JP2009301510A - Inclination analyzing apparatus, method and program - Google Patents

Abstract

【Task】
Macro-analyze the inclination direction with the desired accuracy from precise ground data.
[Solution]
The smoothing program (14) spatially smoothes the elevation value of the ground data {Pi (x, y, z)} in the target area. The tilt direction calculation program (16) calculates the tilt direction from the smoothed ground data. The grouping program (18) groups adjacent points having the same inclination direction value according to the calculation result of the inclination direction calculation program (16). The smoothing program (20) smoothes an inclination direction group having a predetermined threshold area or less among the inclination direction groups generated by the grouping program (18).
[Selection] Figure 1

Description

  The present invention relates to an apparatus, method, and program for macro-analyzing a slope of land.

  The ground surface can be three-dimensionally measured in plane by aerial laser surveying or photogrammetry. The ground surface data (DSM (Digital Surface Model) data) measured in this way has features such as buildings and trees on the ground. By removing these features, ground data, so-called numerical terrain model ( Three-dimensional ground surface data of DTM (digital Terrain Model) or digital elevation model (DEM: Digital Elevation Model) can be obtained.

  Note that DSM data, DTM data, and DEM data are generally rearranged on a fixed square lattice (for example, a 1 m square lattice) for ease of post-processing.

Patent Document 1 describes that the slope is calculated from an elevation value difference between adjacent grid points.
JP 2007-048185 A

  Since both DSM data and DTM data are mainly intended for detection of minute shape changes, the accuracy is improved by miniaturization of the lattice unit.

  On the other hand, there is a desire to know the inclination direction or inclination angle of the ground surface. For example, in the land asset evaluation, the inclination direction of the terrain to which the adjacent road belongs affects the evaluation price. From the viewpoint of sunshine, the correction rate is set so that roads belonging to the south slope have higher values than roads belonging to other slope directions, and roads belonging to the north slope have lower values.

  Traditionally, the direction of the slope of such roads has been determined by photo interpretation of aerial photographs, estimation from topographic maps, and field reconnaissance, but advanced interpretation is required for interpretation of aerial photographs and estimation from topographic maps. Skill is required, and the latter requires a lot of time and manpower.

  In addition, there is a desire to know the inclination angle of the ground roughly in various civil engineering works.

  Although it is possible to calculate the ground azimuth from high-precision DTM data, for example, when using 1 m grid ground data, the slope azimuth or tilt angle can be calculated at each grid point. It is too high-definition compared to other uses.

  An object of the present invention is to present an apparatus, a method, and a program for macro-analyzing an inclination direction or inclination of a ground from ground data in accordance with such a demand.

  An inclination analysis apparatus according to the present invention includes an elevation smoothing means for spatially smoothing an elevation value of ground data, and an inclination orientation calculating means for calculating an inclination orientation from the ground data smoothed by the elevation smoothing means. , Grouping means for grouping adjacent points having the same inclination direction value according to the calculation result of the inclination direction calculating means, and an inclination direction group having a predetermined threshold area or less among the inclination direction groups generated by the grouping means And an inclination azimuth smoothing means for smoothing.

  An inclination analysis method according to the present invention includes an elevation smoothing step for spatially smoothing an elevation value of ground data, an inclination orientation calculating step for calculating an inclination orientation from the ground data smoothed by the elevation smoothing step, and A grouping step for grouping adjacent points having the same tilt direction value according to the calculation result of the tilt direction calculation step, and a tilt direction group having a predetermined threshold area or less among the tilt direction groups generated by the grouping step And a tilt azimuth smoothing step for smoothing.

  An inclination analysis program according to the present invention is an inclination analysis program for causing a computer to analyze an inclination direction of the ground, and an altitude smoothing function for spatially smoothing an altitude value of the ground data and smoothing by the altitude smoothing function. The tilt direction calculation function that calculates the tilt direction from the converted ground data, the grouping function that groups adjacent points with the same tilt direction value according to the calculation result of the tilt direction calculation function, and the grouping function And an inclination azimuth smoothing function for smoothing an inclination azimuth group having a predetermined threshold area or less.

  According to the present invention, it is possible to perform a macro analysis with a desired accuracy on the inclination direction from precise ground data.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a schematic block diagram of an embodiment of the present invention, and FIG. 2 shows an operation flowchart of this embodiment. This embodiment is actually realized by a computer program.

The hard disk 10 stores the ground data {Pi (x, y, z)} of the target area three-dimensionally measured by laser aerial survey or photogrammetry (S1). The ground data {P _i (x, y, z)} is aligned on, for example, a 1 m grid point, and P _i (x, y, z) is an xyz coordinate value (latitude, longitude, and latitude) of the grid point P _i. Altitude).

