Method for displaying correction image for surveying instrument, surveying instrument, and target light position specifying method for automatic collimation or automatic tracking of surveying instrument

Abstract

To provide a surveying device capable of accurate tracking even with a reflecting mirror rotating on the optical axis of an image sensor.SOLUTION: A surveying instrument captures a first image at a first position of a scanning mirror, rotates the scanning mirror from the first position by a first angle in a rotational direction of a rotation axis to move the scanning mirror to a second position, captures a second image at the second position, obtains a rotation center coordinate of the second image relative to the first image using the first image, the second image, and the first angle measured by an angle measurement sensor, and generates a corrected image in which rotation and movement of the second image in the direction of the rotation axis are corrected using the rotation center coordinate, the first angle, and the second image.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present disclosure relates to a method for displaying a corrected image of a surveying instrument, a surveying instrument, and a method for identifying a target light position for automatic collimation or automatic tracking of the surveying instrument. [Background technology]

[0002] A surveying device has been studied that includes a light receiving element that receives reflected distance measuring light from the object to be measured, a tracking light receiving element that receives reflected light of tracking light emitted to the object to be measured, and an imaging unit that receives background light, in which the distance measuring light, tracking light, and background light are coaxial (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-23609 Summary of the Invention [Problem to be solved by the invention]

[0004] In surveying instruments in which the distance measurement light, tracking light, and background light are coaxial, a reflector that rotates on the optical axis of the image sensor is provided, and when the collimating optical axis is rotated up and down in the vertical direction, the reflector rotates along the rotation axis, and the image reflected by the reflecting surface rotates and moves, and since the image sensor is fixed inside the surveying instrument, the captured two-dimensional image rotates and moves.

[0005] Furthermore, since the target position that appears as the difference between the light-emitting image and the light-extinction image is used during tracking by the surveying instrument, it was necessary to correct and display the deviation caused by the rotation and movement of the captured image.

[0006] Therefore, an object of the present disclosure is to enable accurate tracking even in a surveying instrument equipped with a reflecting mirror that rotates on the optical axis of an imaging element. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the presently disclosed method for displaying a corrected image of a surveying instrument includes a surveying instrument equipped with an imaging unit having an imaging element for capturing an image, a scanning mirror that rotates along one of a horizontal and vertical rotation axis and has a flat reflecting surface inclined with respect to the rotation axis, an angle measurement sensor that measures the rotation angle of the rotation axis, a control unit, an imaging unit that is fixed within a base unit without rotating along the rotation axis, and a base unit that has the scanning mirror, the angle measurement sensor, and the control unit installed therein, and when an image captured by the imaging unit is displayed on a display unit of the surveying instrument or a display unit of a mobile terminal, the imaging unit The method includes a first imaging step of capturing a first image at a first position of the scanning mirror; a rotation step in which the control unit rotates the scanning mirror from the first position by a first angle in the rotation direction of the rotation axis and moves it to a second position; a second imaging step in which the imaging unit captures a second image at the second position; an image correction step in which the control unit generates a corrected image by correcting the rotation and movement of the second image in the rotation axis direction using the rotation center coordinates, the first angle, and the second image; and a corrected image display step in which the control unit displays the corrected image on the display unit of the surveying instrument or the display unit of the mobile terminal in place of the second image.

[0008] In order to achieve the above-mentioned object, the surveying instrument of the present disclosure comprises an imaging unit having an imaging element for capturing an image, a scanning mirror that rotates along one of a horizontal and a vertical rotation axis and has a flat reflecting surface inclined with respect to the rotation axis, an angle measurement sensor that measures the rotation angle of the rotation axis, a control unit, and a base unit that incorporates the imaging unit, scanning mirror, angle measurement sensor, and control unit, wherein the imaging unit is fixed within the base unit without rotating along the rotation axis, and the image captured by the imaging unit is displayed on a display unit of the surveying instrument, or When displaying on the display unit of the portable terminal, the imaging unit captures a first image at a first position of the scanning mirror, the control unit rotates the scanning mirror from the first position by a first angle in the rotation direction of the rotation axis and moves it to a second position, the imaging unit captures a second image at the second position, the control unit uses the rotation center coordinates, the first angle, and the second image to generate a corrected image that corrects the rotation of the second image and the movement in the rotation axis direction, and the control unit displays the corrected image on the display unit of the surveying instrument or the display unit of the portable terminal in place of the second image.

[0009] In order to achieve the above-mentioned object, a target light position specifying method for automatic collimation or automatic tracking of a surveying instrument includes a surveying instrument including an imaging unit having an imaging element for capturing an image, a scanning mirror that rotates along one of a horizontal and vertical rotation axis and has a flat reflecting surface inclined with respect to the rotation axis, an angle measuring sensor that measures the rotation angle of the rotation axis, a control unit, a base unit that includes the imaging unit that is fixed within a base unit without rotating along the rotation axis, the scanning mirror, the angle measuring sensor, and the control unit, and a target that can emit and extinguish light, the imaging unit detecting a first light at a first position of the scanning mirror where the light is emitted or extinguished in a first state. a rotation step in which the control unit rotates the scanning mirror from the first position by a first angle in the rotation direction of the rotation axis and moves it to a second position; a second imaging step in which the imaging unit captures a second image at the second position in a second state in which light emission or extinction is different from the first state; an image correction step in which the control unit generates a corrected image using the rotation center coordinates, the first angle, and the second image, correcting the rotation of the second image and the movement in the rotation axis direction; and a target position identification step in which the control unit obtains a difference image between the first image and the corrected image and identifies the target light position using the difference image.

[0010] In order to achieve the above-mentioned object, the surveying device of the present disclosure is a surveying device capable of automatic collimation or automatic tracking of a target light position, and is equipped with an imaging unit having an imaging element for capturing an image, a scanning mirror that rotates along one of a horizontal and vertical rotation axis and has a flat reflecting surface inclined with respect to the rotation axis, an angle measurement sensor that measures the rotation angle of the rotation axis, a control unit, a base unit that does not rotate along the rotation axis and that has the imaging unit, scanning mirror, angle measurement sensor, and control unit installed inside, and a target that can emit and extinguish light. The imaging unit captures a first image at a first position of the scanning mirror where light emission or extinction is in a first state, the control unit rotates the scanning mirror from the first position by a first angle in the rotation direction of the rotation axis and moves it to a second position, the imaging unit captures a second image at the second position where light emission or extinction is in a second state different from the first state, the control unit generates a corrected image by correcting the rotation and movement of the second image using the rotation center coordinates, the first angle, and the second image, and the control unit obtains a difference image between the first image and the corrected image and identifies the target light position using the difference image. [Effects of the Invention]

[0011] According to the present disclosure using the above means [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a surveying instrument according to the present disclosure. [Figure 2] FIG. 2 is a diagram illustrating a distance measuring unit of the surveying device of the present disclosure. [Figure 3] FIG. 2 is a side view showing a beam splitter surface of the multilayer optical element. [Figure 4] 10A and 10B are diagrams illustrating a case where the imaging surface does not rotate. [Figure 5] FIG. 10 is a diagram illustrating a case where rotation of the imaging surface occurs. [Figure 6] FIG. 1 is a diagram illustrating a calibration method according to an example embodiment of the present disclosure. [Figure 7] FIG. 2 is a functional block diagram of the surveying device of the present disclosure. [Figure 8] FIG. 10 is a flowchart illustrating the process flow of the calibration method of the present disclosure. [Figure 9] FIG. 1 is a diagram illustrating a calibration method according to an example embodiment of the present disclosure. [Figure 10] FIG. 10 is a flowchart illustrating the process flow of the calibration method of the present disclosure. [Figure 11] FIG. 10 is a flowchart illustrating the processing flow of the image correction method of the present disclosure. [Figure 12] FIG. 10 is a schematic diagram illustrating target light position identification. [Figure 13] FIG. 10 is a flowchart illustrating the process flow of the target light position identification method of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. For convenience of explanation, a laser scanner will be described as an example, but the present disclosure is also applicable to other surveying devices. Furthermore, since the basic hardware configuration example is the same as the conventional example, the more distinctive configuration of the present disclosure can be understood from the description that follows <Rotation and Movement of Captured Images> below. The hardware configuration of the surveying device is also an important feature of the present disclosure.

