Surveying rods and systems

Abstract

This enables the acquisition of images of a quality suitable for high-precision photogrammetry. [Solution] A terminal device 12, which is a computer that executes the program according to the present invention, sequentially acquires and displays video footage of the surveying rod 11 output from the camera 123. For each still image constituting the video, the terminal device 12 identifies several accuracy estimation parameters, such as the angle between the shooting direction of the camera 123 and the normal direction of the surveying rod 11, and the clarity of the image, and estimates the accuracy of the photogrammetry based on the identified accuracy estimation parameters. When the estimated accuracy satisfies predetermined conditions, the terminal device 12 notifies the user or automatically captures or generates a still image.

Description

Technical Field

[0001] The present invention relates to the technology of photogrammetry.

Background Art

[0002] There is a photogrammetry technology in which two measurement scales (hereinafter referred to as "measurement scale pair") that are paired are arranged side by side on the surface of the object to be measured, and based on an image taken by a photographing device so that the measurement scale pair is within the field of view, the positional relationship between different points on the surface of the object to be measured is measured. As a patent document describing such a technology, for example, there is Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Due to reasons such as the image of the measurement scale being unclear, photogrammetry using the image may not be possible, or even if photogrammetry is possible, the accuracy of the result may be low.

[0005] In view of the above circumstances, an object of the present invention is to provide means capable of acquiring an image of a quality suitable for high-precision photogrammetry.

Means for Solving the Problems

[0006] To solve the above-mentioned problems, the present invention provides a program for a computer to perform the following processes: acquiring video output from a camera that photographs a surveying rod, which is placed or formed on an object to be measured and has three or more lines drawn on it that form three or more intersections on a plane whose relative positions are known; and displaying a screen on a display device that displays the video acquired in the acquisition process in real time and also displays a guide display object which is a display object that guides the position and size of the image of the surveying rod.

[0007] Furthermore, the present invention provides a program for a computer to perform the following processes: acquiring an image of an object to be measured, on which a measuring rod is placed or formed on the surface, with three or more lines forming three or more intersection points whose relative positions are known drawn on a plane, by a photographing device; identifying one or more of the following as accuracy estimation parameters with respect to the image acquired in the acquisition process: the position of the measuring rod within the field of view of the photographing device; the angle between the shooting direction of the photographing device and the direction of the normal of the measuring rod; the resolution of the scale indicated by the measuring rod in the image taken by the photographing device; the clarity of the image of the measuring rod included in the image taken by the photographing device; and the contrast of the image taken by the photographing device; and estimating the accuracy of photogrammetry using the image of the measuring rod taken by the photographing device based on the accuracy estimation parameters identified in the identification process.

[0008] Furthermore, the present invention provides a method for generating a trained model by machine learning using training data in which a computer generates a trained model using training data in which the accuracy of photogrammetry using the image captured by the camera is the target variable, and the computer generates a trained model using training data in which the computer generates a trained model using training data, with the computer generating a trained model using training data in which the computer generates a trained model using training data, with the computer generating a trained model using training data, training data using training data to determine the accuracy of photogrammetry using the image captured by the camera, and training data to determine the accuracy of photogrammetry using the image captured by the camera, which are identified from an image captured by the camera of a training rod that is placed or formed on an object to be measured and has three or more lines drawn on it that form three or more intersections on a plane whose relative positions to each other are known. [Effects of the Invention]

[0009] According to the present invention, images of a quality suitable for high-precision photogrammetry can be obtained. [Brief explanation of the drawing]

[0010] [Figure 1] A diagram showing the configuration of a surveying system according to one embodiment. [Figure 2] A diagram showing a pair of surveying rods according to one embodiment. [Figure 3] A diagram showing a group of straight lines forming the outer edges of multiple squares that constitute the staggered pattern of a surveying rod according to one embodiment. [Figure 4] A diagram showing the configuration of a terminal device according to one embodiment. [Figure 5] A diagram showing the configuration of a server device according to one embodiment. [Figure 6] A diagram showing a shooting screen displayed by a terminal device according to one embodiment. [Figure 7] A flowchart of the processing performed by the processor of a terminal device according to one embodiment. [Figure 8] A diagram illustrating the process of identifying and distinguishing intersections performed by a terminal device according to one embodiment. [Figure 9] A diagram showing the configuration of a data table stored by a server device according to one embodiment. [Figure 10] A diagram illustrating a line forming an intersection point of surveying scales according to a modification example. [Figure 11] A diagram illustrating a line forming an intersection point of surveying scales according to a modification example. [Figure 12] A diagram for explaining the merits of surveying scales according to a modification example. [Figure 13] A diagram illustrating a pair of surveying scales according to a modification example. [Figure 14] A diagram illustrating a pair of surveying scales according to a modification example. [Figure 15] A diagram illustrating a surveying scale according to a modification example. [Figure 16] A diagram illustrating a surveying scale according to a modification example. [Figure 17] A diagram showing the configuration of a data table stored in a server device according to a modification example. [Figure 18] A diagram illustrating a surveying scale according to a modification example.

Mode for Carrying Out the Invention

[0011] The surveying system 1 according to an embodiment of the present invention will be described below. FIG. 1 is a diagram showing the configuration of the surveying system 1. The surveying system 1 is a system for photogrammetrically measuring the positional relationship between different points on the surface of the object to be measured 9.

[0012] The surveying system 1 includes a surveying scale 11S (an example of a first surveying scale) and a surveying scale 11T (an example of a second surveying scale) fixedly arranged on the surface of the object to be measured 9 by adhesion or the like, a terminal device 12 used by a user, and a server device 13 that communicates with the terminal device 12.

[0013] In the example of FIG. 1, a crack 91 has occurred in the object to be measured 9, and the surveying scale 11S and the surveying scale 11T are arranged with the crack 91 interposed therebetween. The surveying system 1 measures the positional relationship between a reference point on the surveying scale 11S and a measurement point on the surveying scale 11T using an image taken with both the surveying scale 11S and the surveying scale 11T within the field of view.

[0014] Figure 2 shows a surveying rod 11S and a surveying rod 11T. The surveying rod 11S is the reference surveying rod, and the surveying rod 11T is the surveying rod being surveyed. The surveying rods 11S and 11T constitute a surveying rod pair 10. Hereafter, when the surveying rods 11S and 11T are not distinguished from each other, they will be referred to as the surveying rod 11.

[0015] The surveying rod 11 comprises a plate-shaped or sheet-shaped medium and an image formed on the surface of the medium by printing, laser engraving, or the like.

[0016] The image of the surveying rod 11 contains a staggered pattern of the same shape and size. The image of the surveying rod 11T contains a QR code (registered trademark). Alternatively, the image of the surveying rod 11S may contain the QR code instead of the image of the surveying rod 11T. This QR code is a mark that identifies the surveying rod from other similar surveying rods. In other words, decoding this QR code yields identification information that distinguishes the surveying rod 11T containing that QR code from other surveying rods 11T.

[0017] Figure 3 shows the group of straight lines that form the outer edges of the multiple squares that make up the staggered pattern drawn on the surveying rod 11. In other words, the group of straight lines shown in Figure 3 is the group of straight lines drawn by the staggered pattern on the surveying rod 11.

[0018] The group of straight lines drawn by the staggered pattern of the surveying rod 11 includes line segments L1 to L4, which are four parallel line segments spaced at a distance D, and line segments M1 to M4, which are four parallel line segments perpendicular to line segments L1 to L4 and spaced at a distance D.

[0019] The lengths of line segments L1 and M1 are three times the distance D. Line segments L1 and M1 are positioned such that one of their endpoints coincides at the intersection point P(1,1).

[0020] The lengths of line segments L2 and M2 are three times the distance D. One endpoint of line segment L2 coincides with the intersection point P(2,1) on line segment M1, which is a distance D from the intersection point P(1,1), and it extends in the same direction as line segment L1 extends from the intersection point P(1,1). One endpoint of line segment M2 coincides with the intersection point P(1,2) on line segment L1, which is a distance D from the intersection point P(1,1), and it extends in the same direction as line segment M1 extends from the intersection point P(1,1).

[0021] The lengths of line segments L3 and M3 are twice the distance D. One endpoint of line segment L3 coincides with the intersection point P(3,1), which is twice the distance D from the intersection point P(1,1) on line segment M1, and it is positioned to extend in the same direction as line segment L1 extends from intersection point P(1,1). One endpoint of line segment M3 coincides with the intersection point P(1,3), which is twice the distance D from the intersection point P(1,1) on line segment L1, and it is positioned to extend in the same direction as line segment M1 extends from intersection point P(1,1).

[0022] The lengths of line segments L4 and M4 are distance D. One endpoint of line segment L4 coincides with the intersection point P(4,1) (i.e., the other endpoint of line segment M1), which is three times the distance D from the intersection point P(1,1) on line segment M1, and is positioned to extend in the same direction as line segment L1 extends from intersection point P(1,1). One endpoint of line segment M4 coincides with the intersection point P(1,4) (i.e., the other endpoint of line segment L1), which is three times the distance D from the intersection point P(1,1) on line segment L1, and is positioned to extend in the same direction as line segment M1 extends from intersection point P(1,1).

