Measuring tape reading device, measuring tape reading method, and program

Abstract

In digital measuring tapes, it is possible to measure length without having to read the scale lines on the tape. [Solution] The tape measure reading device 1 includes an imaging unit 12 that images the scale markings attached to the tape of the tape measure, a scale marking recognition unit 133 that recognizes the numbers of the scale markings and the positions of the scale lines corresponding to the scale markings in the image captured by the imaging unit 12, an image distance calculation unit 134 that calculates the in-image distance from a reference position in the image to the position of the scale line corresponding to the scale markings based on the image, and a measurement value calculation unit 135 that calculates the measurement value of the tape measure based on the numbers of the scale markings in the image, the in-image distance, and the positional relationship between the position of the scale line corresponding to the scale markings and the measurement end position defined in the image.

Description

Technical Field

[0001] The present disclosure relates to a tape measure reading device, a tape measure reading method, and a program.

Background Art

[0002] There is a tape measure as a tool for measuring the length of an object. The tape measure winds and stores a tape with graduations in a case and is pulled out for use. When using an ordinary tape measure, the user pulls out the graduated tape from the case to measure the length of the object to be measured, and visually observes the graduations and graduation characters attached to the tape to obtain the measured value. On the other hand, a digital tape measure has been proposed that can obtain the measured value as digital data instead of by visual reading by the user.

[0003] Patent Document 1 discloses a tape measure reading device that images graduation lines and graduation characters attached to the tape of a tape measure, calculates the in-image distance from a reference position in the captured image to the graduation line corresponding to the graduation character, and calculates the measured value of the tape measure based on the recognized graduation characters in the captured image, the in-image distance, and the positional relationship between the captured image and the reading position.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the technique described in Patent Document 1, in order to measure the length with a tape measure, it is necessary to read both the graduation line and the graduation character attached to the tape of the tape measure. However, since the graduation line of the tape of the tape measure may fade or disappear due to use and aging deterioration, there is a risk that the graduation line cannot be read.

[0006] This disclosure is made to solve the problems described above, and aims to enable the measurement of length in a digital tape measure without having to read the scale lines attached to the tape. [Means for solving the problem]

[0007] To achieve the above objective, the tape measure reading device according to this disclosure comprises an imaging unit, a scale character recognition unit, an in-image distance calculation unit, and a measurement value calculation unit. The imaging unit captures images of the scale characters attached to the tape of the tape measure. The scale character recognition unit recognizes the numbers of the scale characters and the positions of the scale lines corresponding to the scale characters in the image captured by the imaging unit. The in-image distance calculation unit calculates the in-image distance from a reference position in the image to the position of the scale line corresponding to the scale character, based on the image. The measurement value calculation unit calculates the measurement value of the tape measure based on the numbers of the scale characters in the image, the in-image distance, and the positional relationship between the position of the scale line corresponding to the scale character and the measurement end position defined in the image. [Effects of the Invention]

[0008] According to this disclosure, in a digital measuring tape, by recognizing the numbers of the scale characters and the positions of the scale lines corresponding to the scale characters in the captured image, it becomes possible to measure length without having to read the scale lines attached to the tape of the measuring tape. [Brief explanation of the drawing]

[0009] [Figure 1] Perspective view showing an example configuration of a tape measure reading device according to an embodiment. [Figure 2] (a) A diagram showing the positional relationship between the imaging unit and the tape measure when the camera lens is a wide-angle lens, (b) A diagram showing the positional relationship between the imaging unit and the tape measure when the camera lens is a non-wide-angle lens. [Figure 3] A diagram showing an example of the functional configuration of a tape measure reading device according to an embodiment. [Figure 4] A diagram showing an example of an image captured according to the embodiment. [Figure 5]A figure showing an example of a pattern image according to the embodiment. [Figure 6] A diagram showing an example of a method for calculating the measurement value of a measuring tape according to an embodiment. [Figure 7] This figure shows an example of a method for correcting measured values ​​using the scaling ratio of the scale markings according to the embodiment. [Figure 8] Flowchart showing the measurement value display process according to the embodiment [Figure 9] Flowchart showing the unit length scale character reading process according to the embodiment [Figure 10] Flowchart showing the division scale character reading process according to the embodiment [Figure 11] Flowchart showing the measurement value calculation process according to the embodiment [Figure 12] A diagram showing an example of the hardware configuration of a tape measure reading device according to an embodiment. [Modes for carrying out the invention]

[0010] The tape measure reading device, tape measure reading method, and program according to this embodiment will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

[0011] (Embodiment) The configuration of the measuring tape reading device 1 according to this embodiment will be explained with reference to Figure 1. Figure 1 is a perspective view showing an example of the configuration of the measuring tape reading device 1 according to this embodiment. As shown in Figure 1, the measuring tape reading device 1 is attached to the measuring tape 2. The measuring tape 2 consists of a tape 21 and a case 22 which is a container for the tape. Although not shown, the case 22 has an opening for inserting and removing the tape 21.

[0012] The tape 21 is marked with scale characters for each unit length, and between the scale characters for each unit length, scale characters for each length obtained by dividing the unit length by a predetermined number are marked. For example, when the unit length is 10 cm, scale characters 10, 20, 30,... are marked in white characters with a red background at positions of 10 cm, 20 cm, 30 cm,... on the tape 21. Also, between the scale characters for each unit length, scale characters 1, 2, 3,..., 9 are marked at every 1 cm obtained by dividing 10 cm of the unit length into 10 parts. Hereinafter, the scale characters for each unit length are referred to as unit length scale characters, and the scale characters for each length obtained by dividing the unit length by a predetermined number are referred to as divided scale characters. When collectively referring to the unit length scale characters and the divided scale characters, they are simply referred to as scale characters. Also, the length obtained by dividing the unit length by a predetermined number is referred to as the divided width.