[0014] <Example of hardware configuration of surveying equipment> 1 is a schematic cross-sectional view showing a surveying instrument according to the present disclosure. The surveying instrument 1 is, for example, a laser scanner, and is composed of a leveling unit 2 attached to a tripod (not shown), and a surveying instrument main body 3 attached to the leveling unit 2. The surveying instrument 1 is capable of performing both prism measurement and non-prism measurement.

[0015] The surveying instrument main body 3 includes a fixed section 4, a base section 5, a horizontal rotation shaft 6 (second rotation shaft), a horizontal rotation bearing 7, a horizontal rotation motor 8 as a horizontal rotation drive section, a horizontal angle encoder 9 as a horizontal angle detector, a vertical rotation shaft 11 (first rotation shaft), a vertical rotation bearing 12, a vertical rotation motor 13 as a vertical rotation drive section, a vertical angle encoder 14 as a vertical angle detector, a scanning mirror 15 as a vertical rotation section, an operation panel 16 that serves as both an operation section and a display section, a control section 17, a memory section 18, a distance measurement section 19, etc. The control section 17 includes a CPU specialized for this instrument or a general-purpose CPU, and is equipped with a calculation function and is capable of information processing using application programs stored in the memory section 18 or memory. The horizontal angle encoder 9 and vertical angle encoder 14 are collectively referred to as an angle measurement sensor.

[0016] The horizontal rotary bearing 7 is fixed to the fixed part 4. The horizontal rotary shaft 6 has a vertical axis 6a, and is rotatably supported by the horizontal rotary bearing 7. The base part 5 is supported by the horizontal rotary shaft 6, and the base part 5 rotates integrally with the horizontal rotary shaft 6 in the horizontal direction.

[0017] A horizontal rotation motor 8 is provided between the horizontal rotation bearing 7 and the base frame part 5, and the horizontal rotation motor 8 is controlled by the control unit 17. The control unit 17 causes the horizontal rotation motor 8 to rotate the base frame part 5 about the axis 6a.

[0018] The relative rotation angle of the support unit 5 with respect to the fixed unit 4 is detected by a horizontal angle encoder 9. A detection signal from the horizontal angle encoder 9 is input to a control unit 17, which calculates horizontal angle data. The control unit 17 performs feedback control on the horizontal rotation motor 8 based on the horizontal angle data.

[0019] Furthermore, a vertical rotation shaft 11 having a horizontal axis 11a is provided on the base part 5. The vertical rotation shaft 11 is rotatable via a vertical rotation bearing 12. The intersection of the axis 6a and the axis 11a is the emission position of the distance measuring light, and is also the origin of the coordinate system of the surveying device main body 3.

[0020] A recess 21 is formed in the base 5. One end of the vertical rotation shaft 11 extends into the recess 21, and a scanning mirror 15 is fixed to the one end, and the scanning mirror 15 is housed in the recess 21.

[0021] A vertical angle encoder 14 is provided at the other end of the vertical rotation shaft 11. A vertical rotation motor 13 is provided on the vertical rotation shaft 11, and the vertical rotation motor 13 is controlled by a control unit 17. The control unit 17 causes the vertical rotation motor 13 to rotate the vertical rotation shaft 11, and the scanning mirror 15 is rotated around the axis 11a.

[0022] The rotation angle of scanning mirror 15 is detected by vertical angle encoder 14, and the detection signal is input to control unit 17. Control unit 17 calculates vertical angle data of scanning mirror 15 based on the detection signal, and performs feedback control on vertical rotation motor 13 based on the vertical angle data.

[0023] The horizontal angle data, vertical angle data, measurement results, measurement point intervals, and measurement angle intervals calculated by the control unit 17 are stored in the memory unit 18. The memory unit 18 may be a magnetic storage device such as an HDD, an optical storage device such as a CD or DVD, or a semiconductor storage device such as a RAM, ROM, DRAM, memory card, or USB memory. The memory unit 18 may be detachable from the base unit 5, or may be capable of transmitting data to an external storage device or external data processing device via a communication device (not shown).

[0024] The memory unit 18 stores various programs such as a sequence program for controlling the distance measurement operation, a calculation program for calculating distance by the distance measurement operation, a calculation program for calculating an angle based on horizontal angle data and vertical angle data, a calculation program for calculating the three-dimensional coordinates of a desired measurement point based on the distance and angle, a tracking program for tracking an object to be measured, a setting program for setting the interval between measurement points and the interval between measurement angles, a control program for controlling the drive of the light amount adjustment member, a calibration program using the center of rotation, etc. Furthermore, the control unit 17 executes various programs to perform various processes.

[0025] The operation panel 16 is, for example, a touch panel, and serves as both an operation section for inputting distance measurement instructions and measurement conditions, and a display section for displaying distance measurement results and the like.

[0026] Next, the distance measurement unit 19 will be described with reference to FIG.

[0027] The distance measurement unit 19 mainly includes a distance measurement light emitting unit 22, a distance measurement light receiving unit 23, a tracking light emitting unit 24, a tracking light receiving unit 25, a laser pointer light emitting unit 26, and an imaging unit 27. The distance measurement unit is made up of the distance measurement light emitting unit 22 and the distance measurement light receiving unit 23. The tracking light emitting unit 24 and the tracking light receiving unit 25 make up a tracking unit.

[0028] The distance measurement light emitting unit 22 has an emission optical axis 29. The distance measurement light emitting unit 22 also has a light emitting element 31, such as a laser diode (LD), arranged on the emission optical axis 29, a projection lens 32, and a beam combiner 33 which is a first deflection optical member, and also has a multilayer film optical element 34 which serves as a second deflection optical member arranged on the reflected optical axis of the emission optical axis 29 reflected by the beam combiner 33. Furthermore, a scanning mirror 15 is arranged on the reflected optical axis of the emission optical axis reflected by the multilayer film optical element 34.

[0029] The projection lens 32, the beam combiner 33, and the multilayer optical element 34 constitute a distance measurement projection optical system. In this embodiment, the exit optical axis 29, the reflected optical axis of the exit optical axis 29 reflected by the beam combiner 33, and the reflected optical axis of the exit optical axis 29 reflected by the multilayer optical element 34 are collectively referred to as the exit optical axis 29.

[0030] The light emitting element 31 emits pulses of a laser beam (invisible light) of an infrared or near-infrared wavelength as distance measuring light, or emits bursts of a laser beam as distance measuring light.

[0031] The beam combiner 33 has optical properties of transmitting light of a specific wavelength and reflecting light of another specific wavelength coaxially with the transmitted light. The beam combiner 33 transmits the tracking light and reflects the distance measurement light emitted from the light emitting element 31 so that the distance measurement light is coaxial with the tracking light. In other words, the beam combiner 33 is located on a common optical path of the distance measurement light and the tracking light. Note that the beam combiner 33 may be configured to reflect the tracking light and transmit the distance measurement light.

[0032] The multilayer optical element 34 is, for example, a plate-like glass having a predetermined thickness, and is inclined with respect to the exit optical axis 29. One surface (first incident surface) of the multilayer optical element 34 located close to the light emitting element 31 is a long-pass filter surface 35 on which a long-pass filter film that transmits infrared light or near-infrared light and reflects visible light is vapor-deposited.

[0033] The other surface (second entrance surface) of the multilayer optical element 34 located away from the light emitting element 31 is a beam splitter surface 37 on which a beam splitter film 36 is vapor-deposited.

[0034] The thickness and tilt angle of the multilayer optical element 34 are set so that the distance measurement light emitting unit 22 (tracking light emitting unit 24) and the laser pointer light emitting unit 26 (imaging unit 27) are separated and a predetermined optical axis distance can be ensured between the emission optical axis 29 (tracking optical axis 49) and the laser pointer optical axis 55 (imaging optical axis 59). The multilayer optical element 34 also functions as an optical axis separating optical member for separating the emission optical axis 29 (tracking optical axis 49) and the laser pointer optical axis 55 (imaging optical axis 59).

