JP7579535B2 - Surveying system, surveying device, surveying method, and surveying program - Google Patents

Description

The present invention relates to a technique for surveying structures such as bridge piers.

Traditionally, total stations and laser scanners have been used as surveying methods for structures. With these surveying methods, measurements are taken by installing a total station or similar device in a location where the measurement points can be seen. However, with conventional surveying methods, depending on the construction location and size of the structure, a great deal of work may be required or there may be high risk. For example, consider a bridge, which is made up of a superstructure and a substructure. Conventionally, when surveying the substructure before starting construction of the superstructure, aerial work vehicles are set up and the survey is carried out by climbing up to the piers. For high piers and in mountainous areas in particular, it is necessary to install lifting equipment, and for piers in rivers, it is necessary to use wire bridges or a crane mounted on the piers.

Japanese Patent Application Publication No. 8-285588

One method to solve this problem is photogrammetry, which uses a camera mounted on an unmanned aerial vehicle known as a drone to perform measurements based on image data captured by the camera (see Patent Document 1). However, current photogrammetry technology has measurement errors on the order of centimeters, making it insufficient for use in measurements that require precision on the order of millimeters.

The present invention was made in consideration of the above circumstances, and its purpose is to provide a surveying system, device, method, and program that is easy to use and has low risk.

To achieve the above object, the present invention is a surveying system for surveying the top surface of a structure, comprising: a laser scanner for performing laser scanning on an area including the boundary between the top surface and the side surface of the structure from the side surface and below the top surface to obtain first point cloud data; an unmanned aerial vehicle equipped with a camera for capturing an image of the area including the boundary between the top surface and the side surface of the structure and the top surface from the air above the top surface to obtain image data; and a superimposition means for superimposing second point cloud data of the area including the boundary between the top surface and the side surface of the structure and the top surface, calculated from the image data, on the first point cloud data based on the first point cloud data and the second point cloud data of the boundary.

The present invention is also a surveying method for surveying the top surface of a structure, comprising the steps of: acquiring first point cloud data by laser scanning an area including a boundary between the top surface and the side surface of the structure from the side surface and below the top surface using a laser scanner; acquiring image data by capturing an image of the area including the boundary between the top surface and the side surface of the structure and the top surface from the air above the top surface using a camera mounted on an unmanned aerial vehicle; calculating second point cloud data for the area including the boundary between the top surface and the side surface of the structure and the top surface from the image data; and superimposing the second point cloud data on the first point cloud data based on the first point cloud data and the second point cloud data for the boundary.

The present invention also relates to a surveying device for surveying the top surface of a structure, comprising: a point cloud data acquisition means for acquiring first point cloud data acquired by a laser scanner installed below the top surface of the structure and second point cloud data calculated based on image data captured by a camera mounted on an unmanned aerial vehicle flying in the air above the top surface of the structure; and a superimposition means for superimposing the second point cloud data on the first point cloud data, the first point cloud data being acquired by laser scanning an area including a boundary between the top surface and the side surface of the structure, the second point cloud data being calculated from image data captured for an area including the boundary between the top surface and the side surface of the structure and the top surface, and the superimposition means superimposing the second point cloud data on the first point cloud data based on the first point cloud data and the second point cloud data at the boundary.

According to the present invention, the second point cloud data, which has a relatively large error and is calculated from image data captured by the camera of the unmanned aerial vehicle, is superimposed on the first point cloud data, which has a relatively small error, acquired by the laser scanner, so that it is possible to reduce surveying errors even for the top surface of a structure that cannot be directly observed by the laser scanner. This eliminates the need to perform dangerous and time-consuming work at height to measure the top surface of a structure, improving workability.

1 is a configuration diagram of a surveying system according to a first embodiment; Functional block diagram of a surveying device according to a first embodiment Survey procedure using the survey system according to the first embodiment FIG. 1 is a configuration diagram of a surveying system according to a second embodiment. A functional block diagram of a surveying device according to a second embodiment.

(First embodiment)
A surveying system according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a configuration diagram of the surveying system, and Fig. 2 is a functional block diagram of a surveying device.

In this embodiment, the substructure of a bridge (also called the substructure or the skeleton) is used as an example of the structure to be surveyed. This embodiment also describes a case in which, after the substructure is completed and before the superstructure begins, the positions of one or more bearings installed on the top surface of the completed substructure are surveyed, and the distance between corresponding bearings installed on the top surfaces of adjacent substructures is also surveyed. Note that the distance between adjacent substructures is on the order of 10 to 100 meters, while the allowable error in the bearing positions and the distance between the bearings is on the order of millimeters.

