Surveying staff pair

Abstract

To automate surveying work by making it possible to identify the size of the figure drawn on the actual surveying staff from an image of the surveying staff. [Solution] A figure showing three or more points with known positional relationships and size information showing the size of the figure are drawn on the surveying staff 11. The figure drawn on the surveying staff 11 is a polygon painted in different colors, and indicates the intersection of the boundaries of two adjacent areas painted in different colors. The positional relationship of these intersections is known. An image taken of the surveying staff 11 contains size information of the figure drawn on the surveying staff 11, so it is possible to identify the size of the figure drawn on the actual surveying staff 11 shown in the image from the image.

Description

[Technical Field]

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

[0002] There is a photogrammetry technique in which two pairs of surveying staffs (hereinafter referred to as "surveying staff pair") are placed side by side on the surface of an object to be surveyed, and the positional relationships of different points on the surface of the object to be surveyed are measured based on images taken with a photographing device so that the surveying staff pair is within the field of view. Patent Document 1, for example, is an example of a patent document that describes such a technique. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-123008 Summary of the Invention [Problem to be solved by the invention]

[0004] Since it is not possible to determine the size of the figure drawn on the actual surveying staff from an image of the surveying staff described in Patent Document 1, it is not possible to automate surveying work.

[0005] The present invention aims to automate surveying work by making it possible to identify the size of a figure drawn on an actual surveying staff from an image of the staff. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the present invention provides: A pair of surveying staffs, each consisting of a first surveying staff and a second surveying staff, is fixedly placed on the surface of an object to be surveyed in order to photogrammetry the positional relationship between a reference point and a measurement point on the surface of the object, wherein each of the first surveying staff and the second surveying staff has: A shape showing three or more points with known relative positions is depicted. , On either the first surveying staff or the second surveying staff, Size information indicating the size of the graphic is depicted Surveying staff versus to provide. [Effects of the Invention]

[0010] According to the present invention, it is possible to identify the size of a figure drawn on the actual surveying staff photographed from an image of the surveying staff. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing the configuration of a surveying system according to an embodiment. [Figure 2] FIG. 1 illustrates a pair of surveying staffs according to an embodiment. [Figure 3] FIG. 10 is a diagram showing a group of straight lines forming the outer edges of a plurality of squares that make up the staggered pattern of a surveying staff according to one embodiment. [Figure 4] FIG. 2 is a diagram showing the configuration of a terminal device according to an embodiment. [Figure 5] FIG. 2 is a diagram showing the configuration of a server device according to an embodiment. [Figure 6] FIG. 10 is a diagram showing a shooting screen displayed by a terminal device according to an embodiment. [Figure 7] FIG. 4 is a flowchart of a process performed by a processor of a terminal device according to an embodiment. [Figure 8] 10A and 10B are diagrams for explaining a process of specifying and identifying an intersection performed by a terminal device according to an embodiment; [Figure 9] FIG. 4 is a diagram showing the configuration of a data table stored in a server device according to an embodiment. [Figure 10] FIG. 10 is a diagram illustrating lines forming intersections of a surveying staff according to a modified example. [Figure 11] FIG. 10 is a diagram illustrating lines forming intersections of a surveying staff according to a modified example. [Figure 12] FIG. 10 is a diagram for explaining the advantages of a surveying staff according to a modified example. [Figure 13] FIG. 10 is a diagram illustrating a pair of surveying staffs according to a modified example. [Figure 14] FIG. 10 is a diagram illustrating a pair of surveying staffs according to a modified example. [Figure 15] FIG. 10 is a diagram illustrating a surveying staff according to a modified example. [Figure 16]FIG. 10 is a diagram illustrating a surveying staff according to a modified example. [Figure 17] FIG. 10 is a diagram showing the configuration of a data table stored in a server device according to a modified example. [Figure 18] FIG. 10 is a diagram illustrating a surveying staff according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0012] A surveying system 1 according to one embodiment of the present invention will be described below. Figure 1 is a diagram showing the configuration of the surveying system 1. The surveying system 1 is a system that performs photogrammetry to measure the positional relationship between different points on the surface of an object 9 to be surveyed.

[0013] The surveying system 1 comprises a surveying staff 11S (an example of a first surveying staff) and a surveying staff 11T (an example of a second surveying staff) fixedly positioned on the surface of the object to be surveyed 9 by adhesive or the like, a terminal device 12 used by a user, and a server device 13 that communicates between the terminal device 12.

[0014] In the example of Figure 1, a crack 91 has occurred in the object to be surveyed 9, and surveying staff 11S and surveying staff 11T are placed on either side of the crack 91. The surveying system 1 measures the positional relationship between the reference point on surveying staff 11S and the survey point on surveying staff 11T using an image captured with both surveying staff 11S and surveying staff 11T within the field of view.

[0015] FIG. 2 shows surveying staff 11S and surveying staff 11T. Surveying staff 11S is a reference surveying staff, and surveying staff 11T is a surveying staff to be surveyed. Surveying staff 11S and surveying staff 11T constitute a surveying staff pair 10. Hereinafter, when there is no need to distinguish between surveying staff 11S and surveying staff 11T, they will be referred to as surveying staff 11.

[0016] The surveying staff 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.

[0017] The image of the surveying staff 11 contains a houndstooth pattern of the same shape and size. The image of the surveying staff 11T contains a QR code (registered trademark). Note that a QR code may be included in the image of the surveying staff 11S instead of the surveying staff 11T. This QR code is a mark that distinguishes the surveying staff from other surveying staffs of the same type. In other words, decoding this QR code provides identification information that distinguishes the surveying staff 11T containing the QR code in its image from other surveying staffs 11T.

[0018] 3 is a diagram showing a group of straight lines forming the outer edges of a plurality of squares that make up the houndstooth pattern drawn on the surveying staff 11. In other words, the group of straight lines shown in FIG. 3 are the group of straight lines drawn by the houndstooth pattern of the surveying staff 11.

[0019] The group of straight lines drawn by the houndstooth pattern of the surveying staff 11 includes line segments L1 to L4, which are four line segments arranged parallel to each other at an interval of distance D, and line segments M1 to M4, which are four line segments arranged parallel to each other at an interval of distance D and perpendicular to line segments L1 to L4.

[0020] The length of line segment L1 and line segment M1 is three times the distance D. Line segment L1 and line segment M1 are positioned so that one of their endpoints coincides at intersection point P(1,1).

[0021] The lengths of line segments L2 and M2 are three times the distance D. Line segment L2 is positioned so that one end point coincides with intersection point P(2,1), which is a distance D away from intersection point P(1,1) on line segment M1, and extends from intersection point P(1,1) in the same direction as line segment L1. Line segment M2 is positioned so that one end point coincides with intersection point P(1,2), which is a distance D away from intersection point P(1,1) on line segment L1, and extends from intersection point P(1,1) in the same direction as line segment M1.

[0022] The lengths of line segments L3 and M3 are twice the distance D. Line segment L3 is positioned so that one end point coincides with intersection point P(3,1) on line segment M1, which is twice the distance D from intersection point P(1,1), and extends from intersection point P(1,1) in the same direction as line segment L1. Line segment M3 is positioned so that one end point coincides with intersection point P(1,3), which is twice the distance D from intersection point P(1,1) on line segment L1, and extends from intersection point P(1,1) in the same direction as line segment M1.

[0023] The lengths of line segments L4 and M4 are a distance D. Line segment L4 is positioned so that one end point coincides with intersection point P(4,1) on line segment M1 (i.e., the other end point of line segment M1), which is three times the distance D away from intersection point P(1,1) on line segment M1, and extends from intersection point P(1,1) in the same direction as line segment L1. Line segment M4 is positioned so that one end point coincides with intersection point P(1,4) on line segment L1 (i.e., the other end point of line segment L1), which is three times the distance D away from intersection point P(1,1) on line segment L1, and extends from intersection point P(1,1) in the same direction as line segment M1.