[0013] In the figure, X, Y, and Z indicate coordinate axes, and the X-axis, Y-axis, and Z-axis are orthogonal to each other. The direction in which the tape 21 is pulled straight out from the opening of the case 22 is indicated by Y, and the height direction is indicated by Z. Hereinafter, the positive direction of the Z-axis is referred to as "up" and the negative direction is referred to as "down".

[0014] In the example of FIG. 1, the tape measure reading device 1 is mounted on the negative direction side of the X-axis of the tape measure 2, but not limited thereto, the tape measure reading device 1 may be configured to be mounted on the positive direction side of the X-axis of the tape measure 2. The tape measure reading device 1 captures an image of the scale characters attached to the tape 21 pulled out from the opening of the case 22, reads the scale characters from the captured image, and acquires the measurement value by the tape measure 2. The tape measure reading device 1 includes a housing 11 that can be mounted on the tape measure 2, an imaging unit 12 that captures an image of the tape 21 pulled out from the case 22 of the tape measure 2, an information processing unit 13 that analyzes the captured image by the imaging unit 12 to recognize the scale characters in the captured image and calculates the measurement value, and an output unit 14 that outputs the measurement value. Although not shown, the tape measure reading device 1 includes an operation unit that sends an imaging instruction to the imaging unit 12 and a power supply unit that supplies power.

[0015] The housing 11 is a housing having a structure that can be attached to the measuring tape 2. The structure that can be attached to the measuring tape 2 may be, for example, a claw-shaped one that can fix and hold the measuring tape 2, or a space into which the measuring tape 2 can be inserted and fixed. An output unit 14 is provided on the upper surface of the housing 11. An information processing unit 13 is housed inside the housing 11. The housing 11 is integrated with the imaging unit 12, and an imaging window 121, which is an opening for imaging, is provided on the lower surface of the imaging unit 12. The housing 11 is attached to the measuring tape 2 at a position where the tape 2 pulled out from the opening of the case 22 passes under the imaging window 121 of the imaging unit 12. The housing 11 includes a guide portion 111 that defines the measurement end position. The measurement end position defined by the guide portion 111 is, for example, the position of the center in the Y-axis direction of the imaging range of the camera of the imaging unit 12.

[0016] Although not shown, a camera is built into the imaging unit 12. The camera of the imaging unit 12 is, for example, a camera composed of a CMOS (Complementary Metal-Oxide-Semiconductor) image sensor, a CCD (Charge Coupled Device) image sensor, or the like. The camera images the tape 2 from the imaging window 121 on the lower surface of the imaging unit 12.

[0017] The imaging unit 12 images in an imaging range including one or more unit length scale characters attached to the tape 2. The unit length scale character is, for example, a white character on a red background in 10 cm units, and the imaging range including one or more unit length scale characters is, for example, 11 cm in length of the long side. By setting the imaging range to the range including one or more unit length scale characters on the tape 2, it is possible to obtain an imaging image necessary for calculating the measurement value in one imaging, and the power consumption by imaging can be reduced.

[0018] Figure 2(a) shows the positional relationship between the imaging unit 12 and the tape 21 of the measuring tape 2 when the camera lens of the imaging unit 12 is a wide-angle lens. Figure 2(b) shows the positional relationship between the imaging unit 12 and the tape 21 of the measuring tape 2 when the camera lens of the imaging unit 12 is a non-wide-angle lens. As shown in Figure 2(a), when the camera lens of the imaging unit 12 is a wide-angle lens, the distance between the imaging unit 12 and the tape 21 of the measuring tape 2 can be shortened. This makes it possible to make the measuring tape reading device 1 more compact. The image distortion caused by wide-angle shooting is corrected by the information processing unit 13. If it is not necessary to shorten the distance between the imaging unit 12 and the tape 21 of the measuring tape 2, a non-wide-angle lens may be used for the camera lens of the imaging unit 12, as shown in Figure 2(b). In this case, it is not necessary to correct the distortion of the image in the scale character recognition unit 133.

[0019] The user aligns the leading edge of the tape 21, which serves as the measurement base point, with the starting position of the object to be measured, pulls out the tape 21, and aligns the guide section 111 with the ending position of the object to be measured. The user operates the control section of the tape measure reading device 1 to send an imaging command to the imaging unit 12. Upon receiving the imaging command, the camera of the imaging unit 12 captures an image of the tape 21 through the imaging window 121 on the bottom surface of the imaging unit 12 and sends imaging information indicating the captured image to the information processing unit 13.

[0020] The information processing unit 13 recognizes the numbers of the scale characters in the captured image and the positions of the scale lines corresponding to the scale characters, as indicated by the received imaging information. Based on the numbers of the scale characters and the positional relationship between the measurement end position and the position of the scale line corresponding to the scale character, it calculates the measured value. The information processing unit 13 sends the measured value information, which indicates the calculated measured value, to the output unit 14.

[0021] The output unit 14 outputs the measurement data received from the information processing unit 13. The output unit 14 is a display device such as an LCD (Liquid Crystal Display) or an organic EL (electroluminescence) display. The output unit 14 is not limited to the top surface of the housing 11, but can be located in a position that is easily visible to the user. Alternatively, the output unit 14 may transmit the measurement data to an external device or system.

