JP2007170821A - Three-dimensional displacement measurement method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of measuring the displacements of many measurement points simply and in a labor-saving manner, by acquiring three-dimensional point group data by measurement, before and after the displacement. <P>SOLUTION: The measurement method comprises a first step of acquiring the three-dimensional point group data of a measured object with a three-dimensional scanner 1; a second step of creating TIN (triangulated irregular network) model of the measured object, based on the three-dimensional point group data and setting it as initial TIN model before the displacement; a third step of acquiring the three-dimensional point group data of the measured object, after the displacement with the three-dimensional scanner 1 in measuring the displacement; and a fourth step of overlaying each three-dimensional point group data, after the displacement on the initial TIN model, dropping a perpendicular line from each three-dimensional point group data, after the displacement to the nearest TIN triangle mesh plane of the initial TIN model, and obtaining the distribution state by using the perpendicular line length as the displacement amount. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a three-dimensional displacement measurement method for measuring displacements of a large number of measurement points in a simple and labor-saving manner.

  Displacement measurement is an important management item in many construction works and management, such as construction and management of various structures, earth work or construction and management of earth structures, and measures against landslides. Various methods have been proposed for the purpose of improving the efficiency, saving labor, improving accuracy, and the like.

  For example, in Patent Document 1 below, in a tank shape management automatic measurement method for managing changes in the shape of a tank installed at a base, it is installed at a tank measurement point from two known points installed above the tank. The measurement target is scanned, the oblique distance and altitude angle from each known point to the measurement point are measured, and the coordinate value of the measurement point is calculated from the oblique distance and altitude angle of the measurement point and the horizontal distance between the two known points. An automatic measuring method for tank shape management for calculating the above has been proposed.

  Moreover, in the following Patent Document 2, a plurality of measurement points are set in advance on the ground, and after repeatedly measuring the positions of the measurement points after an arbitrary period, the positions of the measurement points already measured and the measurement measured this time are measured. A ground displacement measurement method for measuring the displacement of each measurement point position over time by comparing the position of each point with the position of the measurement point already measured and the position of the measurement point measured this time. When comparing, obtain the distance between the position of each measurement point that has already been measured and the position of each measurement point that has been measured this time, and the position of one measurement point that has already been measured and the position of one measurement point that has been measured this time. When the distance is smaller than a predetermined value, the position of the one measurement point already measured and the position of the one measurement point measured this time are regarded as the same measurement point position, and between these measurement points, When the distance is the position of the measurement point Ground displacement measuring method for the displacement over the course have been proposed.

Furthermore, in the following Patent Document 3, the measurement point is determined by measuring the position variation amount of the measurement point with reference to the reference point using the reference light emitted from the reference point toward the measurement point. In the ground fluctuation measuring method for grasping the ground fluctuation amount of a predetermined area including the position fluctuation amount of the reference point, the position fluctuation amount of the reference point is measured based on a fixed point set separately, and the position fluctuation amount is used as a reference. A ground fluctuation measuring method for correcting the fluctuation has been proposed.
Japanese Patent Laid-Open No. 10-132564 Japanese Patent Laid-Open No. 7-4965 JP 2000-180163 A

  In addition to the measurement methods described above, other general position measurements (coordinate measurements) often use a total station (electronic tachometer) that combines a light wave rangefinder and an electronic theodolite as measurement equipment. Surveying is performed by installing a target such as a prism at a point (collimation point). That is, a measurement point is set, the coordinate position of this measurement point is measured by a total station, the coordinates are specified, and for example, if displacement measurement is performed, this operation is repeated every predetermined time, and the difference is calculated as a displacement amount. It was.

  However, when one or a plurality of measurement points are focused, even with such a survey method, the survey can be completed in a short time, but the ground displacement or structure where a large number of collimation points are installed. In the case of three-dimensional surveying such as displacement measurement, much time and labor are required for surveying. In addition, the installation of the target on the landslide surface has problems such as many dangers.