[0023] As shown above, there are a total of 13 intersection points P, which are the points where each of the line segments L1 to L4 intersects with each of the line segments M1 to M4. As shown in Figure 3, the intersection points of line segment Li (where i is one of the natural numbers from 1 to 4) and line segment Mj (where j is one of the natural numbers from 1 to 4) are represented as intersection point P(i,j).

[0024] As described above, the positional relationship of the 13 intersection points P is known. Furthermore, the positional relationship of the 13 intersection points P is not rotationally symmetric.

[0025] When the surveying rods 11S and 11T are superimposed so that the 13 intersection points P of the surveying rod 11S and the 13 intersection points P of the surveying rod 11T overlap, the parts of the image of the surveying rod 11S that depict line segments L1-L4 and M1-M4 have different colors from the parts of the image of the surveying rod 11S that overlap with those parts. For example, line segment L1 of the surveying rod 11 is depicted as the sides of the following three squares.

[0026] First square: A square with vertices at intersections P(1,1), P(1,2), P(2,2), and P(2,1). Second square: A square with vertices at intersections P(1,2), P(1,3), P(2,3), and P(2,2). Third square: A square with vertices at intersections P(1,3), P(1,4), P(2,4), and P(2,3).

[0027] Furthermore, the color of the first square on the surveying rod 11S (for example, white) is different from the color of the first square on the surveying rod 11T (for example, black). Also, the color of the second square on the surveying rod 11S (for example, black) is different from the color of the second square on the surveying rod 11T (for example, white). Furthermore, the color of the third square on the surveying rod 11S (for example, white) is different from the color of the third square on the surveying rod 11T (for example, black).

[0028] In this application, "different colors" means that at least one of the hue, lightness, and saturation of the colors is different.

[0029] The intersection point P(1,1) of the surveying rod 11S will be the control point. Also, the intersection point P(1,1) of the surveying rod 11T will be the survey point.

[0030] The coordinate system C is determined by three or more intersection points P of the surveying rod 11S. The coordinate system C is as follows:

[0031] Origin: Intersection point P(1,1) of the 11S measuring rod. X-axis positive direction: Direction from intersection P(1,4) to intersection P(4,1) of the surveying rod 11S. Y-axis positive direction: Direction from intersection P(2,2) to intersection P(1,1) of the surveying rod 11S.

[0032] The coordinate system E is determined by three or more intersection points P of the 11T measuring rod. The coordinate system E is as follows:

[0033] Origin: Intersection point P(1,1) of the 11T measuring rod. X-axis positive direction: Direction from intersection P(1,4) to intersection P(4,1) of the 11T surveying rod. Y-axis positive direction: Direction from intersection P(2,2) to intersection P(1,1) of the 11T surveying rod.

[0034] Figure 4 shows the configuration of the terminal device 12. The terminal device 12 is a computer that includes a memory 121 for storing various data and a processor 122 for performing various data processing according to a program continuously stored in the memory 121. The type of computer for the terminal device 12 is not limited, but it is desirable that it be a small and lightweight computer that can be easily carried by the user.

[0035] Furthermore, the terminal device 12 includes a camera 123 (an example of a shooting device) that generates video and still images by shooting, a touchscreen 124 having a stacked display (an example of a display device) and a touch panel, and a communication interface 125 which is an interface for communication with the server device 13.

[0036] The terminal device 12 may also be equipped with a display and an input device that accepts user input, such as a mouse, instead of the touchscreen 124. Furthermore, at least one of the camera 123, the touchscreen 124 (or a substitute thereof), and the communication interface 125 may be connected to the terminal device 12 as an external device, rather than being built into the terminal device 12.

[0037] In the following description, terminal device 12 is assumed, for example, to be a smartphone capable of communication and calls via a mobile communication network using a communication interface 125.

[0038] Figure 5 shows the configuration of the server device 13. The server device 13 is a computer that includes a memory 131 for storing various data, a processor 132 for performing various data processing according to a program persistently stored in the memory 131, and a communication interface 133 for communication with the terminal device 12.

[0039] The user uses the camera 123 of the terminal device 12 to photograph the pair of measuring rods 10 on the object under survey 9 in order to measure the positional relationship between the reference point and the survey point of the object under survey 9.

[0040] Figure 6 shows the screen displayed by the terminal device 12 when the user photographs the pair of surveying rods 10 on the object to be measured 9 (hereinafter referred to as the "photography screen").

[0041] The shooting screen includes an area R1 which displays the video captured by the camera 123 in real time and also displays a guide display object G; a display object R2 which displays a similarity (hereinafter referred to as "similarity S") indicating the degree of agreement between the image of the surveying rod 11S displayed in area R1 and the guide display object G; a button R3 which is a virtual button that the user touches to instruct the camera 123 to take a still image; and an area R4 which displays a message prompting the user to touch button R3 when it is time for the user to touch button R3.

[0042] The processor 122 of the terminal device 12 performs the following processing while the shooting screen is displayed on the touchscreen 124, according to the program stored in the memory 121.

[0043] This process involves having camera 123 record video and acquiring the video generated by camera 123. This process displays the video acquired from the camera 123 in real time on the touchscreen 124, in the shooting screen area R1. The process involves overlaying a guide display G onto the video acquired from the camera 123, within the area R1 of the shooting screen on the touchscreen 124. A process that continuously calculates the similarity S, which indicates the degree of agreement between the image of the surveying rod 11S displayed in area R1 of the shooting screen and the guide display object G. A process to display a display object R2 on the touchscreen 124, which represents the similarity S that is continuously updated. A process to display a message on the touchscreen 124 in the area R4 of the shooting screen, prompting the user to touch button R3 (for example, "Please press the shutter button.") when the similarity S satisfies a predetermined condition (hereinafter referred to as "condition Q").

[0044] The guiding display object G is a display object that indicates the position and size of the image of the surveying rod 11S displayed in area R1 of the shooting screen. The guiding display object G exemplified in Figure 6 indicates the positions where line segments L1~L4 and M1~M4 of the image of the surveying rod 11S should be captured. However, the format of the guiding display object G can be changed in various ways as long as it indicates the position and size of the image of the surveying rod 11S displayed in area R1 of the shooting screen.

[0045] In order to calculate the similarity S, the processor 122 first recognizes an image of the surveying rod 11S from the image displayed in region R1 using a known image recognition method.

[0046] Next, the processor 122 calculates the similarity S between the image of the recognized surveying rod 11S and the directional sign G.

[0047] As an example, the processor 122 calculates the degree of similarity S as the degree of agreement between the positions of 13 intersection points P (examples of feature points) identified from the image of the surveying rod 11S and the intersection points P (examples of feature points) of the directional sign G. More specifically, for example, the processor 122 associates the 13 intersection points P identified from the image of the surveying rod 11S with the intersection points P of the directional sign G, identifies 13 pairs of intersection points, calculates the distance between two intersection points P for each of those 13 pairs of intersection points, and calculates the similarity S as a value obtained by subtracting the sum of these distances from a constant. Note that the method for calculating the similarity S is not limited to this, and any method may be adopted as long as it is a method that calculates a similarity S as an index value that indicates the degree of agreement between the positions of feature points extracted from the image of the surveying rod 11S and the positions of feature points of the directional sign G corresponding to those feature points.

[0048] Condition Q is, for example, a condition that is satisfied if the similarity S is greater than or equal to a predetermined threshold T. The processor 122 continuously calculates the similarity S and continuously determines whether the similarity S satisfies condition Q. While the similarity S does not satisfy condition Q, it displays a message such as "Align the image with the guide" in area R4 on the touchscreen 124, and while the similarity S satisfies condition Q, it displays a message such as "Press the shutter."

[0049] The processor 122 may also cause the touchscreen 124 to be in an inactive state (not accepting user touch operations on button R3) while the similarity S does not satisfy condition Q, and to be in an active state (accepting user touch operations on button R3) while the similarity S satisfies condition Q.

[0050] The user adjusts the orientation of the terminal device 12 and the distance between the terminal device 12 and the object to be measured 9, while referring to the display object R2, so that the image of the surveying rod 11S displayed in area R1 matches the guidance display object G as closely as possible. In response to this adjustment, the similarity S displayed by the display object R2 changes, and when the similarity S exceeds the threshold T, a message such as "Please take a picture." is displayed in area R4. In response to this message, the user touches button R3.

[0051] In response to a user touching button R3, the processor 122 instructs the camera 123 to take a still image. The camera 123 takes a still image in response to the instruction and outputs the captured still image (hereinafter referred to as "still image I") to the processor 122. The processor 122 acquires the still image I output from the camera 123 and stores the still image I, along with the time it was acquired, in the memory 121.

[0052] Next, processor 122 uses the still image I to perform processing according to the flowchart shown in Figure 7.