  The CPU 12 of the computer includes a smoothing program (or function) 14, a tilt direction calculation program (or function) 16, a grouping program (or function) 18, and a smoothing program (or function) 20. The operation of each program (or function) 14 to 20 will be described step by step.

The CPU 12 or the smoothing program 14 sets an attention point P _n in the ground data {P _i (x, y, z)} (S2). The smoothing program 14 reads, from the hard disk 10 as a smoothing range a specified range centered on the point of interest _Pn (S3), and the ground data {P _i (x, y, z)} by spatial filtering. Smoothing is performed (S4). The smoothing range depends on, for example, how much width unit is desired to obtain the tilt direction. As an example, in the case of land property tax evaluation of land, about 60 m × 60 m is set as the smoothing range. This assumes that about six sites with an area of 100 m ² are arranged in the vertical and horizontal directions, and corresponds to almost the minimum unit for applying the line price.

The inclination azimuth calculation program 16 uses the surrounding ground value smoothed by the smoothing program 14 to calculate the inclination azimuth. For example, the normal of each lattice point can be calculated by vector-combining the inclination angle calculated in the cross section in the east-west direction and the inclination angle calculated in the cross section in the north-south direction. The tilt azimuth can be calculated by projecting this normal onto a horizontal plane. For example, the inclination azimuth angle _AT of the point of interest P _n is given by the following equation:
A _T = 270− (360 / 2π) × ATAN2 ((Z _N −Z _S ) / 2ΔY, (Z _E −Z _W ) / 2ΔX)
It can be calculated. Here, Z _N and Z _S indicate the altitude values of the north and south grid points on the meridian passing through the point of interest P _n , respectively, and ΔY indicates the distance on the meridian between these grid points. Similarly, Z _E and Z _W indicate the altitude values of the east and west grid points on the latitude line passing through the point of interest P _n , respectively, and ΔX indicates the distance on the latitude line between these grid points. ATRAN2 (x1, x2) is a function for obtaining an angle from two arguments x1, x2.

In the present embodiment, the tilt directions are classified into nine types of north, northeast, east, southeast, south, southwest, west, northwest and horizontal. The obtained tilt azimuth angle _AT is quantized into any of these nine ways, and the tilt azimuth value θ _n having any value from 0 to 9 is stored in the hard disk 22 (S5).

Until the tilt azimuth is calculated for all grid points in the target area for which the tilt azimuth is calculated (S6), the point of interest _Pn is updated (S7), and the smoothing process (S3, S4) of the smoothing program 14 and the tilt The tilt direction calculation process (S5) of the direction calculation program 16 is repeated.

  When calculation of the tilt azimuth is completed at all grid points for which the tilt azimuth is to be calculated (S6), the grouping program 18 compares the tilt azimuths of the grid points adjacent to each other, and the grid having the same tilt azimuth between the adjacent grid points. The points are grouped (S8). This can be realized, for example, by sequentially comparing the inclination directions of adjacent lattice points using any lattice point in the target area as a starting point and searching for lattice points having the same inclination direction. The grouping in the present embodiment is merely required to be able to integrally evaluate adjacent lattice points having the same tilt direction.

The grouping program 18 adds a group identification number G (or label number) indicating the same group to lattice points belonging to the same group. The grouping program 18 stores data obtained by adding the inclination direction data θ and the group identification number G to each lattice point P _i (x, y, z) in the hard disk 24. Thereby, each lattice point data P _i is represented by a three-dimensional coordinate value (x, y, z), an inclination direction θ, and a group identification number G. Note that the data P _i (x, y, z) storing the three-dimensional coordinate value of the grid point P _i is data representing a group of adjacent grid points having the same tilt direction (tilt direction group data). Obviously, it can be done separately. Such tilt azimuth group data includes, for example, tilt azimuth values and data indicating the lattice points to which they belong or boundary data defining the regions to which they belong.

Although the smoothing program 14 is applied, the lattice point data P _i grouped with respect to the tilt direction θ _i by the grouping program 18 may still have portions where the tilt directions are locally different. is there. The smoothing program 20 smoothes the spatial minute change of the tilt direction (S9).

  FIG. 3 shows an example of a cross section on the meridian of an area that becomes a north slope as a whole. In the example shown in FIG. 3, the south-facing slope partially appears while being entirely north-facing slope, and a horizontal area appears between the north-facing slope area and the south-facing slope area. The smoothing program 20 eliminates a partial south-facing slope and a horizontal area between the north-facing slope area and the south-facing slope area as shown in FIG.

  Specifically, the minimum area (threshold area) that allows the difference in the interpolated space inclination direction is set, and the inclination direction of the inclination direction group having an area smaller than the threshold area is set to a larger area around the surrounding area (reference area). Replace with the most prevalent tilt orientation. As a result, a minute region having an inclination direction different from that of the surrounding area is deleted. FIG. 4 shows an operation flowchart of the smoothing program 20.