  On the other hand, in recent years, various methods for creating a three-dimensional model using a three-dimensional measuring device such as a three-dimensional scanner or stereo image processing have been proposed. The three-dimensional scanner (laser radar device) sets the horizontal range angle and the vertical range angle so that the object is included inside, and arranges an arbitrary number of actual measurement points evenly within the rectangular range specified thereby. The 3D point cloud data is obtained by measuring the distance from the 3D scanner to each measured point to obtain the 3D data (3D point cloud data) of the object from the distance data and the angle data. Various processes for specifying the shape are performed, and a three-dimensional model is generated. In the stereo image processing, a plurality of imaging devices such as CCD cameras whose optical axes are parallel or whose intersection angle is known are arranged, and the coordinates of the target point are specified by the principle of triangulation. These are techniques used as a method for specifying a shape or specifying coordinates in a three-dimensional space.

  Therefore, the main problem of the present invention is to use a three-dimensional measuring device such as a three-dimensional scanner or stereo image processing and acquire three-dimensional point cloud data at least before and after the displacement, thereby easily and easily changing the displacement of a large number of measurement points. It provides a method for labor saving measurement.

In order to solve the above-mentioned problem, as the present invention according to claim 1, a first step of acquiring three-dimensional point cloud data of a measurement object by a three-dimensional measuring instrument;
A second step of creating a TIN model of the measurement object based on the three-dimensional point cloud data and setting this as an initial TIN model before displacement;
A third step of acquiring three-dimensional point cloud data after displacement of the measurement object by a three-dimensional measuring device during displacement measurement;
The three-dimensional point cloud data after the displacement is superimposed on the initial TIN model, a perpendicular line is drawn from each three-dimensional point cloud data to the closest TIN mesh surface of the initial TIN model, and the perpendicular length is used as a displacement amount. There is provided a three-dimensional displacement measuring method comprising the fourth step of grasping the distribution state.

  According to a second aspect of the present invention, there is provided the three-dimensional displacement measuring method according to the first aspect, wherein the three-dimensional point cloud data is thinned out in the first step.

  As described above in detail, according to the present invention, a large number of three-dimensional point cloud data is acquired by one measurement using a three-dimensional measuring device such as a three-dimensional scanner or stereo image processing, so that a large number of measurement point displacements can be obtained. Measurement can be performed easily and labor-saving.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 to 5 are survey procedure diagrams (part 1) to (part 5) of three-dimensional displacement surveying according to the present invention.

  The three-dimensional displacement measuring method according to the present invention is performed according to the following procedure using a three-dimensional scanner 1 and a computer 2 that performs data processing of the obtained three-dimensional point cloud data.

<First step>
First, as shown in FIG. 1, the three-dimensional scanner 1 is set at an arbitrary position, and two reference points (known points) that are set in advance are collimated, or the three-dimensional scanner is set on a known point. By installing the scanner 1, the installation coordinates (Xa, Ya, Za) of the three-dimensional scanner 1 are obtained. The three-dimensional coordinates (Xa, Ya, Za) are performed in the survey coordinate system (X, Y, Z) and stored in the computer 2.

  Thereafter, the measurement object is scanned by the three-dimensional scanner 1 to acquire three-dimensional data (three-dimensional point cloud data) of the object. In this case, it is desirable to thin out the 3D point cloud data when the data amount of the 3D point cloud data is enormous or to remove noise. Various methods have been proposed for thinning out three-dimensional point cloud data. For example, methods disclosed in Japanese Patent Laid-Open Nos. 6-94428 and 2000-2435 are available. In the former method of reducing the amount of data described in Japanese Patent Laid-Open No. 6-94428, the obtained three-dimensional point cloud data is repeatedly approximated to a specified accuracy to convert it into a parametric function of a curved surface, and the data of the input destination system The latter is a technique described in the format, and the latter method of reducing the amount of data described in Japanese Patent Laid-Open No. 2000-2435 sets the reduction degree (thinning ratio) in advance by user settings, and performs processing that focuses on a certain point for all points. When the number of points being processed is set as a point number and the counter of the points left so far is included, and one point is taken out, (the number of points left) / ( (Point number) is calculated as a determination value, and when the value is smaller than the degree of reduction, thinning is performed, and when it is not, the process of leaving is repeated. For details, see the same publication.

