based on the acquired image, and calculates an indicated value from the detected indicated position of the indicator needle. Specifically, the meter reading device 100 acquires information about the meter scale and indicator needle set by the user from the external device 200, and uses the acquired information to calculate the indicated value from the detected position of the indicator needle. The meter reading device 100 outputs the calculated indicated value to the external device 200, thereby presenting the indicated value to the user. The meter reading device 100 will be described in detail later.

[0014] The external device 200 is, for example, a personal computer (PC) or a mobile terminal. The PC or mobile terminal is assumed to be a PC or mobile terminal used by a user. The external device 200 accepts various information from a user. The user inputs various information by operating, for example, an input device (not shown) such as a mouse or a keyboard provided in the external device 200, or a touch panel display device (not shown) provided in the external device 200. Details of the input of various information by the user will be described later. When the external device 200 receives information relating to the scale and the indicator needle of the meter, the external device 200 outputs the received information to the meter reading device 100. Furthermore, the external device 200 outputs various information. For example, the external device 200 displays on a display device the indicated value read by the meter reading device 100. The user checks the indicated value displayed on the display device.

[0015] An example of the configuration of the meter reading device 100 will be described. As shown in FIG. 1, the meter reading device 100 includes an image acquisition unit 1, an interface unit 2, a polar coordinate conversion unit 3, a pointer detection unit 4, an indication value calculation unit 5, a reading result storage unit 6, a reference image update unit 7, and a reference image storage unit 8. FIG. 2 is a diagram showing an example of the configuration of a main part of the reference image update unit 7 in the meter reading device 100 according to the first embodiment. As shown in FIG. 2, the reference image update unit 7 includes an initial reference image creation unit 71 , an update execution determination unit 72 , an update candidate image creation unit 73 , an update image determination unit 74 , and an erroneous update detection unit 75 .

[0016] In the first embodiment, the meter reading device 100 performs an "initial setting process" for creating an initial reference image D7, and a "reading process" for reading the indicated value of the pointer. In the "initial setting process", the image acquisition unit 1, the interface unit 2, the polar coordinate conversion unit 3, and the initial reference image creation unit 71 function. In the "reading process", the image acquisition unit 1, the interface unit 2, the polar coordinate conversion unit 3, the pointer detection unit 4, the indicated value calculation unit 5, the update implementation determination unit 72, the update candidate image creation unit 73, the update image determination unit 74, and the erroneous update detection unit 75 function. The "initial setting process" and "reading process" will be described in detail later.

[0017] The image acquisition unit 1 acquires an image captured by the imaging device 300. In the following first embodiment, the image captured by the imaging device 300 is also referred to as a "meter image D1."

[0018] Here, Fig. 3 is a diagram showing an example of the meter image D1 in the embodiment 1. For convenience, Fig. 3 shows only the scale of the meter captured in the meter image D1. The origin O, the axis (X, Y), the point P (x, y), the line segment L, and the angle θ in FIG. 3 will be described later.

[0019] The image acquisition unit 1 outputs the meter image D1 acquired from the imaging device 300 to the interface unit 2 and the polar coordinate conversion unit 3.

[0020] The interface unit 2 connects the meter reading device 100 and an external device 200, enabling the user of the meter reading system 1000 to perform various controls and to present information to the user. Specifically, the interface unit 2 acquires information relating to the meter's scale and pointer which is set by the user via the external device 200. In the first embodiment, the information relating to the meter's scale and pointer is referred to as "setting information D2." The setting information D2 is information including the position on the meter image D1 of the rotation axis of the indicator needle that is the object of reading by the meter reading device 100 (hereinafter referred to as the "rotation axis position"), the position on the meter image D1 of the tip of the indicator needle (hereinafter referred to as the "tip position"), the width of the indicator needle on the meter image D1 (hereinafter referred to as the "needle width"), the position of the meter scale on the meter image D1 (hereinafter referred to as the "scale position"), the maximum value that the indicator needle can indicate, and the minimum value that the indicator needle can indicate. In the setting information D2, the position of the axis of rotation of the indicator needle, the position of the tip of the indicator needle, and the position of the meter scale are expressed by coordinates on the meter image D1. Also, in the setting information D2, the needle width is expressed by, for example, the number of pixels on the meter image D1.

[0021] Here, a method for the user to input the setting information D2 from the external device 200 will be described. The user inputs setting information D2 to the interface unit 2 via the external device 200. Fig. 4 is a diagram showing an example of setting information D2 input by the user in the first embodiment.

[0022] For example, the user looks at the meter image D1 displayed on the display device of the external device 200, and inputs the rotation axis position of the indicator needle to be read, the tip position of the indicator needle, the needle width of the indicator needle, the scale position of the meter, and the maximum and minimum indicated values ​​on the meter image D1, thereby inputting the setting information D2. The user, for example, operates an input device of the external device 200 to input an instruction to display an input screen for the setting information D2. Here, the input screen for the setting information D2 is, for example, a screen on which the meter image D1 is displayed, as shown in FIG. 4. The interface unit 2 receives an instruction from the user via the external device 200 to display the input screen for the setting information D2, and upon receiving the instruction, causes the display device to display the input screen for the setting information D2.

[0023] For example, the user operates a mouse provided on the external device 200 to click on the position of the axis of rotation of the indicator needle (shown as "A" in FIG. 4) on the screen on which the meter image D1 is displayed, thereby specifying the position of the axis of rotation of the indicator needle. In this way, the user inputs the position of the axis of rotation of the indicator needle. Similarly, the user inputs the position of the tip of the indicator needle by clicking on the position of the tip of the indicator needle (shown as "B" in FIG. 4) and the scale position (shown as "D" in FIG. 4) on the screen.

[0024] The user also inputs the needle width (indicated by "C" in FIG. 4) and the maximum and minimum indicated values ​​(indicated by "E" in FIG. 4). For example, the interface unit 2 displays an input section (not shown) for the needle width, maximum indicated value, and minimum indicated value together with the meter image D1 on the input screen for the setting information D2. The user operates a keyboard, for example, to input the needle width, maximum indicated value, and minimum indicated value into the input section displayed on the input screen. Note that the maximum indicated value and minimum indicated value indicated by "E" in FIG. 4 are an example image of the maximum indicated value and minimum indicated value input. As described above, the user need only specify the meter scale positions that correspond to at least the maximum and minimum indicated values. If the external device 200 knows the maximum and minimum indicated values ​​together with their positions on the meter image D1, it can complement the values ​​and positions therebetween.

[0025] In the first embodiment, as described above, the input of the setting information D2 by the user from the external device 200 is referred to as "initial setting."

[0026] When the external device 200 receives the setting information D2 input by the user, the external device 200 outputs the setting information D2 to the interface unit 2. The interface unit 2 acquires setting information D2 from the external device 200. The interface unit 2 outputs the acquired setting information D2 to the polar coordinate conversion unit 3, the indication value calculation unit 5, and the reference image update unit .

[0027] Moreover, the interface unit 2 outputs the user presentation information D9 to the external device 200. Here, the user presentation information D9 includes screen information for displaying an input screen for the setting information D2 as described with reference to FIG. 4, which is referred to when the user inputs the setting information D2, and screen information for displaying a screen showing a reading result of the meter read by the meter reading device 100. The interface unit 2 creates screen information for displaying an input screen for the setting information D2 based on, for example, the meter image D1 output from the image acquisition unit 1, and causes the display device of the external device 200 to display the input screen. The interface unit 2 also creates screen information for displaying a screen showing the reading result of the meter based on, for example, information output from the indication value calculation unit 5, and causes the display device of the external device 200 to display the screen showing the reading result. Details of the indication value calculation unit 5 and the information output from the indication value calculation unit 5 will be described later.

[0028] The polar coordinate conversion unit 3 uses the captured image acquired by the image acquisition unit 1, that is, the meter image D1, and the setting information D2 acquired by the interface unit 2 to convert the meter image D1 into polar coordinates. More specifically, the polar coordinate conversion unit 3 performs polar coordinate conversion on the coordinate information included in the meter image D1 and the setting information D2. The center of the polar coordinate transformation is the position of the axis of rotation of the indicator needle. The radius of the polar coordinate transformation is the length of the indicator needle (hereafter referred to as the "indicator needle length") calculated from the axis of rotation and the tip position of the meter's indicator needle, extended by adding a fixed value. In the first embodiment, the meter image D1 converted into polar coordinates is called a "polar coordinate system meter image," and the coordinate information of the meter image D1 converted into polar coordinates is called "polar coordinate system coordinate information."

[0029] FIG. 5 is a diagram showing an example of a polar coordinate system meter image according to the first embodiment. The polar coordinate system meter image shown in FIG. 5 is obtained by polar coordinate conversion of the meter image D1 shown in FIG. 3 and FIG.

[0030] For a pixel on the meter image D1 (for example, P(x, y) in FIG. 3), the polar coordinate conversion unit 3 calculates the angle θ between the reference axis X and the length L of OP extended by adding a fixed value to the indicator needle length, based on the coordinate value when viewed from a reference axis (X, Y) with the rotation axis position of the indicator needle as the origin O, and performs coordinate conversion to the L-θ polar coordinate system, thereby polar coordinate converting the meter image D1 into a polar coordinate system meter image. In the polar coordinate system meter image shown in FIG.

