Position detection method and computer

Abstract

To provide a new position detection method and a computer, for accurately detecting at least one of the three-dimensional coordinate and three-dimensional directional vector of a marker.SOLUTION: A position detection method acquires the information of the three-dimensional coordinate and three-dimensional directional vector of a reference marker 14, when detecting at least one of the three-dimensional coordinate and three-dimensional directional vector of an object marker 11 attached to an object 10, imaging the object marker 11 and the reference marker 14 by an imaging apparatus 3, and calculating at least one of the relative three-dimensional coordinate and three-dimensional directional vector of the object marker 11 with respect to the reference marker 14 on the basis of an image including the captured object marker 11 and reference marker 14.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a position sensing method and a computer. [Background technology]

[0002] Conventionally, there is known a technique for measuring the position and orientation of an object from an image of a marker attached to the object by capturing an image of the marker with a camera. For example, Patent Document 1 discloses a marker that can be attached to an object. A typical marker is a planar pattern that can be attached to an object. A typical marker includes a square black frame and a two-dimensional pattern code printed inside the frame. Then, by capturing an image of the marker with a camera, the relative position and orientation of the marker and the camera can be recognized, and the position and orientation of the object to which the marker is attached can be recognized. In addition, the camera can read information recorded in the marker. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-145559 A Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for a technique that can accurately detect at least one of the three-dimensional coordinates and the three-dimensional direction vector of a marker.

[0005] The present disclosure has been made in consideration of these points, and aims to provide a new position detection method and computer that can accurately detect at least one of the three-dimensional coordinates and three-dimensional direction vector of a marker. [Means for solving the problem]

[0006] The position detection method of the present disclosure includes: A position detection method for detecting at least one of a three-dimensional coordinate and a three-dimensional direction vector of a target marker attached to an object, comprising: acquiring information on three-dimensional coordinates and three-dimensional direction vectors of the fiducial markers; capturing images of the target marker and the reference marker by an imaging device; calculating at least one of a relative three-dimensional coordinate and a three-dimensional direction vector of the target marker with respect to the reference marker based on an image including the captured target marker and the reference marker; Equipped with.

[0007] In the position detection method of the present disclosure, placing an origin marker at the origin and acquiring information on three-dimensional coordinates and three-dimensional direction vectors of the origin marker; imaging the origin marker and the reference marker; calculating a relative three-dimensional coordinate and a three-dimensional direction vector of the reference marker with respect to the origin marker based on an image including the captured origin marker and the reference marker; Further comprising: in the step of acquiring information on the three-dimensional coordinates and three-dimensional direction vector of the reference marker, the acquired information on the three-dimensional coordinates and three-dimensional direction vector of the reference marker are information on the three-dimensional coordinates and three-dimensional direction vector of the reference marker relative to the origin marker, In the step of calculating the relative three-dimensional coordinates and three-dimensional direction vector of the target marker with respect to the reference marker, at least one of the relative three-dimensional coordinates and three-dimensional direction vector of the target marker with respect to the origin marker may also be calculated.

[0008] In the position detection method of the present disclosure, The origin marker may be located on the same plane as the reference marker.

[0009] The position detection method of the present disclosure includes: A position detection method for detecting three-dimensional coordinates and a three-dimensional direction vector of a target marker attached to an object, comprising: acquiring information on three-dimensional coordinates of an origin; placing a fiducial marker at the origin; imaging the fiducial marker with a fixed-position imaging device; calculating information on three-dimensional coordinates of the imaging device relative to the reference marker based on an image including the captured reference marker, thereby acquiring information on three-dimensional coordinates of the imaging device relative to the origin; capturing an image of the target marker by the imaging device; calculating three-dimensional coordinates of the target marker relative to the imaging device based on an image including the captured target marker, and detecting three-dimensional coordinates of the target marker relative to the origin based on the calculated three-dimensional coordinates of the target marker relative to the imaging device; Equipped with.

[0010] In the position detection method of the present disclosure, The imaging device may be capable of changing an imaging direction.