As shown in Fig. 1, the surveying system according to this embodiment includes a laser scanner 200 that laser scans each of the multiple substructures 100 to obtain point cloud data, an unmanned aerial vehicle 300 equipped with a camera 310 that images each of the multiple substructures 100 from the air to obtain image data, and a surveying device 400 that performs surveying based on the data obtained from the laser scanner 200 and the camera 310. The acquisition of point cloud data by the laser scanner 200 and the acquisition of image data by the unmanned aerial vehicle 300 are performed for each substructure 100 by changing the installation position of the laser scanner 200 and the flight position of the unmanned aerial vehicle 300.

Each substructure 100 is formed such that the top surface 110 is horizontal and the direction perpendicular to the side surface 120 is vertical. The top surface 110 is formed with a support 111, which is the object of surveying. At the boundary 130 between the top surface 110 and the side surface 120, a C-surface 131 is formed by chamfering the corner where the top surface 110 and the side surface 120 intersect into a flat surface.

The laser scanner 200 emits laser light and receives the light reflected by an object, and measures the distance to the object based on the time from emission to reception and the phase of the reflected light. The laser scanner 200 scans the laser light into space, measures the distance to each point of the object in the space, and generates point cloud data, which is a collection of three-dimensional spatial coordinates of each point.

The laser scanner 200 is installed below the top surface 110 on which the support 111, which is the object of the survey, is formed. In other words, it is not possible for the laser scanner 200 to observe the top surface 110 including the support 111, and it is important to note that the laser scanner 200 cannot generate point cloud data for the top surface 110 including the support 111.

In the present invention, the laser scanner 200 is installed on the ground at a predetermined distance away from the side surface 120 of the substructure 100, and performs laser scanning on an area including the boundary portion 130 to generate point cloud data. The installation position of the laser scanner 200 is assumed to be known. The installation position of the laser scanner 200 can be obtained by positioning a known reference point with the laser scanner 200. The installation position of the laser scanner 200 can also be obtained by positioning the installation position of the laser scanner 200 with another positioning device such as a total station.

The laser scanner 200 records the generated point cloud data on a specified recording medium. In some embodiments, the laser scanner 200 can transmit the generated point cloud data to an external device connected via a wired or wireless connection. The coordinates of the point cloud data recorded and transmitted by the laser scanner 200 may be relative to the installation position of the laser scanner 200, or may be absolute and corrected based on a known installation position.

The unmanned aerial vehicle 300 is a flying object known as a drone, and flies according to a user's operation command from a remote location or based on a pre-programmed flight plan. The unmanned aerial vehicle 300 is also called a UAV (Unmanned Aerial Vehicle). The unmanned aerial vehicle 300 is equipped with a motor or other power source, a propeller attached to the motor, an inertial measurement unit, a wireless transceiver, a power source, the camera 310 for surveying, and a control device for controlling each part. The inertial measurement unit is used to measure and control the behavior and current position of the unmanned aerial vehicle 300. The inertial measurement unit can include various sensors such as a three-axis acceleration sensor, a three-axis angular velocity sensor, an air pressure sensor, an ultrasonic sensor, a magnetic orientation sensor, and a GNSS (Global Navigation Satellite System) receiver.

The camera 310 captures still or video images to generate image data. The camera 310 records the image data on a predetermined recording medium. In some embodiments, the camera 310 can transmit the image data to an external device connected by wire or wirelessly in real time or all at once after capture. The image data includes, as metadata, the capture conditions such as position information at the time of capture. The position information at the time of capture can be obtained from the inertial measurement unit of the unmanned aerial vehicle 300. The camera 310 can control the capture conditions such as the angle of view and capture direction from the control device of the unmanned aerial vehicle 300. The camera 310 is fixed to the unmanned aerial vehicle 300. In some embodiments, the camera 310 is provided with a drive device for changing the capture direction relative to the unmanned aerial vehicle 300. In some embodiments, the camera 310 is provided with a shock absorbing device for preventing blurring of the image data due to vibration.