[0031] The polar coordinate conversion unit 3 outputs the polar coordinate system meter image and the polar coordinate system coordinate information together as polar coordinate system data D3 to the indicator needle detection unit 4 and the reference image update unit 7.

[0032] The pointer detection unit 4 detects the position of the pointer in the polar coordinate system meter image from the polar coordinate system data D3 output from the polar coordinate conversion unit 3 and the reference image D7 stored in the reference image storage unit 8. In the first embodiment, the position where the pointer exists in the polar coordinate system meter image, in other words, the position of the pointer, is the tip position of the pointer, in other words, the pointing position of the pointer, in the polar coordinate system meter image, the pointer detection unit 4. The pointing position of the pointer in the polar coordinate system meter image is represented by coordinates on the polar coordinate system meter image.

[0033] Here, the reference image D7 will be described. In the first embodiment, reference image D7 is an image showing an indicator needle, which serves as a reference for calculating the indicated position of the indicator needle on the meter. FIG. 6 is a diagram showing an example of a reference image D7 according to the first embodiment. A method for creating the reference image D7 will be described later in the explanation of the reference image update unit 7.

[0034] The reference image D7 stored in the reference image storage unit 8 is provided with information on the creation date and time of the reference image D7 and a use flag. In the first embodiment, the use flag is a flag for making it possible to identify the reference image D7 to be used for reading the meter, in other words, the reference image D7 to be used by the needle detection unit 4 to detect the indicated position of the needle, and is indicated, for example, by "0: unused" or "1: in use". A plurality of reference images D7 can be stored in the reference image storage unit 8. In the first embodiment, the use flag is used to identify the reference image D7 to be used for reading the meter among the plurality of reference images D7. Note that this is merely an example, and it is sufficient that it is possible to identify which reference image D7 is currently to be used for reading the meter among the plurality of reference images D7 stored in the reference image storage unit 8. In the first embodiment, the indicator detection unit 4 acquires from the reference image storage unit 8 a reference image D7 to which a usage flag "1: in use" has been added.

[0035] The pointer detection unit 4 detects the indicated position of the pointer by determining the similarity (hereinafter referred to as the "reference similarity") between the polar coordinate system meter image and the reference image D7 at each coordinate in the declination axis direction of the polar coordinate system meter image (i.e., the horizontal axis in the polar coordinate system meter image of FIG. 5).

[0036] For example, the indicator detection unit 4 calculates the reference similarity by using a known template matching method with the reference image D7 as a template. That is, the indicator detection unit 4 performs template matching on the polar coordinate system meter image with the reference image D7 as a template. 7 is a diagram for explaining an example of template scanning in template matching performed by the indicator needle detection unit 4 in embodiment 1. Note that in Fig. 7, the polar coordinate system meter image is assumed to be the polar coordinate system meter image shown in Fig. 5. Regarding scanning of the template, the indicator needle detection unit 4 aligns the bottom side of the reference image D7 with the rotation axis side of the polar coordinate system meter image, i.e., the bottom side of the image in the polar coordinate system meter image, and scans the template, reference image D7, in the declination axis direction on the polar coordinate system meter image.

[0037] The pointer detection unit 4 obtains the difference in pixel values ​​between the reference image D7 and an area on the polar coordinate system meter image that corresponds to the reference image D7, in other words, that is matched with the reference image D7 (hereinafter referred to as a "matching area"), and calculates the reference similarity so that the smaller the pixel value difference, the higher the reference similarity. Note that the pointer detection unit 4 may, for example, calculate the pixel value difference between the reference image D7 and the matching area for each pixel, and add up the calculated pixel value differences for each pixel to determine the pixel value difference between the reference image D7 and the matching area. Then, the pointer detection unit 4 detects, in the matching region where the reference similarity is maximized, a point corresponding to the tip position of the pointer on the reference image D7 as the indicated position of the pointer.

[0038] At this time, the needle detection unit 4 may weight the reference similarity more closely toward the tip of the needle. That is, when comparing the polar coordinate system meter image with the reference image D7 by template matching, the needle detection unit 4 may perform the comparison by weighting the area corresponding to the tip side of the needle more. It is assumed that the area corresponding to the needle of the reference image D7 in the matching area on the polar coordinate system meter image becomes smaller as it approaches the tip of the needle. In addition, for example, if the meter has multiple needles, the multiple needles may overlap on the side closer to the rotation axis of the needle, and the needle to be read may be blocked. For these reasons, it can be said that the tip side of the needle is more important in detecting the needle. When comparing the polar coordinate system meter image with the reference image D7 by template matching, the needle detection unit 4 performs the comparison by weighting the area corresponding to the tip side of the needle more, thereby making it possible to perform a comparison taking into account the area that is more important in detecting the needle. As a result, the needle detection unit 4 can detect the indicated position of the needle more accurately.

[0039] When the needle detection unit 4 compares the reference image D7 with the polar coordinate system meter image, it creates information (hereinafter referred to as "needle detection information") in which the coordinates of the needle's position, the maximum value of the reference similarity, and an image obtained by cutting out the matching area with the maximum reference similarity correspond to each other. In the first embodiment, the image obtained by cutting out the matching area with the maximum reference similarity is referred to as the "detection position image." The indicator detection unit 4 outputs the created indicator detection time information to the indication value calculation unit 5 as an indicator detection result D4.

[0040] The indication value calculation unit 5 calculates an indication value D5, which is a numerical value indicated by the indicator, from the setting information D2 output from the interface unit 2 and the indicator detection result D4 output from the indicator detection unit 4. The indication value calculation unit 5 may obtain the setting information D2 via the polar coordinate conversion unit 3 and the indicator detection unit 4.

[0041] Here, a method for calculating the instruction value D5 by the instruction value calculation unit 5 will be described with a specific example. The indication value calculation unit 5 determines the relative position of the coordinates of the indication position of the indicator needle included in the indicator needle detection result D4 with respect to the scale position of the meter, and then determines an indication value D5 by linear interpolation based on the maximum and minimum values ​​of the meter. As a specific example, suppose the position of the scale indicating the minimum value of the meter is XMIN=100, the position of the scale indicating the maximum value of the meter is XMAX=200, the minimum value of the meter is VMIN=20, the maximum value of the meter is VMAX=80, and the coordinate of the position indicated by the indicator needle is X=175. At this time, the indication value calculation unit 5 calculates the indication value V indicated by the coordinates of the indication position of the pointer as follows: V=(X-XMIN) / (XMAX-XMIN)*(VMAX-VMIN)+VMIN =(175-100) / (200-100)*(80-20)+20 =75 / 100*60+20 =65 is required.

[0042] When the indication value calculation unit 5 calculates the indication value D5, it combines the indicator detection result D4 output from the indicator detection unit 4 with the calculated indication value D5, and stores information in which the indicator detection result D4 and the indication value D5 are associated with each other as a reading result D6 in the reading result storage unit 6. At this time, the indication value calculation unit 5 adds, for example, the time when the indication value D5 was calculated to the reading result D6, and stores it in the reading result storage unit 6. Moreover, the indication value calculation section 5 outputs to the interface section 2 the indication value detection result D4 output from the indication value detection section 4 and the calculated indication value D5.

[0043] When the indication value calculation unit 5 outputs the indication needle detection result D4 and the indication value D5, the interface unit 2 creates screen information for displaying a screen showing the meter reading result D6 read by the meter reading device 100 based on the output indication needle detection result D4 and indication value D5, as user presented information D9, and outputs the created user presented information D9 to the external device 200. For example, the interface unit 2 creates screen information for displaying a screen showing the instruction value D5. Also, for example, the interface unit 2 may create screen information for displaying a screen showing the instruction value D5 and the reference similarity based on which the instruction value D5 was calculated. For example, by checking the screen displayed on the display device of the external device 200 based on the screen information created by the interface unit 2, the user can understand the instruction value D5 and can also understand how similar the instruction value D5 was to the reference image D7, in other words, how accurate the instruction value D5 is.

[0044] The read result storage unit 6 stores the read result D6. The reading result storage unit 6 does not only store the latest reading result D6 output from the indication value calculation unit 5, but also stores the past several reading results D6. That is, the reading result storage unit 6 is a database that can refer to past data (more specifically, past reading results D6). How many past reading results D6 the reading result storage unit 6 stores is determined in advance as appropriate by the user, etc. 1, the reading result storage unit 6 is provided in the meter reading device 100, but this is merely an example. For example, the reading result storage unit 6 may be provided in a location outside the meter reading device 100 that can be referenced by the meter reading device 100.

[0045] The reference image update unit 7 creates the reference image D7 initially and updates the reference image D7. As shown in FIG. 2, in the first embodiment, reference image update unit 7 includes initial reference image creation unit 71, update execution determination unit 72, update candidate image creation unit 73, update image determination unit 74, and erroneous update detection unit 75.