[0024] The total number of intersection points P, which are the points where each of the line segments L1 to L4 arranged as described above intersects with each of the line segments M1 to M4, is 13. As shown in Fig. 3, the intersection point of a line segment Li (where i is a natural number from 1 to 4) and a line segment Mj (where j is a natural number from 1 to 4) is represented as intersection point P(i,j).

[0025] As described above, the positional relationship of the 13 intersection points P is known. In addition, the positional relationship of the 13 intersection points P is rotationally asymmetric.

[0026] When the surveying staff 11S and the surveying staff 11T are superimposed so that the 13 intersection points P of the surveying staff 11S and the 13 intersection points P of the surveying staff 11T overlap, the color of the portion of the image of the surveying staff 11S depicting the line segments L1 to L4 and the line segments M1 to M4 is different from the color of the portion of the image of the surveying staff 11S depicting the line segments L1 to L4 and the line segments M1 to M4 that overlap with that portion. For example, the line segment L1 of the surveying staff 11S is drawn as the sides of the following three squares.

[0027] First square: A square with vertices P(1,1), P(1,2), P(2,2), and P(2,1). Second square: A square with vertices P(1,2), P(1,3), P(2,3), and P(2,2). Third square: A square with vertices P(1,3), P(1,4), P(2,4), and P(2,3).

[0028] The color of the first square of the surveying staff 11S (e.g., white) is different from the color of the first square of the surveying staff 11T (e.g., black). The color of the second square of the surveying staff 11S (e.g., black) is different from the color of the second square of the surveying staff 11T (e.g., white). The color of the third square of the surveying staff 11S (e.g., white) is different from the color of the third square of the surveying staff 11T (e.g., black).

[0029] In this application, "different colors" means that at least one of the hue, brightness, and saturation of the colors is different.

[0030] The intersection point P(1,1) of the surveying staff 11S is the reference point, and the intersection point P(1,1) of the surveying staff 11T is the measurement point.

[0031] The three or more intersection points P of the surveying staff 11S define a coordinate system C. The coordinate system C is as follows:

[0032] Origin: Intersection point P(1,1) of surveying staff 11S Positive X-axis direction: The direction from the intersection point P(1,4) of the surveying staff 11S to the intersection point P(4,1) Y-axis positive direction: The direction from intersection P(2,2) of the surveying staff 11S to intersection P(1,1)

[0033] The three or more intersection points P of the surveying staff 11T define a coordinate system E. The coordinate system E is the following coordinate system.

[0034] Origin: Intersection point P(1,1) of surveying staff 11T Positive X-axis direction: The direction from the intersection point P(1,4) of the surveying staff 11T toward the intersection point P(4,1) Y-axis positive direction: The direction from the intersection point P(2,2) of the surveying staff 11T toward the intersection point P(1,1)

[0035] 4 is a diagram showing the configuration of terminal device 12. Terminal device 12 is a computer that includes memory 121 that stores various data and processor 122 that processes various data in accordance with programs that are continuously stored in memory 121. Any type of computer can be used for terminal device 12, but it is desirable that it be a small, lightweight computer that can be easily carried by the user.

[0036] The terminal device 12 also includes a camera 123 (an example of a photographing device) that generates moving and still images by photographing, a touch screen 124 having a stacked display (an example of a display device) and a touch panel, and a communication interface 125 that is an interface for communicating with the server device 13.

[0037] The terminal device 12 may be provided with a display and an input device such as a mouse that accepts user operations, instead of the touch screen 124. Furthermore, at least one of the camera 123, the touch screen 124 (or a substitute therefor), and the communication interface 125 may not be built into the terminal device 12, but may be connected to the terminal device 12 as an external device.

[0038] In the following description, the terminal device 12 is assumed to be, for example, a smartphone that is capable of communication and telephone calls via a mobile communication network using the communication interface 125.

[0039] 5 is a diagram showing the configuration of server device 13. Server device 13 is a computer including memory 131 for storing various data, processor 132 for processing various data in accordance with programs continuously stored in memory 131, and communication interface 133 as an interface for communicating with terminal device 12.

[0040] In order to measure the positional relationship between the reference point and the measurement point on the object to be measured 9, the user photographs the pair of measuring staffs 10 on the object to be measured 9 with the camera 123 of the terminal device 12.

[0041] FIG. 6 shows a screen (hereinafter referred to as "photographing screen") displayed by the terminal device 12 when the user photographs the surveying staff pair 10 on the object to be measured 9.

[0042] The shooting screen includes area R1, which displays video captured by camera 123 in real time and also displays guide display G; display object R2, which displays the similarity (hereinafter referred to as "similarity S") indicating the degree of match between the image of the surveying staff 11S displayed in area R1 and the guide display G; button R3, which is a virtual button that the user touches to instruct camera 123 to take a still image; and area R4, which displays a message urging the user to touch button R3 when the user is in a state where they should touch button R3.

[0043] The processor 122 of the terminal device 12 performs the following processing while the photographing screen is displayed on the touch screen 124 in accordance with the program stored in the memory 121.

[0044] A process of causing the camera 123 to capture a moving image and acquiring the moving image generated by the camera 123 through the capture. A process of displaying video captured by the camera 123 in the area R1 of the shooting screen on the touch screen 124 in real time. A process of overlaying and displaying an information display object G on the touch screen 124 in the area R1 of the shooting screen on top of the video acquired from the camera 123. A process of continuously calculating the similarity S, which indicates the degree of match between the image of the surveying staff 11S displayed in the area R1 of the photographing screen and the guide display object G. A process of displaying a display object R2 representing the continuously updated similarity S on the touch screen 124. When the similarity S satisfies a predetermined condition (hereinafter referred to as "condition Q"), a process of displaying a message (e.g., "Please release the shutter") in area R4 of the shooting screen on touch screen 124, urging the user to touch button R3.

[0045] The guide display G is a display that guides the position and size of the image of the surveying staff 11S displayed in the area R1 of the photographing screen. The guide display G illustrated in Fig. 6 indicates the positions where the line segments L1 to L4 and the line segments M1 to M4 of the image of the surveying staff 11S should be captured. However, the form of the guide display G may be changed in various ways as long as it guides the position and size of the image of the surveying staff 11S displayed in the area R1 of the photographing screen.

[0046] To calculate the similarity S, the processor 122 first recognizes the image of the surveying staff 11S from the image displayed in the region R1 using a known image recognition method.

[0047] Next, the processor 122 calculates the similarity S between the recognized image of the surveying staff 11S and the guide object G.

[0048] As one example, the processor 122 calculates the degree of coincidence between the positions of 13 intersection points P (one example of a feature point) identified from the image of the surveying staff 11S and the intersection points P (one example of a feature point) of the guide display G as the similarity S. More specifically, for example, the processor 122 associates the 13 intersection points P identified from the image of the surveying staff 11S with the intersection points P of the guide display G, identifies 13 intersection pairs, calculates the distance between the two intersection points P for each of the 13 intersection pairs, and calculates the sum of these distances by subtracting a constant as the similarity S. Note that the method for calculating the similarity S is not limited to this, and any method may be employed as long as it calculates, as the similarity S, an index value indicating the degree of coincidence between the positions of the feature points extracted from the image of the surveying staff 11S and the positions of the feature points of the guide display G corresponding to those feature points.

[0049] Condition Q is a condition that is met, for example, if similarity S is equal to or greater than a predetermined threshold value T. When processor 122 continuously calculates similarity S, it continuously determines whether similarity S satisfies condition Q, and while similarity S does not satisfy condition Q, it causes touch screen 124 to display a message such as "Please align the image with the guide" in area R4, and while similarity S satisfies condition Q, it causes touch screen 124 to display a message such as "Please release the shutter."

