JP2023022331A - Target for laser scanner surveying - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to easily cope with types of laser scanners used at laser scanner surveying.

SOLUTION: A target for laser scanner surveying includes: a target body 11 having a spherical target surface 13 and a planar target surface 12 made of a cut surface formed by cutting part of a spherical body along a plane; and a ring frame 20 that supports the target body 11 via a rotary support shaft 25 that makes the target body face an irradiation direction of a laser scanner so that the spherical target surface 13 and the planar target surface 12 can be interchanged.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to a target for laser scanner surveying, and more particularly to a target for laser scanner surveying that is used as a mark of a reference point during surveying using a 3D terrestrial laser scanner.

Various types of 3D terrestrial laser scanners (hereinafter referred to as laser scanners) have been developed that can acquire a large amount of point cloud data consisting of three-dimensional coordinates of an object from a remote reference position with high precision in a short time. In addition, by applying this laser scanner to topographical surveying, it becomes possible to create a three-dimensional map based on the work of creating a plan view by conventional surveying. That is, first, the absolute coordinates of the reference point are obtained by surveying with a total station or various GNSS (Global Positioning System) surveys such as GPS and GLONASS, and the area including the target object is measured by laser scanner surveying of the area including the reference point. By acquiring point cloud data, 3D terrain and structure data can be obtained. In surveying using these laser scanners, at least three targets are placed at appropriate positions within the scan target area as marks of reference points for synthesizing point cloud data (Patent Document 1, Non-Patent Document 1 ).

The targets to be placed must conform to the functions of the laser scanner to be used and the specifications of post-processing software compatible with the laser scanner. Therefore, checkerboards, reference spheres (spheres), retroreflectors, corner cubes, etc. are provided as targets. For example, a checkerboard divides the diffuse reflection surface into four quadrants and paints each area in a black and white checkered pattern (checkered pattern), thereby making the reflectance of each area significantly different and recognizing the reflection intensity. Recognize the center point as the boundary edge of each region. The reference sphere is a sphere with high diffuse reflectance, and its contour is recognized from a plurality of scan points irradiated on the sphere surface to recognize the center point of the sphere.

JP 2006-162444 A

Created by Core System Co., Ltd., “3D Survey Procedure (laser scanner edition), [online], Core System Co., Ltd. homepage, [searched on March 15, 2018], Internet <URL: http://coresys.co.jp /ground-survey/3dprocedure/>

The target disclosed in Patent Document 1 is used as a forepoint in the first process of angle measurement and distance measurement by a total station, and also as a reference for synthesizing point cloud data of a structure measured by a three-dimensional laser scanner measuring machine. A prism supporting part that is installed as a point and holds a one-element prism used for angle measurement and distance measurement in the first process, and a reference sphere (sphere) that is used as a scanning target for laser irradiation in the third process. and are placed above and below the pin pole. As an object to be scanned by the three-dimensional laser scanner measuring machine, a target in which a target plate and a one-element prism are combined instead of the reference sphere is exemplified.

As described above, the conventional target must be set on a reference point fixed in advance, or surveyed by a total station or the like to obtain the coordinates. In addition, as described above, the suitable type of target is determined depending on the difference in post-processing software used for point cloud data processing after laser scanner surveying. For example, a spherical target such as a reference sphere can be processed with post-processing software that supports shape recognition, but point cloud data processing cannot be performed with post-processing software that supports only reflection intensity recognition. Since the post-processing software usually depends on the model of the laser scanner, it is necessary to appropriately select the target according to the type of laser scanner used for surveying. Also, if the installed target can be equipped with a GNSS surveying antenna (receiver), it is possible to directly acquire the observation point coordinates of the target position.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to solve the above-described problems of the prior art, to provide a laser scanner that can easily accommodate the types of laser scanners used during laser scanner surveying, and that can integrally hold an antenna for GNSS surveying. To provide a target for surveying.

In order to achieve the above object, a target for laser scanner surveying of the present invention has an overall shape obtained by cutting and removing a part of a spherical body on a plane, and a planar target comprising a spherical target surface and a formed cut surface. a target body having a target surface; and a frame that supports the target body via a rotating part that faces the irradiation direction of the laser scanner so that the spherical target surface and the planar target surface can be interchanged. It is characterized by having

Preferably, the frame is connected to a lower connecting means connectable to the fixed support.

Preferably, the planar target surface has a checkered pattern on the formed cut surface.

