JP5483076B2 - Crustal movement tracking system and crustal movement tracking method - Google Patents

Description

  The present invention relates to a crustal movement tracking system and a crustal movement tracking method for tracking crustal movements.

  Conventionally, as a method of tracking crustal movement, a method of measuring a plurality of position coordinates on the crust and capturing its time series change and relative change is generally used (see, for example, Patent Document 1). On the earth, a plurality of electronic reference points by GPS antennas that receive radio waves from GPS satellites are installed in order to accurately capture position coordinates on the crust. In particular, in Japan, electronic reference points are arranged on a mesh with an interval of about 20 to 25 km, and detailed crustal movement monitoring is performed (for example, see Non-Patent Document 1).

  The initial position of the electronic reference point is given by coordinates in the earth center coordinate system (XYZ coordinate system) with the earth center as the origin. Since these coordinates are given as positions in outer space rather than positions on the crust, it is not easy to grasp their positions on the ground surface. For this reason, the coordinate values in the Earth center coordinate system are mathematically converted to the coordinate values in the Earth ellipsoid model and the plane Cartesian coordinate system, and the position coordinates are expressed in map coordinates such as latitude / longitude / altitude and north / south / east / west / height By tracking changes in the earth, crustal movements are tracked.

  However, although such mathematical conversion is theoretically possible, there is a problem that mathematical conversion becomes difficult in actual positioning with the GPS antenna, and between the converted position coordinate value and the initial XYZ coordinate value. There is a problem that a large positioning error occurs.

  On the other hand, the present patent applicant has already provided the method shown in Patent Document 2. In this method, the earth center coordinate system itself is used, and highly accurate variation information of each electronic reference point is grasped by tracking a relative variation in the distance between two points for each axis of XYZ.

JP 2004-226388 A Japanese Patent No. 4139229

Geospatial Information Authority of Japan, “Reference and Geodetic Observation Data”, [online], [searched on September 1, 2009], Internet <URL: http://www.gsi.go.jp/kizyunten.html>

  By the way, the method shown in the above-mentioned conventional patent document 2 only grasps the fluctuation information of each electronic reference point, and grasps the surface movement of the crust and the relative movement between adjacent electronic reference points. It was difficult.

  The present invention has been made in view of the above, and a crustal movement tracking system and a crustal movement tracking which can easily grasp the surface movement of the crust and the relative movement between adjacent electronic reference points. It aims to provide a method.

In order to solve the above-described problems and achieve the object, a crustal movement tracking system according to claim 1 of the present invention is a crustal movement tracking system for tracking crustal movement, and includes a plurality of electrons provided on the ground. A mesh creation means for creating a mesh based on the position information of the reference point, an analysis means for analyzing a change in the crust based on the change in the position information, and a mesh creation means based on the analysis result of the analysis means A mesh state changing means for changing at least one of the shape and color of the created mesh from a predetermined state to a state in which visibility is improved, and a display means for displaying the mesh whose state has been changed by the mesh state changing means , The mesh creation means converts the earth center coordinates indicating the position information of the electronic reference point into latitude / longitude coordinates, and then divides the Delaunay triangulation, To create a mesh in step to reconvert the center coordinates and said Rukoto.

  The crustal movement tracking system according to claim 2 of the present invention is the above-described crustal movement tracking system according to claim 1, wherein the mesh state changing means includes scaling means for scaling the lengths of sides constituting the mesh. The shape of the mesh is changed to a state in which visibility is improved by scaling of the length of the side by a scaling means.

  Further, the crustal movement tracking system according to claim 3 of the present invention is the above-described claim 1 or 2, wherein the mesh state changing means has color setting means for setting a color of a side constituting the mesh, The color of the mesh is changed to a state where visibility is improved by setting the color of the side by the color setting means.

  Moreover, the crustal movement tracking system according to claim 4 of the present invention is the crustal movement tracking system according to any one of claims 1 to 3, wherein the analysis means analyzes crustal movement based on a change in the area of the mesh. It is characterized by that.

  The crustal movement tracking system according to claim 5 of the present invention is the crustal movement tracking system according to any one of claims 1 to 4, wherein the display means can display the mesh by changing a viewpoint. Features.