  The acquisition of the three-dimensional point cloud data may be performed at two or more locations in order to interpolate the blind spot.

<Second step>
As shown in FIG. 2, a TIN model of the measurement object is created based on the three-dimensional point cloud data acquired in the first step. Here, TIN is a so-called “Triangulated Irregular Network”, and the TIN model is formed by connecting a large number of points having randomly arranged coordinate information with a triangular network. It is a model that expresses a measurement object by a mesh. In creating the TIN model, numbers and coordinates are given to each node, and can be divided into triangular meshes by, for example, a known Voronoi division method. It is desirable to make the mesh large and to make the triangular mesh small for uneven terrain.

  The three-dimensional TIN model obtained by the above procedure is set as an initial TIN model before displacement and stored in the computer 2. A method for creating a TIN model based on the obtained three-dimensional point cloud data is a known method for specifying a shape in a three-dimensional space.

<Third step>
At the time of subsequent displacement measurement, the three-dimensional point cloud data after the displacement of the measurement object is acquired by the three-dimensional scanner 1 as in the first step.

<4th step>
The three-dimensional point cloud data at the time of displacement measurement obtained in the third step is superimposed on the three-dimensional TIN model obtained in the second step as shown in FIG. As shown in Fig. 4, a perpendicular is drawn from each three-dimensional point cloud data (k, k + 1, k + 2) to the closest TIN triangle mesh surface of the initial TIN model, and the perpendicular lengths h1 to h3 are calculated. The amount of displacement. In this case, the displacement amount may be an average value for each TIN triangle mesh surface.

  Then, for example, as shown in FIG. 5, the distribution state of the displacement amount is expressed by a contour map, or a color contour diagram (the displacement amount is divided into 0 to 5 mm, 5 to 10 mm, 10 to 15 mm,...). At the same time, the color is set for each range, and the amount of displacement is grasped by expressing the color with a color corresponding to the amount of displacement.

[Other examples]
(1) In the above embodiment, the point cloud data is acquired using the three-dimensional scanner 1 as the three-dimensional measuring device. However, the imaging is performed by a plurality of CCD cameras or the like whose optical axes are parallel or whose intersection angle is known. You may make it acquire the point cloud data by stereo image processing using the apparatus which has arrange | positioned the apparatus.

It is a surveying procedure figure of the three-dimensional displacement surveying concerning the present invention (the 1). It is a surveying procedure figure of the three-dimensional displacement surveying concerning the present invention (the 2). It is the surveying procedure figure (the 3) of the three-dimensional displacement surveying based on this invention. It is a surveying procedure figure of the three-dimensional displacement surveying concerning the present invention (the 4). It is the surveying procedure figure of the three-dimensional displacement surveying which concerns on this invention (the 5).

Explanation of symbols

  1 ... 3D scanner, 2 ... Computer, 3 ... Displacement measurement surface

Claims (2)

A first step of acquiring three-dimensional point cloud data of a measurement object by a three-dimensional measuring device;
A second step of creating a TIN model of the measurement object based on the three-dimensional point cloud data and setting this as an initial TIN model before displacement;
A third step of acquiring three-dimensional point cloud data after displacement of the measurement object by a three-dimensional measuring device during displacement measurement;
The three-dimensional point cloud data after the displacement is superimposed on the initial TIN model, a perpendicular line is drawn from each three-dimensional point cloud data to the closest TIN mesh surface of the initial TIN model, and the perpendicular length is used as a displacement amount. A three-dimensional displacement measuring method comprising: a fourth step for grasping a distribution state. The three-dimensional displacement measuring method according to claim 1, wherein in the first step, three-dimensional point cloud data is thinned out.

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