[0011] In the position detection method of the present disclosure, In the step of capturing an image of the fiducial marker by the imaging device, the same fiducial marker is captured by a plurality of fixed-position imaging devices arranged at different positions; In the step of acquiring information on three-dimensional coordinates of the imaging devices relative to the origin, information on three-dimensional coordinates of each of the imaging devices relative to the reference marker is acquired by calculating information on three-dimensional coordinates of each of the imaging devices relative to the reference marker based on an image including the reference marker captured by each of the imaging devices, In the step of capturing an image of the target marker by the imaging device, the target marker is captured by each of the imaging devices; In the process of detecting the three-dimensional coordinates of the target marker relative to the origin, the relative three-dimensional coordinates of the target marker with respect to each of the imaging devices may be calculated based on images including the target marker captured by each of the imaging devices, and the three-dimensional coordinates of the target marker with respect to the origin may be detected based on the calculated relative three-dimensional coordinates of the target marker with respect to each of the imaging devices.

[0012] In the position detection method of the present disclosure, Each of the imaging devices may be capable of changing the imaging direction.

[0013] The computer of the present disclosure includes: The control unit executes the program, Acquire information on the three-dimensional coordinates and three-dimensional direction vector of the reference marker; Based on the received image including the target marker and the reference marker captured by an imaging device, the relative three-dimensional coordinates and three-dimensional direction vector of the target marker with respect to the reference marker are calculated.

[0014] The computer of the present disclosure includes: The control unit executes the program, acquiring information on three-dimensional coordinates of an origin; calculating information on three-dimensional coordinates of the imaging device relative to the reference marker based on an image captured by an imaging device and including the reference marker located at the accepted origin, thereby acquiring information on three-dimensional coordinates of the imaging device relative to the origin; Based on an image including the accepted target marker captured by the imaging device, the relative three-dimensional coordinates of the target marker with respect to the imaging device are calculated, and based on the calculated relative three-dimensional coordinates of the target marker with respect to the imaging device, the three-dimensional coordinates of the target marker with respect to the origin are detected. Effect of the Invention

[0015] According to the position detection method and computer of the present disclosure, it is possible to obtain a new position detection method and computer that can accurately detect at least one of the three-dimensional coordinates and the three-dimensional direction vector of a marker. [Brief description of the drawings]

[0016] [Figure 1] 1 is a schematic diagram illustrating a configuration of a position detection system according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic diagram illustrating the principle of detection processing of the position detection system according to the embodiment of the present disclosure. [Diagram 3] FIG. 1 is a schematic diagram illustrating one mode of use of a position sensing system according to an embodiment of the present disclosure. [Figure 4] 1 is a flowchart showing a process flow in a position detection system according to an embodiment of the present disclosure. [Diagram 5] FIG. 13 is a schematic diagram showing a modified example of the position detection system according to the embodiment of the present disclosure, the position detection system including an imaging device capable of changing the imaging direction. [Figure 6] 13A to 13C are schematic diagrams illustrating another embodiment of the position detection system according to the present disclosure, in which a mounting body or the like is used as the target and a plurality of imaging devices are used. [Figure 7] FIG. 13 is a schematic diagram showing a modified example of a position detection system according to an embodiment of the present disclosure, in which various markers are arranged on one surface of an object having a step. [Figure 8] FIG. 13 is a schematic diagram showing a modified example of the position detection system according to the embodiment of the present disclosure, illustrating a usage form in which the number of reference markers used is reduced. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. Fig. 1 to Fig. 4 are diagrams showing a part of a position detection system according to an embodiment of the present disclosure. Of these, Fig. 1 is a schematic diagram showing the configuration of the position detection system according to this embodiment, and Fig. 2 is a schematic diagram showing the principle of detection processing of the position detection system according to this embodiment. Fig. 3 is a schematic diagram showing one mode of use of the position detection system according to this embodiment. Fig. 4 is a flowchart showing the flow of processing in the position detection system according to this embodiment.

[0018] -Location detection system 1- 1 is a block diagram showing the configuration of a position detection system 1 according to this embodiment. The position detection system 1 according to this embodiment includes a computer 2 and an imaging device 3.