[0035] The distance measurement light receiving unit 23 has a light receiving optical axis 41. The distance measurement light receiving unit 23 also has a light receiving unit 42, such as an optical fiber, a light intensity adjustment member 43, and a light receiving prism 44, which are arranged on the light receiving optical axis 41, as well as an imaging lens 45 and a multilayer optical element 34, which are arranged on the light axis of light reflected by the light receiving prism 44 from the light receiving optical axis 41. The light intensity adjustment member 43, the light receiving prism 44, the imaging lens 45, and the multilayer optical element 34 constitute a distance measurement light receiving optical system. In this embodiment, the light receiving optical axis 41 and the light axis of light reflected by the light receiving prism 44 are collectively referred to as the light receiving optical axis 41.

[0036] The light receiving unit 42 is, for example, the light receiving end surface of an optical fiber, and receives the distance measurement light reflected by the object to be measured as reflected distance measurement light. The optical fiber also guides the reflected distance measurement light to a light receiving element provided at a predetermined position, and the reflected distance measurement light is received by the light receiving element. Note that the light receiving element may be provided at the light receiving position of the light receiving unit 42. Hereinafter, the light receiving unit 42 will be referred to as the light receiving element 42.

[0037] The light amount adjustment member 43 is, for example, a parallel flat plate made of glass having a known thickness, and is disposed so as to be perpendicular to the light receiving optical axis 41. The light amount adjustment member 43 can be inserted into and removed from the light receiving optical axis 41 by a drive mechanism 46 such as a solenoid.

[0038] Although not shown, the light intensity adjustment member 43 has a central incident surface for the reflected distance measurement light, which is formed as a light intensity adjustment surface 47 on which, for example, a reflective film is vapor-deposited, and the remaining portion of the surface other than the light intensity adjustment surface 47 is formed as a full transmission surface 48 on which an anti-reflection film is vapor-deposited.

[0039] A window 40 that rotates integrally with the scanning mirror 15 is provided on the optical axis of the distance measurement light reflected by the scanning mirror 15. The window 40 is inclined at a predetermined angle with respect to the optical axis (emission optical axis 29) of the distance measurement light, and prevents the distance measurement light (stray light) reflected by the window 40 from entering the light receiving element 42.

[0040] The tracking light emitting unit 24 has a tracking optical axis 49. The tracking light emitting unit 24 also has a tracking light emitting element 51, a projection lens 52, a beam combiner 33, and a multilayer film optical element 34, which are arranged on the tracking optical axis 49. The projection lens 52, the beam combiner 33, and the multilayer film optical element 34 constitute a tracking projection optical system. In this embodiment, the tracking optical axis 49 and the reflected optical axis of the tracking optical axis 49 reflected by the multilayer film optical element 34 are collectively referred to as the tracking optical axis 49.

[0041] The tracking light emitting element 51 is, for example, a laser diode (LD), and is configured to emit a laser beam (invisible light) of an infrared or near-infrared wavelength different from the wavelength of the distance measuring light as tracking light.

[0042] The tracking light receiving unit 25 has a tracking light receiving optical axis 53. The tracking light receiving unit 25 also has a tracking light receiving element 54 and a light receiving prism 44 provided on the tracking light receiving optical axis 53, as well as an imaging lens 45 and a multilayer film optical element 34 provided on the reflected optical axis of the tracking light receiving optical axis 53 reflected by the light receiving prism 44. The light receiving prism 44, the imaging lens 45, and the multilayer film optical element 34 constitute a tracking light receiving optical system. In this embodiment, the tracking light receiving optical axis 53 and the reflected optical axis of the tracking light receiving optical axis 53 reflected by the light receiving prism 44 are collectively referred to as the tracking light receiving optical axis 53.

[0043] The tracking light receiving element 54 is configured as a light receiving element that receives tracking light reflected by the measurement object as reflected tracking light. The tracking light receiving element 54 is a CCD or CMOS sensor that is a collection of pixels, and the position of each pixel on the image element can be identified. For example, each pixel has pixel coordinates with the center of the tracking light receiving element 54 as the origin, and the position on the image element is identified by the pixel coordinates. Each pixel outputs the pixel coordinates to the control unit 17 along with a light receiving signal.

[0044] The laser pointer light emitting unit 26 has a laser pointer optical axis 55. The laser pointer light emitting unit 26 also has a light emitting element 56, a light projecting lens 57, and a beam splitter 58, which is a third deflection optical member, arranged on the laser pointer optical axis 55, and a multilayer film optical element 34 arranged on the optical axis of the laser pointer optical axis 55 reflected by the beam splitter 58. The long-pass filter surface 35 deflects the laser pointer light coaxially with the ranging light and tracking light. That is, the multilayer film optical element 34 is located on a common optical path of the ranging light, tracking light, laser pointer light, and visible light.

[0045] The projection lens 57, the beam splitter 58, and the multilayer optical element 34 constitute a laser pointer projection optical system. The laser pointer optical axis 55, the reflected optical axis of the laser pointer optical axis 55 reflected by the beam splitter 58, and the reflected optical axis of the laser pointer optical axis 55 reflected by the multilayer optical element 34 are collectively referred to as the laser pointer optical axis 55. The laser pointer optical axis 55 reflected by the beam splitter 58 is parallel to the tracking optical axis 49, for example.

[0046] The light emitting element 56 is, for example, a laser diode (LD) configured to emit visible light such as red light as the laser pointer light. The beam splitter 58 has optical properties of transmitting light at a predetermined transmittance and reflecting light at a predetermined reflectance, and deflects the laser pointer light coaxially with the visible light. In other words, the beam splitter 58 is located on the common optical path of the laser pointer light and the visible light.

[0047] The imaging unit 27 has an imaging optical axis 59. The imaging unit 27 also has an imaging element 61 provided on the imaging optical axis 59, a camera lens group 62 consisting of a plurality of lenses, a beam splitter 58, and a multilayer film optical element 34. The camera lens group 62, the beam splitter 58, and the multilayer film optical element 34 constitute an imaging optical system. The imaging optical axis 59 and the reflected optical axis of the imaging optical axis 59 reflected by the multilayer film optical element 34 are collectively referred to as the imaging optical axis 59.

[0048] The image sensor 61 is a CCD or CMOS sensor that is a collection of pixels, and the position of each pixel on the image sensor can be identified. For example, each pixel has pixel coordinates with the center of the image sensor 61 as the origin, and the position on the image sensor is identified by the pixel coordinates. Each pixel outputs the pixel coordinates to the control unit 17 along with a light reception signal.

[0049] The positions of the laser pointer light emitting unit 26 and the imaging unit 27 are set so that the transmission position of the emission optical axis 29 or the tracking optical axis 49 from the long-pass filter surface 35 coincides with the reflection position of the laser pointer optical axis 55 and the imaging optical axis 59 relative to the long-pass filter surface 35.

[0050] Next, the light-receiving prism 44 will be described in detail with reference to FIG.

[0051] The light receiving prism 44 is configured by integrating a first prism 63, which is a pentagonal dichroic prism having a predetermined refractive index, and a second prism 64, which is a rectangular dichroic prism having a predetermined refractive index.

[0052] The first prism 63 has a first surface 65 facing the imaging lens 45, a second surface 66 opposite the first surface 65, a third surface 67 located below the page in Figure 3, and a fourth surface 68 located above the page in Figure 3.

[0053] The second prism 64 also has a fifth surface 69 in contact with the third surface 67, a sixth surface 71 opposite the fifth surface 69, a seventh surface 72 located on the right side of the page in Figure 3, and an eighth surface 73 located on the left side of the page in Figure 3.