[0053] The processor 122 decodes the QR code contained in the still image I and obtains identification information for the surveying rod 11T (step S1).

[0054] Next, the processor 122 identifies and distinguishes a total of 26 intersection points P indicated by the images of the surveying rods 11S and 11T contained in the still image I (step S2).

[0055] Figure 8 is a diagram illustrating the processing performed by the processor 122 in step S2.

[0056] Figure 8(A) shows still image I. The processor 122 detects multiple intersection points P from the checkerboard pattern contained in the images of the surveying rod 11S and surveying rod 11T included in still image I, using a known corner detection method. Figure 8(B) shows the multiple intersection points P thus detected. In Figure 8(B), the intersection points P are represented as the center points of the X marks (the intersection points of the two line segments that make up X).

[0057] Next, the processor 122 identifies the two furthest apart points from the multiple intersection points P it detected as intersection point A1 and intersection point A2. Figure 8(C) shows intersection points A1 and A2 as identified in this way.

[0058] Next, processor 122 identifies the two points closest to intersection A1 as intersection B1 and intersection C1, and confirms that the lengths of line segments A1B1 and A1C1 are equal and that the angle B1A1C1 is 90 degrees. This confirmation is performed to exclude points that are not intersection P, as these may be mistakenly included in the points detected from still image I. Therefore, processor 122 excludes any points that do not satisfy the above conditions from intersection P. This process will be referred to below as the "adjacent intersection identification process".

[0059] The processor 122 also performs the process of identifying adjacent intersections for intersection A2, and identifies intersections B2 and C2 that are adjacent to intersection A2.

[0060] Figure 8(D) shows the intersections A1-C1 and A2-C2 identified as described above.

[0061] The processor 122 repeats the process of identifying adjacent intersections for each of the newly identified adjacent intersections (for example, intersections B1, C1, B2, and C2 mentioned above) until it identifies 13 intersections starting from intersection A1 (including intersection A1) and 13 intersections starting from intersection A2 (including intersection A2).

[0062] Figure 8(E) shows the newly identified intersection D1 adjacent to intersection B1, intersections E1 and F1 adjacent to intersection C1, intersection D2 adjacent to intersection B2, and intersections E2 and F2 adjacent to intersection C2.

[0063] Figure 8(F) shows the state in which 13 intersections (including intersection A1) starting from intersection A1 and 13 intersections (including intersection A2) starting from intersection A2 have been identified. The 13 intersections (including intersection A1) starting from intersection A1 are the intersection point P group of the surveying rod 11S. The 13 intersections (including intersection A2) starting from intersection A2 are the intersection point P group of the surveying rod 11T.

[0064] The processor 122 identifies the pair with the smallest distance between two intersection points P, one arbitrarily selected from the group of intersection points P of the surveying rod 11S and the other arbitrarily selected from the group of intersection points P of the surveying rod 11T, as intersection point P(1,1). As previously described, the intersection point P(1,1) identified from the group of intersection points P of the surveying rod 11S is the control point, and the intersection point P(1,1) identified from the group of intersection points P of the surveying rod 11T is the survey point. Figure 8(G) shows the state in which the control point and the survey point have been identified.

[0065] Next, the processor 122 identifies each of the other 12 intersection points P based on the positional relationship with respect to intersection point P(1,1) for each of the intersection point P groups of the surveying rod 11S and the surveying rod 11T. That is, the processor 122 identifies which intersection point P is intersection point P(1,2), intersection point P(2,1), etc.

[0066] The above describes the processing performed by the processor 122 in step S2 of Figure 7. Note that the processing in step S2 described above is just one example of the processing performed by the processor 122 for identifying and distinguishing intersections P, and the processor 122 may identify and distinguish intersections P by different processing. For example, the processor 122 may perform grouping of multiple intersections P detected from the checkerboard pattern and identification of each intersection P in each group by matching a reference image representing the positional relationship of the 13 intersections P with a comparison image representing the positional relationship of multiple intersections P detected from the checkerboard pattern in the images of the surveying rod 11S and surveying rod 11T contained in the still image I.

[0067] Following the processing in step S2, the processor 122 converts the image in which the 26 intersection points P are drawn into an orthogonal projection image using a known orthogonal projection transformation method, so that the 26 intersection points P are the intersection points of line segments that are correctly orthogonal to each other (step S3).

[0068] Next, the processor 122 identifies coordinate system C based on the positions of the intersection points P of the surveying rod 11S included in the orthographic projection image obtained by the transformation in step S3, and identifies coordinate system E based on the positions of the intersection points P of the surveying rod 11T included in the orthographic projection image obtained by the transformation in step S3 (step S4).

[0069] Next, the processor 122 identifies the coordinates in coordinate system C of the intersection point P(1,1) of the surveying rod 11T included in the orthographic projection image obtained by the transformation in step S3, i.e., the survey point (step S5). The coordinates of the survey point in coordinate system C, with the reference point as the origin, indicate the positional relationship between the reference point and the survey point (for example, the distance between the reference point and the survey point, and the direction of the survey point as seen from the reference point).

[0070] Next, the processor 122 determines the angle between the X-axis direction of coordinate system C and the X-axis direction of coordinate system E (synonymous with the angle between the Y-axis direction of coordinate system C and the Y-axis direction of coordinate system E) (hereinafter referred to as the "angle between coordinate systems") (step S6). The angle between coordinate systems indicates the positional relationship between coordinate system C and coordinate system E in the direction of rotation (for example, how much the X-axis (or Y-axis) of coordinate system E rotates around its origin (survey point) in coordinate system C).

[0071] Next, the processor 122 stores in memory 121 the time at which the still image I was acquired from camera 123, the identification information of the surveying rod 11T acquired from the QR code in step S1, the coordinates of the survey point in coordinate system C identified in step S5, and the angle between coordinate systems identified in step S6, and also controls the communication interface 125 to transmit this information to the server device 13 (step S7).

[0072] The above is a description of the processing performed by the processor 122 of the terminal device 12 according to the flow chart in Figure 7.

[0073] When the server device 13 receives the acquisition time of the still image I, the identification information of the surveying rod 11T, the coordinates of the survey point, and the angle between coordinate systems transmitted from the terminal device 12, it stores that information.

[0074] When a user takes a photograph of the object to be measured 9 with the camera 123 of the terminal device 12, which has the shooting screen displayed on the touchscreen 124, so that the pair of measuring rods 10 are in the field of view, the identification information of the measuring rod 11T, the coordinates of the measurement point, and the angle between the coordinate systems, which are identified from the still image I obtained by the photograph, are transmitted from the terminal device 12 to the server device 13 along with the time the still image I was taken, and are stored in the server device 13.

[0075] Figure 9 shows the configuration of a data table (hereinafter referred to as the "survey result table") in which the server device 13 stores information received from the terminal device 12. The server device 13 stores, for example, a different survey result table for each identification information of the surveying rod 11T, and each of these survey result tables has a data field "time" that stores the time received from the terminal device 12, a data field "coordinates of the survey point" that stores the coordinates of the survey point received from the terminal device 12, and a data field "angle between coordinate systems" that stores the angle between coordinate systems received from the terminal device 12. The data records included in the survey result table are, for example, sorted in chronological order from oldest to newest.

[0076] The coordinates of the survey point stored in the first data record (the oldest time) in the survey results table indicate the initial positional relationship between the control point and the survey point. Furthermore, the angle between coordinate systems stored in the first data record (the oldest time) in the survey results table indicates the initial positional relationship between coordinate system C and coordinate system E in the direction of rotation.

[0077] Furthermore, the coordinates of the survey points stored in the second row and subsequent rows of the data records included in the survey results table are compared with the coordinates of the survey points stored in the first data record to show the change in the position of the survey points relative to the reference point over time. In addition, the angles between coordinate systems stored in the second row and subsequent rows of the data records included in the survey results table are compared with the angles between coordinate systems stored in the first data record to show the change in the rotation angle around the origin of coordinate system E relative to coordinate system C over time. Therefore, the user of the survey system 1 can, for example, know the speed and direction of expansion of cracks 91 in the object under survey 9 based on the information stored in the survey results table.

[0078] The surveying rod 11 has the following advantages compared to the surveying rod (target) used in the prior art described in Patent Document 1 (hereinafter simply referred to as "prior art").

[0079] (1) Conventional surveying rods indicate the positions of control points, survey points, etc., using circular marks, which requires a process to identify the center point of the marks, and this process increases the surveying error. On the other hand, the surveying rod 11 used in surveying system 1 indicates the positions of control points, survey points, etc., using line intersections, so the process of identifying the center point of the marks as in conventional technology is unnecessary, and higher accuracy surveying results can be obtained compared to when using conventional surveying rods.