[0046] When the initial setting is performed, the initial reference image creating unit 71 cuts out an area where the pointer is captured on the polar coordinate system meter image (hereinafter referred to as the "pointer needle captured area") based on the setting information D2 output from the interface unit 2 and the polar coordinate system data D3 output from the polar coordinate conversion unit 3, and creates an initial reference image D7 from the cut-out pointer captured area. The initial reference image creating unit 71 sets the cut-out pointer captured area as the initial reference image D7. In the first embodiment, the "initial reference image D7" means the reference image D7 used for reading the meter when the meter reading device 100 starts the meter reading operation for the first time, that is, the initial value of the reference image D7. More specifically, the reference image D7 used for reading the meter is the reference image D7 to which the usage flag "in use: 1" is assigned, and the reference image D7 is updated as necessary in the process of the meter reading device 100 performing the meter reading operation for the second time or later. The update of the reference image D7 is performed by the update image determining unit 74. The update image determination unit 74 will be described in detail later.

[0047] In the first embodiment, the above-mentioned pointer image capturing area is a rectangular area on the polar coordinate system meter image. The initial reference image creating unit 71 determines the position and size of the needle imaging region from the tip position and needle width of the needle.

[0048] Here, FIG. 8 is a diagram for explaining an example of the indicator needle image region cut out on the polar coordinate system meter image by the initial reference image creating unit 71 in the first embodiment. In Fig. 8, the needle image capture region is a rectangular region indicated by a dotted line. Note that, for the sake of convenience, only the region surrounding the needle image capture region is shown in Fig. 8 for the polar coordinate system meter image. As shown in Fig. 8, initial reference image creation unit 71 sets an initial reference image D7 as a rectangular area on the polar coordinate system meter image, with the tip position of the pointer as its center, line segments extending from the center in the positive and negative directions of the declination axis (i.e., the horizontal axis) at a distance equal to the needle width plus a preset fixed value as its horizontal sides, and a line segment parallel to a vertical line from the tip position of the pointer to a point on the bottom side of the polar coordinate system meter image as its vertical sides. Information on the tip position of the pointer and the needle width are included in setting information D2. In the first embodiment, "parallel" is not limited to being strictly parallel, but also includes approximately parallel.

[0049] It should be noted that the initial reference image D7 shown in FIG. 8 is merely an example. For example, the initial reference image creation unit 71 may set the length of the vertical axis direction of the polar coordinate system meter image of the reference image D7 to the length of a vertical line from the tip position of the pointer to a point on a line that passes through the base of the pointer and is parallel to the horizontal axis of the polar coordinate system meter image in the polar coordinate system meter image. In other words, the initial reference image creation unit 71 may set the initial reference image D7 to a rectangular area whose side length in the vertical axis direction is shorter than that of the initial reference image D7 shown in FIG. For example, if there is a pattern around the rotation axis, it is better to create reference image D7 by avoiding the area with the pattern. This is to reduce the influence of the pattern when needle detection unit 4 compares the polar coordinate system meter image with reference image D7. One method for reducing the influence of the pattern is to adjust the weight when needle detection unit 4 calculates the reference similarity. Although the reference image D7 is a rectangular region here, this is merely an example, and the reference image D7 can be a region of any suitable shape.

[0050] After creating the initial reference image D7, the initial reference image creating unit 71 causes the created initial reference image D7 to be stored in the reference image storage unit 8. At this time, the initial reference image creating unit 71 assigns a usage flag "1: in use" and information on the creation date and time to the initial reference image D7, and stores it in the reference image storage unit 8.

[0051] The update execution determination unit 72 acquires the latest read result D6 from the read results D6 stored in the read result storage unit 6, and determines whether or not to execute an update process for the reference image D7 from the acquired latest read result D6. More specifically, for example, the update execution determination unit 72 determines whether or not to perform update processing of the reference image D7 depending on whether the reference similarity included in the needle detection result D4 in the reading result D6 is equal to or less than a preset threshold (hereinafter referred to as the "reference similarity determination threshold"). The reference similarity determination threshold is set in advance by a user or the like and stored in a buffer or the like of the update execution determination unit 72. The update execution determination unit 72 determines to perform update processing of the reference image D7 when the reference similarity included in the needle detection result D4 is equal to or less than the reference similarity determination threshold. In the latest reading result D6, the reference similarity included in the needle detection result D4 is the reference similarity when the needle detection unit 4 most recently compared the reference image D7 with the polar coordinate system meter image. When the update execution determination unit 72 determines that update processing of the reference image D7 should be performed, it outputs information indicating that update processing of the reference image D7 should be performed (hereinafter referred to as an “update execution instruction”) to the update candidate image creation unit 73.

[0052] In the first embodiment, the process of updating the reference image D7 refers to a process of recreating the reference image D7 and updating the reference image D7 with the re-created reference image D7. Here, the reference image D7 updated in the process of updating the reference image D7 is the reference image D7 currently being used by the needle detection unit 4 for comparison with the polar coordinate system meter image. More specifically, the reference image D7 updated in the process of updating the reference image D7 is the reference image D7 to which a usage flag "1: in use" has been assigned. In the first embodiment, the reference image D7 that is recreated to update the reference image D7 currently being used by the pointer detection unit 4 for comparison with the polar coordinate system meter image is also referred to as an "update reference image." Creation of the update reference image and updating of the reference image D7 are performed by an update candidate image creation unit 73 and an update image determination unit 74, respectively. Details of the update candidate image creation unit 73 and the update image determination unit 74 will be described next.

[0053] When an update execution instruction is output from the update execution determination unit 72, the update candidate image creation unit 73 acquires the most recent read results D6 from the read results D6 stored in the read result storage unit 6, and creates a plurality of images (hereinafter referred to as "update candidate images") that are candidates for the update reference image based on the most recent acquired read results D6. More specifically, the update candidate image creation unit 73 creates a plurality of update candidate images based on the detection position images included in the pointer detection results D4 in the most recent acquired read results D6.

[0054] An example of how a plurality of update candidate images are created by the update candidate image creating unit 73 will be described. For example, the update candidate image creating unit 73 sets a plurality of detection position images acquired from the read result storage unit 6 as a plurality of update candidate images.

[0055] It should be noted that the above-mentioned creation method is merely an example, and the update candidate image creation unit 73 may create the update candidate image using other methods. For example, the update candidate image creation unit 73 may create images (hereinafter referred to as "processed detection position images") by applying image processing to each of the multiple detection position images obtained from the reading result memory unit 6, and may set the detection position image obtained from the reading result memory unit 6 and the processed detection position image as update candidate images. The image processing applied to the detection position image by the update candidate image creation unit 73 is, for example, brightness change, contrast change, edge emphasis, or noise addition. The update candidate image creation unit 73 may apply any one of these image processing, or may apply a combination of a plurality of these image processing. Note that the image processing of brightness change, contrast change, edge emphasis, or noise addition is well-known image processing, and therefore detailed description thereof will be omitted. By adding the processing detection position image to the update candidate image, the update candidate image creation unit 73 can prepare an update candidate image for an update reference image that enables updating of the reference image D7 to respond to a wider range of environmental changes when updating the reference image D7.

[0056] In addition, when only the most recent reading result D6 is stored in the reading result memory unit 6, the update candidate image creation unit 73 acquires the most recent reading result D6 and creates an update candidate image from the acquired reading result D6.

[0057] The update candidate image creating unit 73 outputs the created update candidate image to the update image deciding unit 74.

[0058] The update image determination unit 74 determines which of the update candidate images is to be used to update the reference image D7, and updates the reference image D7. More specifically, the update image determination unit 74 determines an update reference image from among the multiple update candidate images created by the update candidate image creation unit 73, and updates the reference image D7 with the determined update reference image.

[0059] An example of a method for determining an updating reference image by the updating image determining unit 74 will be described. The update image determination unit 74 determines an update reference image by, for example, calculating the similarity between the polar coordinate system meter image and the update candidate image in the deflection axis direction of the polar coordinate system meter image (hereinafter referred to as "candidate similarity"). The update image determination unit 74 calculates the candidate similarity by template matching using a known template matching method with the update candidate image as a template. The specific method by which the update image determination unit 74 calculates the candidate similarity by template matching with the update candidate image as a template is similar to the specific method by which the pointer detection unit 4 calculates the reference similarity by template matching with the reference image D7 as a template, which has already been described, and therefore a detailed description thereof will be omitted. The update image determination unit 74 calculates candidate similarities for each of the multiple update candidate images. The polar coordinate system meter image is included in the polar coordinate system data D3 output from the polar coordinate conversion unit 3. Note that the arrow from the polar coordinate conversion unit 3 to the update image determination unit 74 is omitted in Fig. 2. The polar coordinate conversion unit 3 may obtain the polar coordinate system data D3 from the polar coordinate conversion unit 3 via the initial reference image creation unit 71, or may obtain the polar coordinate system data D3 directly from the polar coordinate conversion unit 3.