A crustal movement tracking method according to claim 6 of the present invention is a crustal movement tracking method for tracking crustal movement, and creates a mesh based on positional information of a plurality of electronic reference points provided on the ground. On the other hand, based on the analysis result of the change of the crust based on the change of the position information, based on the analysis result, at least one of the shape and color of the mesh is changed from a predetermined state to a state where visibility is improved, In the procedure for creating the mesh, the earth center coordinates indicating the position information of the electronic reference point are converted into latitude / longitude coordinates, and then the Delaunay triangulation is performed. It is characterized in that a mesh is created by a procedure for re-converting to center coordinates .

  The crustal movement tracking method according to claim 7 of the present invention is the above-described crustal movement tracking method, wherein the length of the sides constituting the mesh is scaled and the shape of the mesh is changed to a state in which visibility is improved. It is characterized by doing.

  The crustal movement tracking method according to claim 8 of the present invention is the above-described method according to claim 6 or 7, wherein the color of the side constituting the mesh is set, and the color of the mesh is changed to a state in which visibility is improved. It is characterized by doing.

  A crustal movement tracking method according to claim 9 of the present invention is characterized in that, in any one of claims 6 to 8, the crustal movement is analyzed based on a change in the area of the mesh. .

  A crustal movement tracking method according to claim 10 of the present invention is characterized in that, in any one of claims 6 to 9 described above, the mesh can be displayed by changing a viewpoint.

  According to the crustal movement tracking system of the present invention, a crustal movement tracking system for tracking crustal movement, a mesh creating means for creating a mesh based on positional information of a plurality of electronic reference points provided on the ground, Visibility from a predetermined state of at least one of the shape and color of the mesh created by the mesh creating means based on the analysis result of the crust based on the change in the position information and the analysis result of the analyzing means Since it has a mesh state changing means for changing to a state improved and a display means for displaying the mesh whose state has been changed by the mesh state changing means, by referring to the mesh displayed with improved visibility It is possible to easily grasp the surface movement of the crust and the relative movement between adjacent electronic reference points.

FIG. 1 is a schematic configuration diagram of a crustal movement monitoring system according to the present invention. FIG. 2 is a procedure diagram of the crustal movement monitoring method according to the present invention. FIG. 3 is a display screen view of the crustal movement monitoring system according to the present invention. 4A and 4B are display screen views of the crustal movement monitoring system according to the present invention, where FIG. 4A is an overall view and FIG. 4B is a partially enlarged view. FIG. 5 is an explanatory diagram of the scaled drift vector. FIG. 6 is a perspective view showing the arrangement of the crust plates around the Japanese archipelago. FIG. 7 is an explanatory diagram of the color bars on the sides of the mesh. Figure 8 is a diagram showing an electronic reference point 0 neighborhood mesh diagrams in (a) Figure at time t ₀ is (b) the time t. 9A and 9B are display screen diagrams for explaining setting of viewpoints, where FIG. 9A is an overall view and FIG. 9B is a partially enlarged view. FIG. 10 is a display screen diagram for setting display conditions for analysis results. FIG. 11 is a display screen diagram showing the state of crustal deformation due to a past earthquake, (a) is a figure immediately before the occurrence of the earthquake, (b) is a figure of the day of the earthquake, and (c) is a figure of the day immediately after the occurrence of the earthquake. It is.

  Embodiments of a crustal movement tracking system and a crustal movement tracking method according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  As shown in FIG. 1, a crustal movement tracking system 100 according to the present invention includes a mesh creating means 10, an analyzing means 20, a mesh state changing means 30, a display means 40, and a control means including a CPU for controlling them. 50.

  The mesh creating means 10 creates a mesh based on the electronic reference point position information stored in the database 60. In order to create this mesh, it is possible to use a Delaunay triangulation algorithm that performs mesh division so that no other vertex exists in the circumscribed circle of the triangle.

  The analysis means 20 analyzes the change in the crust based on the change in the position information of the electronic reference point. As will be described later, the analyzing means 20 can also analyze crustal fluctuations based on changes in the mesh area.