[0019] The imaging device 3 captures an image of the target marker 11 attached to the target object 10 and a reference marker 14 that is placed on the placement surface 7 and used for positioning the target marker 11. The three-dimensional coordinates and three-dimensional direction vector of the reference marker 14 relative to the origin on the placement surface 7 are measured in advance, and the position detection system 1 acquires information on the three-dimensional coordinates and three-dimensional direction vector of the reference marker 14 relative to the origin. The position detection system 1 also captures images of the target marker 11 and the reference marker 14 using the imaging device 3. The position detection system 1 also calculates at least one of the relative three-dimensional coordinates and three-dimensional direction vector of the target marker 11 relative to the reference marker 14 based on an image including the captured target marker 11 and reference marker 14. For example, the computer 2 is connected to the imaging device 3 so as to be able to communicate with each other. The imaging device 3 and the computer 2 may also be connected to each other so as to be able to communicate with each other via a communication network such as an Internet line. In this specification, three-dimensional coordinates refer to the coordinates at the center position of the marker, and the three-dimensional direction vector of the marker refers to the direction in which a straight line perpendicular to the plane of the marker extends.

[0020] 2, the target marker 11 is one or more AR markers, and the target marker 11 is attached to the target 10. The target marker 11 is used to grasp the positional relationship of a predetermined position (point m1) of the target marker 10. The size of the target marker 11 is such that it can be imaged by the imaging device 3 when attached to the predetermined position of the target 10.

[0021] As shown in FIG. 2, the reference marker 14 is an AR marker, and is placed on the placement surface 7.

[0022] As shown in FIG. 2, the image capturing device 3 is a camera device that is provided in the position detection system 1, of which one or more (one in the embodiment shown in FIG. 2) are provided.

[0023] In the position detection system 1 configured as above, by capturing images of the target marker 11 and the reference marker 14 by the imaging device 3, information regarding the positions and orientations of the reference marker 14 and the target marker 11 relative to a predetermined position (origin O) can be obtained.

[0024] Next, a description will be given of an example of one usage form of the position detection system 1. In this embodiment, as shown in FIG. 3, an example is also given of a form in which an origin marker 71 is placed at the above-mentioned predetermined position (origin).

[0025] The imaging device 3 also captures an image of an origin marker 71 that is used to position an object (target 10) to be detected and is attached to the origin (point m0) of the placement surface 7 of the target 10. It also captures an image of a reference marker 14 that is placed on the placement surface 7 separately from the origin marker 71. For example, the imaging device 3 is placed on the placement surface 7, is hung, or is held by a person. The imaging device 3 is placed in a position where it can capture images of the reference marker 14 and target marker 11, captures these, and acquires image data.

[0026] Furthermore, multiple reference markers 14 may be placed on the placement surface 7. When the reference marker 14 is placed on the placement surface 7, the reference marker 14 is placed at a position different from the origin marker 71. In this way, one or multiple reference markers 14 are placed on the placement surface 7, and at least one reference marker 14 is imaged by the imaging device 3 due to the movement of the target object 10. The predetermined position on the placement surface 7 where the reference marker 14 is attached is represented as point mk.

[0027] The origin marker 71 is an AR marker that is attached to an origin (point m0) set at a predetermined position on the placement surface 7, and is used for calibration together with the target marker 11 or the reference marker 14. When measuring the coordinates of the predetermined position (point m1) where the target marker 11 is attached from the predetermined position (point m0) where the origin marker 71 is attached, the position of point m1 may be obtained by further measuring the coordinates of the predetermined position (point m1) where the target marker 11 is attached from the predetermined position (point m0) where the origin marker 71 is attached using the predetermined position (point m0) where the origin marker 71 is attached. The predetermined position where the origin marker 71 is attached is represented as point m0. The origin marker 71 is placed on the same plane as the reference marker 14.

[0028] The placement surface 7 is a surface used to define a predetermined position (point m1) of the target object 10, and is a plane on which the reference marker 14 is attached. Here, the predetermined position (point m1) means a specific location where the target object 10 is located, and in the case of a humanoid robot, for example, it may be the center point of a target marker 11 attached to the humanoid robot. The placement surface 7 is also defined by a range that can be imaged by the imaging device 3. Note that in the present disclosure, an example will be described in which the target marker 11 is attached to a location corresponding to the head of a self-propelled humanoid robot.

[0029] The above-mentioned functions are achieved by capturing images of the target marker 11 and the reference marker 14 or the origin marker 71 using the imaging device 3. The above-mentioned functions are also achieved by capturing images of the target marker 11 and the reference marker 14 and the origin marker 71 using the imaging device 3.