[0050] In addition, the processor 122 may cause the touch screen 124 to be in a state (inactive state) in which it does not accept touch operations by the user on the button R3 while the similarity S does not satisfy the condition Q, and may cause the touch screen 124 to be in a state (active state) in which it accepts touch operations by the user on the button R3 while the similarity S satisfies the condition Q.

[0051] While referring to the display object R2, the user adjusts the attitude 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 staff 11S displayed in the area R1 matches the guide 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 becomes equal to or greater than the threshold value T, a message such as "Please release the shutter" is displayed in the area R4. In response to this message, the user touches the button R3.

[0052] In response to a user's touch operation on button R3, processor 122 instructs camera 123 to capture a still image. Camera 123 captures a still image in response to the instruction and outputs the captured still image (hereinafter referred to as "still image I") to processor 122. Processor 122 acquires still image I output from camera 123 and stores still image I in memory 131 together with the time when still image I was acquired.

[0053] Next, the processor 122 uses the still image I to perform processing according to the flowchart shown in FIG.

[0054] The processor 122 decodes the QR code included in the still image I and acquires the identification information of the surveying staff 11T (step S1).

[0055] Next, the processor 122 identifies and identifies a total of 26 intersection points P indicated by the images of the surveying staff 11S and the surveying staff 11T included in the still image I (step S2).

[0056] FIG. 8 is a diagram for explaining the process performed by processor 122 in step S2.

[0057] Fig. 8(A) is a diagram showing a still image I. The processor 122 detects multiple intersection points P from the checkerboard pattern included in the images of the surveying staff 11S and the surveying staff 11T included in the still image I, using a known corner detection method. Fig. 8(B) is a diagram showing the multiple intersection points P detected in this way. In Fig. 8(B), the intersection point P is represented as the center point of an X mark (the intersection point of the two line segments that make up the X).

[0058] Next, processor 122 identifies the two most distant points from among the detected intersection points P as intersection points A1 and A2. Figure 8(C) is a diagram showing intersection points A1 and A2 thus identified.

[0059] Next, processor 122 identifies the two points closest to intersection point A1 as intersection points B1 and C1, and confirms that line segments A1B1 and A1C1 are equal in length and that angle B1A1C1 is 90 degrees. This confirmation is performed to exclude points that are not intersection points P, as they may be mistakenly included among the points detected from still image I. Therefore, processor 122 excludes points that do not satisfy the above conditions from intersection point P. This process will be referred to hereinafter as "adjacent intersection identification process."

[0060] The processor 122 also performs the process of identifying adjacent intersections for the intersection A2, and identifies the intersections B2 and C2 adjacent to the intersection A2.

[0061] FIG. 8(D) is a diagram showing the intersections A1 to C1 and the intersections A2 to C2 identified as described above.

[0062] 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) until 13 intersections (including intersection A1) starting from intersection A1 and 13 intersections (including intersection A2) starting from intersection A2 are identified.

[0063] Figure 8(E) is a diagram showing the state in which intersection D1 adjacent to intersection B1, intersection E1 and intersection F1 adjacent to intersection C1, intersection D2 adjacent to intersection B2, and intersection E2 and intersection F2 adjacent to intersection C2 have been newly identified.

[0064] 8(F) is a diagram showing a 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 a group of intersections P of the surveying staff 11S. The 13 intersections (including intersection A2) starting from intersection A2 are a group of intersections P of the surveying staff 11T.

[0065] The processor 122 identifies the pair of intersection points P with the shortest distance from among pairs of intersection points P arbitrarily selected from the group of intersection points P of the surveying staff 11S and intersection points P arbitrarily selected from the group of intersection points P of the surveying staff 11T as intersection point P(1,1). As described above, the intersection point P(1,1) identified from the group of intersection points P of the surveying staff 11S is the reference point, and the intersection point P(1,1) identified from the group of intersection points P of the surveying staff 11T is the survey point. Figure 8(G) is a diagram showing the state in which the reference point and the survey point have been identified.

[0066] Next, the processor 122 identifies each of the other 12 intersection points P for each of the intersection points P of the surveying staff 11S and the intersection points P of the surveying staff 11T based on their positional relationship with the intersection point P(1,1) as the reference point. That is, the processor 122 identifies which intersection point P is the intersection point P(1,2), the intersection point P(2,1), etc.

[0067] The above is the process performed by the processor 122 in step S2 of Fig. 7. The process of step S2 described above is an example of the process performed by the processor 122 to specify and identify the intersections P, and the processor 122 may specify and identify the intersections P by a different process. For example, the processor 122 may match a reference image that represents the positional relationship of the 13 intersections P with a comparison image that represents the positional relationship of the plurality of intersections P detected from the checkered pattern included in the images of the surveying staffs 11S and 11T included in the still image I, thereby grouping the plurality of intersections P detected from the checkered pattern and identifying each of the intersections P included in each group.

[0068] Following the processing of 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 correctly the intersection points of orthogonal line segments (step S3).

[0069] Next, the processor 122 identifies a coordinate system C based on the positions of the intersection points P of the surveying staff 11S contained in the orthogonal projection image obtained by the transformation in step S3, and identifies a coordinate system E based on the positions of the intersection points P of the surveying staff 11T contained in the orthogonal projection image obtained by the transformation in step S3 (step S4).

[0070] Next, the processor 122 identifies the intersection point P(1,1) of the surveying staff 11T included in the orthogonal projection image obtained by the transformation in step S3, i.e., the coordinates of the survey point in the coordinate system C (step S5). The coordinates of the survey point in the 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).

[0071] Next, processor 122 identifies 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 rotational direction (for example, how much the X-axis (or Y-axis) of coordinate system E rotates around its origin (measurement point) in coordinate system C).

[0072] Next, the processor 122 stores in the memory 121 the time when the still image I was acquired from the camera 123, the identification information of the surveying staff 11T acquired from the QR code in step S1, the coordinates of the surveying point in the coordinate system C identified in step S5, and the angle between the coordinate systems identified in step S6 in association with each other, and controls the communication interface 125 to transmit this information to the server device 13 (step S7).

[0073] This concludes the description of the processing performed by the processor 122 of the terminal device 12 according to the flow of FIG.

[0074] When the server device 13 receives the acquisition time of the still image I, the identification information of the surveying staff 11T, the coordinates of the surveying point, and the angle between the coordinate systems transmitted from the terminal device 12, it stores this information.

[0075] When a user photographs the object to be surveyed 9 at different times using the camera 123 of the terminal device 12, with the photographing screen displayed on the touch screen 124, so that the pair of surveying rods 10 are within the field of view, each time, the identification information of the surveying rod 11T identified from the still image I obtained by photographing, the coordinates of the surveying point, and the angle between the coordinate systems are transmitted from the terminal device 12 to the server device 13 along with the time the still image I was photographed, and are stored in the server device 13.

[0076] 9 is a diagram showing the configuration of a data table (hereinafter referred to as a "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 piece of identification information for the surveying staff 11T, and each of these survey result tables has a data field "time" that stores the time of reception from the terminal device 12, a data field "coordinates of 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 the coordinate systems received from the terminal device 12. The data records included in the survey result table are arranged, for example, in chronological order.

[0077] The coordinates of the survey point stored in the first data record (the oldest one) among the data records contained in the survey result table indicate the initial value of the positional relationship between the reference point and the survey point. Also, the angle between the coordinate systems stored in the first data record (the oldest one) among the data records contained in the survey result table indicates the initial value of the positional relationship in the rotation direction between coordinate system C and coordinate system E.