[0022] Here, the functional configuration of the tape measure reading device 1 will be explained using Figure 3. The tape measure reading device 1 comprises an imaging unit 12, an information processing unit 13, and an output unit 14. The information processing unit 13 includes an imaging information storage unit 131 for storing imaging information, a pattern image information storage unit 132 for storing pattern image information including a pattern image of scale characters, a scale character recognition unit 133 for recognizing the numbers of scale characters and the positions of the scale lines corresponding to the scale characters in the captured image based on the imaging information and the pattern image information, an in-image distance calculation unit 134 for calculating the distance from the measurement end position to the position of the scale line corresponding to the scale characters in the captured image based on the imaging information and the positions of the scale lines corresponding to the scale characters in the captured image recognized by the scale character recognition unit 133, and a measurement value calculation unit 135 for calculating a measurement value based on the numbers of scale characters and the positions of the scale lines corresponding to the scale characters in the captured image recognized by the scale character recognition unit 133 and the distance from the measurement end position to the position of the scale line corresponding to the scale characters in the captured image calculated by the in-image distance calculation unit 134.

[0023] When the imaging unit 12 receives an imaging instruction from the operation unit, it images the tape 21 through the imaging window 121 and sends imaging information indicating the captured image to the information processing unit 13. The imaging information storage unit 131 stores the imaging information received from the imaging unit 12. An example of imaging information is shown in Figure 4. In the example in Figure 4, the unit length scale characters 31 of the captured image indicated by the imaging information are white characters on a red background in 10cm units, and the division scale characters 32 are black characters in 1cm units. The vertical center line 34 of the imaging range 33 is the positive Y-axis end of the guide unit 111 and is the measurement end position.

[0024] Returning to Figure 3, the pattern image information storage unit 132 pre-stores pattern image information that includes pattern images of all scale characters attached to the tape 21, and the relative positions of the scale lines to the scale characters in the pattern images. Alternatively, the relative positions of the scale lines to the scale characters that are common to all pattern images (for example, the vertical center line of the pattern image) may be predetermined. In the latter case, the pattern image information does not need to include the relative positions of the scale lines to the scale characters in the pattern images. An example of pattern image information is shown in Figure 5. Figure 5 is the pattern image of the divided scale character "5". In the example in Figure 5, the relative position of the scale line to the divided scale character "5" is the vertical center line 41 of the pattern image.

[0025] Returning to Figure 3, the scale character recognition unit 133 changes the scaling ratio of the pattern image indicated by the pattern image information (for example, setting the range of change to 80% to 120%), performs pattern matching with the captured image indicated by the imaging information, and selects the pattern image with the highest scaling ratio for both unit-length scale characters and divided scale characters. At this time, if the camera lens of the imaging unit 12 is a wide-angle lens, the scale character recognition unit 133 corrects the distortion of the captured image indicated by the imaging information due to the wide-angle lens before performing pattern matching.

[0026] Next, the scale character recognition unit 133 determines the unit-length scale character and the divided scale character with the highest matching rate. Hereinafter, the unit-length scale character and the divided scale character with the highest matching rate will be referred to as the matching unit-length scale character and the matching divided scale character, respectively. At this time, the scale character recognition unit 133 may be configured to determine whether the highest matching rate of both the unit-length scale character and the divided scale character exceeds a predetermined threshold, and if at least one of the highest matching rates does not exceed the threshold, it may display a reading error on the output unit 14. Based on the captured image, the pattern image with the highest matching rate, and the relative position of the scale lines to the matching unit-length scale character and the matching divided scale character in the pattern image, the scale character recognition unit 133 recognizes the numbers of the matching unit-length scale character and the matching divided scale character in the captured image and the position of the scale lines corresponding to the matching unit-length scale character and the matching divided scale character. The scale character recognition unit 133 may also calculate the relative position of the scale lines to the matching unit-length scale characters and matching division scale characters based on the scaling ratio of the pattern image with the highest matching rate.

[0027] The scale character recognition unit 133 sends to the image distance calculation unit 134 the following information: the numbers of the matching unit length scale characters and matching division scale characters in the captured image, matching scale character information indicating the position of the scale lines corresponding to the matching unit length scale characters and matching division scale characters, and scaling ratio information indicating the scaling ratio at which the matching rate of the matching unit length scale characters and matching division scale characters was highest.

[0028] The image distance calculation unit 134 calculates the distance from a reference position in the captured image to the position of the tick mark corresponding to the matching division tick mark in the captured image, based on the matching tick mark information received from the tick mark recognition unit 133. The image distance calculation unit 134 also calculates the distance from the reference position in the captured image to the measurement end position. Alternatively, the image distance calculation unit 134 may pre-store the distance from the reference position in the captured image to the measurement end position. Hereinafter, the distance from the reference position in the captured image to the position of the tick mark corresponding to the tick mark or the measurement end position is referred to as the image distance. The unit of the image distance is, for example, pixels. The image distance calculation unit 134 sends the matching tick mark information and scaling ratio information received from the tick mark recognition unit 133, along with image distance information indicating the image distance of the matching unit length tick mark, the matching division tick mark, and the measurement end position, to the measurement value calculation unit 135.