[0080] (2) Conventional surveying rods indicate the positions of reference points, survey points, etc., with circular marks. Therefore, when a surveying rod is photographed from an oblique angle, the marks included in the photographed image become ellipses, and the number of parameters that must be identified from the image to determine its center point increases compared to the case of a circle. As a result, when using conventional surveying rods, the direction in which the surveying rod is photographed greatly affects the accuracy of the survey results. On the other hand, the surveying rod 11 used in surveying system 1 indicates the positions of reference points, survey points, etc., with line intersections. Therefore, compared to when using conventional surveying rods, the direction in which the surveying rod 11 is photographed has less influence on the accuracy of the survey results.

[0081] (3) Conventional surveying rods indicate the positions of reference points, survey points, etc., with circular marks. If dirt adheres to the surveying rod or dust adheres to the lens of the camera 123, etc., and dot-like noise images appear in the image of the surveying rod, these noise images may be mistaken for marks, making it easy to incorrectly identify the positions of reference points, survey points, etc. On the other hand, the surveying rod 11 used in the surveying system 1 indicates the positions of reference points, survey points, etc., with line intersections. Therefore, even if dot-like noise images appear in the image of the surveying rod 11, the positions of reference points, survey points, etc., will not be incorrectly identified by these noise images.

[0082] Furthermore, since the aforementioned terminal device 12 displays an image in which the guidance display object G is overlaid on the image captured by the camera 123, the user can adjust the orientation of the terminal device 12 and the distance between the terminal device 12 and the object to be measured 9 so that the image of the surveying rod 11 matches the guidance display object G as closely as possible, thereby enabling the capture of images that yield highly accurate survey results.

[0083] This is because the position and size of the image of the surveying rod 11 captured by camera 123 match the position and size of the guide sign G when camera 123 is photographing the surveying rod 11 from the front, that is, when the shooting direction of camera 123 and the direction of the normal of the surveying rod 11 coincide, thus minimizing errors in the conversion process to an orthographic projection image (step S3 in Figure 7).

[0084] Furthermore, the state in which the position and size of the image of the surveying rod 11 captured by camera 123 coincide with the position and size of the guiding sign G is because the surveying rod 11 is captured in the central area of ​​camera 123's field of view where distortion is minimal. Therefore, by using the image captured in this state for surveying, the impact of image distortion on the accuracy of the surveying results is suppressed.

[0085] Furthermore, according to the terminal device 12 described above, the user is notified of the similarity S between the image of the surveying rod 11 captured by the camera 123 and the guide display object G. When the similarity S is sufficiently high, a message prompting the user to operate the shutter is displayed. As a result, the user can easily capture images that yield sufficiently high-precision survey results by operating the shutter in response to these notifications or messages.

[0086] [Differentiation] The embodiments described above can be modified in various ways within the scope of the technical idea of ​​the present invention. Examples of such modifications are shown below. Furthermore, two or more of the exemplary modifications shown below may be combined and adopted.

[0087] [Variations of a surveying rod] The following shows modified versions of the surveying rod 11. Figure 10 is an example of the lines forming the intersection point P of the surveying rod 11 according to the following modified versions (1) to (4).

[0088] (1) The lines forming the intersection point P of the surveying rod 11 described above are the boundaries of adjacent areas painted in different colors. The boundaries of adjacent areas painted in different colors have no width. If lines with width are used, it is necessary to determine the center of the line, and errors occur in that process. On the other hand, with the surveying rod 11 described above, such errors do not occur.

[0089] However, if the above-mentioned error caused by the wide lines is within an acceptable range, the image of the surveying rod 11 may include wide lines instead of the checkerboard pattern. Figure 10(A) is an example of the lines forming the intersection point P of the surveying rod 11 according to this modified example. (2) The lines forming the intersection point P of the surveying rod 11 described above include a first group of lines (e.g., line segments L1 to L4) arranged parallel to each other, and a second group of lines (e.g., line segments M1 to M4) arranged parallel to each other and perpendicular to those groups of lines. When the first group of lines and the second group of lines are perpendicular to each other, the angle verification process included in the adjacent intersection point identification process performed in step S2 of Figure 7 is easier compared to when they are not perpendicular to each other.

[0090] However, if it is acceptable for the angle verification process to be somewhat complex, the first group of lines and the second group of lines do not have to be orthogonal. Figure 10(B) illustrates the checkerboard pattern of the surveying rod 11 according to this modified example.

[0091] (3) The group of lines forming the intersection points P of the surveying rod 11 described above is not rotationally symmetric. Therefore, regardless of the direction in which the surveying rod 11 is positioned on the object under survey 9, each of the intersection points P of the control points, survey points, etc., can be uniquely identified.

[0092] However, if the surveying rods 11S and 11T are positioned in an appropriate positional relationship with respect to the object 9 being surveyed, then each of the intersection points P, such as the control point and the survey point, can be identified from their positional relationship. Therefore, the group of lines forming the intersection points P of the surveying rods 11 may be rotationally symmetric. Figure 10(C) is an example of a checkerboard pattern of the surveying rods 11 according to this modified example.

[0093] (4) The lines forming the intersection points P of the surveying rod 11 may be any lines, as long as they are three or more lines drawn on a plane that form three or more intersection points P whose relative positions are known to each other. Figure 10(D) is a diagram illustrating the lines forming the intersection points P of the surveying rod 11 according to this modified example.

[0094] (5) In the surveying rod pair 10 described above, a QR code indicating identification information is drawn on the surveying rod 11T, but instead of the surveying rod 11T, the QR code may be drawn on the surveying rod 11S.

[0095] (6) The surveying rod 11T described above has a QR code drawn on it as a mark to distinguish it from other surveying rods 11T. However, the form of the mark to distinguish a surveying rod 11T from other surveying rods 11T is not limited to a QR code. A two-dimensional barcode other than a QR code, or an image representing a code such as a one-dimensional barcode, may be drawn on the surveying rod 11T in place of a QR code. In addition, a sequence of letters, numbers, symbols, etc., may be drawn on the surveying rod 11T in place of a QR code.

[0096] (7) A QR code is drawn on the surveying rod 11T as described above, to serve as a marker to distinguish that surveying rod 11T from other surveying rods 11T. This marker makes it easy to distinguish the object 9 on which the surveying rod 11T is placed from other objects 9 to be measured.

[0097] However, if the object to be measured 9 can be identified by other means, it is not necessary to have a mark on the leveling rod 11T that distinguishes it from other leveling rods 11T.

[0098] (8) The surveying rod 11 described above comprises a plate-shaped or sheet-shaped medium and an image formed on the medium. Alternatively, the surveying rod 11 may not have a medium and may instead have an image formed on the object being surveyed. For example, an object being surveyed may be realized by directly forming an image including a checkerboard pattern or a QR code on the object being surveyed by printing, laser engraving, etc.

[0099] (9) The checkerboard pattern of the surveying rod 11S and the checkerboard pattern of the surveying rod 11T are painted in different colors in areas corresponding to each other. Therefore, the user or device can easily distinguish between the surveying rod 11S and the surveying rod 11T in the two surveying rods 11 included in the surveying rod pair 10 based on their colors.

[0100] However, if the surveying rods 11S and 11T can be distinguished by means other than color, then the surveying rods 11S and 11T do not need to be distinguished by color.

[0101] (10) The figures drawn on the surveying rod 11 (see Figure 3) according to the above embodiment have the following characteristics: (Feature 1) It has a first line segment (line segment L1) and a second line segment (line segment M1) that share the same starting point. (Feature 2) It has one or more polygons (polygons exemplified by six squares such as squares P(1,1), P(1,2), P(2,2), P(2,1), etc.) located on the interior angle side of the first line segment (the line segment exemplified by line segment L1) and the second line segment (the line segment exemplified by line segment M1). (Feature 3) The length of the entire figure in the direction of the angle bisector of the angle formed by the first and second line segments (the length of the line segment P(1,1)P(3,3) is shorter than the length between the endpoints of the first and second line segments (the length of the line segment P(1,4)P(4,1) is an example).

[0102] A surveying rod with the above-mentioned features and a drawn design offers the following advantages: Because it has three or more points drawn, it can be used to measure the positional relationship between two adjacent areas of an object being surveyed. Since the common starting point of the first and second line segments drawn is always located at the tip of the convex part of the outer edge of the entire figure, by using that point as the reference point for one of the surveying rods and the survey point for the other surveying rod, the distance between the reference point and the survey point can be shortened, and as a result, the accuracy of the survey can be improved. Because the entire drawn figure has a long, narrow shape where the angle bisector of the angle formed by the first and second line segments is shorter in the direction of the bisector, it can also be used for surveying objects with a narrow width.

[0103] While possessing the above-described features 1 to 3, a surveying rod with a different figure drawn on it may be used, compared to the surveying rod 11 according to the embodiment described above (see Figure 3). An example of a figure drawn on such a modified surveying rod 11 is shown in Figure 11.

[0104] The figure illustrated in Figure 11(A) has fewer first line segments (line segment L1) and line segments parallel to the first line segment, and fewer second line segments (line segment M1) and line segments parallel to the second line segment, compared to the figure in Figure 3. Furthermore, the figure illustrated in Figure 11(B) has more first line segments (line segment L1) and line segments parallel to the first line segment, and more second line segments (line segment M1) and line segments parallel to the second line segment, compared to the figure in Figure 3.