[0078] The coordinates of the survey points stored in the second and subsequent rows of the data records contained in the survey result table are compared with the coordinates of the survey points stored in the first data record to show changes over time in the position of the survey points relative to the reference point. The angles between the coordinate systems stored in the second and subsequent rows of the data records contained in the survey result table are compared with the angles between the coordinate systems stored in the first data record to show changes over time in the rotation angle around the origin of coordinate system E relative to coordinate system C. Therefore, based on the information stored in the survey result table, the user of the survey system 1 can know, for example, the speed and direction of expansion of crack 91 in the object 9 to be surveyed.

[0079] The surveying staff 11 has the following advantages over the surveying staff (target) used in the prior art described in Patent Document 1 (hereinafter simply referred to as "prior art").

[0080] (1) Conventional surveying staffs indicate the positions of reference points, survey points, etc. using circular marks, so processing to identify the center points of the marks is necessary, and this processing increases surveying errors. On the other hand, the surveying staff 11 used in the surveying system 1 indicates the positions of reference points, survey points, etc. using line intersections, so the processing to identify the center points of the marks required in conventional technology is not necessary, and more accurate surveying results can be obtained compared to when using conventional surveying staffs.

[0081] (2) Conventional surveying staffs indicate the positions of reference points, survey points, etc. using circular marks. Therefore, when the surveying staff is photographed from an oblique angle, the marks included in the photographed image become ellipses, and the number of parameters that must be determined from the image to identify the center point increases compared to the case of a circle. As a result, when using conventional surveying staffs, the photographing direction of the surveying staff has a significant impact on the accuracy of the survey results. On the other hand, the surveying staff 11 used in the surveying system 1 indicates the positions of reference points, survey points, etc. using the intersection of lines. Therefore, compared to when conventional surveying staffs are used, the photographing direction of the surveying staff 11 has a smaller impact on the accuracy of the survey results.

[0082] (3) Because conventional surveying staffs indicate the positions of reference points, survey points, etc. using circular marks, if a dot-shaped noise image appears in an image of the surveying staff due to dirt adhering to the surveying staff or dust adhering to the lens of the camera 123, the noise image is easily mistaken for a mark, and the positions of the reference points, survey points, etc. are easily identified incorrectly. On the other hand, because the surveying staff 11 used in the surveying system 1 indicates the positions of reference points, survey points, etc. using the intersections of lines, even if a dot-shaped noise image appears in an image of the surveying staff 11, the noise image will not cause the positions of the reference points, survey points, etc. to be identified incorrectly.

[0083] Furthermore, since the above-mentioned terminal device 12 displays an image in which the guide display G is overlaid on the image captured by the camera 123, the user can adjust the attitude of the terminal device 12 and the distance between the terminal device 12 and the object to be surveyed 9 so that the image captured of the surveying staff 11 matches the guide display G as closely as possible, thereby making it possible to capture an image that will result in highly accurate surveying results.

[0084] This is because the state in which the position and size of the image of the surveying staff 11 captured in the image taken by the camera 123 match the position and size of the guide display G is the state in which the camera 123 is capturing an image of the surveying staff 11 from the front, i.e., the capturing direction of the camera 123 matches the direction of the normal to the surveying staff 11, and therefore the error in the process of converting to an orthographic projection image (step S3 in Figure 7) is minimized.

[0085] Furthermore, when the position and size of the image of the surveying staff 11 captured in the image taken by the camera 123 matches the position and size of the guide display G, the surveying staff 11 is captured in the central area of ​​the field of view of the camera 123 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 also reduced.

[0086] Furthermore, according to the terminal device 12 described above, the user is notified of the similarity S between the image of the surveying staff 11 captured in the image taken by the camera 123 and the guide display G, and when the similarity S is sufficiently high, a message is displayed urging the user to operate the shutter. Therefore, by operating the shutter in response to the notification or message, the user can easily capture an image that will provide a surveying result with sufficiently high accuracy.

[0087] [Variations] The above-described embodiment can be modified in various ways within the scope of the technical concept of the present invention. Examples of such modifications are shown below. Note that two or more of the following exemplary modifications may be combined and adopted.

[0088] [Modified surveying staff] The following are modified examples of the surveying staff 11. Fig. 10 is a diagram illustrating lines forming the intersection point P of the surveying staff 11 according to the following modified examples (1) to (4).

[0089] (1) The line forming the intersection point P of the above-described surveying staff 11 is the boundary line between adjacent areas painted in different colors. The boundary line between adjacent areas painted in different colors has no width. When a line with width is used, a process is required to identify the center of the line, and errors occur in this process. On the other hand, with the above-described surveying staff 11, such errors do not occur.

[0090] However, if the error caused by the wide lines is within an acceptable range, wide lines may be included instead of the checkerboard pattern in the image of the surveying staff 11. Figure 10(A) is a diagram illustrating an example of lines forming the intersection point P of the surveying staff 11 according to this modification. (2) The lines forming the intersection P of the surveying staff 11 described above include a first group of straight lines (e.g., line segments L1 to L4) arranged parallel to one another and a second group of straight lines (e.g., line segments M1 to M4) arranged parallel to one another and perpendicular to the first group of straight lines. When the first group of straight lines and the second group of straight lines are perpendicular to one another, the process of checking the angle, which is included in the process of identifying adjacent intersections and is performed in step S2 of FIG. 7, is easier than when the first group of straight lines and the second group of straight lines are not perpendicular to one another.

[0091] However, if it is acceptable that the process of checking the angles becomes somewhat more complicated, the first group of straight lines and the second group of straight lines do not have to be perpendicular to each other. Figure 10(B) is a diagram showing an example of a checkerboard pattern on a surveying staff 11 according to this modified example.

[0092] (3) The group of lines forming the intersection points P of the surveying staff 11 described above is rotationally asymmetric. Therefore, regardless of the direction in which the surveying staff 11 is placed on the object to be surveyed 9, each of the intersection points P of the reference points, survey points, etc. can be uniquely identified.

[0093] However, if the surveying staffs 11S and 11T are placed in an appropriate positional relationship with respect to the object to be surveyed 9, each of the intersection points P of the reference points, survey points, etc. can be identified from their positional relationship. Therefore, the group of lines forming the intersection points P of the surveying staff 11 may be rotationally symmetric. Figure 10(C) is a diagram illustrating an example of a checkerboard pattern on the surveying staff 11 according to this modified example.

[0094] (4) The lines forming the intersection point P of the surveying staff 11 may be any lines as long as they are three or more lines drawn on a plane and forming three or more intersection points P whose positional relationships with each other are known. Figure 10(D) is a diagram showing an example of lines forming the intersection point P of the surveying staff 11 according to this modified example.

[0095] (5) In the above-described surveying staff pair 10, a QR code indicating identification information is drawn on the surveying staff 11T, but the QR code may be drawn on the surveying staff 11S instead of the surveying staff 11T.

[0096] (6) A QR code is drawn on the surveying staff 11T described above as a mark for distinguishing the surveying staff 11T from other surveying staffs 11T, but the form of the mark for distinguishing the surveying staff 11T from other surveying staffs 11T is not limited to a QR code. An image representing a code such as a two-dimensional barcode or a one-dimensional barcode other than a QR code may be drawn on the surveying staff 11T instead of the QR code. Also, a string of letters, numbers, symbols, etc. may be drawn on the surveying staff 11T instead of the QR code.

[0097] (7) A QR code is drawn on the above-mentioned surveying staff 11T as a mark for distinguishing the surveying staff 11T from other surveying staffs 11T. This mark makes it possible to easily distinguish the object 9 to be surveyed on which the surveying staff 11T is placed from other objects 9 to be surveyed.

[0098] However, if the object to be surveyed 9 can be identified by other methods, the surveying staff 11T does not need to have a mark drawn on it to distinguish it from other surveying staffs 11T.