[0060] When the update image determination unit 74 calculates the candidate similarity for all of the plurality of update candidate images, it determines, from among the plurality of update candidate images, the update candidate image in which the pointer on that update candidate image is most likely, as the update reference image. More specifically, the update image determination unit 74 compares a plurality of update candidate images with the polar coordinate system meter image to detect an area in the polar coordinate system meter image that is similar to the update candidate image (hereinafter referred to as a "candidate similar area"), and calculates the candidate similarity between the update candidate image and the detected candidate similar area. Then, the update image determination unit 74 determines the update candidate image with the highest candidate similarity as the update reference image. A high candidate similarity means that the pointer on the update candidate image is close to the pointer on the latest polar coordinate system meter image, in other words, the pointer on the update candidate image is likely to be correct. In other words, the pointer on an update candidate image for which a high candidate similarity has been obtained is said to be an pointer captured under environmental conditions similar to the pointer on the meter image D1 captured under the current environmental conditions.

[0061] When the update image determination unit 74 determines the update reference image, it updates the reference image D7 with the determined update reference image. Specifically, the update image determination unit 74 sets the usage flag of a reference image D7 to "0: unused" for the reference image D7 to which a usage flag "1: in use" has been assigned among the reference images D7 stored in the reference image storage unit 8. Then, the update image determination unit 74 assigns a usage flag "1: in use" to the determined update reference image, and stores the update reference image after the usage flag has been assigned in the reference image storage unit 8. As a result, the reference image D7 is updated. Thereafter, the indicator needle detection unit 4 uses the reference image D7 updated by the update image determination unit 74 for comparison with the polar coordinate system meter image.

[0062] The erroneous update detection unit 75 detects an erroneous update in which the reference image D7 stored in the reference image storage unit 8 has been updated with an erroneous reference image D7, and when an erroneous update is detected, returns the reference image D7 to the reference image D7 before the update.

[0063] The erroneous update detection unit 75 obtains the read result D6 from the read result storage unit 6, and detects erroneous updating of the reference image D7 by analyzing the pointer detection result D4 included in the read result D6 in chronological order. For example, the erroneous update detection unit 75 acquires the pointer detection result D4 stored after the timing of updating the reference image D7 in the past from the read result storage unit 6. For example, when the update image determination unit 74 updates the reference image D7 with the update reference image, the update image determination unit 74 notifies the erroneous update detection unit 75 that the reference image D7 has been updated. The erroneous update detection unit 75 may acquire the pointer detection result D4 stored in the read result storage unit 6 after the date and time when the erroneous update detection unit 75 receives the notification from the update image determination unit 74 that the reference image D7 has been updated. The read result D6 stored in the read result storage unit 6 is given the time when the indication value D5 was calculated. The erroneous update detection unit 75 may determine the pointer detection result D4 stored in the read result storage unit 6 after the date and time when the erroneous update detection unit 75 receives the notification from the update image determination unit 74 that the reference image D7 has been updated, from the time given to the read result D6. In FIG. 2, the arrow from the update image determination unit 74 to the erroneous update detection unit 75 is omitted.

[0064] When the erroneous update detection unit 75 acquires the reading result D6, it detects an outlier in the time series distribution of the reference similarity in the pointer detection result D4 included in the acquired reading result D6. Then, the erroneous update detection unit 75 detects erroneous updating of the reference image D7 by determining whether or not the outlier of the reference similarity has increased. For example, when the increase in the outlier of the reference similarity is equal to or greater than a preset threshold (hereinafter referred to as the "outlier determination threshold"), the erroneous update detection unit 75 determines that erroneous updating of the reference image D7 has occurred, in other words, that the update of the reference image D7 by the update image determination unit 74 using the update reference image has been updated using an erroneous update reference image. If the increase in the outlier value of the reference similarity is less than the outlier determination threshold, the erroneous update detection unit 75 determines that there is no erroneous update of the reference image D7; in other words, the update of the reference image D7 by the update image determination unit 74 using the update reference image was an update using the correct update reference image.

[0065] When the erroneous update detection unit 75 detects an erroneous update of the reference image D7, it returns the reference image D7 stored in the reference image memory unit 8 and used by the pointer detection unit 4 to detect the indication position of the pointer to the reference image D7 before the update. Specifically, the erroneous update detection unit 75 sets the usage flag of the reference image D7 (which will be the used reference image) to "0: unused" for which a usage flag "1: in use" has been assigned, and sets the usage flag assigned to the reference image D7 immediately preceding the used reference image to "1: in use." This causes the reference image D7 used by the pointer detection unit 4 to detect the indicated position of the pointer to be restored to the reference image D7 before the update. Thereafter, the pointer detection unit 4 uses the reference image D7 restored to before the update for comparison with the polar coordinate system meter image. The erroneous update detection unit 75 may identify the previous reference image D7 from the information on the creation date and time added to the reference image D7. In the reference image storage unit 8, the reference image D7 is added with information on the creation date and time when the reference image D7 was created.

[0066] The reference image storage unit 8 stores the reference image D7. In the first embodiment, the reference image storage unit 8 does not store only the latest reference image D7, but also stores the past few reference images D7. That is, the reference image storage unit 8 is a database that can refer to past reference images D7. How many past reference images D7 the reference image storage unit 8 stores is determined in advance as appropriate by a user or the like. The reference image storage unit 8 stores the reference image D7 together with information on the date and time of creation of the reference image D7. 1, the reference image storage unit 8 is provided in the meter reading device 100, but this is merely an example. For example, the reference image storage unit 8 may be provided in a location outside the meter reading device 100 that can be referenced by the meter reading device 100.

[0067] The operation of the meter reading device 100 according to the first embodiment will be described separately for the "initial setting process" and the "reading process".

[0068] First, the operation of the meter reading device 100 in the "initial setting process" will be described. FIG. 9 is a flowchart for explaining the operation of the "initial setting process" of the meter reading device 100 according to the first embodiment. As described above, in the "initial setting process", the image acquisition unit 1, the interface unit 2, the polar coordinate conversion unit 3, and the initial reference image creation unit 71 of the reference image update unit 7 function. The meter reading device 100 performs an operation in an "initial setting process" as shown in the flowchart of FIG. 9 once when the power is turned on for the first time after the meter reading device 100 is shipped, for example.

[0069] The image acquisition unit 1 acquires the meter image D1 captured by the imaging device 300 (step ST11). The image acquisition unit 1 outputs the meter image D1 acquired from the imaging device 300 to the interface unit 2 and the polar coordinate conversion unit 3.

[0070] The interface unit 2 acquires the setting information D2 set by the user from the external device 200 (step ST12). Specifically, the interface unit 2 outputs to the external device 200 user presentation information D9, which is screen information for displaying an input screen for the setting information D2 that the user refers to when inputting the setting information D2, and presents the input screen to the user. The interface unit 2 acquires, via the external device 200, the setting information D2 that the user inputs from the input screen by operating the external device 200. The interface unit 2 outputs the acquired setting information D2 to the polar coordinate conversion unit 3, the indication value calculation unit 5, and the reference image update unit .

[0071] The polar coordinate conversion unit 3 converts the meter image D1 into polar coordinates using the meter image D1 acquired by the image acquisition unit 1 in step ST11 and the setting information D2 acquired by the interface unit 2 in step ST12 (step ST13). The polar coordinate conversion unit 3 outputs the polar coordinate system data D3 to the pointer detection unit 4 and the reference image update unit 7.

[0072] The initial reference image creation unit 71 of the reference image update unit 7 cuts out the needle imaging area in which the needle is imaged on the polar coordinate system meter image based on the setting information D2 output from the interface unit 2 in step ST12 and the polar coordinate system data D3 output from the polar coordinate conversion unit 3 in step ST13, and creates an initial reference image D7 from the cut-out needle imaging area (step ST14). After creating the initial reference image D7, the initial reference image creating unit 71 causes the created initial reference image D7 to be stored in the reference image storage unit 8.

[0073] Next, the operation of the meter reading device 100 in the "reading process" will be described. The "reading process" is executed on the premise that the "initial setting process" has been completed. As described above, in the "reading process", the image acquisition unit 1, interface unit 2, polar coordinate conversion unit 3, pointer detection unit 4, indication value calculation unit 5, update implementation determination unit 72 of the reference image update unit 7, update candidate image creation unit 73, update image determination unit 74, and erroneous update detection unit 75 function.