[0105] In the figure illustrated in Figure 11(C), the number of line segments parallel to the first line segment (line segment L1) is different from the number of line segments parallel to the second line segment (line segment M1).

[0106] In the figure shown in Figure 3, the angle between the first line segment (L1) and the second line segment (M1) is 90 degrees. In contrast, in the figure illustrated in Figure 11(D), the angle (interior angle) between the first line segment (L1) and the second line segment (M1) is acute. Also, in the figure illustrated in Figure 11(E), the angle (interior angle) between the first line segment (L1) and the second line segment (M1) is obtuse.

[0107] In the figure illustrated in Figure 11(F), the interval between the first line segment (line segment L1) and two adjacent line segments parallel to the first line segment is different from the interval between the second line segment (line segment M1) and two adjacent line segments parallel to the second line segment.

[0108] In the figure illustrated in Figure 11(G), the distance between the first line segment (line segment L1) and any two adjacent line segments parallel to the first line segment is not constant. Also, in the figure illustrated in Figure 11(G), the distance between the second line segment (line segment M1) and any two adjacent line segments parallel to the second line segment is not constant.

[0109] In the figures illustrated in Figures 3 and 11(A) to 11(G), the starting points of all line segments parallel to the first line segment (line segment L1) lie on the second line segment, and the starting points of all line segments parallel to the second line segment (line segment M1) lie on the first line segment. In contrast, the figure illustrated in Figure 11(H) includes a line segment LX parallel to the first line segment (line segment L1) whose starting point does not lie on the second line segment (line segment M1).

[0110] The figure illustrated in Figure 11(I) has a portion where the polygons positioned on the interior angles of the first line segment (line segment L1) and the second line segment (line segment M1) are not touching. Note that, as in the example in Figure 11(I), if the endpoint of the first line segment (line segment L1) or the second line segment (line segment M1) is not an intersection with another line segment, that endpoint may be used as a known feature point.

[0111] Figures possessing the above-described characteristics 1 to 3 are figures that, as a whole, fit within a flattened triangular region, as illustrated in Figures 3 and 11. Therefore, compared to figures that do not satisfy characteristics 1 to 3, such as the figure in Figure 10(C), the size of the surveying rod 11 on which the figure is drawn (the length in the Y-axis direction in Figure 3, i.e., the length in the direction of the angle bisector of the angle formed by the first and second line segments) can be reduced.

[0112] (11) The surveying rod 11 according to the above embodiment comprises a plate-shaped or sheet-shaped medium and an image formed on the medium, as shown in Figure 2. For example, in the case of the surveying rod 11S shown in Figure 2, the outer edge of the portion of the medium adjacent to the first line segment (line segment L1) is parallel to the first line segment, but the outer edge of the portion adjacent to the second line segment (line segment M1) is not parallel to the second line segment.

[0113] In contrast, the measuring rod 11 may be configured such that the outer edge of the portion adjacent to the first line segment (line segment L1) is parallel to the first line segment, and the outer edge of the portion adjacent to the second line segment (line segment M1) is parallel to the second line segment.

[0114] In this application, "the portion of the outer edge of the medium adjacent to the line segment" means the portion of the outer edge of the medium between the point closest to the starting point of the line segment and the point closest to the ending point of the line segment.

[0115] Figure 12 is a diagram illustrating the advantages of the measuring rod 11 according to this modified example. Figure 12(A) shows the pair of measuring rods 10 from Figure 2, positioned on the object under survey 9 so as to straddle the crack 91. Figure 12(B) shows the pair of measuring rods 10 according to this modified example, positioned on the object under survey 9 so as to straddle the crack 91.

[0116] In Figure 12(A), the portion p1 of the surveying rod 11S that constitutes the pair of surveying rods 10 is not parallel to the second line segment (line segment M1) but protrudes outward. Also, in Figure 12(A), the portion p2 of the surveying rod 11T that constitutes the pair of surveying rods 10 that constitutes the pair of surveying rods 10 is not parallel to the first line segment (line segment L1) but protrudes outward.

[0117] On the other hand, in the surveying rod pair 10 shown in Figure 12(B), the portion p1 of the medium of the surveying rod 11S adjacent to the second line segment (line segment M1) is parallel to the second line segment and does not protrude outwards. Also, in the surveying rod pair 10 shown in Figure 12(B), the portion p2 of the medium of the surveying rod 11T adjacent to the first line segment (line segment L1) is parallel to the first line segment and does not protrude outwards.

[0118] Therefore, compared to using the pair of surveying rods 10 shown in Figure 12(A), using the pair of surveying rods 10 shown in Figure 12(B) allows for a shorter distance d between the intersection point P(1,1) (reference point) of the surveying rods 11S and the intersection point P(1,1) (survey point) of the surveying rods 11T.

[0119] In surveying using the leveling rod pair 10, the shorter the distance between the reference point and the survey point, the higher the accuracy of the survey. Therefore, the leveling rod pair 10 shown in Figure 12(B) can be used to perform surveys with higher accuracy than the leveling rod pair 10 shown in Figure 12(A).

[0120] (12) In the two surveying rods 11 (surveying rod 11S and surveying rod 11T) that constitute the surveying rod pair 10 according to the above embodiment, as shown in Figure 2, the color schemes for drawing multiple line segments that form multiple intersection points P are different between the two surveying rods 11.

[0121] As described above, if the two surveying rods 11 that make up the pair of surveying rods 10 have different color schemes for drawing line segments, when simultaneously photographing the two surveying rods 11 with a camera, if you adjust the aperture (F-number), shutter speed, ISO sensitivity, etc. to prevent overexposure or underexposure in the figure of one of the surveying rods 11 in the captured image, it is likely that overexposure or underexposure will occur in the figure of the other surveying rod 11.

[0122] To avoid the above inconveniences, the color scheme for drawing line segments on the two surveying rods 11 that make up the pair of surveying rods 10 may be made identical.

[0123] In this application, "identical color scheme for drawing line segments" means that the combination of background color and other colors is identical.

[0124] If the color scheme for drawing the line segments of the two surveying rods 11 that constitute a pair of surveying rods 10 is the same, then, in order to distinguish each of the two surveying rods 11, a mark that distinguishes the surveying rod 11 from other similar surveying rods 11 may be drawn on one or both of the mediums, in addition to the line segments that form the multiple intersection points P.

[0125] Figure 13 illustrates a pair of surveying rods 10 in which identification information is printed on one or both of the media to distinguish each of the two surveying rods 11 that make up the pair of surveying rods 10, which have the same color scheme.

[0126] The surveying rods 11S and 11T that make up the pair of surveying rods 10 shown in Figure 13(A) have roughly the same trapezoidal shape. In both the surveying rod 11S and the surveying rod 11T, multiple line segments forming multiple intersection points P are drawn as boundaries between adjacent and different regions, each painted with a color that differs in at least one of its hue, lightness, and saturation (in this case, white and black).

[0127] Furthermore, the color scheme used to draw multiple line segments forming multiple intersection points P is the same for both the surveying rod 11S and the surveying rod 11T. Therefore, unlike the pair of surveying rods 10 in Figure 2, in the pair of surveying rods 10 in Figure 13(A), it is not possible to determine which of the two surveying rods 11 is surveying rod 11S and which is surveying rod 11T based on the color scheme used to draw the line segments.

[0128] Therefore, the medium provided by the surveying rod pair 10 in Figure 13(A), consisting of the surveying rod 11S and the surveying rod 11T, has a region b (an example of a second region) adjacent to a region a (an example of a first region) that is colored for drawing line segments. This region b is tangent to region a from the outside in the direction in which the angle bisectors of the interior angles of the first line segment (line segment L1) and the second line segment (line segment M1) extend. As a result, as shown in Figure 12(B), when the surveying rod pair 10 is positioned on the object to be surveyed 9 so that the distance between the reference point of the surveying rod 11S and the survey point of the surveying rod 11T is as short as possible, the region b of the medium does not affect that distance.

[0129] Furthermore, in area b of the medium of the surveying rod 11S that constitutes the surveying rod pair 10 in Figure 13(A), a QR code (registered trademark) is drawn, which indicates identification information that distinguishes this surveying rod 11S from other surveying rods 11. Similarly, in area b of the medium of the surveying rod 11T that constitutes the surveying rod pair 10 in Figure 13(A), a QR code is drawn, which indicates identification information that distinguishes this surveying rod 11T from other surveying rods 11.

[0130] For example, the terminal device 12 can decode the QR code contained in the image of the pair of surveying rods 10 shown in Figure 13(A) and identify each of the surveying rods 11S and 11T shown in the image.