In the present invention, the unmanned aerial vehicle 300 is flown by remote control or based on a flight plan so that the camera 310 captures an image of an area including the boundary 130 and the top surface 110 of the substructure 100. Here, the top surface 110, which is a part of the subject to be captured, does not need to be the entire area of the top surface 110, but only needs to be an area including the support 111, which is the subject of the survey. The side surface 120 of the substructure 100 may also be included in the captured area. In order for the camera 310 to be able to capture such an area, the unmanned aerial vehicle 300 flies in the sky at least above the top surface 110 of the substructure 100. In this embodiment, in order to capture an image of at least the area of the side surface 120 of the substructure 100 adjacent to the boundary 130, the unmanned aerial vehicle 300 flies in the sky diagonally above the side surface 120 on the side where the laser scan 200 is installed, relative to the top surface 110 of the substructure 100. The camera 310 acquires at least two image data with different capture positions so that point cloud data can be generated from the image data, as described below. The camera 310 can capture multiple image data by capturing video at a predetermined frame rate while the unmanned aerial vehicle 300 is moving.

As shown in FIG. 2, the surveying device 400 includes a point cloud data conversion processing unit 410, a point cloud data acquisition unit 420, a superimposition processing unit 430, a measurement point search unit 440, a surveying calculation unit 450, and a storage unit 460. Each unit of the surveying device 400 is configured by installing a program on a computer equipped with a main processing unit, a main storage unit, an auxiliary storage unit, a display unit, an input device, etc. In some embodiments, the surveying device 400 is configured by dedicated hardware. In some embodiments, the surveying device 400 is configured to be distributed across multiple devices. In some embodiments, the surveying device 400 is implemented on a cloud server.

The point cloud data conversion processing unit 410 converts multiple image data acquired from the camera 310 into point cloud data. Various algorithms used in photogrammetry can be used to convert image data into point cloud data. In the following explanation, the point cloud data generated by the laser scanner 200 described above will be referred to as ground-side point cloud data, and the point cloud data generated by the point cloud data conversion processing unit 410 will be referred to as air-side point cloud data.

In this embodiment, the camera 310 generates video data including position information as image data, and the point cloud data conversion processing unit 410 generates aerial side point cloud data, which is a collection of three-dimensional spatial coordinates, from this video data. The point cloud data conversion processing unit 410 also acquires the video data from the camera 310 via a specified storage medium. The position information included in the image data is measured by the inertial measurement unit of the unmanned aerial vehicle 300. For this reason, it should be noted that the coordinate error of the aerial side point cloud data is usually on the order of centimeters, which does not meet the allowable error of the support position, which is on the order of millimeters.

The point cloud data acquisition unit 420 acquires ground-side point cloud data and aerial-side point cloud data and stores them in the storage unit 460. In this embodiment, the point cloud data acquisition unit 420 acquires ground-side point cloud data from the laser scanner 200 via a specified storage medium, and acquires aerial-side point cloud data from the point cloud data conversion processing unit 410.

The overlay processing unit 430 performs overlay processing on the ground side point cloud data and the aerial side point cloud data stored in the storage unit 460 to generate overlay point cloud data, and stores this overlay point cloud data in the storage unit 460. That is, the aerial side point cloud data is overlaid on the ground side point cloud data based on the ground side point cloud data and the aerial side point cloud data in the boundary unit 130. In other words, the overlay processing unit 430 performs coordinate conversion so that the coordinate system of the aerial side point cloud data, which has a relatively large error, coincides with the coordinate system of the ground side point cloud data, which has a relatively small error, and combines the aerial side point cloud data and the ground side point cloud data into one overlay point cloud data. In other words, the overlay processing unit 430 can also be considered to correct the aerial side point cloud data using the ground side point cloud data.

The superimposition process here is based on the data in the boundary 130, which is the superimposed area of the ground-side point cloud data and the air-side point cloud data. That is, coordinate conversion is performed so that the air-side point cloud data in the boundary 130 matches the ground-side point cloud data in the boundary 130. More specifically, coordinate conversion is performed so that the coordinates of the feature points in the boundary 130 of the substructure 100 included in the air-side point cloud data in the boundary 130 match the coordinates of the feature points included in the ground-side point cloud data in the boundary 130. For this reason, the superimposition processing unit 430 has a feature point extraction function unit that extracts feature points in the boundary 130 from each point cloud data. In this embodiment, the ridge line, which is the boundary line between the boundary 130 and the side surface 120, is extracted as the feature point. The ridge line is also called the pier top outline or C-surface bottom outline.

