JP2022167504A - Target for laser measurement - Google Patents

Abstract

To eliminate the need for replacing a prism target and a scanner target in three-dimensional laser scanner measurement using a laser measurement device which is provided with a total station and a laser scan device or the functions of these two.SOLUTION: A target plate 10 is held to an arm 12 so as to be rotatable around a revolving shaft 11, a first surface 10a of the target plate 10 being adopted as a prism target and a second surface 10b being adopted as a scanner target, with a prism 20 attached to the center of the first surface 10a. A prism target function and a scanner target function are switched by rotating the target plate 10 in the vertical direction.SELECTED DRAWING: Figure 1

Description

The present invention relates to targets used, for example, in three-dimensional laser scanner surveying.

In three-dimensional laser scanner surveying, a pulsed laser beam is irradiated while scanning an object or target range, light reflected from the object or object existing in the target range is received, and light is measured for each reflected light. The three-dimensional coordinates of the reflection points are calculated from the time it takes the laser beam to return and the irradiation angle of the laser light. are getting Since the range that can be scanned with a laser scanner device is limited, when surveying a wide range, multiple scanner targets are installed within the target range, the three-dimensional coordinates of each scanner target are measured, and each scanner target is scanned. A starting target is to scan the laser light over a range and obtain three-dimensional coordinate data of a number of reflection points for each range. If there is an obstacle, the laser scanner device and the scanner target are moved, and the laser light is applied again. The error is then corrected by software based on the 3D coordinates of each scanner target to obtain the 3D shape of the object or area of interest.

FIG. 4 shows a conventional scanner target 110 as described, for example, in US Pat. In FIG. 4 , (a) shows a pattern drawn on one surface (front surface) of the target plate 111 , and (b) shows a pattern drawn on the other surface (back surface) of the target plate 111 . As shown in FIG. 4, the scanner target 110 includes a disk-shaped target plate 111 , a substantially U-shaped arm 112 that holds the target plate 111 so as to be rotatable in the vertical direction about a horizontal axis 113 , and a level table 150 . It consists of a target plate 111 and a shaft portion 114 that holds an arm 112 rotatably in the horizontal direction around a vertical axis. As shown in FIG. 4(a), on one surface of the target plate 111, two orthogonal diameter lines 111a and 111b forming a predetermined angle (for example, 45 degrees) with respect to the horizontal axis 113 are drawn. The surface of the target plate 111 is divided into four by these diameter lines, and the four divided sections are alternately colored white and black. Also, as shown in FIG. 4B, a small white circle 111c with a diameter of several centimeters is drawn at the center of the other surface of the target plate 111, and the other portion 111d is painted black. The target plate 111 is rotated according to the nature of laser scanning, and a surface with high recognition efficiency is used for laser scanning. When black and white are painted separately, since black absorbs light, almost no reflected light returns from the black area. However, since white has high reflectance, the area near the boundary between the black and white areas is gray. , making it difficult to recognize the center of the target plate 111 .

However, as the distance between the laser scanner device and the scanner target increases, it becomes more difficult to recognize the center of the scanner target, and it becomes difficult to accurately measure the three-dimensional coordinates of the reference point for setting the scanner target. Moreover, when the three-dimensional coordinate error of the reference point for setting the scanner target is large, distortion occurs in the three-dimensional shape of the target object or target range obtained by connecting the obtained three-dimensional coordinate data of the reflection points. Therefore, a total station and a prism target are used to accurately measure the three-dimensional coordinates of a reference point for setting a scanner target. Generally, laser scanner devices and total stations are used by being attached to a tripod via a leveling table. For example, first use a total station and a prism target to measure the three-dimensional coordinates of the reference point where the scanner target is installed, replace the total station with a laser scanner device, replace the prism target with a scanner target, and scan the laser light. Obtaining a three-dimensional shape of an object or area of interest has also been performed.