[0074] FIG. 10 is a flowchart for explaining the operation of the "reading process" of the meter reading device 100 according to the first embodiment. For example, when the meter reading device 100 receives an instruction to start an operation from a control unit (not shown) of the meter reading device 100, the meter reading device 100 performs an operation in a "reading process" as shown in the flowchart of FIG. 10. For example, when the meter reading device 100 is powered on or when the control unit receives an instruction to start reading from a user via the external device 200, the control unit refers to the reference image storage unit 8 and confirms that a reference image D7 with a usage flag of "1: in use" is stored. When the control unit confirms that the reference image D7 is stored, the control unit outputs an instruction to start an operation to the image acquisition unit 1, the interface unit 2, the polar coordinate conversion unit 3, the pointer detection unit 4, the indication value calculation unit 5, and the reference image update unit 7. The image acquisition unit 1, the interface unit 2, the polar coordinate conversion unit 3, the pointer detection unit 4, the indication value calculation unit 5, and the reference image update unit 7 start their operations when the instruction to start an operation is output from the control unit as a trigger. Furthermore, for example, when the control unit receives an instruction to end meter reading from a user via the external device 200, the control unit outputs an operation end instruction to the image acquisition unit 1, the interface unit 2, the polar coordinate conversion unit 3, the pointer detection unit 4, the indication value calculation unit 5, and the reference image update unit 7. When an operation end instruction is output from the control unit, the image acquisition unit 1, the interface unit 2, the polar coordinate conversion unit 3, the pointer detection unit 4, the indication value calculation unit 5, and the reference image update unit 7 end their operations. When an operation start instruction is output from the control unit, the image acquisition unit 1, the interface unit 2, the polar coordinate conversion unit 3, the pointer detection unit 4, the indication value calculation unit 5, and the reference image update unit 7 repeatedly perform the operation in the "reading process" as shown in the flowchart of FIG. 10 until an operation end instruction is output. The meter reading device 100 may terminate the operation of the "reading process" as shown in the flowchart of FIG. 10 not only when it receives an instruction from a user via the external device 200 to terminate meter reading, but also in accordance with a condition specific to the meter reading system 1000, such as when a preset time has elapsed or a preset date and time has arrived.

[0075] The image acquisition unit 1 acquires the meter image D1 captured by the imaging device 300 (step ST21). The image acquisition unit 1 outputs the meter image D1 acquired from the imaging device 300 to the interface unit 2 and the polar coordinate conversion unit 3.

[0076] The polar coordinate conversion unit 3 converts the meter image D1 into polar coordinates by using the meter image D1 acquired by the image acquisition unit 1 in step ST21 and the setting information D2 (step ST22). The setting information D2 is the setting information D2 acquired by the interface unit 2 in the "initial setting process" (see step ST12 in FIG. 9). The polar coordinate conversion unit 3 stores the setting information D2 acquired from the interface unit 2 in a buffer or the like of the polar coordinate conversion unit 3. The polar coordinate conversion unit 3 outputs the polar coordinate system data D3 to the pointer detection unit 4 and the reference image update unit 7.

[0077] The indicator detection unit 4 detects the position where the indicator exists in the polar coordinate system meter image from the polar coordinate system data D3 output from the polar coordinate conversion unit 3 in step ST22 and the reference image D7 stored in the reference image storage unit 8 (step ST23). The indicator detection unit 4 outputs an indicator detection result D4 to the indication value calculation unit 5.

[0078] The indication value calculation unit 5 calculates an indication value D5, which is a numerical value indicated by the indicator, from the setting information D2 and the indicator detection result D4 output from the indicator detection unit 4 (step ST24). After calculating the indication value D5, the indication value calculation unit 5 stores the reading result D6 in the reading result storage unit 6. At this time, the indication value calculation unit 5 adds, for example, the time when the indication value D5 was calculated to the reading result D6 and stores it in the reading result storage unit 6. Moreover, the indication value calculation section 5 outputs to the interface section 2 the indication value detection result D4 output from the indication value detection section 4 and the calculated indication value D5.

[0079] When the indication value calculation unit 5 outputs the indication value D5 and the pointer detection result D4 in step ST24, the interface unit 2 creates screen information for displaying a screen showing the meter reading result D6 read by the meter reading device 100 based on the indication value detection result D4 and the indication value D5 outputted, as user presented information D9, and outputs the created user presented information D9 to the external device 200 (step ST25).

[0080] The update execution determination unit 72 of the reference image update unit 7 acquires the latest reading result D6 from the reading results D6 stored in the reading result memory unit 6, and determines whether or not to perform an update process for the reference image D7 from the acquired latest reading result D6 (step ST26).

[0081] In step ST26, if the update execution determination unit 72 determines that an update process for the reference image D7 should be performed (if "YES" in step ST26), that is, if an update execution instruction is output from the update execution determination unit 72, the update candidate image creation unit 73 acquires the most recent several read results D6 from the read result D6 stored in the read result memory unit 6, and creates multiple update candidate images based on the acquired most recent several read results D6 (step ST27). The update candidate image creating unit 73 outputs the created update candidate image to the update image deciding unit 74.

[0082] The update image determination unit 74 determines which of the update candidate images is to be used to update the reference image D7, and updates the reference image D7. More specifically, the update image determination unit 74 determines an update reference image from among the multiple update candidate images created by the update candidate image creation unit 73 in step ST27, and updates the reference image D7 with the determined update reference image (step ST28).

[0083] In step ST26, if the update execution determination unit 72 determines not to perform the update process of the reference image D7 (if the answer is "NO" in step ST26), or if the update image determination unit 74 updates the reference image D7 in step ST28, the operation of the meter reading device 100 proceeds to processing in step ST29.

[0084] The erroneous updating detection unit 75 judges whether or not an erroneous updating in which the reference image D7 stored in the reference image storage unit 8 has been updated with an erroneous reference image D7 has been detected (step ST29). Specifically, the erroneous update detection unit 75 acquires the pointer detection result D4 stored after the timing of updating the reference image D7 in the past from the reading result storage unit 6, and detects an outlier in the time series distribution of the reference similarity in the pointer detection result D4 included in the acquired reading result D6. The erroneous update detection unit 75 then detects the erroneous update of the reference image D7 by determining whether or not the outlier of the reference similarity is increasing.

[0085] When an erroneous update is detected in step ST29 (if "YES" in step ST29), specifically, when the increase in the outlier value of the reference similarity is equal to or greater than the outlier determination threshold, the erroneous update detection unit 75 determines that an erroneous update of the reference image D7 has occurred, in other words, that the update of the reference image D7 by the update image determination unit 74 with the reference image for update was an update with an erroneous reference image for update. The erroneous update detection unit 75 returns the reference image D7 stored in the reference image storage unit 8 and used by the pointer detection unit 4 to detect the indicated position of the pointer to the reference image D7 before the update (step ST30). Then, the operation of the meter reading device 100 ends the process shown in the flowchart of FIG. 10.

[0086] On the other hand, if no erroneous update is detected in step ST29 (if "NO" in step ST29), specifically, if the increase in the outlier of the reference similarity is less than the outlier determination threshold, the erroneous update detection unit 75 determines that there is no erroneous update of the reference image D7, in other words, that the update of the reference image D7 by the update image determination unit 74 with the update reference image was an update with a correct update reference image. Then, the operation of the meter reading device 100 ends the process shown in the flowchart of FIG.

[0087] Through the above-described operations, the meter reading device 100 according to the first embodiment stores past reading results D6, and continues to automatically update the detection standard for the indicator needle (that is, the reference image D7) based on the past reading results D6. Therefore, the meter reading device 100 can reduce the possibility of reading failure even if continuous environmental changes occur when reading a meter. A continuous environmental change is when the brightness gradually changes due to the influence of external light, or when a shadow gradually falls on the meter, and the influence on the meter image D1 gradually appears. In situations where such environmental changes occur, in the conventional methods of the conventional technology described above, the detection criteria for the indicator needle do not change from when they were initially set, so that the accuracy of detecting the indicator needle gradually decreases as the environment changes, and eventually the indicator needle may become undetectable. In contrast, the meter reading device 100 of embodiment 1 automatically updates the reference image D7 so that the reference image D7 has the highest similarity to the area in which the indicator needle is imaged in the latest meter image D1, thereby enabling meter reading that is robust to continuous environmental changes.

[0088] Furthermore, the meter reading device 100 according to the first embodiment is capable of applying various types of image processing when creating candidates for the reference image D7 (update candidate images). Therefore, the meter reading device 100 can also adapt to a wider range of environmental changes.

[0089] Furthermore, when performing template matching using the reference image D7 to detect the indicator needle, the meter reading device 100 according to the first embodiment assigns more weight to the tip of the indicator needle. This is based on the structure of an analog meter in which the tip of the indicator needle indicates the value, and the meter reading device 100 can detect the indicator needle with higher accuracy than when a normal template matching method is used.

[0090] Furthermore, if the reference image D7 is updated automatically with an incorrect reference image D7, there is a problem that it becomes impossible to detect the pointer thereafter. As a countermeasure, the meter reading device 100 stores the reading result D6, analyzes the distribution of similarity (reference similarity) in time series, and detects outliers to detect erroneous updating of the reference image D7. If an erroneous update of the reference image D7 is detected, the reference image D7 can be returned to its pre-update state. This enables the meter reading device 100 to reduce the possibility that the reference image D7 is updated with an incorrect reference image D7 (update reference image).

[0091] <Modification> In the above-described first embodiment, the meter reading device 100 acquires the meter image D1 captured by the imaging device 300 from the imaging device 300, but this is merely an example. For example, the meter reading device 100 may acquire the meter image D1 from a storage device such as a hard disk drive in which a meter image D1 captured in advance is stored. In this case, in the meter reading system 1000, the meter reading device 100 is connected to a storage device instead of the imaging device 300.