[0030] <Computer 2 Configuration> The computer 2 can be used through a communication network such as the Internet. As shown in Fig. 1, the computer 2 has a control unit 4, a storage unit 5, and a communication unit 6. The control unit 4 is composed of a microcomputer including a CPU and a semiconductor memory, and controls the operation of the computer 2. More specifically, the control unit 4 executes a program stored in the storage unit 5, thereby functioning as a receiving means 41, a calculating means 42, and a detecting means 43.

[0031] --Preliminary information acquisition process and imaging process-- The receiving means 41 receives three-dimensional coordinates and three-dimensional direction vectors of the reference marker 14 and the origin marker 71 that have been acquired in advance. By using such a coordinate system that has been acquired in advance, it is possible to easily handle the movement and positioning of the humanoid robot as the target object 10. The receiving means 41 also receives images captured by the imaging device 3. For example, the receiving means 41 receives image data of the origin marker 71, the target marker 11, and the reference marker 14 that have been captured in advance by the imaging device 3.

[0032] -Calculation process- 3, the calculation means 42 calculates the relative three-dimensional coordinates of a predetermined position (point m1) of the object 10 with respect to the attachment position of the target marker 11 attached to the object 10, based on image data including at least the target marker 11 and the reference marker 14 selected from a group including image data of the origin marker 71, the target marker 11, and the reference marker 14 received by the reception means 41. This makes it possible to continue to obtain the relative coordinates and vector of the predetermined position (point m1) of the object 10, for example, without continuously positioning the origin marker 71 at point m0.

[0033] First, the calculation means 42 calculates a homogeneous transformation matrix based on the matrices at the positions of the imaging device 3 (point C) and the reference marker 14 (point mk) from the image data captured by the imaging device 3. c H mk-1 In addition, based on the respective positions of the imaging device 3 (point C) and the target marker 11 (point m1), a homogeneous transformation matrix c H m1 And I asked for c H m1 and c H mk -1 Based on mk H m1 ( c H mk -1 c H m1 Note that a homogeneous transformation matrix is ​​used to efficiently calculate coordinate transformation and rigid body transformation using matrix calculations, and in three-dimensional space, it is expressed by the following equation.

[0034]

number

[0035] In addition, when measuring the coordinates of the predetermined position (point m1) where the target marker 11 is attached from the predetermined position (point m0) where the origin marker 71 is attached, the calculation means 42 calculates a homogeneous transformation matrix based on the matrices at the predetermined position (point m0) of the origin marker 71 and the predetermined position (point mk) of the reference marker 14. m0 H mk Then, the calculation means 42 calculates the calculated m0 H mk and mk H m1 Based on m0 H m1 ( m0 H mkmk H m1 ) is obtained. By measuring the reference marker 14 and the object marker 11 in this manner, the predetermined position of the object marker 11 from the predetermined position of the origin marker 71 can be calculated.

[0036] More specifically, the calculation means 42 calculates the relative three-dimensional coordinates and three-dimensional direction vector of the predetermined position (point mk) of the reference marker 14 with respect to the predetermined position (point m0) of the origin marker 71 based on the image including the coordinates of the predetermined position (point mk) of the reference marker 14 and the coordinates of the predetermined position (point m0) of the origin marker 71 accepted by the acceptance means 41 ( m0 H mk ). In this way, the predetermined position (point mk) of the reference marker 14 is calibrated with respect to the predetermined position (point m0) on the placement surface 7. Furthermore, the calculation means 42 calculates the relative three-dimensional coordinates and three-dimensional direction vector of the predetermined position (point m1) of the target marker 11 with respect to the predetermined position (point mk) of the reference marker 14 based on an image including the coordinates of the predetermined position (point mk) of the reference marker 14 and the coordinates of the predetermined position (point m1) of the target marker 11 accepted by the acceptance means 41 ( mk H m1 ).

[0037] Then, the image capturing device 3 captures images of the origin marker 71, the reference marker 14, and the target marker 11 over time, and the detection means 43 m0 H m1 ( m0 H mkmk H m1 ), it is possible to continue to obtain the coordinates of the predetermined position (point m1) of the target marker 11 in more detail as the target 10 moves.