A total station can accurately measure the distance and angle to a target (with an error of several millimeters), but it requires the use of a prism target with a prism attached as the target. FIG. 5 shows a typical prism target 120 that is commercially available. This prism target 120 is detachable from a leveling table 150. A prism 121 is held so as to be vertically swingable about a horizontal axis 124, and a target plate 122 is attached to the back of the prism 121. and a pedestal 123 for attaching the prism target 120 to the leveling table 150, and the like. The leveling table 150 is used by being attached to a tripod or the like, and is provided with a screw for adjusting the level, a rotary shaft for horizontally rotating or swinging the prism target 120, etc. do). On the surface of the target plate 122, substantially V-shaped or triangular marks 122a and 122b are provided symmetrically with respect to the center (optical axis) of the prism 121. The optical axis of the prism 121 is adjusted with the marks 122a and 122b provided on the target plate 122 as targets. The target plate 122 is fixed to a pedestal 123, and the prism 121 swings in the vertical direction about the horizontal axis 124. Therefore, the adjustable range is narrow. The deviation of 122 from marks 122a and 122b is large, making it difficult to adjust the optical axis. In the conventional prism target 120, the diameter D1 of the prism 121 is relatively large with respect to the width W1 of the target plate 122 (for example, D1/W1=2/3 to 1/2). It was difficult to adjust the optical axis of the

In general, the target mounts of the tribrach 150 are interchangeable and can be mounted even from different manufacturers. However, as described above, the scanner target 110 and the prism target 120 have different structures, for example, the height of the shaft portion 114 of the scanner target 110 and the base 123 of the prism target 120. Even if the scanner target 110 is mounted on the same leveling table 150 after removing the , the center of the target plate 111 does not necessarily match the center (optical axis) of the prism 121 . Also, when replacing the scanner target 110 with the prism target 120, it is difficult to align the center of the scanner target 110 with the center of the prism target 120. FIG. This is probably the same even for products from the same manufacturer. Therefore, when replacing the prism target 120 with the scanner target 110, it is necessary to adjust the height. Similarly, since the height of the laser scanner device and the total station are different, it is necessary to adjust the height by moving the tripod elevator up and down.

Patent Document 2 describes a laser measuring device having a total station function and a laser scanner function (hereinafter referred to as a "laser measuring device"). In the three-dimensional laser scanner survey using such a laser measuring device, prism targets are installed at multiple measurement points, and the total station function is used to accurately measure the three-dimensional coordinate values of each measurement point. , the prism target can be replaced with a scanner target, and the laser scanner function can be used to obtain three-dimensional coordinate data by targeting each scanner target.

JP 2018-96855 A Japanese Patent Application Laid-Open No. 2021-43217

The present invention has been made to solve the problems of the above conventional examples, and is a target used for three-dimensional laser scanner surveying using a total station and a laser scanner device or a laser measurement device having both functions, To provide a target for laser surveying having a function of a prism target and a function of a scanner target in one target without exchanging the prism target and the scanner target.

The target for laser survey according to the present invention is
having a target plate and an arm rotatably holding the target plate around a predetermined rotation axis;
A through hole is provided in the center of the target plate, and a prism is attached to the first surface of the target plate so as to be offset in the optical axis direction so that the prism constant is "0". Characterized by

A first surface of the target plate is divided into four areas by two colored dividing lines that pass through the center of the first surface and are parallel and perpendicular to the rotation axis, and two adjacent areas are different from each other. colored,
The second surface of the target plate is divided into four regions by two orthogonal painted lines that pass through the center of the second surface and are set to form a predetermined angle with respect to the rotation axis. , two adjacent regions may be configured to have different colors.

Also, the different colors applied to the first surface of the target plate may be yellow and black.

Further, a click stop mechanism may be provided between the rotating shaft and the arm so that positioning can be performed every 90 degrees.

Further, it may be constructed such that D/W is in the range of 1/4 to 1/10, where D is the diameter of the prism and W is the width of the target plate.