[0092] In the above-described first embodiment, the needle detection unit 4 in the meter reading device 100 calculates the reference similarity by template matching using the reference image D7 as a template, but this is merely an example. The needle detection unit 4 may calculate the reference similarity by any method as long as the method can obtain the likelihood of detection of the needle in the meter image D1 in the form of a similarity with the reference image D7. For example, the meter reading device 100 may detect the pointer using a convolutional neural network (CNN) that has learned the reference image D7, instead of template matching. More specifically, in the meter reading device 100, the pointer detection unit 4 may compare the polar coordinate system meter image with the reference image D7 using a trained model (hereinafter referred to as a "machine learning model"). The machine learning model receives the polar coordinate system meter image and the reference image D7 as input, and outputs information indicating the position of the pointer on the polar coordinate system meter image. The machine learning model is assumed to be created in advance and stored in a location that can be referenced by the meter reading device 100. The pointer detection unit 4 inputs the polar coordinate system meter image and the reference image D7 into the machine learning model to obtain information indicating the position of the pointer on the polar coordinate system meter image, thereby detecting the position of the pointer on the polar coordinate system meter image. In this case, the meter reading device 100 is configured to include a learning processing unit so that learning is performed every time the reference image D7 is updated in the meter reading device 100.

[0093] In addition, in the above-described embodiment 1, in the meter reading device 100, the update candidate image creation unit 73 refers to the most recent several reading results D6 and creates an update candidate image based on the detection position image included in the indicator needle detection result D4 in each reading result D6, but this is merely one example. For example, the update candidate image creation unit 73 may acquire the past read results D6 at a certain time interval, instead of the most recent few times, from the read result storage unit 6. For example, the update candidate image creation unit 73 may acquire the read results D6 up to 5 minutes ago at 10 second intervals, and set the update candidate image based on the detection position image included in the pointer detection result D4 in each of the past read results D6 at 10 second intervals. There is a possibility that the detection position images in the most recent few read results D6 have little change. The update candidate image creation unit 73 can create update candidate images of various patterns with changes by creating update candidate images based on the past read results D6 at a fixed time interval, more specifically, based on the detection position images included in the pointer detection results D4 in the past read results D6 at a fixed time interval. As a result, the update image determination unit 74 can determine an update reference image from the update candidate images of various patterns with changes when updating the reference image D7.

[0094] In the above first embodiment, the meter reading device 100 is configured to include the polar coordinate conversion unit 3, but this is merely an example. The meter reading device 100 does not require the polar coordinate conversion unit 3 as an essential component. In a configuration without the polar coordinate conversion unit 3, in the meter reading device 100, the needle detection unit 4 detects the indication position on the captured image (meter image D1) of the needle by comparing the captured image (meter image D1) acquired by the image acquisition unit 1 with the reference image D7, and creates a needle detection result D4 based on the comparison result between the captured image (meter image D1) when the indication position is detected and the reference image D7. The reference image update unit 7 recreates the reference image D7 (update reference image) based on the needle detection result D4 created by the needle detection unit 4 when comparing the captured image (meter image D1) with the reference image D7, and updates the reference image D7 with the recreated update reference image. In addition, the initial reference image creation unit 71 of the reference image update unit 7 cuts out a needle imaging area in which the needle is imaged on the captured image (meter image D1) based on the captured image (meter image D1) acquired by the image acquisition unit 1 and the setting information D2, and creates a reference image D7 from the cut-out needle imaging area.

[0095] In this case, the image acquisition unit 1 outputs the captured image (meter image D1) to the interface unit 2, the indicator needle detection unit 4, and the reference image update unit . Moreover, the process of step ST13 is omitted in the operation of the meter reading device 100 shown in the flowchart of Fig. 9. Moreover, the process of step ST22 is omitted in the operation of the meter reading device 100 shown in the flowchart of Fig. 10. However, when comparing the captured image (meter image D1) with the reference image D7 created from the captured image (meter image D1), it is necessary to take into consideration rotation and the like. The meter reading device 100 includes a polar coordinate conversion unit 3, and can easily compare the captured image (meter image D1) with the reference image D7 by comparing the captured image with the polar coordinate meter image. For example, in the case of comparing the polar coordinate meter image with the reference image D7 by template matching, the meter reading device 100 can easily perform the comparison by scanning the reference image D7, which is a template, in the direction of the deflection axis on the polar coordinate meter image.

[0096] In the above first embodiment, the meter reading device 100 includes the initial reference image creating unit 71, but this is merely an example. The meter reading device 100 does not require the initial reference image creating unit 71 as an essential component. In the case where the initial reference image creating unit 71 is not provided, for example, an administrator or the like creates an initial reference image D7 when the meter reading device 100 is shipped, and stores it in the reference image storage unit 8. In this case, the meter reading device 100 can be configured not to perform the "initial setting process." The operation of the meter reading device 100 shown in the flowchart of Fig. 9 becomes unnecessary. In this case, a process in which the interface unit 2 acquires setting information D2 is added between the process of step ST21 and the process of step ST22 in the operation of the meter reading device 100 shown in the flowchart of Fig. 10.

[0097] In addition, in the above embodiment 1, the erroneous update detection unit 75 may be configured to detect an erroneous update of the reference image D7 at a predetermined timing, and if an erroneous update is detected, to perform a process of returning the reference image D7 to the reference image D7 before the update. In this case, for example, a step is added to the operation of the meter reading device 100 shown in the flowchart of Fig. 10, before the processing of step ST29, in which the erroneous update detection unit 75 determines whether or not it is time to detect an erroneous update of the reference image D7. When the erroneous update detection unit 75 determines that it is time to detect an erroneous update of the reference image D7, the operation of the meter reading device 100 proceeds to the processing of step ST29.

[0098] In the above embodiment 1, the meter is a rotary analog meter, but this is merely an example. For example, the meter may be an analog meter having an indicator needle that moves up and down or left and right.

[0099] In addition, in the above-mentioned first embodiment, the meter reading device 100 is provided in the meter, but this is merely an example. For example, the meter reading device 100 may be provided in a device external to the meter reading device 100, such as a server. Also, for example, in the meter reading device 100, some of the image acquisition unit 1, interface unit 2, polar coordinate conversion unit 3, pointer detection unit 4, indication value calculation unit 5, and reference image update unit 7 may be provided in the meter, and the rest may be provided in the server, so that the meter and the server form a system.

[0100] 11A and 11B are diagrams illustrating an example of a hardware configuration of the meter reading device 100 according to the first embodiment. In the first embodiment, the functions of the image acquisition unit 1, the interface unit 2, the polar coordinate conversion unit 3, the pointer detection unit 4, the indicated value calculation unit 5, the reference image update unit 7, and a control unit (not shown) are realized by a processing circuit 101. That is, the meter reading device 100 includes the processing circuit 101 for storing past reading results D6 and controlling automatic updating of the detection standard for the pointer (i.e., the reference image D7) based on the results. The processing circuit 101 may be dedicated hardware as shown in FIG. 11A, or may be a processor 104 that executes a program stored in a memory as shown in FIG. 11B.

[0101] When the processing circuit 101 is dedicated hardware, the processing circuit 101 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof.

[0102] When the processing circuit is the processor 104, the functions of the image acquisition unit 1, the interface unit 2, the polar coordinate conversion unit 3, the pointer detection unit 4, the indication value calculation unit 5, the reference image update unit 7, and the control unit (not shown) are realized by software, firmware, or a combination of software and firmware. The software or firmware is described as a program and stored in the memory 105. The processor 104 reads out and executes the program stored in the memory 105 to execute the functions of the image acquisition unit 1, the interface unit 2, the polar coordinate conversion unit 3, the pointer detection unit 4, the indication value calculation unit 5, the reference image update unit 7, and the control unit (not shown). That is, the meter reading device 100 includes a memory 105 for storing a program that, when executed by the processor 104, results in the execution of steps ST11 to ST14 in FIG. 9 and steps ST21 to ST30 in FIG. 10 described above. It can also be said that the program stored in the memory 105 causes the computer to execute the procedures or methods of the image acquisition unit 1, the interface unit 2, the polar coordinate conversion unit 3, the pointer detection unit 4, the indication value calculation unit 5, the reference image update unit 7, and a control unit (not shown). Here, the memory 105 corresponds to, for example, a non-volatile or volatile semiconductor memory such as a RAM, a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), an EEPROM (registered trademark; description will be omitted hereinafter) (Electrically Erasable Programmable Read-Only Memory), a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, a DVD (Digital Versatile Disc), and the like.

[0103] The functions of the image acquisition unit 1, the interface unit 2, the polar coordinate conversion unit 3, the pointer detection unit 4, the indication value calculation unit 5, the reference image update unit 7, and the control unit (not shown) may be partially realized by dedicated hardware and partially realized by software or firmware. For example, the functions of the image acquisition unit 1 and the interface unit 2 may be realized by a processing circuit 101 as dedicated hardware, and the functions of the polar coordinate conversion unit 3, the pointer detection unit 4, the indication value calculation unit 5, the reference image update unit 7, and the control unit (not shown) may be realized by a processor 104 reading out and executing a program stored in a memory 105. The read result storage unit 6 and the reference image update unit 7 are configured with a memory 105 or a hard disk drive or the like. The meter reading device 100 also includes an input interface device 102 and an output interface device 103 that perform wired or wireless communication with devices such as an external device 200 or an image capturing device 300.