[0099] (8) The above-described surveying staff 11 includes a plate- or sheet-like medium and an image formed on the medium, but instead, the surveying staff 11 may not include a medium and the image may be formed on the object to be surveyed. For example, an object to be surveyed including the surveying staff 11 may be realized by forming an image including a checkered pattern or a QR code directly on the object to be surveyed by printing, laser engraving, or the like.

[0100] (9) In the checkered patterns of the surveying staff 11S and the surveying staff 11T, the corresponding areas are painted in different colors. Therefore, a user or a device can easily distinguish the surveying staff 11S and the surveying staff 11T of the two surveying staffs 11 included in the surveying staff pair 10 based on their colors.

[0101] However, if the surveying staff 11S and the surveying staff 11T can be distinguished by a factor other than color, the surveying staff 11S and the surveying staff 11T do not have to be distinguished by color.

[0102] (10) The figure drawn on the surveying staff 11 (see FIG. 3) according to the embodiment described above has the following features. (Feature 1) It has a first line segment (line segment L1) and a second line segment (line segment M1) that have 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)) arranged on the interior angle side of the first line segment (a line segment exemplified by line segment L1) and the second line segment (a line segment exemplified by line segment M1). (Feature 3) The length of the entire figure in the direction of the bisector of the angle formed by the first and second line segments (the length exemplified by the length of line segment P(1,1)P(3,3)) is shorter than the length between the end points of the first and second line segments (the length exemplified by the length of line segment P(1,4)P(4,1)).

[0103] A surveying staff with a graphic having the above characteristics has the following advantages: Since three or more points are drawn, it can be used to measure the positional relationship between two adjacent areas of the 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 of one surveying staff of a pair and the surveying point of the other surveying staff, the distance between the reference point and the surveying point can be shortened, thereby improving the accuracy of the surveying. The entire figure drawn is a long, thin shape with a short length in the direction of the bisector of the angle formed by the first and second line segments, so it can also be used to survey narrow objects.

[0104] A surveying staff having the above features 1 to 3 but having a different figure drawn thereon from the surveying staff 11 according to the embodiment described above (see FIG. 3) may be employed. An example of a figure drawn on the surveying staff 11 according to such a modified example is shown in FIG. 11.

[0105] The figure illustrated in Fig. 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 Fig. 3. Also, the figure illustrated in Fig. 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 Fig. 3.

[0106] In the figure illustrated in FIG. 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).

[0107] In the figure shown in Figure 3, the angle between the first line segment (line segment L1) and the second line segment (line segment M1) is 90 degrees. In contrast, in the figure shown in Figure 11(D), the angle (interior angle) between the first line segment (line segment L1) and the second line segment (line segment M1) is an acute angle. Also, in the figure shown in Figure 11(E), the angle (interior angle) between the first line segment (line segment L1) and the second line segment (line segment M1) is an obtuse angle.

[0108] In the figure illustrated in Figure 11(F), the distance between two adjacent line segments among the first line segment (line segment L1) and a line segment parallel to the first line segment is different from the distance between two adjacent line segments among the second line segment (line segment M1) and a line segment parallel to the second line segment.

[0109] In the figure illustrated in Fig. 11(G), the interval between the first line segment (line segment L1) and two adjacent line segments parallel to the first line segment is not constant. Also, in the figure illustrated in Fig. 11(G), the interval between the second line segment (line segment M1) and two adjacent line segments parallel to the second line segment is not constant.

[0110] 3 and 11(A) to 11(G), the starting points of all line segments parallel to the first line segment (line segment L1) are on the second line segment, and the starting points of all line segments parallel to the second line segment (line segment M1) are on the first line segment. In contrast, the figure illustrated in Fig. 11(H) includes line segments parallel to the first line segment (line segment L1) that include a line segment LX whose starting point is not on the second line segment (line segment M1).

[0111] The figure illustrated in Figure 11(I) has a portion where the polygons located on the interior corner sides of the first line segment (line segment L1) and the second line segment (line segment M1) are not in contact with each other. Note that, as in the example of Figure 11(I), if the end point of the first line segment (line segment L1) or the second line segment (line segment M1) is not an intersection with another line segment, the end point may be used as a feature point whose position is known.

[0112] A figure having the above-mentioned features 4 and 5 is a figure that fits into a flat triangular area as a whole, as in the figures exemplified in Figures 3 and 11. Therefore, compared to a figure that does not satisfy features 4 and 5, such as the figure in Figure 10(C), the size of the surveying staff 11 on which the figure is drawn (the length in the Y direction in Figure 3, i.e., the length in the direction of the bisector of the angle formed by the first line segment and the second line segment) can be made smaller.

[0113] (11) The surveying staff 11 according to the embodiment described above includes a plate- or sheet-like medium and an image formed on the medium, as shown in Fig. 2. For example, in the case of the surveying staff 11S shown in Fig. 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.

[0114] In contrast, the medium provided in the surveying staff 11 may be configured so 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.

[0115] In this application, "a portion of the outer edge of a medium adjacent to a line segment" means a portion of the outer edge of the medium between the point closest to the start point of the line segment and the point closest to the end point of the line segment.

[0116] Figure 12 is a diagram for explaining the advantages of the surveying staff 11 according to this modified example. Figure 12(A) is a diagram showing the pair of surveying staffs 10 of Figure 2 placed on the object to be surveyed 9 so as to sandwich the crack 91. Figure 12(B) is a diagram showing the pair of surveying staffs 10 according to this modified example placed on the object to be surveyed 9 so as to sandwich the crack 91.

[0117] In the medium of the surveying staff 11S constituting the surveying staff pair 10 shown in Figure 12(A), a portion p1 adjacent to the second line segment (line segment M1) is not parallel to the second line segment but protrudes outward. Also, in the medium of the surveying staff 11T constituting the surveying staff pair 10 shown in Figure 12(A), a portion p2 adjacent to the first line segment (line segment L1) is not parallel to the first line segment but protrudes outward.

[0118] On the other hand, a portion p1 of the medium of the surveying staff 11S constituting the surveying staff pair 10 shown in Figure 12(B) adjacent to the second line segment (line segment M1) is parallel to the second line segment and does not protrude outward. Also, a portion p2 of the medium of the surveying staff 11T constituting the surveying staff pair 10 shown in Figure 12(B) adjacent to the first line segment (line segment L1) is parallel to the first line segment and does not protrude outward.

[0119] Therefore, compared to when using the pair of surveying staffs 10 shown in Figure 12(A), when using the pair of surveying staffs 10 shown in Figure 12(B), the distance d between the intersection point P(1,1) (reference point) of the surveying staff 11S and the intersection point P(1,1) (survey point) of the surveying staff 11T can be shortened.

[0120] In a survey using the surveying staff pair 10, the shorter the distance between the reference point and the surveying point, the higher the accuracy of the survey. Therefore, the surveying staff pair 10 shown in Figure 12(B) can perform a survey with higher accuracy than the surveying staff pair 10 shown in Figure 12(A).

[0121] (12) In the two surveying staffs 11 (surveying staff 11S and surveying staff 11T) that make up the surveying staff pair 10 according to the embodiment described above, as shown in FIG. 2, the color schemes for drawing the multiple line segments that form the multiple intersection points P are different between the two surveying staffs 11.

[0122] As described above, if the color schemes for drawing lines on the two surveying staffs 11 that make up the surveying staff pair 10 are different, when the two surveying staffs 11 are photographed simultaneously with a photographing device, if the aperture (F-number), shutter speed, ISO sensitivity, etc. are adjusted to prevent whiteout or blackout in the part of the photographed image where the figure of one of the surveying staffs 11 is captured, it is likely that whiteout or blackout will occur in the part of the photographed image where the figure of the other surveying staff 11 is captured.

[0123] In order to avoid the above inconvenience, the colors used to draw the lines on the two surveying staffs 11 that make up the surveying staff pair 10 may be the same.