Thus, according to the present invention, in three-dimensional laser scanner surveying using a total station and a laser scanning device, or a laser measuring device having both functions, the prism target and the scanner target are not exchanged, and the scanner can be used with one target. Three-dimensional laser scanner surveying can be continuously performed only by accurately measuring the three-dimensional coordinates of the reference point where the target is set and rotating the target plate in the vertical direction.

1 is a perspective view of a laser survey target according to an embodiment of the present invention, viewed from the first surface side of the target plate; FIG. The perspective view which looked at the said target for laser surveys from the 2nd surface side of a target plate. Sectional drawing of the said target plate. FIG. 1 shows a conventional scanner target; The figure which shows the conventional prism target.

A laser survey target according to an embodiment of the present invention will be described. FIG. 1 is a diagram of the laser survey target 1 viewed from the first surface side 10a of the target plate 10, showing a state of being used as a prism target. FIG. 2 is a diagram of the laser survey target 1 viewed from the second surface side 10b of the target plate 10, and shows a state in which it is used as a scanner target. Also, FIG. 3 shows a cross section of the target plate 10 and a prism 20 which will be described later. As can be seen from FIGS. 1 and 2, the laser survey target 1 can be used both as a prism target and as a scanner target by rotating the target plate 10, and can function as a total station and a laser scanning device or both. In three-dimensional laser scanner surveying using a laser measuring device equipped with a prism target and a scanner target, there is no need to replace the prism target and the scanner target.

As shown in FIGS. 1 and 2, the laser survey target 1 includes a target plate 10, an arm 12 that holds the target plate 10 so as to be rotatable around a predetermined rotation axis (horizontal axis) 11, and a target plate 10. and a shaft portion 13 for attaching the arm 12 to the leveling table. Further, as shown in FIG. 1, a prism 20 is attached to the first surface 10a of the target plate 10 via a prism holder 21. As shown in FIG. Further, the first surface 10a of the target plate 10 is divided into four areas by two colored dividing lines 10c and 10d that pass through the center of the first surface 10a and are parallel and perpendicular to the rotation axis 11. As a mark for recognition, two adjacent regions are given different colors (for example, yellow and black). On the other hand, as shown in FIG. 2, the second surface 10b of the target plate 10 passes through the center of the second surface 10b and is set to form a predetermined angle (for example, 45 degrees) with respect to the rotation axis 11. It is divided into four areas by two orthogonal dividing lines 10e and 10f, and two adjacent areas are given different colors (for example, white and black) as marks for recognizing the center. The centers of the first surface 10a and the second surface 10b of the target plate 10 (the center of the target plate 10) are aligned, and a through hole 14 is provided in the center of the target plate 10. As shown in FIG. The target plate 10 is formed of, for example, a metal plate such as aluminum or a resin plate such as FRP (Fiber Reinforced Plastic). Although the planar shape of the target plate 10 is rectangular in FIGS. 1 and 2, it may be circular.