[0054] The first prism 63 and the second prism 64 are integrated via a third surface 67 and a fifth surface 69. In addition, the corner formed by the second surface 66 and the third surface 67 of the first prism 63 is chamfered to form a chamfered portion 74. The chamfered portion 74 makes the first prism 63 a pentagonal prism. In addition, the chamfered portion 74 causes the areas of the third surface 67 and the fifth surface 69 to match, and the first prism 63 and the second prism 64 form a flush light-receiving prism 44.

[0055] The surface (incident surface) of first surface 65 is a fully transmissive surface provided with an anti-reflection coating. First surface 65 is perpendicular to light-receiving optical axis 41 and tracking light-receiving optical axis 53, and the angle of incidence of each optical axis with respect to first surface 65 is 0°.

[0056] A reflective film is provided on the second surface 66. The second surface 66 is inclined at a predetermined angle with respect to the light-receiving optical axis 41 and the tracking light-receiving optical axis 53, and is configured to reflect the reflected distance measuring light and reflected tracking light that have passed through the first surface 65 toward the first surface 65 so that they are incident on the first surface 65 at an angle equal to or greater than the critical angle. Here, the angle of the optical axis with respect to the surface means the angle between the normal to the surface and the optical axis.

[0057] Furthermore, the third surface 67 is inclined at a predetermined angle with respect to the light-receiving optical axis 41 and the tracking light-receiving optical axis 53 reflected by the first surface 65. A dichroic filter film is provided on the third surface 67 or on the boundary surface between the third surface 67 and the fifth surface 69. The dichroic filter film is configured to reflect the reflected distance measuring light and transmit the reflected tracking light. In other words, the third surface 67 or the boundary surface between the third surface 67 and the fifth surface 69 serves as a separation surface for separating the reflected distance measuring light and the reflected tracking light. The dichroic filter film may also be configured to transmit the reflected distance measuring light and reflect the reflected tracking light.

[0058] The fourth surface 68 is a fully transmissive surface provided with an anti-reflection coating, and is configured to fully transmit the reflected distance measuring light reflected by the third surface 67. The fourth surface 68 is also perpendicular to the light receiving optical axis 41, and the angle of incidence of the light receiving optical axis 41 with respect to the fourth surface 68 is 0°.

[0059] A reflecting surface is provided on the seventh surface 72. The seventh surface 72 is inclined at a predetermined angle with respect to the tracking light receiving optical axis 53. For example, the seventh surface 72 is configured so that the reflected tracking light that has passed through the third surface 67 or the boundary surface between the third surface 67 and the fifth surface 69 is incident on the seventh surface 72 at an angle equal to or greater than the critical angle and is reflected toward the eighth surface 73.

[0060] The eighth surface 73 is a fully transmitting surface provided with an anti-reflection coating, and is configured to fully transmit the reflected tracking light reflected by the seventh surface 72. Furthermore, the eighth surface 73 is perpendicular to the tracking receiving light optical axis 53, and the angle of incidence of the tracking receiving light optical axis 53 with respect to the eighth surface 73 is 0°. Note that the sixth surface 71 is not provided with a reflective coating or the like, as the reflected tracking light is not incident thereon.

[0061] Next, a case where measurement and tracking are performed by the surveying instrument 1 having the distance measurement unit 19 will be described. In the following description, a movable measurement object such as a prism is measured. The various operations of the distance measurement unit 19 are performed by the control unit 17 executing various programs.

[0062] The distance measurement unit 19 is controlled by the control unit 17. The light emitting element 31 emits a laser beam with a partial red or near-infrared wavelength as distance measurement light, which enters the beam combiner 33 via the projection lens 32. The distance measurement light reflected by the beam combiner 33 passes through the long-pass filter surface 35 of the multilayer optical element 34, is reflected by the beam splitter film 36 of the beam splitter surface 37, and then passes through the long-pass filter surface 35 again. The distance measurement light is deflected during its transmission through the long-pass filter surface 35. The distance measurement light transmitted through the long-pass filter surface 35 is deflected at a right angle by the scanning mirror 15 and is irradiated onto a predetermined measurement target through the window 40.

[0063] The optical axis (emission optical axis 29) of the distance measurement light emitted from scanning mirror 15 coincides with axis 11a. When scanning mirror 15 rotates around axis 11a, the distance measurement light rotates (scans) in a plane that is perpendicular to axis 11a and includes axis 11a.

[0064] The distance measurement light reflected by the object to be measured (reflected distance measurement light) enters scanning mirror 15 through window 40 and is reflected at a right angle by scanning mirror 15. After passing through multilayer optical element 34, the reflected distance measurement light enters light-receiving prism 44 while being focused by imaging lens 45.

[0065] The reflected distance measuring light that has passed through the first surface 65 is internally reflected successively by the second surface 66, the first surface 65, and the third surface 67 (or the boundary surface between the third surface 67 and the fifth surface 69), and then enters the fourth surface 68 at an incident angle of 0°. The reflected distance measuring light that has entered the fourth surface 68 also passes through the fourth surface 68 and is received by the light receiving element 42 via the light amount adjustment member 43.

[0066] The reflected distance measuring light reflected by the second surface 66 is incident on the first surface 65 at an angle equal to or greater than the critical angle, and is therefore totally reflected by the first surface 65. The reflected distance measuring light that is internally reflected within the light-receiving prism 44 is configured not to interfere with the chamfered portion 74. In other words, the chamfered portion 74 is formed outside the optical path of the reflected distance measuring light.

[0067] In addition, the thickness of the light intensity adjusting member 43 is known. Therefore, the extension of the optical path length of the reflected distance measuring light caused by the insertion of the light intensity adjusting member 43 can be easily corrected by subtracting an offset value based on the plate thickness from the measurement result.

[0068] The control unit 17 measures the distance for each pulse of the distance measuring light (Time Of Flight) based on the time difference between the light emission timing of the light emitting element 31 and the light reception timing of the light receiving element 42 (i.e., the round trip time of the pulsed light) and the speed of light. The light emitting element 31 is capable of changing the light emission timing, i.e., the pulse interval, as well as the light emission repetition frequency and the peak power of the pulse.

[0069] The base 5 and scanning mirror 15 each rotate at a constant speed, and the vertical rotation of the scanning mirror 15 and the horizontal rotation of the base 5 cooperate to perform two-dimensional scanning with the distance measurement light. Furthermore, distance measurement data (slant distance) is obtained by measuring the distance for each pulse of light, and vertical angle data and horizontal angle data can be obtained by detecting the vertical angle and horizontal angle for each pulse of light using the vertical angle encoder 14 and horizontal angle encoder 9. Three-dimensional coordinates corresponding to the object to be measured can be calculated using the vertical angle data, horizontal angle data, and distance measurement data. Furthermore, by rotating the scanning mirror 15 and irradiating the distance measurement light in a rotary manner, three-dimensional point cloud data can be obtained.

[0070] The reflected distance measuring light reflected by the object to be measured has a greater amount of light in the center when measuring a short distance and a greater amount of light in the peripheral area when measuring a long distance. Therefore, the light attenuation effect of the light amount adjusting surface 47 acts mainly on the reflected distance measuring light when measuring a short distance.

[0071] In parallel with the distance measurement operation, the tracking light emitting element 51 emits an infrared or near-infrared laser beam as tracking light, which is invisible light with a different wavelength from the distance measurement light. The emitted tracking light enters the beam combiner 33 via the light projector lens 52. The tracking light that passes through the beam combiner 33 passes through the long-pass filter surface 35 coaxially with the distance measurement light, is reflected by the beam splitter film 36 of the beam splitter surface 37, and then passes through the long-pass filter surface 35 again. Note that the tracking light is deflected in the same way as the distance measurement light while passing through the long-pass filter surface 35. The tracking light that passes through the long-pass filter surface 35 is deflected at a right angle by the scanning mirror 15 and is irradiated onto the specified measurement target through the window 40.

[0072] The reflected tracking light reflected by the object to be measured is reflected by the scanning mirror 15, and after passing through the multilayer optical element 34 while being deflected, is focused by the imaging lens 45 and enters the light receiving prism 44.