[0038] The programs executed by the control unit 4 are not limited to those stored in the storage unit 5. As the programs executed by the control unit 4, those transmitted from an external device to the control unit 4 via the communication unit 6, those stored in a storage medium such as a USB memory attached to the computer 2, those stored in a server (e.g., a cloud server) other than the computer 2, etc. may be used.

[0039] The storage unit 5 is composed of a hard disk drive (HDD), a random access memory (RAM), a read only memory (ROM), a solid state drive (SSD), etc. Various programs including a program executed by the control unit 4 are stored in the storage unit 5. The storage unit 5 also stores images captured by the imaging device 3. Details of the information stored in the storage unit 5 will be described later.

[0040] The communication unit 6 is, for example, a wired LAN (Local Area Network) module, a wireless LAN module, etc., and includes an interface for performing wired or wireless communication. That is, the communication unit 6 is configured from a communication interface configured to communicate with other devices via a communication network.

[0041] Next, various processes in this embodiment will be described with reference to the usage form of the position detection system 1 shown in Fig. 3 and the flowchart shown in Fig. 4. Note that the operation of the position detection system 1 described below is performed by the control unit 4 of the computer 2 executing a program stored in the storage unit 5.

[0042] <Calibration process> First, the user attaches the reference marker 14 and the origin marker 71 to the placement surface 7 .

[0043] Next, the user captures an image of the reference marker 14 using the imaging device 3 to obtain information on the three-dimensional coordinates and three-dimensional direction vector of a predetermined position (point mk) of the reference marker 14, in other words, the coordinates, with a predetermined position (point C) of the imaging device 3 as a reference point (step S10). The obtained data is accepted by the accepting means 41.

[0044] <Detection process> Next, the imaging device 3 captures images of the target marker 11 and the reference marker 14 attached to the target object 10 (step S11). At this time, the coordinates of a predetermined position (point m1) of the target marker 11 and a predetermined position (point mk) of the reference marker 14 are acquired from the captured image with respect to a predetermined position (point C) of the imaging device 3 as a reference, and are accepted by the acceptance means 41.

[0045] Next, the calculation means 42 calculates the relative three-dimensional coordinates and three-dimensional directional vector of the specified position (point m1) of the target marker 11 relative to the specified position (point mk) of the reference marker 14 based on the image including the coordinates of the specified position (point mk) of the reference marker 14 and the coordinates of the specified position (point m1) of the target marker 11 accepted by the acceptance means 41 (step S12).

[0046] After step S12, the image capturing device 3 captures the reference marker 14 and the target marker 11 over time, and the detection means 43 mk H m1 By continuously detecting the target marker 11, the coordinates of a predetermined position (point m1) of the target marker 11 are continuously acquired as the target marker 11 moves.

[0047] According to the position detection method of the present embodiment configured as described above, the position detection method of the present disclosure acquires information on the three-dimensional coordinates and three-dimensional direction vector of the reference marker 14 when detecting at least one of the three-dimensional coordinates and three-dimensional direction vector of the target marker 11 attached to the object 10. Next, the image capturing device 3 captures images of the target marker 11 and the reference marker 14. Next, based on the captured image including the target marker 11 and the reference marker 14, at least one of the three-dimensional coordinates and three-dimensional direction vector of the target marker 11 relative to the reference marker 14 is calculated.

[0048] According to such a position detection method, by continuously capturing an image of the target marker 11 by the imaging device 3, the coordinates accompanying the movement of the target object 10 can be acquired over time. To explain in more detail, a technique has been known in the past in which a marker is attached to the target object and the marker is captured by a camera to measure the position and orientation of the target object from the image of the marker. A technique for detecting at least one of the three-dimensional coordinates and the three-dimensional direction vector of the marker with high accuracy has been desired. According to the position detection method having the above configuration, by calculating the three-dimensional coordinates and the three-dimensional direction vector of the target marker 11 relative to the reference marker 14, the three-dimensional coordinates of a predetermined position (point m1) on the target object 10 to which the target marker 11 is attached can be detected from the image of the target marker 11, thereby solving the above-mentioned problems.