The front view which showed the different target surface of one embodiment (1st Embodiment) of the target for laser scanner surveys of this invention. FIG. 2 is a side view showing different angular states of the embodiment of the laser scanner survey target shown in FIG. 1; State explanatory drawing which showed the installation state example of the target for laser scanner surveying. State explanatory drawing which showed the installation state example of the target for laser scanner surveying. State explanatory drawing which showed the work state of laser scanner survey work. State explanatory drawing which showed the work state of laser scanner survey work. The front view which showed other embodiment (2nd Embodiment) of the target for laser scanner surveys. The front view which showed other embodiment (3rd Embodiment) of the target for laser scanner surveys. The perspective view which showed other embodiment (4th Embodiment) of the target for laser scanner surveys. FIG. 10 is a cross-sectional view schematically showing a cross section of a ring frame of the laser scanner survey target shown in FIG. 9;

[First embodiment]
DESCRIPTION OF THE PREFERRED EMBODIMENTS A configuration of a laser scanner survey target according to a first embodiment of the present invention and application to surveying will be described below with reference to the accompanying drawings.

Each figure in FIG. 1 is a front view of a laser scanner survey target (hereinafter simply referred to as target 10) of this embodiment, and each figure in FIG. 2 is a side view. The target 10 is composed of a double structure ring frame 20 and a target body 11 rotatably supported by the ring frame 20 about rotation support shafts 25 and 26 .

As shown in FIGS. 1 and 2(a), the ring frame 20 consists of two rings with slightly different diameters, an inner ring 21 and an outer ring 22, formed by processing a narrow thin plate into a circular shape. , and are connected by a rotation support shaft 26 as a second rotation support shaft provided at a horizontal diameter position between the inner ring 21 and the outer ring 22 so as to be positioned concentrically. The inner ring 21 can rotate 360° with respect to the outer ring 22 around the rotation support axis.

The target body 11 is held via rotation support shafts 25 as first rotation support shafts provided at upper and lower positions of the vertical diameter of the inner surface of the inner ring 21 . 1 and 2(a), the target body 11 is a hemispherical body having a diameter slightly smaller than the diameter of the inner ring 21, and rotates around a rotation support shaft 25 provided at an upper and lower position. It can rotate. In FIG. 2A, the target body 11 before and after being rotated by 180° is indicated by a solid line and a chain double-dashed line.

The target body 11 of this embodiment is made of a hollow hemispherical body with a diameter of 200 mm, which is formed by molding an aluminum plate. Its surface consists of a circular plane and a hemispherical plane, and the surface of the circular plane when viewed from the front (Fig. 1(a)) is divided into four quadrants passing through the center of the circle. The target surface 12 is painted in a checkered pattern (checkered pattern), and the target surface 12 as a whole has a clear reflection intensity difference. A hemispherical surface (FIG. 1(b)) is painted white and constitutes a target surface 13 having a predetermined reflectance. Since the target body 11 having a larger diameter can be used for long-distance surveying, it is preferable to determine the diameter according to the distance of the survey target area. In addition, materials such as metal and synthetic resin can be appropriately used in consideration of ease of handling and durability.

As described above, the target body 11 is rotatably supported in the horizontal and vertical directions at the initial position (each figure in FIG. 1). By doing so, the target surfaces 12 and 13 can be interchanged. FIG. 2(a) shows a state in which the target body 11 can be rotated 180° around the rotation support shaft so that the target surfaces 11 and 12 can be turned over. are integrally tilted about the rotation support shaft 26 from the initial position by the tilt angle θ. By rotating the two rotary support shafts 25 and 26 by a predetermined angle, the angle and direction of the target surfaces 12 and 13 are made to face the irradiation unit of the laser scanner (not shown), and the laser beam is irradiated. It is preferable to adjust so as to reliably reflect the laser beam.

As shown in FIG. 1(a), on the outer peripheral surfaces of the upper and lower ends of the outer ring, there are an upper connecting shaft 31 as a connecting means with a GNSS receiver, which will be described later, and a tripod leveling base as a fixed support. A lower connecting shaft 32 is attached as a connecting means for connecting to, for example. In this embodiment, both the connecting shafts 31 and 32 are made of round steel bars, and the lower end of the lower connecting shaft 32 is formed with a male threaded portion 32a having a predetermined diameter. As the male thread, a 5/8 inch thread, which is standardly used, for example, in a leveling table for a surveying prism is formed. On the other hand, the upper end of the upper connecting shaft 31 is formed with a female threaded portion 31a having a predetermined diameter. As the female screw, a 5/8 inch screw is formed on the lower surface of the GNSS receiver (receiving antenna) to which a male screw generally used as a connecting portion can be fitted. If the screw diameter on the leveling stand side or the GNSS receiver side to be used is different from the above, it can be adjusted by using an adapter or the like corresponding to the screw diameter.