[0104] As described above, the meter reading device 100 according to the first embodiment is configured to include an image acquisition unit 1 that acquires an image (meter image D1), a needle detection unit 4 that detects the position of the needle on the image (meter image D1) by comparing the image (meter image D1) acquired by the image acquisition unit 1 with a reference image D7 showing the needle that serves as a reference for detecting the position of the needle on the meter, and creates a needle detection result D4 based on the comparison result between the image (meter image D1) when the image position is detected and the reference image D7, and a reference image update unit 7 that recreates the reference image D7 based on the needle detection result D4 created by the needle detection unit 4 when comparing the image (meter image D1) with the reference image D7, and updates the reference image D7 with the recreated reference image D7, which is an update reference image. Therefore, the meter reading device 100 can prevent a decrease in reading accuracy even if the environmental conditions under which the meter is photographed change. In other words, even if continuous environmental changes occur during meter reading, the meter reading device 100 can reduce the possibility of reading failure. The meter reading device 100 automatically updates the reference image D7 so that the reference image D7 has the highest similarity to the area in which the indicator needle is captured in the latest meter image D1, and therefore can perform meter reading that is robust against continuous environmental changes.

[0105] Furthermore, in the meter reading device 100 according to the first embodiment, the reference image update unit 7 includes an update candidate image creation unit 73 which creates a plurality of update candidate images that are candidates for the update reference image based on the detection position image, and an update image determination unit 74 which determines, from the plurality of update candidate images created by the update candidate image creation unit 73, an update candidate image in which the indicator needle is likely to be displayed, as the update reference image. When updating the reference image D7, the meter reading device 100 creates multiple update candidate images and selects an update reference image from among them, thereby enabling the reference image D7 to be updated in response to a wide range of environmental changes.

[0106] Specifically, the update candidate image creation unit 73 sets a plurality of detection position images included in the needle detection result D4 as a plurality of update candidate images. This enables the meter reading device 100 to update the reference image D7 in response to a wide range of environmental changes.

[0107] In addition, the update candidate image creation unit 73 creates a processed detection position image by applying image processing to the multiple detection position images included in the needle detection result D4, and sets the multiple detection position images and the multiple processed detection position images as update candidate images. This enables the meter reading device 100 to update the reference image D7 in response to a wider range of environmental changes.

[0108] Furthermore, in the meter reading device 100 according to the first embodiment, when the pointer detection unit 4 compares the polar coordinate system meter image with the reference image D7, the comparison is performed such that the area corresponding to the tip side of the pointer is weighted more. This enables the meter reading device 100 to detect the indicator needle with higher accuracy. The meter reading device 100 can also obtain a similar effect by weighting the area corresponding to the tip side of the indicator needle more heavily when comparing the captured image (meter image D1) with the reference image D7.

[0109] Furthermore, in the meter reading device 100 according to embodiment 1, the reference image update unit 7 is configured to detect erroneous updates of the reference image D7 by analyzing the pointer detection results D4 in chronological order, and is configured to include an erroneous update detection unit 75 that returns the reference image D7 to the reference image D7 before the update when an erroneous update is detected. This enables the meter reading device 100 to reduce the possibility that the reference image D7 is updated with an incorrect reference image D7 (update reference image).

[0110] Furthermore, in the meter reading device 100 according to the first embodiment, the reference image updating unit 7 is configured to include an initial reference image creating unit 71 that cuts out a needle imaged area in which the needle is imaged on the captured image (meter image D1) based on the captured image (meter image D1) acquired by the image acquiring unit 1 and setting information D2 related to the meter scale and the needle, and creates a reference image D7 from the cut-out needle imaged area. The needle detection unit 4 detects the indication position on the captured image (meter image D1) of the needle by comparing the captured image (meter image D1) acquired by the image acquiring unit 1 with the reference image D7 created by the initial reference image creating unit 71. The meter reading device 100 can set the initial reference image D7 to a reference image D7 that corresponds to the environmental conditions of the meter.

[0111] Furthermore, the meter reading device 100 according to the first embodiment includes a polar coordinate conversion unit 3 that converts the captured image (meter image D1) into polar coordinates using the captured image (meter image D1) acquired by the image acquisition unit 1 and setting information D2 related to the meter scale and the pointer, and the pointer detection unit 4 is configured to detect the indication position of the pointer on the polar coordinate system meter image and create a pointer detection result D4 by comparing the polar coordinate system meter image, which is the captured image (meter image D1) after the polar coordinate conversion by the polar coordinate conversion unit 3, with a reference image D7. The reference image update unit 7 recreates the reference image D7 based on the pointer detection result D4 created by the pointer detection unit 4 when comparing the polar coordinate system meter image with the reference image D7, and updates the reference image D7 with the recreated update reference image. The meter reading device 100 can easily compare the captured image (meter image D1) with the reference image D7 by performing the comparison on a polar coordinate system meter image.

[0112] In addition, in the present disclosure, any of the components of the embodiments may be modified or any of the components of the embodiments may be omitted.

[0113] Various aspects of the present disclosure are summarized below as appendices.

[0114] (Appendix 1) A meter reading device that calculates an indication value, which is a numerical value indicated by an indicator needle, from an indication position of the indicator needle on a captured image detected based on an image of at least a dial of a meter, an image acquisition unit for acquiring the captured image; a needle detection unit that detects the indicated position of the needle on the captured image by comparing the captured image acquired by the image acquisition unit with a reference image of the needle, which serves as a reference for detecting the indicated position of the needle in the meter, and creates a needle detection result based on a comparison result between the captured image and the reference image when the indicated position is detected; a reference image updating section that recreates the reference image based on the needle detection result created by the needle detection section when comparing the captured image with the reference image, and updates the reference image with an updating reference image that is the recreated reference image; A meter reading device comprising: (Appendix 2) an indication value calculation section that calculates the indication value based on the indication needle detection result generated by the indication needle detection section and setting information related to the scale of the meter and the indication needle; 2. The meter reading device of claim 1, comprising: (Appendix 3) the needle detection result includes a detection position image obtained by cutting out a region in the captured image that is determined to be similar to the reference image; The reference image update unit an update candidate image creation unit that creates a plurality of update candidate images that are candidates for the update reference image based on the detection position image; An update image determination unit that determines, from among the plurality of update candidate images created by the update candidate image creation unit, an update candidate image in which the pointer is likely to be present, as the update reference image. 3. The meter reading device according to claim 1 or 2, (Appendix 4) The update image determination unit For a plurality of the updating candidate images, the updating candidate images are compared with the captured image to detect a candidate similar region in the captured image that is similar to the updating candidate image, a candidate similarity between the updating candidate images and the detected candidate similar region is calculated, and the updating candidate image having a high calculated candidate similarity is determined to be the updating reference image. 4. The meter reading device of claim 3. (Appendix 5) The update candidate image creation unit sets the detection position image as the update candidate image. 5. The meter reading device according to claim 3 or 4. (Appendix 6) The update candidate image creation unit creates a processed detection position image by performing image processing on the detection position image, and sets the detection position image and the processed detection position image as the update candidate image. 5. The meter reading device according to claim 3 or 4. (Appendix 7) The image processing includes brightness modification, contrast modification, edge enhancement, or noise addition. 7. The meter reading device of claim 6. (Appendix 8) The pointer detection unit performs the comparison between the captured image and the reference image by weighting an area corresponding to a tip side of the pointer more heavily. 8. The meter reading device of claim 1, (Appendix 9) The reference image update unit includes an erroneous update detection unit that detects an erroneous update of the reference image by analyzing the pointer detection result in a time series and returns the reference image to the reference image before the update when the erroneous update is detected. 9. The meter reading device of any one of claims 1 to 8. (Appendix 10) the pointer detection result includes a detection position image obtained by cutting out an area determined to be similar to the reference image in the captured image, and a reference similarity between the detection position image and the reference image, The erroneous update detection unit detects the erroneous update of the reference image by determining whether or not an outlier of the reference similarity increases after the reference image is updated, based on the pointer detection results in time series. 10. The meter reading device of claim 9. (Appendix 11) the reference image update unit includes an initial reference image creation unit that cuts out an indicator needle image capture area in which the indicator needle is imaged from the captured image based on the captured image acquired by the image acquisition unit and setting information related to the scale of the meter and the indicator needle, and creates the reference image from the cut-out indicator needle image area; The pointer detection unit detects the indication position of the pointer on the captured image by comparing the captured image acquired by the image acquisition unit with the reference image created by the initial reference image creation unit. 11. The meter reading device of any one of claims 1 to 10. (Appendix 12) The pointer detection unit compares the captured image with the reference image by template matching using the reference image as a template, and detects the indication position of the pointer on the captured image from coordinates of an area on the captured image that has a high similarity to the reference image. 12. The meter reading device of any one of claims 1 to 11. (Appendix 13) The pointer detection unit compares the captured image with the reference image using a machine learning model that receives the captured image and the reference image as input and outputs information indicating the pointing position on the captured image, and detects the pointing position on the captured image by inputting the captured image and the reference image to the machine learning model to obtain information indicating the pointing position on the captured image. 12. The meter reading device of any one of claims 1 to 11. (Appendix 14) a polar coordinate conversion unit that converts the captured image into a polar coordinate system using the captured image acquired by the image acquisition unit and setting information related to the scale of the meter and the indicator needle, the pointer detection unit detects the indication position of the pointer on the polar coordinate system meter image by comparing the polar coordinate system meter image, which is the captured image after the polar coordinate conversion by the polar coordinate conversion unit, with the reference image, and creates the pointer detection result; The reference image update unit recreates the reference image based on the needle detection result created by the needle detection unit when comparing the polar coordinate system meter image with the reference image, and updates the reference image with the update reference image, which is the recreated reference image. 14. The meter reading device of any one of claims 1 to 13. (Appendix 15) A meter reading program for calculating an indication value, which is a numerical value indicated by an indicator needle, from an indication position of the indicator needle on a captured image detected based on an image of at least a dial of a meter, comprising: Computer, an image acquisition unit for acquiring the captured image; a needle detection unit that detects the indicated position of the needle on the captured image by comparing the captured image acquired by the image acquisition unit with a reference image of the needle, which serves as a reference for detecting the indicated position of the needle in the meter, and creates a needle detection result based on a comparison result between the captured image and the reference image when the indicated position is detected; a reference image updating section that recreates the reference image based on the needle detection result created by the needle detection section when comparing the captured image with the reference image, and updates the reference image with an updating reference image that is the recreated reference image; A meter reading program to function as a (Appendix 16) A meter reading method for calculating an indication value, which is a numerical value indicated by an indicator needle, from an indication position of the indicator needle on a captured image detected based on an image of at least a dial of a meter, comprising: An image acquisition unit acquires the captured image; a step in which a needle detection unit detects the indicated position of the needle on the captured image by comparing the captured image acquired by the image acquisition unit with a reference image showing the needle, the reference image being used as a reference for detecting the indicated position of the needle in the meter, and creates a needle detection result based on a comparison result between the captured image and the reference image when the indicated position is detected; a reference image updating unit re-creating the reference image based on the needle detection result generated by the needle detection unit when comparing the captured image with the reference image, and updating the reference image with the re-created reference image for update; A meter reading method comprising: [Explanation of symbols]