[0131] The surveying rod pair 10 in Figure 13(B) differs from the surveying rod pair 10 in Figure 13(A) in that the area b of the medium of one of the surveying rods 11 (in this case, surveying rod 11S) does not have identification information written on it. The area b of the medium of the surveying rod 11S in Figure 13(B) is used, for example, as an area where the user can freely write notes with a pen or the like. In this case, the surveying rod 11S is not distinguishable from other surveying rods 11, but this surveying rod pair 10 is distinguishable from other surveying rod pairs 10 by the identification information of the surveying rod 11T.

[0132] The leveling rod pair 10 in Figure 13(C) differs from the leveling rod pair 10 in Figure 13(A) in that one of the leveling rods 11 (in this case, leveling rod 11S) does not have region b. In this case as well, similar to the leveling rod pair 10 in Figure 13(B), leveling rod 11S is not distinguishable from the other leveling rods 11, but this leveling rod pair 10 is distinguishable from the other leveling rod pairs 10 by the identification information of leveling rod 11T.

[0133] In the pair of surveying rods 10 illustrated in Figure 13, a QR code is depicted as a distinguishing mark for surveying rod 11 from other similar surveying rods 11. However, this distinguishing mark may be depicted in a form other than a QR code. For example, the distinguishing mark for surveying rod 11 from other similar surveying rods 11 may be depicted as an image showing a code other than a QR code, such as a two-dimensional barcode or a one-dimensional barcode, or it may be depicted as characters, symbols, etc., that are easily recognizable by humans.

[0134] Figure 14 illustrates a pair of surveying rods 10 in which two surveying rods 11 that make up the pair of surveying rods 10 are configured such that the two surveying rods 11 have the same color scheme for drawing line segments, but the shapes of the figures drawn by the line segments are different, making it possible to distinguish which of the two surveying rods 11 is surveying rod 11S and which is surveying rod 11T. In Figure 14, the surveying rods 11S and 11T that make up the pair of surveying rods 10 have different shapes of figures drawn by line segments that are symmetrical to each other. Therefore, surveying rods 11S and 11T can be distinguished based on the shapes of these figures, that is, the arrangement of the intersection point P.

[0135] [Modified representations of information other than the points drawn on the surveying rod] In the embodiment described above, for example, the surveying rod 11T shown in Figure 2 has a figure having three or more characteristic points used for surveying (hereinafter referred to as "surveying figure"), and in addition, identification information that distinguishes the surveying rod 11 from other surveying rods 11 is depicted using a QR code (registered trademark). The information depicted on the surveying rod 11 in addition to the surveying figure is not limited to identification information that distinguishes the surveying rod 11 from other surveying rods 11.

[0136] For example, the surveying rod 11S shown in Figure 2 has the surveying figure shown in Figure 3 drawn on it by color-coding, but it is not possible to determine the size of the surveying figure drawn on the actual surveying rod 11S from an image of the surveying rod 11S that was photographed.

[0137] Therefore, in addition to the surveying figure, size information indicating the size of the surveying figure may be drawn on the surveying rod 11.

[0138] Figure 15 is an example of a surveying rod 11 relating to this modified example. In addition to the surveying figure, the surveying rod 11 in Figure 15(A) has identification information "123456" to distinguish it from other surveying rods 11, and size information "length of one side of the square = 10 mm" depicted in text and a QR code.

[0139] As illustrated in Figure 15(A), the terminal device 12 can determine the size of the surveying figure in the image by recognizing the characters in the image of the surveying rod 11 using OCR (Optical Character Recognition) or by decoding the QR code.

[0140] In Figure 15(B), the surveying rod 11 has, in addition to the surveying figure, a QR code and numbers indicating identification information "123456" to distinguish this surveying rod 11 from other surveying rods 11, a scale bar indicating the actual unit length of the surveying rod 11, and letters indicating the unit length (in this case, 10 mm).

[0141] According to the surveying rod 11 illustrated in Figure 15(B), for example, the terminal device 12 can recognize the characters in the image of the surveying rod 11 using OCR (Optical Character Recognition) to determine the unit length, and then determine the size of the surveying figure in the image based on the length of the scale bar in the image of the surveying rod 11 and the unit length recognized from the characters.

[0142] Furthermore, in addition to the surveying figure, the surveying rod 11 may also have identification information for referencing the size information of the surveying figure, rather than the size information of the surveying figure itself. In the terminal device 12 or server device 13, the size of the surveying figure captured in the image may be determined based on the identification information captured in the image of the surveying rod.

[0143] Figure 16 is an example of a surveying rod 11 according to this modified example. In addition to the surveying diagram, the surveying rod 11 in Figure 16 has identification information "123456" written in letters and a QR code to distinguish it from other surveying rods 11.

[0144] Figure 17 shows the configuration of the data table stored in the server device 13 of the surveying system 1 according to this modified example.

[0145] Figure 17(A) shows the structure of a data table (hereinafter referred to as the "figure table") that stores data for each of several different survey figures. Here, "different survey figures" means survey figures that differ in at least one of their shape and size. The figure table has the following data fields.

[0146] [Shape ID] field: Stores shape identification information to identify the shape used for surveying. [Shape Information] field: Stores shape information indicating the shape of the figure used for surveying. [Size Information] field: Stores size information indicating the dimensions of the figure used for surveying.

[0147] Shape information, for example, is information indicating the coordinates of three or more feature points of a survey figure, but any description format is acceptable as long as it indicates the positional relationship between three or more feature points of a survey figure. For example, an image representing the figure may be stored as shape information in a figure table.

[0148] Size information, for example, when shape information indicates the coordinates of three or more feature points of a survey figure, is information that indicates the physical length of one coordinate unit (e.g., 1 millimeter) in the coordinate system that defines those coordinates. However, as long as it is information indicating the size of a survey figure, the description format may be any format.

[0149] Hereinafter, the shape information and size information of a particular surveying figure will be referred to as the geometric information of that surveying figure.

[0150] Figure 17(B) shows the structure of a data table (hereinafter referred to as the "leveling rod table") that stores data for each of several different leveling rods 11. Here, "several different leveling rods 11" refers to each of the actual leveling rods 11. Therefore, data for different leveling rods 11 on which the same leveling figure is drawn is stored in different data records in the leveling rod table. The leveling rod table has the following data fields.

[0151] [Measuring Rod ID]: Stores measuring rod identification information to identify the measuring rod 11. [Shape ID]: Stores one of the shape IDs stored in the [Shape ID] field of the shape table.

[0152] In addition to the above-mentioned leveling rod ID and figure ID, the leveling rod table may also store the name of the object to which the leveling rod 11 is attached, the object's location on Earth (latitude, longitude, etc.), and information about the object's manager.

[0153] In this modified example, for instance, when a user photographs the surveying rod 11 shown in Figure 16 using the camera 123 of the terminal device 12, the terminal device 12 decodes the QR code in the captured image and obtains the rod identification information "123456" for the surveying rod 11. The terminal device 12 then sends a request to the server device 13 to transmit graphic information including the rod identification information "123456" read from the QR code.

[0154] When the server device 13 receives a request to transmit graphic information from the terminal device 12, it searches the leveling rod table (Figure 17(B)) for a data record corresponding to the leveling rod identification information "123456" included in the transmission request. Subsequently, the server device 13 searches the graphic table (Figure 17(A)) for a data record corresponding to the graphic ID included in the data record found in the leveling rod table. The server device 13 transmits the graphic information (shape information and size information) included in the data record found in the graphic table to the terminal device 12 as a response to the transmission request.

[0155] The terminal device 12 receives graphic information (shape information and size information) transmitted from the server device 13 as a response to a transmission request, and uses the received graphic information for measurement (for example, processing according to the flow in Figure 7).

[0156] In the embodiment described above, the surveying process that was performed by the terminal device 12 (for example, the process following the flow in Figure 7) may be performed by the server device 13. In that case, the terminal device 12 transmits the image captured by the camera 123 to the server device 13, and the server device 13 reads the leveling rod identification information from the image. Alternatively, the terminal device 12 may read the leveling rod identification information from the image captured by the camera 123, transmit the read leveling rod identification information to the server device 13, and the server device 13 may use that leveling rod identification information.

[0157] Alternatively, the terminal device 12 may receive a graphic table and a measuring rod table from the server device 13, and the terminal device 12 may identify shape information corresponding to the measuring rod identification information read from the image.

[0158] Note that the data table configuration illustrated in Figure 17 is just one example, and other configurations may be used as long as the size information corresponding to the measuring rod identification information can be identified. For example, a table may be used in which the measuring rod ID is the primary key and the shape information and size information are fields, obtained by integrating a figure table (master table) with the figure ID as the primary key as illustrated in Figure 17 and a measuring rod table with the measuring rod ID as the primary key and the figure ID as a field.

[0159] In this modified example, the shape of the surveying figure drawn on the surveying rod 11 is not limited to that shown in Figure 3. Figure 18 is an example of a surveying rod 11 on which a surveying figure of a different shape from that of the surveying figure in Figure 3 is drawn.

[0160] In Figure 18(A), the surveying rod 11 has a surveying figure drawn on it that consists of a single square. As in this example, the number of polygons included in a surveying figure is not limited to multiple sides.