[0029] The measurement value calculation unit 135 calculates the measurement value of the measuring tape 2 based on the matching scale character information, scaling ratio information, and in-image distance information received from the in-image distance calculation unit 134. Specifically, the measurement value calculation unit 135 determines, for example, whether the position of the scale line corresponding to the matching division scale character in the captured image, as indicated by the matching scale character information, is to the left of the position of the scale line corresponding to the matching unit length scale character. If the position of the scale line corresponding to the matching division scale character is to the left of the position of the scale line corresponding to the matching unit length scale character, the measurement value calculation unit 135 calculates the scale value using the formula: scale value = number of matching unit length scale character + number of matching division scale character - unit length. If the position of the scale line corresponding to the matching division scale character is to the right of the position of the scale line corresponding to the matching unit length scale character, the measurement value calculation unit 135 calculates the scale value using the formula: scale value = number of matching unit length scale character + number of matching division scale character.

[0030] The measurement value calculation unit 135 calculates the measurement value using the formula: Measurement value = Scale value + (In-image distance of matching division scale character - In-image distance of measurement end position) ÷ Number of pixels of division width. The measurement value calculation unit 135 determines whether the matching division scale character or the matching unit length scale character is closer to the measurement end position. Based on the scaling ratio information, the measurement value calculation unit 135 corrects the measurement value using the scaling ratio of the matching division scale character or matching unit length scale character closer to the measurement end position. The measurement value calculation unit 135 sends the corrected measurement value information to the output unit 14. The output unit 14 displays the measurement value information received from the information processing unit 13.

[0031] By correcting the measured value with a magnification / reduction ratio, it becomes unnecessary to use guides such as slit rollers to eliminate the gap between the tape 21 of the measuring tape 2 and the object being measured, thereby simplifying the structure of the measuring tape reading device 1. Furthermore, the efficiency of the length measurement work is improved by eliminating the need to hold the tape down by hand. Conversely, if the measuring tape reading device 1 has a structure that includes guides such as slit rollers to eliminate the gap between the tape 21 of the measuring tape 2 and the object being measured, the scale character recognition unit 133 may perform pattern matching with the captured image indicated by the imaging information without changing the magnification / reduction ratio of the pattern image indicated by the pattern image information.

[0032] Here, a specific example of the measurement value of the measuring tape 2 will be explained using Figure 6. In the example in Figure 6, the matching unit length scale character is "20" and the matching division scale character is "5". The reference position is the right end of the imaging range 33, the unit length is 10 cm, and the division width is 1 cm. The number of pixels in a division width of 1 cm is assumed to be 138. The in-image distance calculation unit 134 calculates the in-image distance d1 of the matching division scale character "5" based on the matching scale character information received from the scale character recognition unit 133. The in-image distance calculation unit 134 is assumed to have the in-image distance d2 of the measurement end position stored in advance. The in-image distance calculation unit 134 sends the matching scale character information and scaling ratio information received from the scale character recognition unit 133, along with the in-image distance information indicating the in-image distances d1 and d2, to the measurement value calculation unit 135. The in-image distances d1 and d2 are assumed to be 787 pixels and 759 pixels, respectively.

[0033] The measurement value calculation unit 135 determines that the position of the tick mark corresponding to the matching division tick mark "5" in the captured image, as indicated by the matching tick mark character information, is to the left of the position of the tick mark corresponding to the matching unit length tick mark "20". The measurement value calculation unit 135 calculates the tick mark value = 20 (number of matching unit length tick mark character) + 5 (number of matching division tick mark character) - 10 (unit length) = 15. The measurement value calculation unit 135 calculates the measurement value = 15 (tick mark value) + {787 (distance in image d1) - 759 (distance in image d2)} ÷ 138 (number of pixels in the division width) = 15.2 (rounded to two decimal places). The measurement value calculation unit 135 determines which of the matching division scale character "5" or the matching unit length scale character "20" is closer to the measurement end position, and corrects the measurement value 15.2 using the magnification / reduction ratio of the matching division scale character "5" that is closer to the measurement end position, based on the magnification / reduction ratio information.

[0034] An example of a method for correcting the measured value using the magnification / reduction ratio of the matching division scale character or matching unit length scale character closer to the measurement end position will be explained with reference to Figure 7. As shown in Figure 7, when there is a gap between the tape 21 of the measuring tape 2 and the upper surface of the object to be measured 3, the measured value can be corrected using the trigonometric functions of a triangle composed of sides a, b, and c, assuming that the opening of the case 22 of the measuring tape 2 is on a plane parallel to the upper surface of the object to be measured 3. First, the distance d3 from the imaging window of the imaging unit 12 to the plane parallel to the upper surface of the object to be measured 3 and the distance d4 from the opening of the case 22 to the measurement end position are distances defined by the structure of the measuring tape reading device 1, and are therefore stored in advance by the measured value calculation unit 135. The distance d5 from the imaging window (lens) of the imaging unit 12 to the plane parallel to the upper surface of the tape 21 is estimated based on the magnification / reduction ratio of the matching division scale character or matching unit length scale character closer to the measurement end position. Since the method for estimating distance d5 depends on the focal length of the camera in the imaging unit 12, the measurement value calculation unit 135 stores, for example, a calculation formula for estimating distance d5 that has been determined in advance.

[0035] The length of side a is distance d4. The length of side b is distance (d3-d5). The length of side c is {d4}.2 +(d3-d5) 2 It is the square root of}. The measurement value calculation unit 135 calculates cosθ = d4 / {d4} to the measurement value. 2 +(d3-d5) 2 The value is corrected by multiplying by}. This allows the measurement to be brought closer to the value obtained when there is no gap between the tape 21 of the measuring tape 2 and the top surface of the object being measured 3.