[0073] The reflected tracking light that has passed through the first surface 65 is internally reflected by the second surface 66 and the first surface 65 in that order, and then passes through the third surface 67 (or the boundary surface between the third surface 67 and the fifth surface 69). The reflected tracking light that has passed through the third surface 67 is internally reflected by the seventh surface 72, and then passes through the eighth surface 73 at an incident angle of 0°, and is received by the tracking light-receiving element 54.

[0074] The reflected tracking light reflected by the second surface 66 is incident on the first surface 65 at an angle equal to or greater than the critical angle, and the reflected tracking light transmitted through the third surface 67 (or the boundary surface between the third surface 67 and the fifth surface 69) is reflected by the seventh surface 72 at an angle equal to or greater than the critical angle and then incident on the eighth surface 73. Therefore, the reflected tracking light is totally reflected by the first surface 65 and the seventh surface 72.

[0075] The control unit 17 calculates the deviation between the center of the tracking light receiving element 54 and the incident position of the reflected tracking light, and based on the deviation, controls the horizontal rotation motor 8 and the vertical rotation motor 13 so that the incident position of the reflected tracking light is the center of the tracking light receiving element 54. In this way, the surveying instrument main body 3 tracks the object to be measured.

[0076] Furthermore, in parallel with the distance measurement and tracking operations described above, the light emitting element 56 emits a laser beam, for example, with a wavelength in the red visible light region, as laser pointer light. The emitted laser pointer light is incident on the beam splitter 58 via the light projector lens 57. The laser pointer light reflected by the beam splitter 58 is reflected by the long-pass filter surface 35 of the multilayer optical element 34 so as to be coaxial with the distance measurement light and tracking light. The laser pointer light reflected by the long-pass filter surface 35 is deflected at a right angle by the scanning mirror and is irradiated onto the measurement object through the window 40. Here, since the laser pointer light is coaxial with the distance measurement light, the irradiation position of the distance measurement light coincides with the irradiation position of the laser pointer light.

[0077] The laser pointer light reflected by the object to be measured (reflected laser pointer light) enters distance measurement unit 19 coaxially with the reflected distance measuring light, reflected tracking light, and visible light (background light). The reflected laser pointer light and visible light are reflected by long-pass filter surface 35 and enter image pickup element 61 via beam splitter 58 and camera lens group 62.

[0078] The reflected laser pointer light and visible light enter the image sensor 61, allowing the control unit 17 to capture an image centered on the reflected laser pointer light, i.e., an image centered on the distance measurement light. The image captured here can also be used for specifying and aiming at the measurement target. Alternatively, an image of only background light may be captured without activating the light-emitting element 56.

[0079] As described above, in this embodiment, the tracking light-receiving element 54 and the imaging element 61 are coaxial and separate members. Therefore, the tracking light-receiving element 54 and the imaging element 61 can each receive a sufficient amount of light, which increases the distance (reaching distance) at which tracking and imaging are possible, and enables tracking and imaging to be performed with high accuracy even at long distances.

[0080] <Rotation and movement of captured images> In the surveying instrument described above, the optical system is fixed inside the base 5, and the scanning mirror 15 is used to scan light, making the vertical rotation mechanism lighter and realizing a surveying instrument with better responsiveness and a wider measurement range. However, there are problems in that the reflecting surface of the reflector is tilted with respect to the optical axis, the image reflected by the reflecting surface rotates and moves, and the imaging element is fixed inside the surveying instrument, so the captured two-dimensional image rotates and moves.

[0081] When the surveying device 1 captures an image, if the imaging unit 27 is configured to rotate and move in synchronization with the base unit 5, the image captured by the imaging unit 27 will not rotate. Specifically, as shown in Figure 4, assume that the imaging optical axis of the imaging element 61, which is the image sensor of the imaging unit 27, is initially positioned so that it coincides with the Z axis, i.e., faces horizontally. At this time, IMa is the area that can be received by the image sensor.

[0082] Next, when the base unit 5 is rotated vertically upward (in the Y direction) by θ° using the vertical rotation motor 13, the imaging unit 27 and its optical axis also rotate θ° in synchronization with this. The area that can be received by the image sensor then transitions from IMa to IMb, but the image does not rotate at that time. The amount of transition ΔY in the Y direction from IMa to IMb can be calculated by using the vertical angle encoder 14 as an angle measuring sensor to measure the rotation θ°.

[0083] Similarly, when the base 5 rotates vertically downward by θ°, the imaging unit 27 and its optical axis also rotate downward by θ° in synchronization. The area that can be received by the image sensor then transitions from IMa to IMb, resulting in a deviation of ΔY. The same is true for the horizontal direction, but this will not be discussed here.

[0084] Next, a case where a reflecting mirror (scanning mirror 15) that rotates on the imaging optical axis of imaging element 61, as in the present disclosure, will be described. In Fig. 5, unlike Fig. 4, imaging unit 27 is located in front (for convenience of illustration, imaging unit 27 is placed below scanning mirror 15), and the imaging optical axis of imaging unit 27 is aligned with the horizontal direction via reflection by scanning mirror 15. This state is the initial position.

[0085] 1, scanning mirror 15 is arranged with its reflective surface tilted relative to the horizontal and vertical rotation axes of support unit 5 (for example, tilted at 45° as shown in FIG. 1), and the rotation of vertical rotation axis 11 (first rotation axis) enables the reflective surface to be scanned in the vertical direction. However, since the reflective surface also rotates at this time, the image received by the image sensor of imaging unit 27 involves rotation and shifts in the X and Y directions, and is not a simple tilt movement of the image as shown in FIG.

[0086] As shown in Figure 5, assume that the image sensor is initially in a state where an image of light-receiving region IMr is captured at an initial position with a vertical angle of 0° and a horizontal angle of 0°. When scanning the optical axis of imaging unit 27 in the vertical direction, scanning mirror 15 must rotate, for example, upward by θ° along vertical rotation axis 11. Since the reflective surface of scanning mirror 15 also rotates during this process, the image received by the image sensor becomes image IMr1, which not only rotates by θ° from the initial position but also has a shift that shifts in the X and Y directions. A similar phenomenon occurs when rotating downward by θ°.

[0087] Therefore, the present inventors recognized the need to calibrate the image deviations in the rotational, vertical and horizontal directions each time the scanning mirror rotates, and investigated means for solving this problem.

[0088] <How to obtain the center of rotation for calibration> (First method) FIG. 6 is a diagram for explaining an example of obtaining the rotation center of the present disclosure. FIG. 7 is a functional block diagram of a surveying device, and FIG. 8 is a flowchart showing the processing flow. In order to correct image misalignment, the rotation center must be obtained. Here, the image before vertical angle rotation is referred to as image A (first image), and the image after vertical angle rotation is referred to as image B (second image). Images A and B are different images captured by vertical rotation, but they have overlapping image areas (groups of pixels containing common feature points). In the example of FIG. 6, for example, mountain ridges and tree parts overlap and can be used as common feature points.

[0089] Although the explanation is out of order, first, in step S101, imaging unit 27 captures a first image that serves as a reference at a first position of scanning mirror 15 (first imaging step). This is as described above. The first position is merely a reference position and is not limited to a horizontal angle of 0° and a vertical angle of 0°. Furthermore, since it is only necessary to know the relative positional relationship between the first position and a second position (described later), the second position (described later) may also be used as a reference.

[0090] Next, in step S102, control unit 17 rotates scanning mirror 15 from the first position by a predetermined angle (first angle) in the rotation direction of the vertical rotation axis, and moves it to a second position (rotation step). This is also as described above. However, the first angle is limited to a range that includes the feature points common to image A and image B as images.

[0091] Then, in step S103, a second image (image B) is captured at a second position (second image step).

[0092] Here, the vertical rotation angle θ of images A and B about vertical rotation axis 11 is known because it has been measured by vertical angle encoder 14 (angle measurement sensor). If the rotation angle is θ°, then reverse rotation processing of image B by an angle equivalent to this θ° will result in reverse-rotated image Br. Therefore, next in step S104, control unit 17 performs reverse rotation processing of the second image by the same angle as the first angle measured by the angle measurement sensor, thereby obtaining a reverse-rotated image (reverse-rotation image formation step).