The rotating shaft 11 is made of, for example, FRP, and has a substantially cylindrical member whose portion that contacts the target plate 10 is cut flat. , is attached from the second surface 10b side with screws or the like. The prism target is for accurately obtaining the coordinates of the reference point of the scanner target. Therefore, as shown in FIG. 3, the target plate 10 is rotatably attached to the arm 12 via the rotating shaft 11, and the second surface 10b of the target plate 10, that is, the scanner target, is held vertically. The center of the side is on the rotation center line of the rotation shaft 11 (in FIG. 3, the intersection 11b of the optical axis L of the prism 20 and the central axis C of the shaft portion 13: substantially the same position as the rear end portion 20c of the housing 20a of the prism 20). set to be located. The first surface 10a of the target plate 10, that is, the center of the prism target side, is vertically offset from the rotation center line of the rotating shaft 11 by the thickness of the target plate 10 (for example, 2 mm) with respect to the plate surface. ing. Therefore, the center of the first surface 10a of the target plate 10 functioning as a prism target coincides with the center of the second surface 10b functioning as a scanner target. When this target 1 for laser surveying is mounted on a leveling table and its horizontality is adjusted, the rotating shaft 11 becomes horizontal. A click stop mechanism is provided between the rotating shaft 11 and the arm 12 . Specifically, the surface of the rotating shaft 11 facing the arm 12 is formed with, for example, a cross-shaped groove 11a that is parallel and perpendicular to the surface of the target plate 10, and the arm 12 is provided with, for example, a ball and a spring. A configured stop 16 is provided. Therefore, the target plate 10 can be horizontally and vertically positioned every 90 degrees. When this laser survey target 1 is mounted on a leveling table and its horizontality is adjusted, the rotating shaft 11 becomes horizontal, so that the target plate 10 can be easily held vertically and horizontally. A fixing screw 15 for fixing the rotating shaft 11 so that it cannot rotate is provided at the connecting portion between the rotating shaft 11 and the arm 12 . The outer peripheral portion of the shaft portion 13 has an outer diameter conforming to the standard so that it can be mounted on a commercially available leveling table. Although not shown, the inner diameter portion of the shaft portion 13 is provided with screw holes 13a and 13b having different sizes (standards) in two steps so that it can be directly attached to a tripod or the like.

As shown in FIG. 3, the prism holder 21 has a threaded hole (female screw) 21a formed so as to face the through hole 14 of the target plate 10 when attached to the target plate 10 . A male screw 20b is also formed on the rear end side surface of the housing 20a of the prism 20 to be screwed into the screw hole 21a. Therefore, when the prism 20 is mounted on the prism holder 21 , the optical axis L of the prism 20 is aligned with the center of the target plate 10 and the prism 20 is perpendicular to the first surface of the target plate 10 . ing. The prism holder 21 may be fixed to the target plate 10 using an adhesive, or may be fixed by screwing or the like.

As is well known, each prism for a prism target has a unique prism constant. The prism constant is defined by the refractive index of the prism material, the height of the prism, and the amount of offset of the prism vertex from the axis of rotation. As described above, the through hole 14 is provided in the center of the target plate 10, and the prism 20 is arranged so that the prism constant of the prism 20 becomes "0" so that the prism 20 does not need to be corrected by the prism constant. It is mounted with a shift (that is, offset) in the optical axis direction (the direction perpendicular to the plate surface of the target plate 10). In the example shown in FIG. 3, the rear end 20c of the housing 20a of the prism 20 is offset so as to enter the through hole 14, and the second surface 10b of the target plate 10 and the rear end of the housing of the prism 20 are aligned. The end portion 20c is substantially flush. Therefore, the three-dimensional coordinates of the reference point (the second reference point described later) at which the laser survey target 1 is installed, which is measured using the total station function and the prism target function of the laser survey target 1, can be obtained without correcting the prism constant. It can be used as is.

Next, how to use the laser survey target 1 will be described. A tripod is installed at the place (first reference point) where the total station and the laser scanning device are installed, the total station is attached to the tripod via a leveling stand, and the three-dimensional coordinates of the first reference point are measured. Also, one or a plurality of laser survey targets 1 are placed on an object or target range to be surveyed by a three-dimensional laser scanner so that the first surface 10a of the target plate 10 faces the total station. , the optical axis L of the prism 20 is adjusted to face the total station with the marks (painted lines 10c and 10d perpendicular to each other) provided on the first surface 10a as targets. As described above, as marks on the first surface 10a of the target plate 10, the four divided areas are colored in yellow and black, respectively. As described above, when the first surface 10a of the target plate 10 is painted in white and black, almost no reflected light returns from the black area. The vicinity of the boundary of the area becomes a gray gradation, making it difficult to recognize the center of the target plate. On the other hand, since yellow has a lower reflectance than white, the boundaries between the black and yellow regions, that is, the dividing lines 10c and 10d are easily recognizable. Then, using a total station, the three-dimensional coordinates of the installation location (second reference point) of the laser survey target 1 are measured. When the three-dimensional coordinates of the second reference point are measured, the total station is replaced with a laser scanning device, and as indicated by arrow A, the target plate 10 of the target for laser survey 1 is rotated 180 degrees in the vertical direction, and the target The second surface 10b of the plate 10 is set to face the laser scanning device, and the laser scanning device is used to scan the laser beam in a predetermined range based on the target 1 for laser surveying. Get the 3D coordinates of the target area.