[0124] In this application, the color scheme for drawing lines being the same means that the combination of background colors and colors other than the background color is the same.

[0125] If the color scheme for drawing the lines of the two surveying staffs 11 that make up the surveying staff pair 10 is the same, in order to identify each of the two surveying staffs 11, in addition to the multiple lines that form the multiple intersection points P, marks that distinguish the surveying staff 11 from other surveying staffs 11 of the same type may be drawn on the media of one or both of the two surveying staffs 11.

[0126] Figure 13 is a diagram illustrating a pair of surveying rods 10 in which identification information is printed on one or both of the media to distinguish between the two surveying rods 11 of the same color scheme that make up the pair of surveying rods 10.

[0127] The media of the surveying staffs 11S and 11T that make up the surveying staff pair 10 shown in Figure 13(A) have roughly the same trapezoidal shape. In both the surveying staffs 11S and 11T, multiple line segments that form multiple intersection points P are drawn as boundaries between adjacent different areas that are painted in colors (in this case, white and black) that differ in at least one of hue, lightness, and saturation.

[0128] The surveying staff 11S and the surveying staff 11T use the same color scheme to draw the multiple line segments that form the multiple intersection points P. Therefore, unlike the pair of surveying staffs 10 in Figure 2, in the pair of surveying staffs 10 in Figure 13(A), it is not possible to identify which of the two surveying staffs 11 is the surveying staff 11S and which is the surveying staff 11T depending on the color scheme to draw the line segments.

[0129] Therefore, the media provided on the surveying staffs 11S and 11T constituting the surveying staff pair 10 in Fig. 13(A) have an area b (an example of a second area) adjacent to an area a (an example of a first area) colored for drawing a line segment. This area b contacts area a from the outside in the direction of the bisector of the interior angle between the first line segment (line segment L1) and the second line segment (line segment M1). Therefore, as shown in Fig. 12(B), when the surveying staff pair 10 is placed on the object to be surveyed 9 so as to make the distance between the reference point of the surveying staff 11S and the measurement point of the surveying staff 11T as short as possible, area b of the media does not affect that distance.

[0130] Then, in the medium area b of the surveying scale 11S that constitutes the surveying scale pair 10 in Fig. 13(A), a QR code (registered trademark) indicating identification information for identifying this surveying scale 11S from other surveying scales 11 is drawn. Also, in the medium area b of the surveying scale 11T that constitutes the surveying scale pair 10 in Fig. 13(A), a QR code indicating identification information for identifying this surveying scale 11T from other surveying scales 11 is drawn.

[0131] For example, the terminal device 12 can decode the QR code included in the image of the surveying scale pair 10 in Fig. 13(A) to identify each of the surveying scale 11S and the surveying scale 11T shown.

[0132] The surveying scale pair 10 in Fig. 13(B) is different from the surveying scale pair 10 in Fig. 13(A) in that no identification information is drawn in the medium area b of one of the surveying scales 11 (in this case, the surveying scale 11S). The medium area b of the surveying scale 11S in Fig. 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 scale 11S is not identified from other surveying scales 11, but this surveying scale pair 10 is identified from other surveying scale pairs 10 by the identification information of the surveying scale 11T.

[0133] The surveying scale pair 10 in Fig. 13(C) is different from the surveying scale pair 10 in Fig. 13(A) in that the medium of one of the surveying scales 11 (in this case, the surveying scale 11S) does not have the area b. Also in this case, similar to the surveying scale pair 10 in Fig. 13(B), the surveying scale 11S is not identified from other surveying scales 11, but this surveying scale pair 10 is identified from other surveying scale pairs 10 by the identification information of the surveying scale 11T.

[0134] 13, a QR code is depicted as a mark for distinguishing the surveying staff 11 from other surveying staffs 11 of the same type, but the mark may be depicted in a form other than a QR code. For example, the mark for distinguishing the surveying staff 11 from other surveying staffs 11 of the same type may be depicted as an image showing a code such as a two-dimensional code or a one-dimensional barcode other than a QR code, or may be depicted using characters, symbols, etc. that are easily recognizable by humans.

[0135] Figure 14 is a diagram illustrating a surveying staff pair 10 configured so that the two surveying staffs 11 that make up the surveying staff pair 10 have the same color scheme for drawing line segments but different shapes of figures drawn by the line segments, so that it is possible to distinguish which of the two surveying staffs 11 that make up the surveying staff pair 10 is the surveying staff 11S and which is the surveying staff 11T. The surveying staffs 11S and 11T that make up the surveying staff pair 10 in Figure 14 have different shapes of figures drawn by line segments that are line-symmetrical to each other, so the surveying staffs 11S and 11T can be distinguished based on the shapes of these figures, i.e., the arrangement of the intersection points P.

[0136] [Variations regarding information other than points drawn on a surveying staff] In the above-described embodiment, for example, the surveying staff 11T shown in Fig. 2 has a figure having three or more characteristic points used in surveying (hereinafter referred to as a "survey figure"), and in addition thereto, identification information for distinguishing the surveying staff 11 from other surveying staffs 11 is drawn using a QR code (registered trademark). The information drawn on the surveying staff 11 in addition to the survey figure is not limited to the identification information for distinguishing the surveying staff 11 from other surveying staffs 11.

[0137] For example, the surveying staff 11S shown in Figure 2 has the surveying figure shown in Figure 3 painted in different colors, but it is not possible to determine the size of the surveying figure drawn on the actual surveying staff 11S photographed from an image of this surveying staff 11S.

[0138] Therefore, in addition to the survey figure, size information indicating the size of the survey figure may be drawn on the surveying staff 11.

[0139] Figure 15 is a diagram illustrating a surveying staff 11 according to this modified example. In addition to the survey figure, the surveying staff 11 in Figure 15(A) has identification information "123456" that distinguishes this surveying staff 11 from other surveying staffs 11, and size information "length of one side of a square = 10 mm" written in characters and a QR code.

[0140] According to the surveying staff 11 illustrated in Figure 15(A), for example, the terminal device 12 can identify the size of the surveying figure shown in the image by recognizing the characters shown in the image of the surveying staff 11 using OCR (Optical Character Recognition) or by decoding the QR code.

[0141] In addition to the surveying figure, the surveying staff 11 in Figure 15 (B) is also printed with a QR code and numbers indicating the identification information "123456" that distinguishes this surveying staff 11 from other surveying staffs 11, a scale bar indicating the unit length of the actual surveying staff 11, and letters indicating the unit length (in this case, 10 mm).

[0142] With the surveying staff 11 illustrated in Figure 15(B), for example, the terminal device 12 can recognize the characters appearing in an image of the surveying staff 11 using OCR (Optical Character Recognition) to identify the unit length, and can then identify the size of the surveying figure appearing in the image based on the length in the image of the scale bar appearing in the image of the surveying staff 11 and the unit length recognized from the characters.

[0143] Furthermore, in addition to the survey figure, the surveying staff 11 may be printed with identification information for referencing the size information of the survey figure, rather than the size information of the survey figure itself, and the terminal device 12 or the server device 13 may determine the size of the survey figure shown in an image of the surveying staff based on the identification information shown in the image.

[0144] Figure 16 is a diagram illustrating a surveying staff 11 according to this modified example. In addition to the survey figure, the surveying staff 11 in Figure 16 has identification information "123456" written in characters and a QR code to distinguish this surveying staff 11 from other surveying staffs 11.

[0145] FIG. 17 is a diagram showing the configuration of a data table stored in the server device 13 provided in the surveying system 1 according to this modified example.