[0093] At this point, the angular relationship between image A and reverse-rotated image Br matches, but there is a shift in the image in the horizontal and vertical directions, and a shift in the viewpoint due to tilt in the vertical direction.

[0094] Next, in order to correct the deviation of the viewpoint movement due to the tilt in the vertical direction, in step S105, the control unit 17 shifts the reverse-rotated image by the same amount in the opposite direction as the first movement amount on the image corresponding to the first angle, thereby obtaining a reverse-rotated, reverse-shifted image (reverse-rotated, reverse-shifted image formation step). In other words, the image center is shifted in the direction opposite to the vertical viewpoint movement due to the rotation of the vertical angle. For convenience, this is called reverse shift. As described with reference to FIG. 4, this reverse shift moves the image center by a difference ΔY corresponding to the known rotation angle θ°. For example, if image B is obtained from image A by rotating it vertically upward, the center Cb is reverse-shifted downward to obtain the reverse-shifted center Cb, as shown in (3) of FIG. 6. At this time, a reverse-rotated, reverse-shifted image Brs is obtained, with the reverse-shifted center Cb as the image center.

[0095] Next, in step S106, the control unit 17 performs image matching between the first image (image A) and the reverse-rotated, reverse-shifted image Brs, and calculates the difference in the positions of feature points commonly included in the first image and the reverse-rotated, reverse-shifted image Brs (image matching step). That is, image matching is performed between image A and the reverse-rotated, reverse-shifted image Brs, and the shift amounts of the positions (pixel coordinates) of the common feature points are calculated. At this time, a horizontal shift amount Δx and a vertical shift amount Δy, which are the movement amounts on the pixel coordinates for matching the common feature points between image A and the reverse-rotated, reverse-shifted image Brs, are obtained.

[0096] Next, in step S107, the control unit 17 shifts the image center position of the reverse-rotated and reverse-shifted image Brs by the difference in the positions of the feature points, and obtains the rotation center coordinates of the second image relative to the first image (rotation center calculation step). That is, the position of the reverse-shift center Cb on the image is shifted based on the shift amount ΔxΔy. Then, the shifted position is obtained as the rotation center Cr of the image.

[0097] If such a center of rotation Cr can be determined, it becomes possible to calibrate the surveying instrument using the center of rotation Cr and the known vertical rotation angle θ, even when the image rotation described above occurs. Note that if the center of rotation Cr calculated using such a calibration method is registered (stored in the memory unit 18), calibration will not be necessary every time. Alternatively, various optical adjustments may be performed using this center of rotation Cr, making it unnecessary to register the center of rotation Cr.

[0098] (Second method) Next, the second method for determining the center of rotation will be described. Fig. 8 is a diagram for explaining an example of the method for determining the center of rotation according to the present disclosure. Fig. 9 is a flowchart showing the processing flow. However, in order to use the method described below, it is necessary to have a mechanism that allows the base unit 5 to rotate 180° horizontally and the scanning mirror 15 to rotate 180° vertically.

[0099] First, in step S201, imaging unit 27 captures a first image at a first position of scanning mirror 15 (first imaging step). Here, the first image in the second embodiment is image C shown in Fig. 9. Image C is an image obtained at a vertical angle of 0° and a horizontal angle of 0°, and includes feature point Sc1.

[0100] Next, in step S202, control unit 17 rotates scanning mirror 15 180° from the first position in the direction of rotation of the first rotation axis, then rotates 180° in the direction of the second rotation axis, and moves it to a second position (forward and reverse rotation step). Next, imaging unit 27 captures a second image at the second position (second image step). Here, the second image in the second embodiment is image D shown in FIG. 9. Image D is obtained. Image D includes feature point Sc2. Feature point Sc2 is a feature point corresponding to feature point Sc1.

[0101] Next, in step S203, the control unit 17 connects the common feature points included in the first image and the second image with a line segment, calculates the coordinates of the midpoint of the line segment, and obtains the coordinates of the rotation center of the second image relative to the first image (rotation center calculation step). That is, the image C and the image D are superimposed, and a line segment is connected between the feature points Sc1 and Sc2. Then, the position of the midpoint of the line segment is obtained as the rotation center Cr. In this way, the rotation center of the image can also be obtained.

[0102] <Correction and display of rotated captured images> (Display of the corrected image on the display of the surveying device or the display of the mobile terminal) If the rotation center of an image can be determined as described above, it can be used to correct a rotated and tilted image and display it. The flow of this process will be explained using Figure 11.

[0103] First, imaging unit 27 captures a first image (not shown) at a first position of scanning mirror 15 (first imaging step). This first image is not a correction target, but serves as one of the reference images used in the above calibration method.

[0104] Next, control unit 17 rotates scanning mirror 15 from the first position by a first angle (θ) in the horizontal or vertical (assumed to be vertical here) rotation direction of the rotation axis, and moves it to a second position (rotation step).

[0105] Next, the imaging unit 27 captures a second image (image E) at a second position (second imaging step). This second image involves rotation and movement of the image area, and is an image that requires correction. Up to this point, the processing flow is the same as that of the calibration method described above.

[0106] Next, in step S301, the control unit 17 obtains the rotation center coordinates of the second image relative to the first image using the first image, the second image, and the first angle measured by the angle measurement sensor (rotation center calculation step). For this, the rotation center coordinates Cr of the second image are obtained by the above-mentioned method using the first image, the second image, and the angle θ of the rotational movement of the horizontal or vertical rotation axis between the first image and the second image.

[0107] Next, in step S302, the control unit 17 uses the rotation center coordinate Cr, the first angle θ, and the second image (image E) to generate a corrected image in which the rotation of the second image and the movement in the direction of the rotation axis (for example, the vertical rotation axis) are corrected (image correction step). This will be described in more detail below.

[0108] First, since the rotation angle θ of image E and the rotation center coordinate Cr are known from the previous processing, rotation cancellation processing is performed using this information. For example, if image E is considered to be an image that has been rotated θ°, then the rotation of θ° can be canceled by applying a reverse rotation processing of -θ° to cancel this. The image that has been reverse-rotated in this way is called the rotation-cancelled image Ec1.

[0109] Next, it is necessary to cancel out the movement in the horizontal or vertical direction. Here, the image is rotated by θ° in the vertical direction, and the captured image area is shifted by ΔY in the Y direction (vertical direction). Therefore, if the image area is shifted by -ΔY, the movement in the horizontal or vertical direction can be canceled out as well as the rotation direction. This cancellation of the image area in the opposite horizontal or vertical direction is called shift cancellation processing. The image obtained by performing shift cancellation processing on the above rotation cancellation image Ec1 is called the rotation-shift cancellation image Ec2. This rotation-shift cancellation image is the corrected image.

[0110] Next, in step S303, the control unit 17 displays the corrected image on the display unit of the surveying instrument 1 or the display unit of the mobile terminal 100 in place of the second image (corrected image display step). Referring again to Fig. 7, the display unit can be displayed on a display device such as the display unit of the surveying instrument 1 (Fig. 7 shows the display unit as part of the configuration of the operation panel 16 as an example, but is not limited to this example) or the display unit of the mobile terminal 100, which is a general-purpose computer device capable of wireless electrical communication with the surveying instrument 1 via the communication unit 24C and the communication unit 114 (Fig. 7 shows the display unit as part of the configuration of the touch panel as an example, but is not limited to this example).

[0111] Here, image E and rotation-shift-cancelled image Ec2 are rotated extremely for the sake of convenience in explaining the invention, resulting in an angular difference; however, in reality, the angular difference is even smaller, or by continuously and automatically performing such processing at short intervals, the common pixel area (i.e., the area where image pixels overlap) between image E and rotation-shift-cancelled image Ec2 can be made large, so that a reduction in resolution due to the correction processing is unlikely to occur.