[0049] In the detection method of the present embodiment, as described above, the origin marker 71 is placed at the origin, and information on the three-dimensional coordinates and three-dimensional direction vector of the origin marker 71 is obtained. Next, the origin marker 71 and the reference marker 14 are imaged. Next, based on the image including the imaged origin marker 71 and the reference marker 14, the relative three-dimensional coordinates and three-dimensional direction vector of the reference marker 14 with respect to the origin marker 71 are calculated. Here, when obtaining the information on the three-dimensional coordinates and three-dimensional direction vector of the reference marker 14, the obtained information on the three-dimensional coordinates and three-dimensional direction vector of the reference marker 14 is information on the relative three-dimensional coordinates and three-dimensional direction vector of the reference marker 14 with respect to the origin marker 71. In addition, when calculating the relative three-dimensional coordinates and three-dimensional direction vector of the target marker 11 with respect to the reference marker 14, at least one of the relative three-dimensional coordinates and three-dimensional direction vector of the target marker 11 with respect to the origin marker 71 may also be calculated. In this case, by measuring the relative position of the reference marker 14 with respect to the origin marker 71 in advance, the position of the target marker 11 with respect to the origin marker 71 can be detected, and the target can be imaged even if the angle of view of the imaging device 3 is small.

[0050] Furthermore, in the detection method of this embodiment, as described above, the origin marker 71 may be arranged on the same plane as the reference marker 14. In this case, by arranging the origin marker 71 on the same plane as the reference marker 14, the coordinate systems in the surface directions of the origin marker 71 and the reference marker 14 can be handled together.

[0051] Furthermore, in computer 2 of this embodiment, control unit 4 executes a program to acquire information on the three-dimensional coordinates and three-dimensional direction vector of reference marker 14. Also, based on the received image including target marker 11 and reference marker 14 captured by imaging device 3, computer 2 calculates the relative three-dimensional coordinates and three-dimensional direction vector of target marker 11 with respect to reference marker 14. In this case, by calculating the relative three-dimensional coordinates and three-dimensional direction vector of target marker 11 with respect to reference marker 14, computer 2 can detect the three-dimensional coordinates of a predetermined position (point m1) on object 10 to which target marker 11 is attached from the image of target marker 11.

[0052] In the computer 2 of this embodiment, the control unit 4 executes a program to obtain information on the three-dimensional coordinates of the origin. Based on an image including the reference marker 14 located at the accepted origin captured by the imaging device 3, information on the three-dimensional coordinates of the imaging device 3 relative to the reference marker 14 is calculated to obtain information on the three-dimensional coordinates of the imaging device 3 relative to the origin. Based on an image including the accepted target marker 11 captured by the imaging device 3, the relative three-dimensional coordinates of the target marker 11 relative to the imaging device 3 are calculated, and based on the calculated relative three-dimensional coordinates of the target marker 11 relative to the imaging device 3, the three-dimensional coordinates of the target marker 11 relative to the origin are detected. In this case, the computer 2 can obtain coordinates related to the movement of the target marker 10 by measuring the target marker 10 using the imaging device 3.

[0053] The position detection method and computer 2 according to the present disclosure are not limited to the above-described aspects, and various modifications can be made.

[0054] In the present embodiment, the embodiment has been described by exemplifying a form in which the target marker 11 is arranged on a humanoid robot, but the present invention is not limited to this. For example, as shown in FIG. 6, after acquiring the self-position of the imaging device 3, the self-position measurement and self-position estimation of the target 10, such as a moving body such as a rock, a robot, a drone, or an AGV, may be performed. In this case, a fixed-position camera is used as the imaging device 3. This makes it possible to measure the relative positional deviation at a plurality of points of the target 10. For example, in the position detection method, first, information on the three-dimensional coordinates of the origin is acquired. Next, a reference marker 14 is arranged at the origin as a predetermined position on the arrangement surface 7. At this time, the coordinates of the reference marker 14 are acquired in advance. In addition, the reference marker 14 is imaged by a fixed-position camera. In addition, information on the three-dimensional coordinates of the fixed-position camera relative to the reference marker 14 is calculated based on an image including the imaged reference marker 14, thereby acquiring information on the three-dimensional coordinates of the fixed-position camera relative to the origin. Thereafter, the target marker 11 arranged on the target 10 is imaged by the fixed-position camera. Furthermore, based on the captured image including the target marker 11, the three-dimensional coordinates of the target marker 11 relative to the fixed-position camera are calculated. Then, based on the calculated three-dimensional coordinates of the target marker 11 relative to the fixed-position camera, the three-dimensional coordinates of the target marker 11 relative to the origin are detected. At this time, after the coordinates of the reference marker 14 are acquired, the reference marker 14 may be removed. This makes it possible to acquire coordinates relating to the movement of the target 10 by measuring the target 10 with the imaging device 3. Furthermore, in cases where the target 10 does not move much, such as in civil engineering management, the measurement accuracy can be improved by measuring the coordinates multiple times and performing statistical processing.