  Based on the analysis result of the analysis unit 20, the mesh state change unit 30 changes at least one of the shape and color of the mesh created by the mesh creation unit 10 from a predetermined state to a state where visibility is improved.

  The mesh state changing unit 30 includes a scaling unit 32 that performs scaling of the lengths of the sides constituting the mesh. The shape of the mesh is changed to a state in which the visibility is improved by scaling the length of the side by the scaling means 32.

  The mesh state changing unit 30 further includes a color setting unit 34 for setting the color of the sides constituting the mesh. Then, the color of the mesh is changed to a state in which the visibility is improved by setting the color of the side by the color setting means 34.

  The display means 40 displays the mesh whose state has been changed by the mesh state changing means 30, and is composed of a monitor or the like that can display this mesh on the screen. As will be described later, the display unit 40 can display the mesh by changing the viewpoint.

  In addition, as shown in FIG. 2, the crustal movement tracking method according to the present invention acquires position data of electronic reference points (step S1), and meshes based on position information of a plurality of electronic reference points provided on the ground. (Step S2), the crustal fluctuation is analyzed based on the change in the position information (step S3), and at least one of the shape and color of the mesh is determined from the predetermined state based on the analysis result. (Step S4), and the mesh whose state has been changed is displayed (step S5). Below, the procedure of the processing content by this invention is demonstrated concretely.

(1) Creation of mesh As initial position coordinates, coordinates based on a three-dimensional (hereinafter sometimes referred to as 3D) Earth center coordinate system of N domestic reference points (N = 1228) are used. By generating a mesh connecting adjacent electronic reference points, a list of edges connecting two electronic reference points can be created. One mesh element is represented by a triangle composed of three sides with the electronic reference point as a vertex. An index is assigned to each vertex.

  By the way, the Delaunay triangulation algorithm (Droney triangulation) described above does not generate a triangle mesh from a vertex set in 2D (two-dimensional) space, or generate a cell like a pyramid from a vertex set in 3D space. Although it is possible, a triangle such as a Delaunay triangle cannot be directly generated from a vertex set in 3D space. However, the electronic reference point base is located on the ground surface, and its latitude and longitude are different. Therefore, the earth center coordinates are first converted into latitude / longitude coordinates, and a triangular mesh (Delaunay diagram) is generated on the ground surface using this Delaunay triangulation algorithm (Delaunay triangulation). After that, the latitude / longitude coordinates are reconverted to the earth center coordinates to finish the mesh in 3D space.

  When coordinate conversion is performed, N = 1228 (latitude, longitude) sets of data are obtained. If the Delaunay triangulation algorithm is applied to this, 2445 triangles are created. However, as shown in the display screen diagram of FIG. 3, the mesh generated at this stage also includes the triangle 1 having vertices far away. Therefore, as shown in FIG. 4, long sides are excluded by a predetermined threshold (for example, 55 km), and a set of triangles is generated so as to follow the shape of the Japanese archipelago.

(2) Scaling The earth center coordinate value of the electronic reference point is in units of meters, but in 3D graphics, it is necessary to reduce the scale so as to fit in a unit cube. Therefore, the coordinate value is divided by the average radius of 6400 km of the earth, and this is used as the graphic coordinates when displayed on the screen.

  In addition, the fluctuation of the crust over time is so small that it can be ignored (the fluctuation is about 1 to 2 cm per year, which is very small compared to the average radius of the earth, 640,000,000 cm). It looks as if it is, and it cannot recognize the time variation of the crust. For this reason, the drift of the electronic reference point should be visualized in an exaggerated manner with respect to the initial position so that the deformation of the mesh and the drift of the electronic reference point base can be easily grasped. Scale the drift. By doing so, it becomes possible to easily grasp the surface movement of the crust and the relative movement between adjacent electronic reference points.

  The drift itself can be defined by the difference between the initial time and the current time. As the drift, an absolute drift that is a relative drift from the center of the earth or a relative drift that is a relative drift from a predetermined point on the ground surface can be used.

Next, the drift scaling method will be described.
As shown in FIG. 5, let X (t ₀ ) i and X (t) i be the coordinate vector of the electronic reference point i at times t ₀ and t, and let the time drift dXi be the vector X (t) i−X ( t ₀ ) i.