[0036] Here, the flow of the measurement value display processing performed by the tape measure reading device 1 will be explained using Figure 8. The measurement value display processing shown in Figure 8 starts, for example, when power is turned on to the tape measure reading device 1. If no operation to send an imaging instruction is performed on the operation unit of the tape measure reading device 1 (step S11; NO), the process moves to step S20. If an operation to send an imaging instruction is performed on the operation unit (step S11; YES), the imaging unit 12 images the tape 21 from the imaging window 121 (step S12) and sends imaging information indicating the captured image to the information processing unit 13. The imaging information storage unit 131 stores the imaging information received from the imaging unit 12 (step S13). In the example of imaging information in Figure 4, the unit length scale characters 31 of the captured image indicated by the imaging information are white characters on a red background in 10cm units, and the divided scale characters 32 are black characters in 1cm units. The vertical center line 34 of the imaging range 33 is the positive Y-axis end of the guide section 111, and is the measurement end position.

[0037] Returning to Figure 8, the scale character recognition unit 133 performs a unit-length scale character reading process (step S14) to read unit-length scale characters and a segmented scale character reading process (step S15) to read segmented scale characters.

[0038] The unit-length scale character reading process defined in step S14 will be explained using Figure 9. The scale character recognition unit 133 extracts the area of ​​the background color of the unit-length scale character from the captured image indicated by the captured image information (step S21). For example, if the unit-length scale character is white text on a red background, the scale character recognition unit 133 extracts the red area from the captured image. The scale character recognition unit 133 binarizes the extracted area (step S22) and corrects the distortion of the captured image indicated by the imaging information (step S23).

[0039] The scale character recognition unit 133 repeats the following process for each unit-length scale character pattern image (step S24). The scale character recognition unit 133 reads the pattern image information of the unit-length scale character from the pattern image information storage unit 132 (step S25). The scale character recognition unit 133 repeats the following process within a predetermined range of change (step S26). The scale character recognition unit 133 changes the scaling ratio of the pattern image (step S27) and performs pattern matching with the captured image indicated by the imaging information (step S28). The scale character recognition unit 133 obtains the matching rate between the captured image and the pattern image and the coordinates of the pattern image in the captured image (step S29). When the repetition ends (step S30), the scale character recognition unit 133 stores the number of the pattern image with the highest matching rate for the unit-length scale character, the matching rate, and the coordinates in the captured image (step S31). When the repetition of processing for each unit-length scale character pattern image is completed (step S32), the scale character recognition unit 133 determines the unit-length scale character with the highest matching rate (step S33) and terminates the process.

[0040] The segmented scale character reading process defined in step S15 will be explained using Figure 10. The scale character recognition unit 133 extracts the region containing the segmented scale characters from the captured image indicated by the captured image information (step S41). For example, if the segmented scale characters are the numbers 1 to 9, the scale character recognition unit 133 extracts the region containing the numbers 1 to 9 from the captured image. The scale character recognition unit 133 binarizes the extracted region (step S42) and corrects the distortion of the captured image indicated by the imaging information (step S43).

[0041] The scale character recognition unit 133 repeats the following process for each divided scale character pattern image (step S44). The scale character recognition unit 133 reads the pattern image information of the divided scale character from the pattern image information storage unit 132 (step S45). The scale character recognition unit 133 repeats the following process within a predetermined range of change (step S46). The scale character recognition unit 133 changes the scaling ratio of the pattern image (step S47) and performs pattern matching with the captured image indicated by the imaging information (step S48). The scale character recognition unit 133 obtains the matching rate between the captured image and the pattern image and the coordinates of the pattern image in the captured image (step S49). When the repetition ends (step S50), the scale character recognition unit 133 stores the number of the pattern image with the highest matching rate for the divided scale character, the matching rate, and the coordinates in the captured image (step S51). After the repetition of processing for each segmented tick mark pattern image is completed (step S52), the tick mark recognition unit 133 determines the segmented tick mark with the highest matching rate (step S53), calculates the position of the tick line corresponding to the segmented tick mark in the captured image based on the coordinates and scaling ratio of the pattern image with the highest matching rate in the captured image (step S54), and then terminates the process.

[0042] Returning to Figure 8, the scale character recognition unit 133 determines whether the highest matching rate of both the unit-length scale characters and the divided scale characters exceeds a threshold (step S16). If at least one of the highest matching rates does not exceed the threshold (step S16; NO), the scale character recognition unit 133 displays a reading error on the output unit 14 (step S17), and the process proceeds to step S20. If a reading error is not displayed on the output unit 14, steps S16 and S17 may be omitted. If both highest matching rates exceed the threshold (step S16; YES), the scale character recognition unit 133 sends matching scale character information, which indicates the numbers of the matching unit-length scale characters and matching divided scale characters in the captured image and the positions of the corresponding scale lines, and scaling ratio information, which indicates the scaling ratio at which the matching unit-length scale characters and matching divided scale characters had the highest matching rate, to the in-image distance calculation unit 134. The image distance calculation unit 134 and the measurement value calculation unit 135 perform a measurement value calculation process (step S18) to calculate the measurement value.

