KR101008395B1 - Apparatus for detecting orthometric height correction point - Google Patents

Abstract

PURPOSE: A device for detecting an orthometric height correction point is provided to satisfy a calculated gradient with a predetermined condition by using data with each point within an airborne laser scan image. CONSTITUTION: A device for detecting an orthometric height correction point comprises a node generation unit(21), a searching area setting unit(22), an orthometric height candidate setting unit(23), and an orthometric height correction point detecting unit(24). The node generation unit creates one or more virtual boundaries with different size magnification. The searching area setting unit is connected to the node generation unit and has a circular shape of a first radius. The orthometric height candidate setting unit is connected to the searching area setting unit. The orthometric height correction point detecting unit is connected to the orthometric height candidate setting unit.

Description

Point elevation correction point detection device {APPARATUS FOR DETECTING ORTHOMETRIC HEIGHT CORRECTION POINT}

The present invention relates to an apparatus for detecting an elevation elevation point, and more particularly, to generate nodes at a predetermined interval in a target area in an airborne laser scan image, and at least one candidate elevation correction point in a predetermined area centered on each node. After selecting, the candidate height correction point that detects candidates that have no step height and that the slope calculated from the data of each point in the airborne laser scan image satisfy the predetermined condition as the elevation height correction point It relates to a detection device.

The normal elevation correction point is a point used to correct an ellipse height obtained through a GPS (Global Positioning System) survey to a normal elevation, and is generally disposed at equal distributions (average 5 km intervals) in the target area as shown in FIG. .

It is good to select these normal height correction points as a place where the step is not severe and the slope is gentle. This is because when the elevation is corrected by using the elevation elevation point located near the boundary of the opening of the stepped road or other facility, an error may occur as much as the height of the opening or the step near the boundary.

Conventional elevation elevation point detection method has been selected in consideration of the topographic conditions and distance requirements while the observer checks the topographic map by eye, and thus efficiency and accuracy are inferior, especially the optimal elevation point is often not selected. There was a problem that occurred.

In order to solve the above problems of the prior art, the present invention generates nodes at predetermined intervals in a target area in the airborne laser scan image, and selects at least one elevation elevation point candidate in a predetermined area centered on each node. Among the candidates selected, candidates that have no step height and whose slopes, which are calculated using the data of each point in the airborne laser scan image, satisfy predetermined conditions are detected as normal height correction points. SUMMARY OF THE INVENTION An object of the present invention is to provide a device for detecting a level elevation correction point capable of detecting a level elevation correction point.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention which are not mentioned can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

The apparatus of the present invention for achieving the above object is a device for detecting an elevation elevation point in the target area in the airborne laser scan image consisting of a plurality of points having a plane coordinate value and a height value, A node generation unit generating at least one virtual boundary line having a same shape but different from the boundary line of the target area, and generating nodes at predetermined intervals on the boundary line and the virtual boundary line; A search area setting unit configured to set an elevation elevation candidate search area in the form of a circle centering on each node generated by the node generator; A normal elevation correction point candidate selecting unit generating at least one candidate member along a center line that vertically bisects the candidate search region set by the search region setting unit; And a distance between a point having the minimum height value and a point having the maximum height value while a difference between a minimum height value and a maximum height value among the points in the candidate circle generated by the normal elevation correction point candidate selection unit exceeds a first threshold value. A normal elevation correction point detection unit for detecting candidate sources that are less than the second threshold and the slope does not exceed the third threshold as the normal elevation correction point, wherein the normal elevation correction point detection unit is represented by Equation A below. It is characterized by calculating the inclination through.

Equation A

는 X의 평균,

는 Y의 평균, n은 후보원내 점의 수를 각각 의미한다. 아울러 i는 n개 점들의 순차를 나타낸다.
Where X is the independent variable, distance from the center of the candidate circle, Y is the dependent variable, height is the intercept, b is the slope,

Is the mean of X,

Is the mean of Y, and n is the number of points in the candidate circle. In addition, i represents a sequence of n points.