3 and 4 are state explanatory diagrams showing an installation example of the laser scanner survey target 10 (target 10) of the present invention. As shown in FIG. 3, the target 10 is mounted on the leveling table 3 attached to the surveying tripod 2 via the lower connecting shaft 32 . The GNSS receiver 4 is installed above the target 10 via an upper connecting shaft 31, and the leveling table 3, the target 10, and the GNSS receiver 4 are installed substantially vertically via connecting shafts 31 and 32. ing. In the example shown in FIG. 3, by rotating the target body 11 by a predetermined angle around the rotation support shafts 25 and 26, the checkered target surface 12 faces the laser scanner (not shown). is adjusted to As a result, the laser beam L (schematically illustrated by the arrow line) emitted from a laser scanner (not shown) located on the lower right side of the figure can be reliably reflected.

In FIG. 4, by rotating the target body 11 about the rotation support shaft 25 by 180° from the state shown in FIG. It shows an example of surveying with At this time, the central axis 25c of the rotation support shaft 25 that supports the target body 11 is set so as to pass through the center of a complete sphere including the hemisphere of the target body 11 (matching the center of the circle of the circular target surface). Therefore, even if the target body 11 is rotated around the rotation support shaft 25, the center position of the sphere does not change. At this time, it is preferable to adjust the angle so that the contour of the hemispherical target surface 13 is substantially circular when viewed from a laser scanner (not shown).

5 and 6 are explanatory diagrams showing an embodiment of laser scanner survey work using the target 10 of the present invention. The use of the target 10 of the present invention in laser scanner surveying will be briefly described with reference to each figure. In each figure, the targets 10A, 10B, and 10C are drawn closer than they are actually arranged for the sake of explanation. As shown in the figure, three targets 10A, 10B, and 10C are placed so as to be visible in the survey target area. For example, the laser scanner 1 is installed so as not to cause data missing portions due to blind spots due to existing structures 5 and the like. 10B and 10C are used. The installation positions of the targets 10A, 10B, and 10C are preferably determined so that the laser scanner survey can be performed efficiently and there is no difference in the density of point cloud data acquired at different positions. In FIG. 5, one of the three targets 10 is installed on the leveling table 3 of the surveying tripod 2, and the other two are fixed and held on the existing structure 5 as a fixed part in a stable state. It is In this embodiment, a checkered target surface 12 is used as the target 10 .

As shown in FIG. 5, the laser scanner 1 irradiates a laser beam within a survey target area including three targets 10A, 10B, and 10C. The laser beam L at that time reaches and is reflected by the natural topography, the existing structure 5, and the target 10 in the survey target area, and the point cloud data consisting of the three-dimensional coordinates and the reflection intensity at each position is generated by the laser scanner 1. obtained by the side. At this time, as shown in FIG. 5, the GNSS receiver 4 is installed above each target 10A, 10B, 10C. In parallel with the laser scanner survey, the GNSS survey using the GNSS receiver 4 can acquire the absolute coordinates that serve as the reference of each target 10 . By applying these absolute coordinates to synthesis of point cloud data, three-dimensional data of topography and structures within the survey target area can be created with high accuracy. In addition, in GNSS surveying, a known positioning method can be appropriately adopted. 5 and 6, part of the irradiated laser light is schematically shown as laser light L. As shown in FIG.

In order to obtain other point cloud data within the survey target area, FIG. showing the situation. At this time, the orientation of the checkered target surface 12 of the target 10 is adjusted so as to face the laser scanner 1 at the new position. In FIG. 6, since the checkered target surface 12 of the target body 11 faces the laser scanner 1, the hemispherical target surface 13 on the back side is visible.

After that, the targets 10 are appropriately placed so that at least three targets 10 are arranged within the irradiation range of the laser beam even at positions other than those shown in FIGS. The point cloud data within the target area is obtained by performing laser scanner surveying. After the survey is completed, the point cloud data acquired at multiple locations are combined and processed by known post-processing software as a data processing process, and the result of the specification according to the application such as 3D topographic data within the survey target area, structure data, etc. can create things.