The measurement point search unit 440 searches for point cloud data related to the survey object from the superimposed point cloud data, calculates the position (coordinate data) of the survey object as the survey result, and stores it in the memory unit 460. Specifically, the measurement point search unit 440 extracts characteristic points related to the survey object from the superimposed point cloud data, calculates the position (coordinate data) of this characteristic point as the survey result, and stores it in the memory unit 460. In this embodiment, the measurement point search unit 440 calculates the position (coordinate data) of the support 111 provided on the upper surface 110 of the substructure 100.

The above-mentioned processing by the superposition processing unit 430 and the measurement point search unit 440 is performed for each of the acquired ground-side point cloud data. In this embodiment, the positions (coordinate data) of one or more supports 111 provided on the upper surface 110 of each of the multiple substructures 100 are calculated for each of the ground-side point cloud data acquired by the laser scanner 200 for each of the multiple substructures 100.

The survey calculation unit 450 calculates the distance between any of the survey objects from the positions (coordinate data) of the multiple survey objects surveyed by the measurement point search unit 440. In this embodiment, the distance between corresponding supports 111 provided on the upper surface 110 of adjacent substructures 100 is calculated, output as the survey result, and stored in the memory unit 460.

The procedure for surveying according to this embodiment will be described with reference to the flowchart in FIG. 3. First, the laser scanner 200 is used to perform laser scanning of the area including the boundary portion 130 from the side of the side surface 120 and below the top surface 110 to obtain ground-side point cloud data (step S1).

The camera 310 mounted on the unmanned aerial vehicle 300 is used to capture an image of the area including the boundary 130 and the upper surface 110 from the air above the upper surface 110 to obtain image data (step S2-1). Next, aerial side point cloud data for the area including the boundary 130 and the upper surface 110 is generated from the image data (step S2-2).

The above steps S1 to S2-2 are carried out for each structure to be surveyed. In this embodiment, they are carried out for each of the multiple substructures 100.

Next, the surveying device 400 superimposes the flight-side point cloud data on the ground-side point cloud data based on the ground-side point cloud data at the boundary 130 and the flight-side point cloud data to generate superimposed point cloud data (step S3). Next, the surveying device 400 calculates the positions (coordinate data) of the measurement points from the superimposed point cloud data (step S4). Finally, the surveying device 400 calculates the distance between any measurement points (step S5). In this embodiment, the distance between corresponding supports 111 provided on the upper surface 110 of adjacent substructures 100 is calculated.

Note that the acquisition of image data in step S2-1 may be performed prior to the acquisition of ground-side point cloud data in step S1.

With this type of surveying system, aerial point cloud data, which has a relatively large error, is superimposed on ground point cloud data, which has a relatively small error, so that surveying errors can be reduced even for the top surface 110 of the substructure 100, which cannot be directly observed by the laser scanner 200. This eliminates the need to perform dangerous and time-consuming work at height to measure the top surface of the substructure 100, improving workability.

Second Embodiment
A surveying system according to a second embodiment of the present invention will be described with reference to the drawings. Fig. 4 is a configuration diagram of the surveying system, and Fig. 5 is a functional block diagram of a surveying device.

The surveying system of this embodiment differs from the first embodiment in that it further includes a positioning device 500 that performs laser positioning, as shown in FIG. 4, and in the surveying process in the surveying device 400. The rest of the configuration is the same as in the first embodiment, so only the differences will be explained here.

The positioning device 500 measures the position (coordinates) of a predetermined reference point included in the scan area of the substructure 100 by the laser scanner 200 by laser positioning. In this embodiment, a total station is used as the positioning device 500. The installation position of the positioning device 500 is assumed to be known. The installation position of the positioning device 500 can be acquired by positioning another known reference point by the positioning device 500. The predetermined reference point can be any point in the boundary portion 130. The predetermined reference point can also be any point other than the boundary portion 130. The measurement result by the positioning device 500 is provided to the surveying device 400. The predetermined reference point may also be a component of the substructure 100, or may be one installed in the substructure 100 for surveying. In this embodiment, any corner of the substructure 100 is used as the reference point.

As shown in FIG. 5, the surveying device 400 is equipped with a reference point position acquisition unit 470 that acquires the reference point position measured by the positioning device 500 and stores it in the memory unit 460. There is no restriction on the method of acquiring the reference point position. For example, it may be acquired via a specified storage medium. In addition, the positioning device 500 and the surveying device 400 may be connected by wire or wirelessly to transmit and receive the reference point position. In addition, the reference point position may be manually input into the measuring device 400.