[0043] The unit-length scale character reading process defined in step S18 will be explained using Figure 11. The image distance calculation unit 134 calculates the in-image distance of the matching unit-length scale character and the matching division scale character based on the matching scale character information received from the scale character recognition unit 133 (step S61). If the image distance calculation unit 134 has not previously stored the in-image distance of the measurement end position, it calculates the in-image distance of the measurement end position here. The image distance calculation unit 134 sends the matching scale character information and scaling ratio information received from the scale character recognition unit 133, along with the in-image distance information indicating the in-image distance of the matching unit-length scale character, the matching division scale character, and the measurement end position, to the measurement value calculation unit 135.

[0044] The measurement value calculation unit 135 determines whether the position of the matching division scale character in the captured image, as indicated by the matching scale character information received from the image distance calculation unit 134, is to the left of the position of the matching unit length scale character (step S62). If the position of the matching division scale character is to the right of the position of the matching unit length scale character (step S62; NO), the measurement value calculation unit 135 calculates the scale value using the formula: scale value = number of matching unit length scale character + number of matching division scale character (step S63). If the position of the matching division scale character is to the left of the position of the matching unit length scale character (step S62; YES), the measurement value calculation unit 135 calculates the scale value using the formula: scale value = number of matching unit length scale character + number of matching division scale character - unit length (step S64).

[0045] The measurement value calculation unit 135 calculates the measurement value using the formula: measurement value = scale value + (in-image distance of matching division scale character - in-image distance of measurement end position) ÷ number of pixels of division width (step S65). The measurement value calculation unit 135 determines whether the matching division scale character or the matching unit length scale character is closer to the measurement end position (step S66). Based on the scaling ratio information, the measurement value calculation unit 135 corrects the measurement value using the scaling ratio of the matching division scale character or the matching unit length scale character closer to the measurement end position (step S67), and terminates the process. The measurement value calculation unit 135 sends the calculated measurement value information to the output unit 14.

[0046] Returning to Figure 8, the output unit 14 displays the measurement value information received from the information processing unit 13 (step S19). If the power to the tape measure reading device 1 is not turned off (step S20; NO), the process returns to step S11 and steps S11 to S20 are repeated. When the power to the tape measure reading device 1 is turned off (step S20; YES), the process ends.

[0047] According to the tape measure reading device 1 of this embodiment, with a digital tape measure, by recognizing the numbers of the scale characters and the positions of the scale lines corresponding to the scale characters in the captured image, it becomes possible to measure the length without reading the scale lines attached to the tape measure. Furthermore, by omitting the function of reading the scale lines, the processing related to measurement is simplified, reducing processing time and making length measurement work more efficient. When the imaging range is enlarged, the imaging environment tends to vary, and the accuracy of image recognition decreases, but the accuracy of image recognition can be improved by enlarging and reducing the pattern image and performing pattern matching when recognizing the scale characters.

[0048] The hardware configuration of the tape measure reading device 1 will be explained using Figure 12. As shown in Figure 12, the tape measure reading device 1 includes a temporary storage unit 301, a storage unit 302, a calculation unit 303, an input unit 304, a transmitting / receiving unit 305, and a display unit 306. The temporary storage unit 301, storage unit 302, input unit 304, transmitting / receiving unit 305, and display unit 306 are all connected to the calculation unit 303 via a BUS.

[0049] The calculation unit 303 is, for example, a CPU (Central Processing Unit). The calculation unit 303 executes the processing of the scale character recognition unit 133, the image distance calculation unit 134, and the measurement value calculation unit 135 according to the control program stored in the storage unit 302.

[0050] The temporary storage unit 301 is, for example, RAM (Random-Access Memory). The temporary storage unit 301 loads the control program stored in the storage unit 302 and uses it as a work area for the calculation unit 303.

[0051] The storage unit 302 is a non-volatile memory such as flash memory, hard disk, DVD-RAM (Digital Versatile Disc - Random Access Memory), or DVD-RW (Digital Versatile Disc - ReWritable). The storage unit 302 pre-stores a program for causing the calculation unit 303 to perform processing on the tape measure reading device 1, and also supplies the information stored in this program to the calculation unit 303 according to the instructions of the calculation unit 303, and stores the information supplied from the calculation unit 303. The imaging information storage unit 131 and the pattern image information storage unit 132 are configured in the storage unit 302.

[0052] The input unit 304 is an interface device that connects input devices such as keyboards, pointing devices, and voice input devices to the BUS. Information entered by the user is supplied to the calculation unit 303 via the input unit 304. The input unit 304 functions as an operation unit.

[0053] The transmitting / receiving unit 305 is a network termination device or wireless communication device connected to a network, and a serial interface or LAN (Local Area Network) interface connected to them. When the output unit 14 transmits measurement information to an external device or system, the transmitting / receiving unit 305 functions as the output unit 14.

[0054] The display unit 306 is a display device such as an LCD (Liquid Crystal Display) or an organic EL (electroluminescence) display. When the output unit 30 is configured to display importance information on the screen, the display unit 306 functions as the output unit 14.

[0055] The processing of the imaging unit 12, information processing unit 13, and output unit 14 of the tape measure reading device 1 shown in Figure 3 is performed by a control program that uses resources such as the temporary storage unit 301, calculation unit 303, storage unit 302, input unit 304, transmission / reception unit 305, and display unit 306 for processing.

[0056] Furthermore, the aforementioned hardware configuration and flowchart are examples only and can be changed and modified as needed.