[0112] By correcting the image in this way, even in surveying instruments equipped with a reflector that rotates on the optical axis of the imaging element, the rotated image can be observed in its original state, thereby enabling accurate tracking.

[0113] <Automatic collimation or tracking of target light using corrected images> Next, we will explain automatic target pointing or automatic tracking, which is an important function of surveying instruments. Surveying instruments use retroreflecting prisms (also commonly referred to as prisms) as targets, which are different from the optical elements such as prisms used in the internal optical system, to measure the position of the target and the distance to the target. Automatic tracking refers to continuously tracking a moving retroreflecting prism and automatically measuring the distance and angle to the measurement object. Automatic pointing refers to automatically pointing a telescope or the like toward a specified target (e.g., a retroreflecting prism). Here, automatic tracking continuously tracks a moving object, while automatic pointing is different in that the task is completed once the telescope is pointed at the specified target, and does not necessarily move continuously. The technology in this disclosure may be used in either case.

[0114] The target is not limited to a target in which light emitted from a light-emitting unit (e.g., a laser light-emitting unit) of a surveying instrument is reflected by a retroreflecting prism and returned to the surveying instrument as reflected light. For example, the target may be a target equipped with a light-emitting unit such as an LED element or a laser element, and capable of switching between a light-emitting state and a light-extinguishing state.

[0115] A method for identifying the position of a target from an image will be described below. FIG. 12 is a schematic diagram for explaining target light position identification. In this figure, image α captures an image of imaging area 1, and the target is in a first state (light-emitting state). Assume that image β captures an image of imaging area 2 after the rotation axis is moved θ° in the vertical direction from this position. When image β is captured, the target is not emitting light and is in a second state (extinction state). Note that if the light-emitting state is the first state, a different extinction state may be the second state, and if the extinction state is the first state, a different light-emitting state may be the second state.

[0116] The relationship between images α and β is such that, when the optical axis of the surveying instrument (the optical axis of the telescope) is scanned vertically, there is a difference ΔY in the image capture area of ​​the images, and there is also a difference in the presence or absence of light emission and extinction. Even when the image capture areas of the images are different, a difference image between an image in which the target light is emitted and an image in which the target light is extinct can be obtained by moving the images by a known rotation angle using an angle measurement sensor, superimposing one image on the other, or adjusting the position using image matching to obtain the difference. This allows a target light image in which the effects of ambient light and other factors are offset. Once a target light image is obtained, the control unit 17 can calculate the target light position using the difference in pixel coordinates between the target light position and the image center position.

[0117] Furthermore, unlike the case shown in this figure, if, for example, the optical axis of the surveying instrument is stationary and the only difference between the two images is the extinction of the target's light emission, it is clear that the position of the target light can be identified by taking the difference between the two images.

[0118] However, in a surveying instrument equipped with a reflecting mirror that rotates on the optical axis of the image pickup device, the image rotates and also moves, so the above method cannot be used as is.

[0119] Taking the above into consideration, the target light position specifying method will be described with reference to Fig. 13. Fig. 13 is a flowchart showing the process flow of the target light position specifying method.

[0120] First, in step S401, imaging unit 27 captures a first image (image F) at a first position of scanning mirror 15 where light emission or extinction is in a first state (here, the light emission state) (first imaging step).

[0121] Next, in step S402, control unit 17 rotates scanning mirror 15 from the first position by a first angle (θ) in the rotation direction of the rotation axis, and moves it to a second position (rotation step).

[0122] Next, in step S403, the imaging unit 27 captures a second image (image G) at a second position in a second state (here, the extinction state) in which the light emission or extinction is different from the first state (second imaging step).

[0123] Next, in step S404, the control unit 17 obtains the rotation center coordinate Cr of the second image relative to the first image using the first image, the second image, and the first angle measured by the angle measurement sensor (rotation center calculation step). Note that this step can be omitted if the rotation center coordinate Cr has already been stored in the storage unit 18 or if the rotation has already been adjusted. Up to this point, the process is the same as above except for the state of quenching of the target's light emission, so a description thereof will be omitted.

[0124] Next, in step S405, the control unit 17 generates a corrected image Gc by correcting the rotation of the second image and the movement in the direction of the rotation axis using the rotation center coordinates Cr, the first angle, and the second image (image correction step). The method for obtaining the corrected image Gc is the same as the image correction method described above, and therefore, a description thereof will be omitted.

[0125] Next, in step S406, the control unit 17 obtains a difference image DI between the first image (image F) and the corrected image Gc, and identifies the target light position using the difference image DI (target position identification step). In the identification of the target light position described in Fig. 12, the target light position was identified using the difference image between images α and β, which does not require consideration of image rotation. In other words, in step S406, an image in which movement due to rotation has been corrected is used instead of image G to identify the target light position using a method similar to that in Fig. 12.

[0126] Strictly speaking, it is not enough to simply use the corrected image Gc instead of the image G. Since the image G is rotated by a vertical angle θ° with respect to the image F, it is necessary to generate a difference image with the movement-corrected image Gc, which is further moved and corrected by that amount. This corresponds to the fact that the image β is moved by θ with respect to the image α in FIG. 12. The movement-corrected image Gc2 is obtained by further performing a shift offset process (a -ΔY correction as an image) on the corrected image Gc by the vertical angle θ.

[0127] This makes it possible to obtain a difference image DI from which the target light position can be identified using images F and G scanned in the vertical direction. If the target light position can be identified in this way, automatic collimation or automatic tracking of the target becomes possible.

[0128] Therefore, by correcting the deviation caused by the rotation and movement of the captured image and identifying the target light position that appears as the difference between the light-emitting image and the extinction image, accurate tracking can be performed even in surveying instruments equipped with a reflector that rotates on the optical axis of the image sensor.

[0129] Although the explanation of this disclosure is concluded above, the new technology of this disclosure can be realized in various other forms, and part of the content can be omitted, modified, or replaced within the scope of the gist of this disclosure. The examples and their modifications shown in this disclosure are also within the scope and gist of this disclosure, and are treated as technologies that should be protected by the scope of the claims, and are equivalent or similar to them.