[0146] Figure 17(A) shows the structure of a data table (hereinafter referred to as "figure table") that stores data on each of a plurality of different survey figures. Note that "different survey figures" here means survey figures that differ in at least one of shape and size. The figure table has the following data fields:

[0147] [Figure ID] field: Stores figure identification information that identifies the survey figure. [Shape Information] field: Stores shape information that indicates the shape of the survey figure. [Size Information] field: Stores size information that indicates the size of the survey figure.

[0148] The shape information is, for example, information indicating the coordinates of each of three or more characteristic points of a survey figure, but any description format is acceptable as long as it is information indicating the positional relationship of three or more characteristic points of a survey figure. For example, an image representing a figure may be stored in the figure table as shape information.

[0149] For example, when the shape information indicates the coordinates of three or more characteristic points of a survey figure, the size information indicates the physical length of one coordinate unit (e.g., 1 millimeter) in the coordinate system that defines those coordinates. However, as long as the information indicates the size of the survey figure, any description format is acceptable.

[0150] Hereinafter, the shape information and size information of a certain survey figure will be referred to as the figure information of that survey figure.

[0151] Figure 17(B) shows the structure of a data table (hereinafter referred to as the "staff table") that stores data relating to each of a plurality of different surveying staffs 11. Note that "a plurality of different surveying staffs 11" here means each of the actual surveying staffs 11. Therefore, data relating to different surveying staffs 11 on which the same survey figure is drawn is stored in different data records in the staff table. The staff table has the following data fields:

[0152] [Staff ID]: Stores staff identification information that identifies the surveying staff 11. [Figure ID]: Store one of the figure IDs stored in the [Figure ID] of the figure table.

[0153] In addition to the above-mentioned staff ID and figure ID, the staff table may also store the name of the surveying object to which the surveying staff 11 is attached, the position of the object on the Earth (latitude, longitude, etc.), information about the manager of the object, etc.

[0154] In this modified example, for example, when a user photographs the surveying staff 11 shown in Fig. 16 using the camera 123 of the terminal device 12, the terminal device 12 decodes the QR code shown in the photographed image and obtains the staff identification information "123456" of the surveying staff 11. The terminal device 12 transmits to the server device 13 a request to send graphic information including the staff identification information "123456" read from the QR code.

[0155] When the server device 13 receives a request to send graphic information from the terminal device 12, it searches the staff table (FIG. 17(B)) for a data record corresponding to the staff identification information "123456" included in the request. Next, the server device 13 searches the graphic table (FIG. 17(A)) for a data record corresponding to the graphic ID included in the data record searched for in the staff table. The server device 13 transmits the graphic information (shape information and size information) included in the data record searched for in the graphic table to the terminal device 12 as a response to the request.

[0156] The terminal device 12 receives the graphic information (shape information and size information) sent from the server device 13 in response to the transmission request, and uses the received graphic information for measurement (for example, processing according to the flow in FIG. 7).

[0157] In the above-described embodiment, the surveying process (for example, the process according to the flow chart in FIG. 7) that is to be performed by the terminal device 12 may be performed by the server device 13. In this case, the terminal device 12 may transmit an image captured by the camera 123 to the server device 13, and the server device 13 may read the staff identification information from the image. Alternatively, the terminal device 12 may read the staff identification information from the image captured by the camera 123, transmit the read staff identification information to the server device 13, and the server device 13 may use the staff identification information.

[0158] Alternatively, the terminal device 12 may receive the graphic table and the staff table from the server device 13, and the terminal device 12 may specify the shape information according to the staff identification information read from the image.

[0159] Note that the configuration of the data table illustrated in Fig. 17 is just one example, and other configurations may be adopted as long as it is possible to identify size information corresponding to the staff identification information. For example, a table having the staff ID as the primary key and having shape information and size information as fields may be used, which is obtained by integrating the figure table (master table) having the figure ID as the primary key illustrated in Fig. 17 and the staff table having the staff ID as the primary key and the figure ID as a field.

[0160] In this modification, the shape of the survey figure drawn on the surveying staff 11 is not limited to that shown in Fig. 3. Fig. 18 is a diagram illustrating a surveying staff 11 on which a survey figure of a different shape from that of the survey figure in Fig. 3 is drawn.

[0161] 18(A) shows a survey figure made up of one square drawn on the surveying staff 11. As in this example, the number of polygons included in the survey figure is not limited to a plurality of polygons.

[0162] 18(B) shows a survey figure made up of four equilateral triangles drawn on the surveying staff 11. As in this example, the shape of the polygon included in the survey figure is not limited to a quadrangle.

[0163] The surveying staff 11 in FIG. 18(C) depicts a survey figure consisting of four right-angled triangles. As in this example, the polygons included in the survey figure are not limited to regular polygons. Furthermore, the ratio of the lengths of the three sides of the right-angled triangle depicted on the surveying staff 11 in FIG. 18(C) is 3:4:5. For example, if the length of the hypotenuse is 10 mm, the lengths of the other two sides are 6 mm and 8 mm, and all of the lengths of the sides are natural numbers. When a polygon in which all the lengths of the sides are rational numbers is depicted on the surveying staff 11 in this way, the amount of rounding off during surveying calculations is reduced, which may result in improved surveying accuracy.

[0164] The surveying staff 11 in Figure 18(D) has a surveying figure drawn thereon that is composed of one square and four isosceles triangles. As in this example, the surveying figure may be composed of polygons of different shapes.

[0165] The surveying staff 11 in Figure 18(E) has a survey figure drawn on it that is composed of three points (more precisely, three small circles that are spaced apart). As in this example, the survey figure may be composed of three or more points (more precisely, three or more small circles that are spaced apart). In this case, the center points of the small circles become the characteristic points used in the surveying.

[0166] 18(F), the staff identification information and size information are drawn inside the survey figure. As in this example, the staff identification information and size information may be drawn inside the survey figure on the survey staff 11.

[0167] 18(F) is drawn by lines rather than by different colors. As in this example, the survey figure may be drawn by lines.

[0168] In the surveying staff 11 of Figure 18(G), the QR code indicating the staff identification information and size information also serves as the surveying figure. In this case, for example, the vertices of the three corners where small squares are located among the four corners of the QR code are used as three characteristic points for surveying. Furthermore, as the size information of this surveying staff 11, for example, information indicating one side of the square that is the overall shape of the QR code (the distance between two adjacent vertices among the vertices of the three corners where small squares are located among the four corners of the QR code) is used.

[0169] In the above example, the staff identification information is drawn on the surveying staff 11, but instead of or in addition to the staff identification information, graphic identification information may be drawn on the surveying staff 11. In this case, the terminal device 12 or the server device 13 reads the graphic identification information from the image captured by the camera 123, and searches the graphic table for shape information and size information corresponding to the read graphic identification information (graphic ID).

[0170] Alternatively, staff identification information including figure identification information may be used. For example, staff identification information may be used in which the first m digits are figure identification information and the following n digits are identification information for identifying individual surveying staffs among surveying staffs on which the same survey figure is drawn. In this case, the terminal device 12 or the server device 13 reads the staff identification information from the image captured by the camera 123, and searches the figure table for shape information and size information corresponding to the figure identification information (figure ID) included in the read staff identification information.

[0171] [Variations of the processing performed by the surveying system] Below, a modified example of the processing performed by the surveying system 1 will be shown. (13) When the similarity S satisfies a predetermined condition, the processor 122 of the terminal device 12 described above displays a message prompting the user to touch the button R3 on the touch screen 124. Alternatively, when the similarity S satisfies a predetermined condition, the processor 122 may perform a process of generating a still image from a video acquired from the camera 123.

[0172] In this modification, a still image generated by the processor 122 from a moving image is used as the still image I. Therefore, the user does not need to perform a touch operation on the button R3 (that is, an operation to release the shutter).