[0057] The core components of the tape measure reading device 1, such as the calculation unit 303, temporary storage unit 301, storage unit 302, input unit 304, transmission / reception unit 305, and display unit 306, can be implemented using a standard computer system, rather than a dedicated system. For example, the tape measure reading device 1 can be configured by distributing a computer-readable recording medium such as a flexible disk, CD-ROM (Compact Disc - Read Only Memory), or DVD-ROM (Digital Versatile Disc - Read Only Memory) containing a computer program for performing the aforementioned operations, and then installing the computer program on a computer. Alternatively, the computer program can be stored in a storage device on a server device on a communication network such as the Internet, and the tape measure reading device 1 can be configured by downloading it from a standard computer system.

[0058] Furthermore, if the functions of the tape measure reading device 1 are realized through a division of labor between the OS (Operating System) and the application program, or through cooperation between the OS and the application program, then only the application program portion may be stored on the recording medium or storage device.

[0059] Furthermore, it is possible to superimpose a computer program onto the carrier wave and provide it via a communication network. For example, the computer program may be posted on a bulletin board system (BBS) on the communication network and provided via the communication network. The system may then be configured to execute the aforementioned processing by starting this computer program and running it under the control of the OS, just like other application programs.

[0060] In the above embodiment, an example was described in which the tape measure reading device 1 images the tape 21 pulled out from the opening of the case 22, reads the unit length scale characters and division scale characters attached to the tape 21 from the captured image, and obtains the measurement value from the tape measure 2. However, the invention is not limited to this example. For example, the scale characters attached to the tape 21 may be scale characters that display all digits. In this case, the imaging unit 12 images within an imaging range that includes two or more scale characters that display all digits attached to the tape 21, the in-image distance calculation unit 134 calculates the distance from a reference position in the captured image to the position of the scale line corresponding to the scale character that displays all digits in the captured image, and the measurement value calculation unit 135 calculates the measurement value based on the distance from the reference position in the captured image to the position of the scale line corresponding to the scale character that displays all digits calculated by the in-image distance calculation unit 134 and the distance from the reference position in the captured image to the measurement end position.

[0061] Although preferred embodiments have been described in detail above, the invention is not limited to the embodiments described above, and various modifications and substitutions can be made to the embodiments described above without departing from the scope of the claims.

[0062] The various aspects of this disclosure are summarized below as an appendix.

[0063] (Note 1) An imaging unit that captures the scale markings on the tape of a measuring tape, A scale character recognition unit recognizes the numbers of the scale characters and the positions of the scale lines corresponding to the scale characters in the captured image captured by the imaging unit, An image distance calculation unit calculates the in-image distance from a reference position within the captured image to the position of the tick mark corresponding to the tick mark character, based on the captured image. A measurement value calculation unit calculates the measurement value of the tape measure based on the numbers of the scale characters in the captured image, the distance within the image, and the positional relationship between the position of the scale line corresponding to the scale character and the measurement end position defined in the captured image. A tape measure reading device equipped with [a specific feature]. (Note 2) The system further includes a pattern image information storage unit that stores pattern image information, including the pattern image of the aforementioned scale characters. The aforementioned scale character recognition unit is, The scaling factor of the pattern image included in the pattern image information is changed to perform pattern matching with the captured image, the pattern image with the highest scaling factor matching rate for the scale characters is selected, and the position of the numbers of the scale characters and the corresponding scale lines in the captured image are recognized based on the captured image, the selected pattern image, and the relative positions of the scale lines in the selected pattern image. The tape measure reading device described in Appendix 1. (Note 3) The pattern image information further includes the relative position of the tick marks to the tick marks in the pattern image. The measuring tape reading device described in Appendix 2. (Note 4) The aforementioned scale markings are, It includes unit-length scale characters, which are scale characters for each unit length, and divided scale characters, which are scale characters for each length obtained by dividing the unit length into a predetermined number of parts. The aforementioned scale character recognition unit is, The scaling factor of the pattern image included in the pattern image information is changed to perform pattern matching with the captured image, the pattern image with the highest scaling factor matching rate for the unit length scale characters and the divided scale characters is selected, one matching unit length scale character is determined from the unit length scale characters selected from the pattern image that has the highest matching rate, one matching divided scale character is determined from the divided scale characters selected from the pattern image that has the highest matching rate, and the positions of the numbers of the matching unit length scale characters and the matching divided scale characters and the corresponding scale lines in the captured image are recognized. The image distance calculation unit, The distance from the reference position in the captured image to the position of the tick mark corresponding to the matching division tick mark in the captured image is calculated. A tape measure reading device as described in Appendix 2 or 3. (Note 5) The image distance calculation unit, The distance in pixels from the reference position in the captured image to the position of the tick line corresponding to the matching division tick character in the captured image is calculated. The measuring tape reading device described in Appendix 4. (Note 6) The imaging unit is The imaging range includes one or more of the unit length scale characters attached to the tape. A tape measure reading device as described in Appendix 4 or 5. (Note 7) The imaging unit is Image is taken within the aforementioned imaging range using a lens capable of wide-angle imaging. The measuring tape reading device described in Appendix 6. (Note 8) The system further includes a display unit that displays the measurement value of the measuring tape calculated by the measurement value calculation unit. A tape measure reading device as described in any of the appendices 1 to 7. (Note 9) The tape measure reading device performs the following: The system recognizes the numbers of the scale markings and the positions of the corresponding scale lines in the captured image of the scale markings attached to the tape of a measuring tape. Based on the captured image, the distance within the image from a reference position within the captured image to the position of the tick mark corresponding to the tick mark is calculated. Based on the numbers of the scale characters in the captured image, the distance within the image, and the positional relationship between the position of the scale line corresponding to the scale character and the measurement end position defined in the captured image, the measurement value of the measuring tape is calculated. How to read a tape measure. (Note 10) Computers, A scale character recognition unit that recognizes the numbers of the scale characters and the position of the scale line corresponding to the scale characters in an image captured of the scale characters attached to the tape of a measuring tape. An image distance calculation unit calculates the in-image distance from a reference position within the captured image to the position of the tick mark corresponding to the tick mark character, based on the captured image, and A measurement value calculation unit calculates the measurement value of the tape measure based on the numbers of the scale characters in the captured image, the distance within the image, and the positional relationship between the position of the scale line corresponding to the scale character and the measurement end position defined in the captured image. A program that makes it function as such. [Explanation of Symbols]