[0161] The surveying rod 11 in Figure 18(B) has a surveying figure drawn on it that is composed of four equilateral triangles. As this example shows, the shape of the polygon included in the surveying figure is not limited to a quadrilateral.

[0162] The surveying rod 11 in Figure 18(C) has a surveying figure drawn on it that is composed of four right triangles. As this example shows, the polygons included in the surveying figure are not limited to regular polygons. Also, the ratio of the lengths of the three sides of the right triangle drawn on the surveying rod 11 in Figure 18(C) is 3:4:5, so if the length of the hypotenuse is 10 millimeters, the lengths of the other two sides will be 6 millimeters and 8 millimeters, and so on, with all the side lengths being natural numbers. In this way, when a polygon with rational side lengths is drawn on the surveying rod 11, the amount of rounding of fractions during calculations for surveying is reduced, and as a result, the accuracy of the survey may be improved.

[0163] In Figure 18(D), the surveying rod 11 has a surveying figure drawn on it, which consists of one square and four isosceles triangles. As in this example, the surveying figure may be composed of polygons of different shapes.

[0164] In Figure 18(E), the surveying rod 11 has a surveying figure drawn on it, consisting of three points (more precisely, three small circles that are separated from each other). As in this example, the surveying figure may be composed of three or more points (more precisely, three or more small circles that are separated from each other). In this case, the center points of the small circles become the feature points used in the survey.

[0165] In Figure 18(F), the leveling rod 11 has leveling rod identification information and size information drawn inside the surveying figure. As in this example, the position where the leveling rod identification information and size information are drawn on the leveling rod 11 may be inside the surveying figure.

[0166] Furthermore, the surveying figure drawn on the surveying rod 11 in Figure 18(F) is drawn with lines rather than using different colors. As in this example, surveying figures may also be drawn with lines.

[0167] In Figure 18(G), the surveying rod 11 incorporates a QR code that serves as both a surveying graphic and a rod identification and size information. In this case, for example, the vertices of the three corners where the smaller squares are located are used as three feature points for surveying. The size information for this surveying rod 11 is, for example, information representing the side length of the square that makes up the entire QR code (the distance between two adjacent vertices among the three corners where the smaller squares are located).

[0168] In the example described above, the leveling rod 11 is assumed to have leveling rod identification information drawn on it. However, instead of, or in addition to, the leveling rod identification information may be drawn on the leveling rod 11. In that case, the terminal device 12 or server device 13 reads the graphic identification information from the image captured by the camera 123, and retrieves and uses the shape information and size information corresponding to the read graphic identification information (graphic ID) from the graphic table.

[0169] Furthermore, leveling rod identification information including figure identification information may be used. For example, leveling rod identification information may be used in which the upper m digits are figure identification information, and the following n digits are identification information that distinguishes individual leveling rods among leveling rods on which the same surveying figure is drawn. In this case, the terminal device 12 or server device 13 reads the leveling rod identification information from the image captured by the camera 123, and retrieves and uses shape information and size information corresponding to the figure identification information (figure ID) contained in the read leveling rod identification information from the figure table.

[0170] [Variations of the processes performed by the surveying system] The following shows a modified version of the process performed by surveying system 1. (13) The processor 122 of the terminal device 12 described above displays a message on the touchscreen 124 prompting the user to touch button R3 when the similarity S satisfies predetermined conditions. Alternatively, the processor 122 may perform a process to generate a still image from the video acquired from the camera 123 when the similarity S satisfies predetermined conditions.

[0171] In this modified example, a still image generated from the video by processor 122 is used as still image I. Therefore, the user does not need to perform a touch operation on button R3 (i.e., the shutter operation).

[0172] (14) The processor 122 of the terminal device 12 described above displays a message on the touchscreen 124 prompting the user to touch button R3 when the similarity S satisfies predetermined conditions. Alternatively, the processor 122 may perform the process of instructing the camera 123 to take a still image and acquiring the still image I taken by the camera 123 in response to that instruction when the similarity S satisfies predetermined conditions.

[0173] In this modified example, the process of taking a still image I by pressing the shutter is performed automatically by the terminal device 12. Therefore, the user does not need to touch button R3 (i.e., perform the shutter operation).

[0174] (15) The processor 122 of the terminal device 12 described above calculates the similarity S and notifies the user when the similarity S satisfies predetermined conditions. Alternatively, instead of calculating the similarity S, the processor 122 may estimate the accuracy of the photogrammetry and notify the user when the estimated accuracy (hereinafter referred to as "accuracy X") satisfies predetermined conditions.

[0175] In this modified example, the processor 122 first identifies one or more of the following (a) to (e) as accuracy estimation parameters for each image (for example, a still image corresponding to each frame) that makes up the video acquired from the camera 123 in order to estimate the accuracy X.

[0176] (a) Position of the measuring rod 11 within the field of view of camera 123 (b) Angle between the shooting direction of camera 123 and the direction of the normal of the surveying rod 11 (c) Resolution of the scale indicated by the measuring rod 11 in the image captured by camera 123 (d) The clarity of the image of the measuring rod 11 included in the image captured by camera 123. (e) Contrast of the image taken by camera 123

[0177] (a) is the position of the image of the surveying rod 11 in the image captured by camera 123 (for example, the position of a representative point such as the centroid of the area occupied by the image of the surveying rod 11). Generally, the further this position of the image of the surveying rod 11 is from the center of the image captured by camera 123, the more the image of the surveying rod 11 will be distorted, and the more likely the accuracy of the survey results will decrease.

[0178] The angle in (b) indicates the degree to which the shooting direction of camera 123, that is, the direction of the optical axis of the lens of camera 123, deviates from the direction directly facing the plane on which the surveying rod 11 is positioned. This angle is calculated using a known orthographic projection transformation method. The larger this angle, the greater the error that appears in the transformation to the orthographic projection image in step S3 of Figure 7, and the more likely the accuracy of the surveying results is to decrease.

[0179] The resolution in (c) is the number of pixels per unit length in the image, determined by the distance D between two adjacent intersection points P shown in the image of the leveling rod 11. For example, if the distance D between two adjacent intersection points P on the actual leveling rod 11 is 15 mm, and the number of pixels between the two adjacent intersection points P in the image of the leveling rod 11 is 4.5 million pixels, then the resolution in (c) is 300,000 pixels / mm, obtained by dividing 4.5 million by 15. The lower this resolution, the more likely the accuracy of the survey results is to decrease.

[0180] (d) The sharpness is an indicator of how well the image is in focus; the lower the value, the more likely the accuracy of the survey results is to decrease. This sharpness is determined by known methods (for example, methods that calculate it based on the power spectrum of the image, methods that use machine learning models such as deep learning, methods that calculate it using the Laplacian derivative, etc.).

[0181] (e) Contrast is the difference in brightness (luminance difference) between the brightest and darkest parts of an image. The larger the value, the easier it is to recognize the outlines and patterns of the objects in the image.

[0182] Based on the identified accuracy estimation parameters, the processor 122 estimates the accuracy X of the photogrammetry using the image captured by the camera 123 on the measuring rod 11.

[0183] Methods for estimating accuracy X based on accuracy estimation parameters include, but are not limited to, methods using known multivariate analyses or machine learning models.

[0184] For example, in the case of using a machine learning model, for each image of a pair of surveying rods 10 placed on various objects 9 to be measured, training data is prepared with the values ​​(a) to (d) above related to that image as explanatory variables and the accuracy of the photogrammetry results using that image as the target variable. Then, the computer is made to perform machine learning using this training data to generate a machine learning model (trained model). During operation, the processor 122 inputs the values ​​(a) to (d) above identified from the images acquired from the camera 123 as explanatory variables into the machine learning model and obtains the accuracy X output from the machine learning model as the target variable.

[0185] The processor 122 uses the accuracy X estimated as described above in place of the similarity S in the embodiment described above. Therefore, in this modified example, for example, the display object R2 on the shooting screen represents accuracy X instead of similarity S. When accuracy X satisfies a predetermined condition (for example, accuracy X is greater than or equal to a predetermined threshold U), a message such as "Please press the shutter button." is displayed in the area R4 of the shooting screen, and button R3 is activated.

[0186] Even with this modification, images that yield sufficiently high-precision survey results can be easily captured.

[0187] Furthermore, if the aforementioned predetermined condition regarding accuracy X is, for example, "accuracy X is greater than or equal to a predetermined threshold U," the threshold U may be changed, for example, according to the accuracy of the survey results required by the user.

[0188] When this variant is combined with the above-described variant (10), the processor 122, when accuracy X satisfies a predetermined condition, performs the process of generating a still image from the video acquired from the camera 123, instead of displaying a message on the touchscreen 124 prompting the user to touch button R3.

[0189] Furthermore, when this modified version is combined with the modified version (11) described above, the processor 122, when the accuracy X satisfies a predetermined condition, instead of displaying a message on the touchscreen 124 prompting the user to touch button R3, performs the process of instructing the camera 123 to take a still image and acquiring the still image I taken by the camera 123 in response to that instruction.