By changing the scale factor k (eg, k = 10 ⁶ ) and adding the scaled drift vector kdXi to the initial position X (t ₀ ) i, the change in the graphic coordinates is clarified. The scaled graphic coordinates are as follows.
_{Xgraph (t) i = (X} (t 0) i + kdXi) / R

This is written in scalar form as follows:
_{xgraph (t) i = [x} (t 0) i + k (x (t) i-x (t 0) i)] / R
_{ygraph (t) i = [y} (t 0) i + k (y (t) i-y (t 0) i)] / R
_{zgraph (t) i = [z} (t 0) i + k (z (t) i-z (t 0) i)] / R

  Further, the scaled drift may be calculated as a relative drift from a predetermined point (reference point) on the ground surface. Thus, by obtaining the relative drift from the reference point, it is possible to represent the state of the fluctuation of the crustal plate around the Japanese archipelago.

As shown in FIG. 6, at least three crustal plates (Philippine plate, continental plate, Pacific plate) intersect around the Japanese archipelago. These three crustal plates move in a complex manner with each other, and the spatial relative deformation results in different results by changing the reference point. For example, when a certain point B (not shown) is taken as a relative reference point (reference point), the relative drift of the electronic reference point i is dXi−dX _B , and the scaled graphic coordinates are Xgraph (t) i = [X (T ₀ ) i + k (dXi−dX _B )] / R.

This is written in scalar form as follows:
_{xgraph (t) i = [x} (t 0) i + k (x (t) i-x (t 0) i) - (x (t) B -x (t 0) B)] / R
_{ygraph (t) i = [y} (t 0) i + k (y (t) i-y (t 0) i) - (y (t) B -y (t 0) B)] / R
_{zgraph (t) i = [z} (t 0) i + k (z (t) i-z (t 0) i) - (z (t) B -z (t 0) B)] / R

  As a method of selecting the reference point, it is preferable to select a point as far as possible from the intersecting region of the crust plates (for example, on a different crust plate such as Hiroshima, Sendai, Aogashima, etc.). As a method for setting the reference point, an electronic reference point closest to the designated latitude / longitude may be automatically searched by designating an arbitrary latitude / longitude.

(3) Setting of color bar indicating expansion / contraction state between electronic reference points Setting of color bar for more clearly visualizing expansion / contraction of the crust will be described. First, define the drawing of the object. An electronic reference point that is a vertex of the triangular mesh is drawn on the screen by a small spherical object, and a line segment between the electronic reference points that is a side of the mesh is drawn on the screen by a thin line or a tubular object.

  As shown in FIG. 7, in order to balance the hue of the color among these objects, first, the color is defined only by the vertices. The color of the line segment (side) defined by the two vertices and the color of the triangle defined by the three vertices are automatically assigned by interpolation calculation based on the vertex colors. In this case, the color hue may be assigned so as to continuously change along the line segment.

  Each electronic reference point is assigned a color at each time. The graphic color value displayed on the screen is a scalar real value V that takes a value from 0 to 1, and is associated with the RGB color table. In the system of the present invention, a color is assigned to an object based on this color table and is drawn on the screen. A number of methods for mapping input coordinates to scalar real values V are known. Here, a case will be described in which a mapping method based on a difference in coordinates at two different times is used as follows.

[Mapping method]
This mapping method uses the drift value of the selected electronic reference point as shown in the scaling above. That is, the length di of the drift vector is defined without a scale as follows.

di = | dXi | (in the case of an absolute drift value)
di = | dXi−dX _B | (in the case of relative drift value)

Next, the scalar Vi is defined as follows. Here, d _max is a predetermined parameter.
Vi = di / d _max (when d <d _max )
Vi = 1 (except in the above case)
This Vi is mapped to the above color table to visualize the surface crustal movement. This visualization can be done for absolute drift and relative drift.

[Coloring method for area fluctuation]
Next, a coloring method in area variation will be described.
First, consider a mesh triangle formed by an electronic reference point and surrounding electronic reference points at times t ₀ and t.