[0064] 1 Measuring tape reading device, 2 Measuring tape, 3 Object to be measured, 12 Imaging unit, 13 Information processing unit, 14 Output unit, 21 Tape, 22 Case, 31 Unit length scale characters, 32 Divided scale characters, 33 Imaging range, 34 Centerline, 41 Centerline, 111 Guide unit, 121 Imaging window, 131 Imaging information storage unit, 132 Pattern image information storage unit, 133 Scale character recognition unit, 134 Image distance calculation unit, 135 Measurement value calculation unit, 301 Temporary storage unit, 302 Storage unit, 303 Calculation unit, 304 Input unit, 305 Transmit / receive unit, 306 Display unit, d1~d5 Distance, a~c Side.

Claims

1. An imaging unit that captures the scale markings on the tape of a measuring tape, A scale character recognition unit recognizes the numbers of the scale characters and the positions of the scale lines corresponding to the scale characters in the captured image captured by the imaging unit, An image distance calculation unit calculates the in-image distance from a reference position within the captured image to the position of the tick mark corresponding to the tick mark character, based on the captured image. A measurement value calculation unit calculates the measurement value of the tape measure based on the numbers of the scale characters in the captured image, the distance within the image, and the positional relationship between the position of the scale line corresponding to the scale character and the measurement end position defined in the captured image. A measuring tape reading device equipped with [a specific feature].

2. The system further includes a pattern image information storage unit that stores pattern image information, including the pattern image of the aforementioned scale characters. The aforementioned scale character recognition unit is, The scaling factor of the pattern image included in the pattern image information is changed to perform pattern matching with the captured image, the pattern image with the highest scaling factor matching rate for the scale characters is selected, and the position of the numbers of the scale characters and the corresponding scale lines in the captured image are recognized based on the captured image, the selected pattern image, and the relative positions of the scale lines in the selected pattern image. The measuring tape reading device according to claim 1.

3. The pattern image information further includes the relative position of the tick marks to the tick marks in the pattern image, The measuring tape reading device according to claim 2.

4. The aforementioned scale markings are, It includes unit-length scale characters, which are scale characters for each unit length, and divided scale characters, which are scale characters for each length obtained by dividing the unit length into a predetermined number of parts. The aforementioned scale character recognition unit is, The scaling factor of the pattern image included in the pattern image information is changed to perform pattern matching with the captured image, the pattern image with the highest scaling factor matching rate for the unit length scale characters and the divided scale characters is selected, one matching unit length scale character is determined from the unit length scale characters selected from the pattern image that has the highest matching rate, one matching divided scale character is determined from the divided scale characters selected from the pattern image that has the highest matching rate, and the positions of the numbers of the matching unit length scale characters and the matching divided scale characters and the corresponding scale lines in the captured image are recognized. The image distance calculation unit, The distance from the reference position in the captured image to the position of the tick mark corresponding to the matching division tick mark in the captured image is calculated. The measuring tape reading device according to claim 2 or 3.

5. The image distance calculation unit, The distance in pixels from the aforementioned reference position to the position of the tick mark corresponding to the matching division tick mark character in the captured image is calculated. The measuring tape reading device according to claim 4.

6. The imaging unit is The imaging range includes one or more of the unit length scale characters attached to the tape. The measuring tape reading device according to claim 4.

7. The imaging unit is Image is taken within the aforementioned imaging range using a lens capable of wide-angle imaging. The measuring tape reading device according to claim 6.

8. The system further includes a display unit that displays the measurement value of the measuring tape calculated by the measurement value calculation unit. A measuring tape reading device according to any one of claims 1 to 3.

9. The tape measure reading device performs the following: The system recognizes the numbers of the scale markings and the positions of the corresponding scale lines in the captured image of the scale markings attached to the tape of a measuring tape. Based on the captured image, the distance within the image from a reference position within the captured image to the position of the tick mark corresponding to the tick mark is calculated. Based on the numbers of the scale characters in the captured image, the distance within the image, and the positional relationship between the position of the scale line corresponding to the scale character and the measurement end position defined in the captured image, the measurement value of the measuring tape is calculated. How to read a tape measure.

10. Computers, A scale character recognition unit that recognizes the numbers of the scale characters and the position of the scale line corresponding to the scale characters in an image captured of the scale characters attached to the tape of a measuring tape. An image distance calculation unit calculates the in-image distance from a reference position within the captured image to the position of the tick mark corresponding to the tick mark character, based on the captured image, and A measurement value calculation unit calculates the measurement value of the tape measure based on the numbers of the scale characters in the captured image, the distance within the image, and the positional relationship between the position of the scale line corresponding to the scale character and the measurement end position defined in the captured image. A program that makes it function as such.

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