[0115] 100 meter reading device, 1 image acquisition unit, 2 interface unit, 3 polar coordinate conversion unit, 4 pointer detection unit, 5 indication value calculation unit, 6 reading result storage unit, 7 reference image update unit, 71 initial reference image creation unit, 72 update execution determination unit, 73 update candidate image creation unit, 74 update image determination unit, 75 erroneous update detection unit, 8 reference image storage unit, 200 external device, 300 imaging device, 1000 meter reading system, 101 processing circuit, 102 input interface device, 103 output interface device, 104 processor, 105 memory.

Claims

1. A meter reading device that calculates an indication value, which is a numerical value indicated by an indicator needle, from an indication position of the indicator needle on a captured image detected based on an image of at least a dial of a meter, an image acquisition unit for acquiring the captured image; a needle detection unit that detects the indicated position of the needle on the captured image by comparing the captured image acquired by the image acquisition unit with a reference image of the needle, which serves as a reference for detecting the indicated position of the needle in the meter, and creates a needle detection result based on a comparison result between the captured image and the reference image when the indicated position is detected; a reference image updating section that recreates the reference image based on the needle detection result created by the needle detection section when comparing the captured image with the reference image, and updates the reference image with an updating reference image that is the recreated reference image; A meter reading device comprising:

2. an indication value calculation section that calculates the indication value based on the indication needle detection result generated by the indication needle detection section and setting information related to the scale of the meter and the indication needle; 2. The meter reading device of claim 1, comprising:

3. the needle detection result includes a detection position image obtained by cutting out a region in the captured image that is determined to be similar to the reference image; The reference image update unit an update candidate image creation unit that creates a plurality of update candidate images that are candidates for the update reference image based on the detection position image; and an update image determination unit that determines, from among the plurality of update candidate images created by the update candidate image creation unit, an update candidate image in which the pointer is likely to be present, as the update reference image.

3. The meter reading device according to claim 1 or 2.

4. The update image determination unit For a plurality of the updating candidate images, the updating candidate images are compared with the captured image to detect a candidate similar region in the captured image that is similar to the updating candidate image, a candidate similarity between the updating candidate images and the detected candidate similar region is calculated, and the updating candidate image having a high calculated candidate similarity is determined to be the updating reference image.

4. The meter reading device of claim 3.

5. The update candidate image creation unit sets the detection position image as the update candidate image.

4. The meter reading device of claim 3.

6. The update candidate image creation unit creates a processed detection position image by performing image processing on the detection position image, and sets the detection position image and the processed detection position image as the update candidate image.

4. The meter reading device of claim 3.

7. The image processing includes brightness modification, contrast modification, edge enhancement, or noise addition.

7. The meter reading device of claim 6.

8. The pointer detection unit performs the comparison between the captured image and the reference image by weighting an area corresponding to a tip side of the pointer more heavily.

2. The meter reading device of claim 1.

9. The reference image update unit includes an erroneous update detection unit that detects an erroneous update of the reference image by analyzing the pointer detection result in a time series and returns the reference image to the reference image before the update when the erroneous update is detected.

2. The meter reading device of claim 1.

10. the pointer detection result includes a detection position image obtained by cutting out an area determined to be similar to the reference image in the captured image, and a reference similarity between the detection position image and the reference image; The erroneous update detection unit detects the erroneous update of the reference image by determining whether or not an outlier of the reference similarity increases after the reference image is updated, based on the pointer detection results in time series.

10. The meter reading device of claim 9.

11. the reference image update unit includes an initial reference image creation unit that cuts out an indicator needle image capture area in which the indicator needle is imaged from the captured image based on the captured image acquired by the image acquisition unit and setting information related to the scale of the meter and the indicator needle, and creates the reference image from the cut-out indicator needle image area; The pointer detection unit detects the indication position of the pointer on the captured image by comparing the captured image acquired by the image acquisition unit with the reference image created by the initial reference image creation unit.

2. The meter reading device of claim 1.

12. The pointer detection unit compares the captured image with the reference image by template matching using the reference image as a template, and detects the indication position of the pointer on the captured image from coordinates of an area on the captured image that has a high similarity to the reference image.

2. The meter reading device of claim 1.

13. The pointer detection unit compares the captured image with the reference image using a machine learning model that receives the captured image and the reference image as input and outputs information indicating the pointing position on the captured image, and detects the pointing position on the captured image by inputting the captured image and the reference image to the machine learning model to obtain information indicating the pointing position on the captured image.

2. The meter reading device of claim 1.

14. a polar coordinate conversion unit that converts the captured image into a polar coordinate system using the captured image acquired by the image acquisition unit and setting information related to the scale of the meter and the indicator needle, the pointer detection unit detects the indication position of the pointer on the polar coordinate system meter image by comparing the polar coordinate system meter image, which is the captured image after the polar coordinate conversion by the polar coordinate conversion unit, with the reference image, and creates the pointer detection result; The reference image update unit recreates the reference image based on the needle detection result created by the needle detection unit when comparing the polar coordinate system meter image with the reference image, and updates the reference image with the update reference image, which is the recreated reference image.

2. The meter reading device of claim 1.

15. A meter reading program for calculating an indication value, which is a numerical value indicated by an indicator needle, from an indication position of the indicator needle on a captured image detected based on an image of at least a dial of a meter, comprising: Computer, an image acquisition unit for acquiring the captured image; a needle detection unit that detects the indicated position of the needle on the captured image by comparing the captured image acquired by the image acquisition unit with a reference image of the needle, which serves as a reference for detecting the indicated position of the needle in the meter, and creates a needle detection result based on a comparison result between the captured image and the reference image when the indicated position is detected; a reference image updating section that recreates the reference image based on the needle detection result created by the needle detection section when comparing the captured image with the reference image, and updates the reference image with an updating reference image that is the recreated reference image; A meter reading program to function as a

16. A meter reading method for calculating an indication value, which is a numerical value indicated by an indicator needle, from an indication position of the indicator needle on a captured image detected based on an image of at least a dial of a meter, comprising: An image acquisition unit acquires the captured image; a step in which a needle detection unit detects the indicated position of the needle on the captured image by comparing the captured image acquired by the image acquisition unit with a reference image showing the needle, the reference image being used as a reference for detecting the indicated position of the needle in the meter, and creates a needle detection result based on a comparison result between the captured image and the reference image when the indicated position is detected; a reference image updating unit re-creating the reference image based on the needle detection result generated by the needle detection unit when comparing the captured image with the reference image, and updating the reference image with the re-created reference image for update; A meter reading method comprising:

Images