FIG. 8 (a), the line connecting the (b), the electronic reference point in time _{t 0} and t and (represented by index 0), (represented by an index 1, 2, 3, 4) adjacent electronic reference point The area of the region composed of the sides is defined as the sum of adjacent triangles S (t ₀ ) and S (t) as follows.
S (t ₀ ) = S01 + S02 + S03 + S04
S (t) = S11 + S12 + S13 + S14
Here, S01, S02, S03, S04, S11, S12, S13 and S14 are the areas of the triangular elements shown in FIG.

Next, an area (region) change P (t) is defined as follows.
P (t) = p (S (t) · S (t ₀ )) / S (t ₀ )
Here, p is a predetermined parameter, and for example, a value of 10 ⁶ can be used.

Next, colors are defined as in Example 1 and Example 2 below.
(Example 1) Area fluctuation (in the case of absolute value display)
V = | P (t) | (provided that | P (t) | <1)
V = 1 (except in the above case)

(Example 2) Area variation V = -1 (where P (t) <-1)
V = 1 (provided that P (t)> 1)
V = P (t) (however, other than above)

  In Example 2 above, when V is negative, it means that the region (area) is compressed, and when it is positive, it indicates that the region (area) is expanded. Based on this V, a surface area change is visualized. This visualization can be done for absolute drift and relative drift.

(4) Setting of viewpoint (camera / view) As shown in FIG. 9, the result of the crustal movement that has undergone the above-described processing such as scaling is displayed in a global center coordinate system by a mesh that models the Japanese archipelago. It is possible to display by changing the viewpoint for each region so that the movement of the crustal movement in the east, west, north and south directions shown in a normal map (planar orthogonal coordinate system) can be easily grasped. This viewpoint switching display is performed by depressing each button indicated by the oval part 2 in the screen. By rotating the display angle on the screen in each of the X, Y, and Z coordinate axes by this button operation, the crustal movement can be seen from various viewpoints and angles.

(5) Setting of analysis conditions and display (output) conditions As shown in the display screen of FIG. 10, the above analysis such as scaling is performed by “drift value”, “area variation”, “area variation (absolute value)”, Set a threshold value in the input field (input field indicated by GPS Drift Value Range etc. on the right side of the figure) for setting "ellipsoidal height" etc., and output the results indicated by changes in hue and shape to the monitor screen or printer To do. This display setting may be a setting that enables display in the latitude / longitude coordinate system as well as the earth center coordinate system, and a color inversion function may be added to the display setting of the color bar.

  Thus, according to the present invention, it is possible to clearly display the state of crustal movement around the Japanese archipelago on a plane by the change in the hue of the sides of the mesh and the change in the mesh shape. Therefore, the user can easily grasp the surface movement of the crust and the relative movement between adjacent electronic reference points, and can easily follow up the abnormal movement of the crust and the stability. .

  In addition, according to the conventional method that directly uses the earth center coordinate value (position data) that is initially assigned to each electronic reference point, it is possible to accurately detect each electronic reference point by capturing the relative movement of each axis of XYZ. Although it is possible to grasp the movement, it is difficult to grasp the correlation with the surrounding electronic reference points. However, according to the present invention, the area variation of a triangle or polygon formed between an electronic base point and a plurality of surrounding electronic reference points is grasped by the three-dimensional coordinates of the earth center coordinate system. can do. Furthermore, by simultaneously acquiring the length variation of each triangle or polygon, it is possible to grasp in a plane which direction the expansion / contraction has occurred in which region.

  FIGS. 11A to 11C show the state of crustal deformation caused by a past earthquake (the Tokachi-oki earthquake that occurred on September 26, 2003) as a drift value. FIG. 11A is a diagram immediately before the occurrence of the earthquake, FIG. 11B is a diagram of the date of occurrence of the earthquake, and FIG.

  As shown in FIGS. 11 (a) to 11 (c), it is possible to grasp the crustal deformation before and after the earthquake step by step, and it is easy to see to which area the large crustal deformation after the earthquake has propagated. I can grasp it. The state of crustal deformation obtained in this way can be an effective data for earthquake disaster countermeasures.