[0130] An example of the configuration of this embodiment is as follows. [1] A method for displaying a corrected image of a surveying instrument, comprising: an imaging unit having an imaging element for capturing an image; a scanning mirror that rotates along a rotation axis in either a horizontal direction or a vertical direction and has a flat reflecting surface that is inclined with respect to the rotation axis; an angle measurement sensor for measuring a rotation angle of the rotary shaft; A control unit; a base unit that includes the imaging unit, the imaging unit being fixed in the base unit without rotating along the rotation axis, the scanning mirror, the angle measuring sensor, and the control unit therein; When the image captured by the imaging unit is displayed on the display unit of the surveying instrument or the display unit of the mobile terminal, a first imaging step in which the imaging unit captures a first image at a first position of the scanning mirror; a rotating step in which the control unit rotates the scanning mirror from the first position by a first angle in a rotation direction of the rotation shaft and moves the scanning mirror to a second position; a second imaging step in which the imaging unit captures a second image at the second position; an image correction step in which the control unit generates a corrected image by correcting the rotation and the movement of the second image in the direction of the rotation axis, using the rotation center coordinates, the first angle, and the second image; a correction image display step in which the control unit displays the correction image on the display unit of the surveying instrument or the display unit of the mobile terminal instead of the second image. [2] A surveying device, an imaging unit having an imaging element for capturing an image; a scanning mirror that rotates along a rotation axis in either a horizontal or vertical direction and has a flat reflecting surface that is inclined with respect to the rotation axis; an angle measurement sensor for measuring a rotation angle of the rotary shaft; A control unit; a base unit that includes the imaging unit, the scanning mirror, the angle measurement sensor, and the control unit; Equipped with the imaging unit is fixed in the base unit without rotating along the rotation axis, When the image captured by the imaging unit is displayed on the display unit of the surveying instrument or the display unit of the mobile terminal, the imaging unit captures a first image at a first position of the scanning mirror; the control unit rotates the scanning mirror from the first position by a first angle in a rotation direction of the rotation shaft and moves the scanning mirror to a second position; the imaging unit captures a second image at the second position; the control unit generates a corrected image in which the rotation of the second image and the movement in the rotation axis direction are corrected using the rotation center coordinates, the first angle, and the second image; The control unit displays the corrected image instead of the second image on a display unit of the surveying instrument or a display unit of a mobile terminal. [3] A target light position specifying method for automatic collimation or automatic tracking of a surveying instrument, comprising: an imaging unit having an imaging element for capturing an image; a scanning mirror that rotates along a rotation axis in either a horizontal direction or a vertical direction and has a flat reflecting surface that is inclined with respect to the rotation axis; an angle measurement sensor for measuring a rotation angle of the rotary shaft; A control unit; a surveying instrument including a base unit that includes the imaging unit, the scanning mirror, the angle measuring sensor, and the control unit, the imaging unit being fixed within the base unit without rotating along the rotation axis; Using targets capable of luminescence and quenching, a first imaging step in which the imaging unit captures a first image at a first position of the scanning mirror where light emission or extinction is in a first state; a rotating step in which the control unit rotates the scanning mirror from the first position by a first angle in a rotation direction of the rotation shaft and moves the scanning mirror to a second position; a second imaging step in which the imaging unit captures a second image at the second position in a second state in which light emission or extinction is different from the first state; an image correction step in which the control unit generates a corrected image in which the rotation of the second image and the movement in the rotation axis direction are corrected, using the rotation center coordinates, the first angle, and the second image; a target position identification step in which the control unit obtains a difference image between the first image and the corrected image, and identifies the target light position using the difference image. [4] A surveying device capable of automatically aiming or automatically tracking a target light position, an imaging unit having an imaging element for capturing an image; a scanning mirror that rotates along a rotation axis in either a horizontal or vertical direction and has a flat reflecting surface that is inclined with respect to the rotation axis; an angle measurement sensor for measuring a rotation angle of the rotary shaft; A control unit; a surveying instrument including a base unit that includes the imaging unit, the scanning mirror, the angle measuring sensor, and the control unit, the imaging unit being fixed within the base unit without rotating along the rotation axis; a target capable of emitting and quenching light; the imaging unit captures a first image at a first position of the scanning mirror where light emission or extinction is in a first state; the control unit rotates the scanning mirror from the first position by a first angle in a rotation direction of the rotation shaft and moves the scanning mirror to a second position; the imaging unit captures a second image at the second position in a second state where light emission or extinction is different from the first state; the control unit generates a corrected image by correcting the rotation and movement of the second image using the rotation center coordinates, the first angle, and the second image; The control unit obtains a difference image between the first image and the corrected image, and identifies the target light position using the difference image. [Explanation of symbols]

[0131] 1 Surveying equipment 3 Surveying device body 5 Tray section 8 Horizontal rotation motor 9 Horizontal angle encoder 13 Vertical rotation motor 14 Vertical angle encoder 15 Scanning mirror 17 Control Unit 19 Distance measurement unit 22 Distance measurement light emission part 23 Distance measurement light receiver 24 Tracking light emission part 25 Tracking light receiver 26 Laser pointer light emission unit 27 Imaging unit 33 Beam Combiner 34 Multilayer optical elements 43 Light intensity adjustment member 44 Receiving prism 63 First Prism 64 Second Prism 76 Receiving prism 84 Receiving prism 89 Receiving prism

Claims

1. A method for displaying a corrected image of a surveying instrument, comprising: an imaging unit having an imaging element for capturing an image; a scanning mirror that rotates along a rotation axis in either a horizontal direction or a vertical direction and has a flat reflecting surface that is inclined with respect to the rotation axis; an angle measurement sensor for measuring a rotation angle of the rotary shaft; A control unit; a base unit that includes the imaging unit, the imaging unit being fixed in the base unit without rotating along the rotation axis, the scanning mirror, the angle measuring sensor, and the control unit therein; When the image captured by the imaging unit is displayed on the display unit of the surveying instrument or the display unit of the mobile terminal, a first imaging step in which the imaging unit captures a first image at a first position of the scanning mirror; a rotating step in which the control unit rotates the scanning mirror from the first position by a first angle in a rotation direction of the rotation axis and moves the scanning mirror to a second position; a second imaging step in which the imaging unit captures a second image at the second position; an image correction step in which the control unit generates a corrected image by correcting the rotation and the movement of the second image in the direction of the rotation axis, using the rotation center coordinates, the first angle, and the second image; a correction image display step in which the control unit displays the correction image on the display unit of the surveying instrument or the display unit of the mobile terminal instead of the second image.

2. A surveying device, an imaging unit having an imaging element for capturing an image; a scanning mirror that rotates along a rotation axis in either a horizontal or vertical direction and has a flat reflecting surface that is inclined with respect to the rotation axis; an angle measurement sensor for measuring a rotation angle of the rotary shaft; A control unit; a base unit that includes the imaging unit, the scanning mirror, the angle measurement sensor, and the control unit; Equipped with the imaging unit is fixed in the base unit without rotating along the rotation axis, When the image captured by the imaging unit is displayed on the display unit of the surveying instrument or the display unit of the mobile terminal, the imaging unit captures a first image at a first position of the scanning mirror; the control unit rotates the scanning mirror from the first position by a first angle in a rotation direction of the rotation shaft and moves the scanning mirror to a second position; the imaging unit captures a second image at the second position; the control unit generates a corrected image in which the rotation of the second image and the movement in the rotation axis direction are corrected using the rotation center coordinates, the first angle, and the second image; The control unit displays the corrected image instead of the second image on a display unit of the surveying instrument or a display unit of a mobile terminal.

3. A target light position specifying method for automatic collimation or automatic tracking of a surveying instrument, comprising: an imaging unit having an imaging element for capturing an image; a scanning mirror that rotates along a rotation axis in either a horizontal direction or a vertical direction and has a flat reflecting surface that is inclined with respect to the rotation axis; an angle measurement sensor for measuring a rotation angle of the rotary shaft; A control unit; a surveying instrument including a base unit that includes the imaging unit, the scanning mirror, the angle measuring sensor, and the control unit, the imaging unit being fixed within the base unit without rotating along the rotation axis; Using targets capable of luminescence and quenching, a first imaging step in which the imaging unit captures a first image at a first position of the scanning mirror where light emission or extinction is in a first state; a rotating step in which the control unit rotates the scanning mirror from the first position by a first angle in a rotation direction of the rotation axis and moves the scanning mirror to a second position; a second imaging step in which the imaging unit captures a second image at the second position in a second state in which light emission or extinction is different from the first state; an image correction step in which the control unit generates a corrected image in which the rotation of the second image and the movement in the rotation axis direction are corrected, using the rotation center coordinates, the first angle, and the second image; a target position identification step in which the control unit obtains a difference image between the first image and the corrected image and identifies the target light position using the difference image.

4. A surveying device capable of automatically aiming or automatically tracking a target light position, an imaging unit having an imaging element for capturing an image; a scanning mirror that rotates along a rotation axis in either a horizontal or vertical direction and has a flat reflecting surface that is inclined with respect to the rotation axis; an angle measurement sensor for measuring a rotation angle of the rotary shaft; A control unit; a surveying instrument including a base unit that includes the imaging unit, the scanning mirror, the angle measuring sensor, and the control unit, the imaging unit being fixed within the base unit without rotating along the rotation axis; a target capable of emitting and quenching light; the imaging unit captures a first image at a first position of the scanning mirror where light emission or extinction is in a first state; the control unit rotates the scanning mirror from the first position by a first angle in a rotation direction of the rotation shaft and moves the scanning mirror to a second position; the imaging unit captures a second image at the second position in a second state in which light emission or extinction is different from the first state; the control unit generates a corrected image by correcting the rotation and movement of the second image using the rotation center coordinates, the first angle, and the second image; The control unit obtains a difference image between the first image and the corrected image, and identifies the target light position using the difference image.

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