The smoothing program 20 refers to the ground data {P _i (x, y, z, θ, G) from the hard disk 24 (S11), and searches for an inclination direction group having an area smaller than the threshold area (S12). By calculating the number of grid points having the same group identification number using the group identification number G of the ground data {P _i (x, y, z, θ, G)} as a key, it is easily smaller than the threshold area. You can discover the tilt direction group.

  When a tilt direction group having an area smaller than the threshold area is found (S13), a reference area wider than the threshold area including the found tilt direction group as a center is set (S14). For example, the center of the tilt azimuth group is set as a grid point located at the center of east-west and north-south of the grid point belonging to this group, and the center of the reference area is made to coincide with the center of this tilt azimuth group. The reference area is set to be the same as the search range in the smoothing program 14, for example. Thereby, the spatial filter processing equivalent to the smoothing of the altitude value (spatial filter processing) can be applied to the tilt direction. Of course, the size of the reference area may be appropriately determined according to the application.

  A maximum number of inclination directions are searched in the reference area (S15). This is also to determine which direction the reference area is oriented on average. The detected tilt direction of the tilt direction group is replaced with the value of the largest number of tilt directions in the reference area, but at this stage, it is temporarily stored in the internal memory (S16). A processed flag is set for the found tilt direction group.

From the ground data {P _i (x, y, z, θ, G), an unprocessed inclination direction group having an area smaller than the threshold area is searched again (S12). If an unprocessed tilt orientation group having an area smaller than the threshold area is found (S13), steps S14, S15, and S16 are repeated.

If an inclination direction group having an area smaller than the threshold area is not found (S13), the value of the inclination direction temporarily stored in step S16 is substituted into the ground data {P _i (x, y, z, θ, G) ( S17). That is, the replacement is actually performed, and the fine change in the tilt direction is eliminated. At this stage, the adjacent lattice points may belong to different inclination direction groups while having the same inclination direction. Therefore, the smoothing program 20 calls the grouping program 18 and re-executes the grouping of the tilt directions (S18). Thereby, the lattice points belonging to different inclination direction groups can be combined into one inclination direction group while the inclination directions are the same at the adjacent lattice points.

  As described above, in this embodiment, an appropriate inclination direction can be obtained from a macro viewpoint by two-level smoothing of the smoothing of the altitude (S4) and the smoothing of the obtained inclination direction (S9). it can.

  For smoothing the azimuth direction, if a azimuth direction group that is less than or equal to the threshold area surrounded by a certain azimuth direction group is surrounded by another azimuth azimuth group, a process of including it in the other azimuth azimuth group is also considered. It is done.

  Although the embodiment for obtaining the inclination direction has been described, in step S5, the inclination angle in the latitude direction and the inclination angle in the meridian direction can be obtained. That is, the normal (inclination angle and inclination direction) of each lattice point can be obtained. It seems that it is sufficient that the tilt angle itself is quantized to a unit of about 10 degrees, for example. If the inclination angle is also obtained, steps S8 and S9 are omitted according to the application. When steps S8 and S9 are executed, the inclination is smoothed as a vector (inclination direction, inclination angle). The threshold area and the reference area are narrower than in the case of only the tilt direction.

  In the above embodiment, the inclination direction of the target lattice point is calculated while partially smoothing the ground surface around the target lattice point. However, the ground surface of the target area is collectively smoothed, and the obtained smooth ground The inclination azimuth of each lattice point may be calculated with respect to the surface.

  As in the above embodiment, the method of calculating the inclination direction of the target lattice point while partially smoothing the ground surface around the target lattice point is smoothed according to the undulation and unevenness of the ground surface and the degree thereof. Parameter can be changed for each smoothing target, and more flexible processing is possible. Also, trial and error processing is facilitated. Since the necessary amount of data is reduced, it becomes possible to develop the necessary data in the memory and calculate the tilt azimuth of the point of interest, thereby shortening the calculation time.

  Although the invention has been described with reference to specific illustrative embodiments, various modifications and alterations may be made to the above-described embodiments without departing from the scope of the invention as defined in the claims. This is obvious to an engineer in the field to which the present invention belongs, and such changes and modifications are also included in the technical scope of the present invention.

1 shows a schematic block diagram of an embodiment of the present invention. It is an operation | movement flowchart of a present Example. It is an example of the section shape of the ground used as an application object of a present Example. 4 is an operation flowchart of the smoothing program 20.