[0190] (16) The order of the processes shown in Figure 7 may be changed as appropriate. For example, the process of decrypting the QR code and obtaining identification information of the surveying rod 11T (step S1), which is performed first in Figure 7, may be performed after the process of determining the angle between coordinate systems (step S6).

[0191] (17) In the embodiments described above, some of the processing that would be performed by the processor 122 of the terminal device 12 may be performed by the processor 132 of the server device 13. For example, the terminal device 12 may transmit a still image I to the server device 13, and the processing according to the flow in Figure 7 may be performed by the processor 132 of the server device 13. Also, some or all of the processing that would be performed by the processor 132 of the server device 13 in the embodiments described above may be performed by the processor 122 of the terminal device 12.

[0192] (18) In the embodiment described above, the similarity S, which indicates the degree of agreement between the image of the surveying rod 11 and the guide sign G, is defined as the degree of agreement between the position of the feature points (3 or more) of the image of the surveying rod 11 and the position of the feature points (3 or more) of the guide sign G corresponding to those feature points. However, the similarity S may be any other index as long as it indicates the degree of agreement between the image of the surveying rod 11 and the guide sign G.

[0193] For example, any of the following may be calculated as the similarity score S. The area of ​​the overlap between the area occupied by the image of the surveying rod 11 and the area occupied by the directional sign G. The ratio of the area occupied by the image of the surveying rod 11 to the area occupied by the guidance sign G is the ratio of the overlapping area of ​​the area occupied by the guidance sign G to the area occupied by the guidance sign G.

[0194] Furthermore, compared to the similarity S calculated based on the area of ​​the overlapping portion, the similarity S calculated based on the distance between corresponding feature points is superior in that it changes depending on the degree of agreement between the shooting direction and the normal direction of the plane of the surveying rod 11.

[0195] [Other variations] (19) The use of the surveying rod 11 is not limited to measuring the positional relationship between two points on the object to be measured 9 as described above. Furthermore, the surveying rod 11 does not necessarily have to be used in a pair of surveying rods 11S and 11T. For example, if it is to measure the direction of the normal to the surface of the object to be measured 9, only one terminal device 12 needs to be placed on the object to be measured 9.

[0196] (20) In the embodiment described above, the entity that photographs the object to be measured 9 on which the surveying rod pair 10 is placed is assumed to be a user (person), but that entity may be a device such as a drone.

[0197] (21) In the above-described embodiment, the camera 123 that photographs the object to be measured 9 on which the surveying rod 11 is placed is built into the terminal device 12 or connected to the terminal device 12, but an image taken by a camera not connected to the terminal device 12 may also be used. In that case, the terminal device 12 will not display the guidance display G, nor will it display the similarity S between the captured image and the guidance display G, but the use of the surveying rod 11 makes it easier to obtain survey results with higher accuracy compared to when a conventional surveying rod is used.

[0198] (22) In the above-described embodiment, the coordinate system corresponding to the surveying rod 11 (coordinate system C corresponding to the surveying rod 11S, or coordinate system E corresponding to the surveying rod 11S) was determined as follows. Origin: Intersection P(1,1) Positive X-axis direction: Direction from intersection point P(1,4) to intersection point P(4,1) Y-axis positive direction: Direction from intersection point P(2,2) to intersection point P(1,1)

[0199] The method for determining the coordinate system corresponding to the surveying rod 11 is not limited to the above, and the coordinate system may be determined by any method, as long as it is based on the positions of three or more intersection points P that are not all on the same line, as identified from the image of the surveying rod 11.

[0200] (23) In the above-described embodiment, the leveling rod 11T is assumed to have three or more lines drawn on it that form three or more intersection points P, similar to the leveling rod 11S. However, if the angles between coordinate systems are not required from the information obtained from photogrammetry, the number of lines drawn on the leveling rod 11T may be two or less, and the number of intersection points P formed by those lines may be two or less. For example, two intersecting lines may be drawn on the leveling rod 11T, and only one intersection point P may be formed between those two lines.

[0201] (24) In the embodiments and modified examples (15) described above, the processor 122 of the terminal device 12 estimates the accuracy X of photogrammetry based on the video acquired in real time from the camera 123. This function for estimating accuracy X is not limited to real-time video recording, but may also be applied to videos or still images that have been recorded in the past and are already stored in the memory 121, etc.

[0202] For example, the processor 122 acquires a previously recorded video file specified by the user, identifies the accuracy estimation parameters (leveling rod position, angle, resolution, sharpness, contrast) described in the modified example (15) for each frame (still image) that makes up the video, and estimates the accuracy X based on the identified accuracy estimation parameters. For example, the processor 122 generates the first frame in the video in which the accuracy X is equal to or greater than a predetermined threshold as the still image to be used for photogrammetry. Alternatively, the processor 122 estimates the accuracy X for all frames that make up the video and generates the frame in which the highest accuracy X is estimated to be obtained as the still image to be used for photogrammetry. This makes it possible to extract images suitable for photogrammetry from recorded videos.

[0203] Furthermore, the processor 122 may similarly estimate the accuracy X for still images (which may be frames that make up a video) already stored in memory 121 or the like, and notify the user of the estimated accuracy X by displaying it together with the still image on, for example, the touchscreen 124.

[0204] (25) In the modified examples (15) or (24) described above, the accuracy X estimated with respect to the photogrammetry using the image captured by the camera 123 may be stored in the memory 121 or server device 13, etc., in association with the results of the photogrammetry. This allows the user to know not only the results of the photogrammetry but also the accuracy of the results of the photogrammetry. [Explanation of symbols]

[0205] 1...Surveying system, 11...Surveying rod, 12...Terminal device, 13...Server device, 121...Memory, 122...Processor, 123...Camera, 124...Touchscreen, 125...Communication interface, 131...Memory, 132...Processor, 133...Communication interface.

Claims

1. On the computer, A process to acquire an image of an object to be measured, which is placed or formed on the surface of an object, on which a surveying rod is placed or formed, on which three or more lines forming three or more intersection points whose relative positions are known are drawn, is photographed by a photographing device. Regarding the image acquired in the acquisition process described above, the process involves identifying, as accuracy estimation parameters, the position of the measuring rod within the field of view of the imaging device, the angle between the imaging direction of the imaging device and the direction of the normal of the measuring rod, the resolution of the scale indicated by the measuring rod in the image captured by the imaging device, the clarity of the image of the measuring rod included in the image captured by the imaging device, and the contrast of the image captured by the imaging device, one or more of these parameters. Based on the accuracy estimation parameters identified in the aforementioned identification process, the process involves estimating the accuracy of photogrammetry using the image captured by the imaging device on the surveying rod. A program to execute.

2. To the aforementioned computer, Process to display the aforementioned accuracy on a display device. The program according to claim 1 for executing the following:

3. To the aforementioned computer, A process to obtain the results of photogrammetry using the aforementioned image, A process to store the results of the aforementioned photogrammetry in association with the accuracy. The program according to claim 1 for executing the following:

4. To the aforementioned computer, In the process of acquiring the aforementioned image, the video captured by the camera is acquired, In the process of identifying the accuracy estimation parameters, the accuracy estimation parameters are identified for each of the images that make up the video, When the accuracy meets predetermined conditions, a process is performed to notify the user. The program according to claim 1 for executing the following:

5. To the aforementioned computer, In the process of acquiring the aforementioned image, the video captured by the camera is acquired, In the process of identifying the accuracy estimation parameters, the accuracy estimation parameters are identified for each of the images that make up the video, When the accuracy satisfies predetermined conditions, a process is performed to generate a still image from the video acquired from the shooting device. The program according to claim 1 for executing the following:

6. To the aforementioned computer, In the process of acquiring the aforementioned image, the video captured by the camera is acquired, In the process of identifying the accuracy estimation parameters, the accuracy estimation parameters are identified for each of the images that make up the video, When the accuracy satisfies predetermined conditions, the process of instructing the imaging device to take a still image, A process to acquire a still image captured by the camera in response to the instructions in the aforementioned process. The program according to claim 1 for executing the following:

7. The computer generates a trained model using training data, with the accuracy of photogrammetry using the captured image being the target variable. This model is determined from an image captured by a camera, in which the computer identifies the position of the leveling rod within the field of view of the camera, the angle between the camera's shooting direction and the direction of the normal to the leveling rod, the resolution of the image captured by the camera at the scale indicated by the leveling rod, the clarity of the image of the leveling rod included in the image captured by the camera, and the contrast of the image captured by the camera as explanatory variables. A method for providing this.

8. To the aforementioned computer, In the process of estimating the accuracy of the photogrammetry, the accuracy estimation parameters identified in the process of identifying the accuracy estimation parameters are input as explanatory variables into the trained model generated by the method according to claim 7, and the accuracy output as the target variable from the trained model is obtained. The program according to claim 1.

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