The overlay processing unit 430 has a function of correcting the ground-side point cloud data or the overlay point cloud data using the reference point positions. Therefore, the overlay processing unit 430 has a function of extracting a predetermined reference point as a feature point from the ground-side point cloud data or the overlay point cloud data.

According to this surveying system, as in the first embodiment, aerial point cloud data with a relatively large error is superimposed on ground point cloud data with a relatively small error, so that surveying errors can be reduced even for the upper surface 110 of the substructure 100 that cannot be directly observed by the laser scanner 200. However, in order to further improve the accuracy in the configuration of the first embodiment, it is necessary to use a more expensive laser scanner 200. On the other hand, in this embodiment, correction is performed using a positioning device 500, which is generally cheaper than the laser scanner 200, so that accuracy can be improved at a low cost. Other effects are the same as those of the first embodiment.

Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment, and various improvements and modifications may be made without departing from the spirit and scope of the present invention.

For example, in the above embodiment, the surveying device 400 is provided with a point cloud data conversion processing unit 410 that calculates aerial point cloud data from image data captured by the camera 310, but this processing unit may be implemented in another computer or in the unmanned aerial vehicle 300.

In addition, in the above embodiment, the substructure of a bridge was described as the structure to be surveyed, but the present invention can also be implemented with other structures.

Reference Signs List 100: Structure 110: Top surface 120: Side surface 130: Boundary 200: Laser scanner 300: Unmanned aerial vehicle 310: Camera 400: Surveying device 410: Point cloud data conversion processing unit 420: Point cloud data acquisition unit 430: Superposition processing unit 440: Measurement point search unit 450: Surveying calculation unit 450
460...Storage unit 470...Reference point position acquisition unit

Claims (6)

A surveying system for surveying a top surface of a structure, comprising:
a laser scanner that performs laser scanning on an area including a boundary between an upper surface and a side surface of the structure from a side surface side and below the upper surface to acquire first point cloud data;
An unmanned aerial vehicle equipped with a camera that captures an image of a boundary between the upper surface and the side surface of the structure and an area including the upper surface from the air above the upper surface to acquire image data;
and a superimposition means for superimposing second point cloud data for a region including a boundary between a top surface and a side surface of the structure and the top surface, calculated from the image data, onto the first point cloud data based on the first point cloud data and the second point cloud data for the boundary portion. a positioning device for performing laser positioning of a predetermined reference point of the structure,
2. The surveying system according to claim 1, wherein the superimposing means corrects at least the first point cloud data based on position information of the reference point measured by the positioning device. The surveying system according to claim 1 or 2, wherein the camera captures an image from the air at an angle above a side surface of the structure relative to an upper surface of the structure so that the side surface of the structure is captured. A surveying method for surveying the top surface of a structure, comprising the steps of:
a step of acquiring first point cloud data by performing laser scanning on an area including a boundary between an upper surface and a side surface of the structure from a side surface side and below the upper surface using a laser scanner;
A step of acquiring image data by capturing an image of a boundary between a top surface and a side surface of the structure and an area including the top surface from the air above the top surface using a camera provided on the unmanned aerial vehicle;
calculating second point cloud data in an area including a boundary between a top surface and a side surface of the structure and the top surface from the image data;
and superimposing the second point cloud data on the first point cloud data based on the first point cloud data and the second point cloud data in the boundary portion. A surveying device for surveying the top surface of a structure,
a point cloud data acquisition means for acquiring first point cloud data acquired by a laser scanner installed below the top surface of the structure and second point cloud data calculated based on image data captured by a camera mounted on an unmanned aerial vehicle flying in the air above the top surface of the structure;
a superimposing means for superimposing the second point cloud data on the first point cloud data,
the first point cloud data is acquired by laser scanning an area including a boundary between an upper surface and a side surface of the structure,
the second point cloud data is calculated from image data captured of a boundary between a top surface and a side surface of the structure and an area including the top surface,
The surveying instrument according to claim 1, wherein the superimposing means superimposes the second point cloud data on the first point cloud data based on the first point cloud data and the second point cloud data in the boundary portion. A surveying program that causes a computer to function as the surveying instrument according to claim 5.

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