[0055] Furthermore, the position detection system 1 may include a plurality of imaging devices 3. In this case, the reference marker 14 and the target marker 11 are captured by the plurality of imaging devices 3, and the three-dimensional coordinates of the target marker 11 relative to the origin are detected based on the captured images.

[0056] 5, the imaging device 3 may be configured to be able to change the imaging direction. In this case, first, information on the three-dimensional coordinates of the origin (point m0) is acquired in advance. Also, a reference marker 14 is placed at the origin (point m0), and the reference marker 14 is imaged by the imaging device 3 with a fixed position. Then, based on the image including the captured reference marker 14, information on the three-dimensional coordinates of the imaging device 3 with a fixed position relative to the reference marker 14 is calculated. This makes it possible to acquire information on the three-dimensional coordinates of the imaging device 3 with a fixed position relative to the origin (point m0) (information on point C0). Then, the imaging device 3 with a fixed position images the target marker 11. Based on the image including the captured target marker 11, the relative three-dimensional coordinates of the target marker 11 relative to the imaging device 3 with a fixed position is calculated. In other words, since information on the three-dimensional coordinates of the fixed-position imaging device 3 relative to the origin (point m0) (information on point C0) is acquired in advance, even if the imaging direction of the fixed-position imaging device 3 has changed (the fixed-position imaging device 3 has rotated), the relative three-dimensional coordinates of the target marker 11 with respect to the fixed-position imaging device 3 can be calculated based on an image including the captured target marker 11, and the three-dimensional coordinates of the target marker 11 with respect to the origin (point m0) can be detected based on the calculated relative three-dimensional coordinates of the target marker 11 with respect to the fixed-position imaging device 3. More specifically, the reference marker 14 is captured by the imaging device 3 whose imaging direction has changed (it has rotated to a position corresponding to C1), and the captured image is received by the receiving means 41. Based on the image received by the receiving means 41, the calculating means 42 calculates the three-dimensional coordinates of the target marker 11 relative to the fixed-position imaging device 3. c1 H m0 -1 , c0 H c1 -1 respectively, m0 H c0 ( c1 H m0 -1 c0 H c1 -1) and measure the coordinates of a predetermined position (point C0) of the imaging device 3 relative to a predetermined position (point m0) of the reference marker 14. Next, the imaging device 3 is rotated, and the target marker 11 is photographed from the position C2 after the rotation. c0 H c2 , c2 H m1 , respectively, m0 H m1 ( m0 H c0c0 H c2c2 H m1 ) is measured to measure the coordinates of a predetermined position (point m1) of the object marker 11 relative to a predetermined position (point m0) of the reference marker 14.

[0057] After the above, at least the target marker 11 is imaged over time by the fixed-position imaging device 3, and the detection means 43 m0 H m1 ( m0 H c0c0 H c2c2 H m1 ), it is possible to continue to obtain the coordinates of the predetermined position (point m1) of the target marker 11 in more detail as the target 10 moves.

[0058] In addition, although the origin marker 71 has been described as being arranged on the same plane as the reference marker 14, this is not limiting. For example, the origin marker 71 does not have to be arranged on the same plane as the reference marker 14 as long as calibration and detection processing are possible. In addition, as shown in Fig. 7, the origin marker 71 and the reference marker 14 may each be arranged on one surface of an object having a step such as a staircase.