  In the above embodiment, the case of using the electronic reference point position data provided by the Geospatial Information Authority of Japan was described as an example, but reference point data by so-called IGS (International GPS Service) or newly installed by the user The GPS antenna positioning data may be added to an observation network for analyzing the position data of the electronic reference point by the Geospatial Information Authority of Japan, and crustal movements may be tracked. By doing this, it is possible to track more detailed crustal movements.

  As described above, the crustal movement tracking system according to the present invention is a crustal movement tracking system that tracks crustal movement, and creates a mesh based on position information of a plurality of electronic reference points provided on the ground. Mesh creating means, analyzing means for analyzing crustal fluctuations based on the change in the position information, and based on the analysis results of the analyzing means, at least one of the shape and color of the mesh created by the mesh creating means Since it is provided with a mesh state changing means for changing from a predetermined state to a state with improved visibility and a display means for displaying a mesh whose state has been changed by the mesh state changing means, the state is displayed with improved visibility. By referring to the mesh, it is possible to easily grasp the surface movement of the crust and the relative movement between adjacent electronic reference points.

  As described above, the crustal movement tracking system and the crustal movement tracking method according to the present invention are useful for tracking crustal movement using the position data of the electronic reference point provided by the Geospatial Information Authority of Japan. It is suitable to easily grasp the relative movement and the relative movement between adjacent electronic reference points.

DESCRIPTION OF SYMBOLS 10 Mesh preparation means 20 Analysis means 30 Mesh state change means 32 Scaling means 34 Color setting means 40 Display means 50 Control means 60 Database 100 Crustal movement tracking system

Claims (10)

A crustal movement tracking system for tracking crustal movement,
A mesh creating means for creating a mesh based on position information of a plurality of electronic reference points provided on the ground;
An analysis means for analyzing a change in the crust based on the change in the position information;
Based on the analysis result of the analyzing means, mesh state changing means for changing at least one of the shape and color of the mesh created by the mesh creating means from a predetermined state to a state where visibility is improved,
Display means for displaying a mesh whose state has been changed by the mesh state changing means ,
It said meshing means converts the geocentric coordinates indicating the position information of the electronic reference point latitude and longitude coordinates, then, after dividing Delaunay triangles, you to create a mesh in steps to reconvert into geocentric coordinates A crustal movement tracking system characterized by   The mesh state changing means has scaling means for scaling the lengths of the sides constituting the mesh, and the mesh shape is made in a state in which visibility is improved by scaling the lengths of the sides by the scaling means. The crustal movement tracking system according to claim 1, wherein the crustal movement tracking system is changed.   The mesh state changing means has color setting means for setting the color of the side constituting the mesh, and the color of the mesh is changed to a state in which visibility is improved by setting the color of the side by the color setting means. The crustal movement tracking system according to claim 1 or 2, characterized in that:   The crustal movement tracking system according to any one of claims 1 to 3, wherein the analyzing unit analyzes a crustal movement based on a change in the area of the mesh. The crustal movement tracking system according to claim 1, wherein the display unit can display the mesh by changing a viewpoint. A crustal movement tracking method for tracking crustal movement,
While creating a mesh based on the position information of a plurality of electronic reference points provided on the ground, analyzing the variation of the crust based on the change of the position information, based on the analysis results, the shape of the mesh and Changing at least one of the colors from a predetermined state to a state where visibility is improved, and displaying the mesh whose state has been changed ;
In the procedure of creating the mesh, the earth center coordinate indicating the position information of the electronic reference point is converted into latitude / longitude coordinates, and then the Delaunay triangulation is performed, and then the mesh is created by reconverting to the earth center coordinate. A crustal movement tracking method characterized by this.   The crustal movement tracking method according to claim 6, wherein scaling of the lengths of sides constituting the mesh is performed to change the shape of the mesh to a state in which visibility is improved.   The crustal movement tracking method according to claim 6 or 7, wherein a color of a side constituting the mesh is set, and the color of the mesh is changed to a state in which visibility is improved.   The crustal movement tracking method according to any one of claims 6 to 8, wherein the crustal movement is analyzed based on a change in the area of the mesh.   The crustal movement tracking method according to any one of claims 6 to 9, wherein the mesh can be displayed by changing a viewpoint.

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