Explanation of symbols

10: Hard disk 12: CPU
14: Smoothing program (or function)
16: Inclination direction calculation program (or function)
18: Grouping program (or function)
20: Smoothing program (or function)
22, 24: Hard disk

Claims (12)

Altitude smoothing means (14) for spatially smoothing the altitude value of the ground data;
An inclination direction calculating means (16) for calculating an inclination direction from the ground data smoothed by the elevation smoothing means;
Grouping means (18) for grouping adjacent points having the same inclination direction value according to the calculation result of the inclination direction calculating means;
An inclination azimuth smoothing means (20) for smoothing an inclination azimuth group having a predetermined threshold area or less among the inclination azimuth groups generated by the grouping means.
An inclination analyzer characterized by comprising: The inclined direction smoothing means is
Means (S12) for searching for an inclination direction group having a predetermined threshold area or less among the inclination direction groups generated by the grouping means;
Means (S15) for detecting a maximum number of inclination directions in a reference area having an area larger than the predetermined threshold area, including an inclination direction group equal to or less than the predetermined threshold area;
Replacement means (S16, S17) for replacing the inclination direction of the inclination direction group having a predetermined threshold area or less with the maximum number of inclination directions
The inclination analysis apparatus according to claim 1, further comprising: The replacement means is
Storage means (S16) for temporarily storing the tilt azimuth of the tilt azimuth group having a predetermined threshold area or less at the maximum number of tilt azimuths;
Means for actually replacing the inclination azimuth of each inclination azimuth group below the predetermined threshold area with the temporarily stored inclination azimuth after the processing of the storage means for all inclination azimuth groups below the predetermined threshold area is completed (S17).
The inclination analysis apparatus according to claim 2, comprising:   The inclination analysis apparatus according to any one of claims 1 to 3, wherein the ground data is given by a plurality of lattice points at a constant interval. An elevation smoothing step (S4) for spatially smoothing the elevation value of the ground data;
An inclination direction calculating step (S5) for calculating an inclination direction from the ground data smoothed in the elevation smoothing step;
A grouping step (S8) for grouping adjacent points having the same inclination direction value according to the calculation result of the inclination direction calculation step;
An inclination azimuth smoothing step (S9) for smoothing an inclination azimuth group having a predetermined threshold area or less among the inclination azimuth groups generated in the grouping step.
An inclination analysis method comprising: The slope orientation smoothing step is
Searching for an inclination direction group having a predetermined threshold area or less among the inclination direction groups generated by the grouping means (S12);
Detecting a maximum number of tilt azimuths in a reference area having an area larger than the predetermined threshold area including a tilt azimuth group equal to or less than the predetermined threshold area (S15);
Replacement step (S16, S17) of replacing the tilt azimuth of the tilt azimuth group having a predetermined threshold area or less with the maximum number of tilt azimuths as the tilt azimuth of the other tilt azimuth group
The gradient analysis method according to claim 5, comprising: The replacement step is
A storage step (S16) for temporarily storing the tilt azimuth of the tilt azimuth group having a predetermined threshold area or less at the maximum number of tilt azimuths;
After the processing of the storing step for all the tilt azimuth groups having a predetermined threshold area or less is completed, the tilt azimuth of each tilt azimuth group having a predetermined threshold area or less is actually replaced with the temporarily stored tilt azimuth (S17).
The gradient analysis method according to claim 6, further comprising:   The slope analysis method according to any one of claims 5 to 7, wherein the ground data is given by a plurality of lattice points at regular intervals. An inclination analysis program for causing a computer to analyze the inclination direction of the ground,
An altitude smoothing function (14) for spatially smoothing the altitude value of the ground data;
An inclination direction calculation function (16) for calculating an inclination direction from the ground data smoothed by the elevation smoothing function;
A grouping function (18) for grouping adjacent points having the same inclination direction value according to the calculation result of the inclination direction calculation function;
An inclination azimuth smoothing function (20) for smoothing an inclination azimuth group having a predetermined threshold area or less among the inclination azimuth groups generated by the grouping function.
An inclination analysis program characterized by comprising: The tilt direction smoothing function is
A function (S12) for searching for a tilt direction group having a predetermined threshold area or less among the tilt direction groups generated by the grouping means;
A function (S15) for detecting a maximum number of inclination directions in a reference area having an area larger than the predetermined threshold area, including an inclination direction group equal to or less than the predetermined threshold area;
Replacement function for replacing the tilt azimuth of the tilt azimuth group having a predetermined threshold area or less with the maximum number of tilt azimuths (S16, S17)
The inclination analysis program according to claim 9, further comprising: The replacement function is
A storage function (S16) for temporarily storing the tilt azimuth of the tilt azimuth group having a predetermined threshold area or less at the maximum number of tilt azimuths;
A function of actually replacing the inclination azimuth of each inclination azimuth group below the predetermined threshold area with the temporarily stored inclination azimuth after the processing of the storage function for all inclination azimuth groups below the predetermined threshold area is completed (S17).
The gradient analysis program according to claim 10, further comprising:   The slope analysis program according to any one of claims 9 to 11, wherein the ground data is given by a plurality of lattice points at a constant interval.

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