As is well known, the beam system of laser light is very small, and the prism target reflects the laser light incident parallel to the optical axis parallel to the optical axis. Therefore, the reflected light from the prism enters the total station only when the light enters parallel to the optical axis of the prism from the total station. Therefore, reducing the diameter of the prism of the prism target does not affect the measurement accuracy. Comparing the first surface 10a functioning as a prism target of the laser survey target 1 according to the present invention shown in FIG. 1 with the conventional prism target shown in FIG. Since it is very small with respect to the width W of the plate 10 (for example, D/W=about 1/4 to 1/10), the intersection of the dividing lines 10c and 10d theoretically coinciding with the optical axis of the prism 20 can be easily made. can be estimated, and it is easy to adjust the optical axis of the prism 20 even from a distant total station. For reference, the diameter of the conventional prism target shown in FIG. The diameter of the prism 20 can be reduced to about 10 to 20 mm, and accordingly the height H of the prism 20 can be reduced. As a result, the prism constant can be corrected to "0" simply by passing the rear end portion 20c of the casing 20a of the prism 20 through the target plate 10 having a thickness of about 2 mm. Moreover, since the protrusion of the tip of the prism 20 from the first surface 10a of the target plate 10 is small, it does not interfere with the rotation of the target plate 10 in the vertical direction.

Further, a click stop mechanism is provided between the rotating shaft 11 and the arm 12 of the laser survey target 1, and positioning can be performed every 90 degrees. It can be held horizontally upwards selectively. Therefore, for example, it is also possible to perform three-dimensional laser scanner surveying from the sky using a drone or the like. Furthermore, since the center of the first surface 10a of the target plate 10 functioning as a prism target coincides with the center of the second surface 10b functioning as a scanner target, the target plate 10 is rotated to perform the prism target function and the scanner target function. Even if you switch , height adjustment is not necessary. Furthermore, if somewhat lower measurement accuracy is acceptable, it is possible to measure the three-dimensional coordinates of the target plate 1 using only the second surface 10b of the target plate 10 that functions as a scanner target.

1 target for laser survey 10 target plate 10a (target plate) first surface 10b (target plate) second surface 11 rotating shaft 11a cross groove (of click stop mechanism) 12 arm 13 shaft 13a, 13b screw hole 14 penetration hole 15 stopper (of click stop mechanism) 20 prism 20a housing (of prism) 20c rear end (of prism) 21 prism holder

Claims (5)

having a target plate and an arm rotatably holding the target plate around a predetermined rotation axis;
A through hole is provided in the center of the target plate, and a prism is attached to the first surface of the target plate so as to be offset in the optical axis direction so that the prism constant is "0". Characteristic laser survey target. A first surface of the target plate is divided into four areas by two colored dividing lines that pass through the center of the first surface and are parallel and perpendicular to the rotation axis, and two adjacent areas are different from each other. colored,
The second surface of the target plate is divided into four regions by two orthogonal painted lines that pass through the center of the second surface and are set to form a predetermined angle with respect to the rotation axis. , two adjacent regions are colored differently from each other,
The laser survey target according to claim 1, characterized in that: 3. The laser survey target of claim 2, wherein the different colors applied to the first surface of the target plate are yellow and black. 4. The target for laser surveying according to claim 1, wherein a click stop mechanism is provided between the rotating shaft and the arm so that the target can be positioned every 90 degrees. 5. The range of any one of claims 1 to 4, wherein D/W=1/4 to 1/10 where D is the diameter of the prism and W is the width of the target plate. laser survey target.

Images