[Second embodiment]
Each figure in FIG. 7 is a front view showing a second embodiment of the target 10 of the present invention. This target 10 has a ring frame 20 composed of one ring 23 for the double ring frame 20 shown in FIG. 1(a). In this target 10, a part of the upper connecting shaft 31 and the lower connecting shaft 32 that support the ring 23 are made movable shafts, so that the ring 23 can be rotated 360° around the rotation support shaft 26 as the second rotation shaft. It consists of a structure that allows Further, a rotation support shaft 25 as a first rotation support shaft is provided at the horizontal diameter position of the inner peripheral surface of the ring 23 , and the target body 11 is held via the rotation support shaft 25 . The target body 11 has exactly the same structure as shown in each figure of FIG. Since the target 10 has a simple structure of the ring frame for holding the target body 11, it is possible to reduce the weight and manufacturing cost. In this modified example, the positional relationship between the rotary support shafts 25 and 26 differs by 90° from that shown in each figure of FIG. It goes without saying that it is the same as the object.

[Third embodiment]
Each figure in FIG. 8 is a front view showing a third embodiment of the target 10 of the present invention. This target 10 comprises a ring frame 20 composed of one ring 23, like the second embodiment shown in FIGS. In this target 10, when the ring 23 is supported, a part of the lower connecting shaft 32 is made a movable shaft so that the ring 23 can be rotated 360° around the rotation support shaft 26 as the second rotation shaft. consists of Other configurations are the same as those of the second embodiment. Specifically, the lower connecting shaft 32 consists of a bolt 34 and a nut 35 . A high nut is used for the nut 35, and a female threaded portion (not shown) on the top receives the bolt 34, and a female threaded portion 32a formed on the lower end of the nut 35 is fixedly supported by a tripod leveling table or the like as a fixed support portion. be done. In this embodiment, a thrust washer 28 is interposed between the bolt 34 , nut 35 and ring 23 . By using this thrust washer 28, the ring 23 can be aligned with the axis of the bolt 34 even when the bolt 34 and the nut 35 are tightened on the lower connecting shaft 32 and the ring 23 is firmly held so as to be sandwiched therebetween. It can be smoothly rotated around the rotation support shaft 26 . On the other hand, the upper connecting shaft 31 consists of a bolt 36 and a nut 37 . A GNSS receiver (not shown) can be fixedly supported above the target 10 via the threaded portion 31 a of the bolt 36 . This target 10 also has a simple structure of a ring-shaped frame for holding the target body 11, so that it is possible to reduce the weight and manufacturing cost.

[Fourth embodiment]
FIG. 9 shows, as another embodiment of the target, a target 10 in which the target body 11 is held by a single wide ring frame 41 instead of the above-described double structure ring frame 20 . The ring frame 41 of the target 10 is a ring-shaped body having a width that is slightly larger than the diameter of the target body 11 and that allows the target body 11 to be held in the ring so as to cover the outer periphery of the target body 11 . As shown in FIG. 9A , the inner peripheral surface 41 a of the ring frame 41 functions as a spherical holding portion 43 with an inner diameter corresponding to the outer diameter of the target body 11 .

In the target 10 shown in FIG. 9 having such a configuration, as shown in FIGS. Then, the target can be arbitrarily rotated in three axial directions so that the target surface faces a predetermined angle and direction. At this time, the target body 11 rotates while being held by the spherical holding surface portion 43 so that the center of the sphere does not change.

In the above description, the target of the present invention is used as a marker for laser scanner surveying, but this target can also be used as a visual marker for stereo camera surveying. A target to be photographed by a stereo camera is placed at a predetermined position, and the checkered pattern or spherical target surface is placed facing the target in stereo, and image analysis is performed to determine the relative distance and angle between the camera and the visible marker. etc. can be grasped. At this time, since the target as the visible marker is equipped with a GNSS receiver, the received data can be analyzed to obtain the absolute coordinates of the visible marker. As an application example of the coordinate information obtained by this stereo camera survey, it is possible to grasp and control the running state, running posture, etc. of a vehicle equipped with a stereo camera.

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope indicated in each claim. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

1 Laser Scanner 4 GNSS Receiver 10 Laser Scanner Survey Target 11 Target Body 12 Planar Target Surface 13 Spherical Target Surface 20, 41 Ring Frame 21 Inner Ring 22 Outer Ring 23 Rings 25, 26 Rotational Support Shaft 28 Thrust Washer 31 Upper Part Connection shaft 32 Lower connection shaft

Claims (3)

Consists of an overall shape obtained by cutting a portion of a spherical body on a plane and removing it,
a target body having a spherical target surface and a planar target surface formed by a cut surface;
a frame that supports the target body via a rotating part that faces the irradiation direction of the laser scanner so that the spherical target surface and the planar target surface can be interchanged;
A target for laser scanner surveying, comprising: 2. The target for laser scanner surveying according to claim 1, wherein the frame is connected with a lower connecting means connectable to the fixed support. 3. The target for laser scanner surveying according to claim 1, wherein said planar target surface has a checkered pattern on the formed cut surface.

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