[0173] (14) When the similarity S satisfies a predetermined condition, the processor 122 of the terminal device 12 described above displays a message prompting the user to touch the button R3 on the touch screen 124. Alternatively, when the similarity S satisfies a predetermined condition, the processor 122 may perform a process of instructing the camera 123 to capture a still image and a process of acquiring the still image I captured by the camera 123 in accordance with the instruction.

[0174] In this modified example, the process of releasing the shutter to capture the still image I is automatically performed by the terminal device 12. Therefore, the user does not need to perform a touch operation on the button R3 (that is, an operation to release the shutter).

[0175] (15) The processor 122 of the terminal device 12 described above calculates the similarity S and notifies the user when the similarity S satisfies a predetermined condition. Instead of calculating the similarity S, the processor 122 may estimate the accuracy of the photogrammetry and notify the user when the estimated value of the accuracy (hereinafter referred to as "accuracy X") satisfies a predetermined condition instead of the similarity S.

[0176] In this modification, the processor 122 first identifies one or more of the following (a) to (d) as accuracy estimation parameters based on the video acquired from the camera 123 in order to estimate the accuracy X:

[0177] (a) Position of the surveying staff 11 within the field of view of the camera 123 (b) Angle between the shooting direction of the camera 123 and the direction of the normal to the surveying staff 11 (c) Resolution of the image captured by the camera 123 at the scale indicated by the surveying staff 11 (d) The clarity of the image of the surveying staff 11 included in the image captured by the camera 123

[0178] The position (a) is the position of the image of the surveying staff 11 in the image captured by the camera 123 (for example, the position of a representative point such as the center of gravity of the area occupied by the image of the surveying staff 11). Generally, the further the position of the image of the surveying staff 11 is deviated from the center of the image captured by the camera 123, the more distorted the image of the surveying staff 11 becomes, and the more likely it is that the accuracy of the surveying results will decrease.

[0179] The angle (b) indicates the degree to which the photographing direction of the camera 123, i.e., the direction of the optical axis of the lens of the camera 123, is deviated from the direction directly facing the plane on which the surveying staff 11 is placed. This angle is calculated using a known orthogonal projection transformation method. The larger this angle is, the larger the error that appears in the transformation to an orthogonal projection image in step S3 of Fig. 7, and the more likely it is that the accuracy of the surveying results will decrease.

[0180] The resolution (c) is the number of pixels per unit length in the image, specified by the distance D between two adjacent intersection points P shown in the image of the surveying staff 11. For example, if the distance D between two adjacent intersection points P on the actual surveying staff 11 is 15 mm and the number of pixels between two adjacent intersection points P on the image of the surveying staff 11 is 4.5 million pixels, the resolution (c) is 300,000 pixels / mm, obtained by dividing 4.5 million by 15. The lower this resolution, the more likely it is that the accuracy of the surveying results will decrease.

[0181] The sharpness (d) is an index value indicating the degree of focus, and the lower the value, the more likely it is that the accuracy of the survey results will decrease. This sharpness is determined by known methods (for example, a method of calculation based on the power spectrum of the image, a method of determination using a machine learning model such as deep learning, a method of calculation using Laplacian derivatives, etc.).

[0182] The processor 122 estimates the accuracy X of the photogrammetry using the image of the surveying staff 11 captured by the camera 123 based on the identified accuracy estimation parameters.

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

[0184] For example, in the method using a machine learning model, a machine learning model is prepared by performing machine learning using training data in which, for each of images taken of a surveying staff pair 10 placed on various objects to be measured 9, the values ​​of (a) to (d) above for the image are used as explanatory variables, and the accuracy of the result of photogrammetry using the image is used as a response variable. During operation, the processor 122 inputs the values ​​of (a) to (d) above identified from the image acquired by the camera 123 into the machine learning model as explanatory variables, and obtains the accuracy X output from the machine learning model as a response variable.

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

[0186] This modification also makes it easy to capture images that provide measurement results with sufficiently high accuracy.

[0187] It should be noted that if the above-mentioned predetermined condition regarding the accuracy X is, for example, "the accuracy X is equal to or greater than a predetermined threshold value U," the threshold value U may be changed according to, for example, the accuracy of the survey results required by the user.

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

[0189] Furthermore, when this variant is combined with the above-mentioned variant (11), when accuracy X satisfies a predetermined condition, instead of displaying a message on touch screen 124 urging the user to touch button R3, processor 122 performs a process of instructing camera 123 to take a still image and a process of acquiring still image I taken by camera 123 in accordance with the instruction.

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

[0191] (17) Some of the processing that is to be performed by processor 122 of terminal device 12 in the above-described embodiment may be performed by processor 132 of server device 13. For example, terminal device 12 may transmit still image I to server device 13, and processing according to the flow of FIG. 7 may be performed by processor 132 of server device 13. Furthermore, some or all of the processing that is to be performed by processor 132 of server device 13 in the above-described embodiment may be performed by processor 122 of terminal device 12.

[0192] (18) In the above-described embodiment, the similarity S, which indicates the degree of match between the image of the surveying staff 11 and the guide display G, indicates the degree of match between the positions of the feature points (three or more) of the image of the surveying staff 11 and the feature points (three or more) of the guide display G corresponding to those feature points. However, the similarity S may be any other indicator as long as it indicates the degree of match between the image of the surveying staff 11 and the guide display G.

[0193] For example, any of the following may be calculated as the similarity S: The area of ​​the overlapping portion between the area occupied by the image of the surveying staff 11 and the area occupied by the guide display G. The ratio of the area of ​​the overlapping portion between the area occupied by the image of the surveying staff 11 and the area occupied by the guide display G to the area occupied by the guide display G.

[0194] In addition, 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 staff 11.

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

[0196] (20) In the above-described embodiment, the subject photographing the object to be measured 9 on which the surveying staff pair 10 is placed is assumed to be a user (person), but the subject may also be a device such as a drone.

[0197] (21) In the above-described embodiment, the camera 123 that photographs the object to be surveyed 9 on which the surveying staff 11 is placed is built into or connected to the terminal device 12, but an image taken by a camera that is not connected to the terminal device 12 may also be used. In this case, the terminal device 12 does not display the guide display G or the similarity S between the photographed image and the guide display G, but by using the surveying staff 11, it is easier to obtain highly accurate surveying results compared to when a surveying staff of the prior art is used.

[0198] (22) In the above-described embodiment, the coordinate system corresponding to the surveying staff 11 (the coordinate system C corresponding to the surveying staff 11S or the coordinate system E corresponding to the surveying staff 11S) is 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) Positive Y-axis direction: direction from intersection point P(2,2) to intersection point P(1,1)

[0199] The method of identifying a coordinate system according to the surveying staff 11 is not limited to the above, and the coordinate system may be identified by any method as long as it is based on the positions of three or more intersection points P identified from an image of the surveying staff 11 that are not all aligned on the same line.

[0200] (23) In the above-described embodiment, the surveying staff 11T has three or more lines drawn thereon, forming three or more intersection points P, similar to the surveying staff 11S. However, if the angle between the coordinate systems is not necessary among the information obtained from photogrammetry, the number of lines drawn on the surveying staff 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 surveying staff 11T, and only one intersection point P may be formed between those two lines. [Explanation of symbols]

[0201] 1...surveying system, 11...surveying staff, 12...terminal device, 13...server device, 121...memory, 122...processor, 123...camera, 124...touch screen, 125...communication interface, 131...memory, 132...processor, 133...communication interface.

Claims

[Claim 1] A pair of measuring rods consisting of a first measuring rod and a second measuring rod fixedly positioned on the surface of an object to be surveyed in order to photogrammetry the positional relationship between a reference point on the surface of the object and a measurement point, a figure indicating three or more points whose positional relationships are known is drawn on each of the first surveying staff and the second surveying staff; Size information indicating the size of the figure is written on either the first surveying staff or the second surveying staff. Pair of surveying rods.

Images