[0059] 8, two of the reference markers 14 among a plurality of reference markers 14 placed on an object such as a wall may be imaged, and then the reference markers 14 may be thinned out. In this case, the calculation means 42 calculates a homogeneous transformation matrix c1 H m0 -1In addition, based on the respective positions of the imaging device 3 (point C1) and the reference marker 14 (point mk1), a homogeneous transformation matrix c1 H mk1 And I asked for c1 H m0 -1 and c1 H mk1 Based on m0 H mk1 ( c1 H m0 -1 c1 H mk1 ) is obtained. In this way, the predetermined position (point mk1) of the reference marker 14 is calibrated with respect to the predetermined position (point m0) of the origin marker 71. Furthermore, the calculation means 42 obtains a homogeneous transformation matrix c2 H mk1 -1 In addition, a homogeneous transformation matrix is ​​calculated based on the respective positions of the predetermined position (point C2) of the imaging device 3 and the predetermined position (point mk2) of the reference marker 14. c2 H mk2 And I asked for c2 H mk1 -1 and c2 H mk2 Based on mk1 H mk2 ( c2 H mk1 -1 c2 H mk2 ) is calculated. In this way, the predetermined position (point mk2) of the reference marker 14 is calibrated based on the predetermined position (point mk1) of the reference marker 14. Then, the calculation means 42 calculates m0 H mk1 and mk1 H mk2 Based on the homogeneous transformation matrix m0 H mk2 ( m0 H mk1mk1 H mk2) is calculated. By repeating such calculations, it is possible to obtain position and orientation information, i.e., three-dimensional coordinates and three-dimensional direction vectors, at predetermined positions (points mk1, mk2, ..., mkn (n is a natural number)) of the reference marker 14 from a predetermined position (point m0) of the origin marker 71. Then, as shown on the right side of FIG. 8, it is possible to reduce the number of locations where the reference marker 14 is placed. [Explanation of symbols]

[0060] 1: Position detection system 2: Computer 3: Imaging device 4: Control section 5: Storage section 6: Communications Department 7: Placement surface 10: Object 11: Target marker 14: Reference marker 41: Reception method 42: Calculation method 43: Detection means 71: Origin marker

Claims

1. A position detection method for detecting at least one of a three-dimensional coordinate and a three-dimensional direction vector of a target marker attached to an object that is an operable detection target, comprising: acquiring information on three-dimensional coordinates and three-dimensional direction vectors of a reference marker used for positioning the target marker; capturing images of the target marker and the reference marker by an imaging device; calculating at least one of a relative three-dimensional coordinate and a three-dimensional direction vector of the target marker with respect to the reference marker based on an image including the captured target marker and the reference marker; Equipped with placing an origin marker at the origin and acquiring information on three-dimensional coordinates and three-dimensional direction vectors of the origin marker; imaging the origin marker and the reference marker; calculating in advance three-dimensional coordinates and a three-dimensional direction vector of the reference marker relative to the origin marker based on an image including the captured origin marker and the reference marker; Further comprising: in the step of acquiring information on three-dimensional coordinates and three-dimensional direction vectors of the reference marker, the acquired information on the three-dimensional coordinates and three-dimensional direction vectors of the reference marker are information on the relative three-dimensional coordinates and three-dimensional direction vectors of the reference marker with respect to the origin marker, A position detection method, in which in the process of calculating the relative three-dimensional coordinates and three-dimensional direction vector of the target marker with respect to the reference marker, at least one of the relative three-dimensional coordinates and three-dimensional direction vector of the target marker with respect to the origin marker is also calculated.

2. The position detection method according to claim 1 , wherein the origin marker is disposed on the same plane as the reference marker.

3. The control unit executes the program, Acquire information on three-dimensional coordinates and three-dimensional direction vectors of a reference marker used for positioning with a target marker attached to an object that is an operable detection target; Calculating three-dimensional coordinates and a three-dimensional direction vector of the target marker relative to the reference marker based on the received image including the target marker and the reference marker captured by an imaging device; An origin marker is placed at the origin, and information on three-dimensional coordinates and three-dimensional direction vector of the origin marker is acquired; taking an image of the origin marker and the reference marker; calculating in advance three-dimensional coordinates and a three-dimensional direction vector of the reference marker relative to the origin marker based on an image including the captured origin marker and the reference marker; when acquiring information on the three-dimensional coordinates and three-dimensional direction vector of the reference marker, the acquired information on the three-dimensional coordinates and three-dimensional direction vector of the reference marker is information on the relative three-dimensional coordinates and three-dimensional direction vector of the reference marker with respect to the origin marker, A computer that, when calculating the relative three-dimensional coordinates and three-dimensional direction vector of the target marker with respect to the reference marker, also calculates at least one of the relative three-dimensional coordinates and three-dimensional direction vector of the target marker with respect to the origin marker.

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