As described above, the present invention generates nodes at a predetermined interval in a target area in an airborne laser scan image, selects at least one elevation elevation point candidate in a predetermined area centering each node, and then selects a step from among the selected candidates. Height) and the candidates whose slopes, which are calculated using the data of each point in the airborne laser scan image, satisfy the predetermined conditions as the normal height correction points, so that the optimal normal height correction points can be detected quickly and efficiently. It can be effective.

1 is an exemplary view showing a general normal height correction point arrangement state,
2 is a block diagram of an embodiment of a device for detecting an elevation height correction point according to the present invention;
3 is a diagram illustrating an embodiment of a node generation process in a node generation unit according to the present invention;
FIG. 4 is a diagram for explaining a process of setting a candidate elevation correction point candidate search region in a search region setting unit according to the present invention; FIG.
5 is an exemplary explanatory diagram for a process of selecting a normal elevation correction point candidate in the normal elevation correction point candidate selecting unit according to the present invention;
6 is an exemplary view of a typical airborne laser scan image,
7 is an exemplary view of a typical three-dimensional airborne laser scan image,
8 is an example of a three-dimensional laser scan image showing the step and the slope used in the present invention,
9 is an exemplary view of an airborne laser scan image in which a normal elevation correction point candidate is set according to the present invention;
10 is an exemplary view illustrating a process of calculating a slope of a normal elevation correction point candidate according to the present invention;
11 is an exemplary view of a normal elevation correction point detected by the normal elevation correction point detection unit according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings, It can be easily carried out. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of an apparatus for detecting a normal elevation correction point according to the present invention.

As shown in FIG. 2, the apparatus for detecting a normal elevation correction point according to the present invention includes a node generation unit 21, a search area setting unit 22, a normal elevation correction point candidate selecting unit 23, and a normal elevation correction. And a point detector 24.

Hereinafter, the node generator 21 will be described in detail with reference to FIG. 3.

As shown in (a), the node generating unit 21 checks the boundary line (A boundary) of the target area (area to detect the elevation correction point). Here, the boundary includes a boundary by an administrative area or a region selected as a project target.

Thereafter, as shown in (b), a first virtual boundary line (B boundary) offset 5 km from the boundary line to the center of the target area is generated, and again from the first virtual boundary line to the center direction of the target area. Create a second virtual boundary line (C boundary) spaced 5 km apart. At this point, the virtual boundary is continuously created as long as it can be created. For example, if the shortest distance from the center point of the target area (the point where two diagonals of a rectangle circumscribe the target area meet) to the boundary line (A boundary) is 24 km, four virtual boundary lines are generated.

Here, the 5km separation distance is the value determined by the regulation to maintain the average 5km distance between the normal elevation correction points recorded in the National Geographic Information Institute Notice No. 2009-593. Can be set to a value.

After that, nodes are created at the boundary line and each virtual boundary line. That is, after defining a random starting point (starting node) on the boundary line and each virtual boundary line, nodes are generated at intervals of 5 km in a clockwise or counterclockwise direction. In this case, the distance between nodes is preferably a straight line distance, but a curved distance is also possible.

In addition, the random starting point defines the starting point of the boundary line (hereafter, the shortest point) where the boundary line meets the center point of the target area (hereinafter, the shortest point), and the line where each virtual boundary line meets the line connecting the center point and the shortest point. It is preferable to select as the starting point of.

Hereinafter, the search region setting unit 22 will be described in detail with reference to FIG. 4.

According to GIS Bulletin 2009-593, it is desirable to find the candidates for normal elevation correction points within a radius of 50m for each node.

To this end, the search region setting unit 22 sets a candidate search region having a radius of 50m around each node as shown in FIG. 4. This makes it possible to comply with the above regulations (up to 5.05 km, spacing of at least 4.95 km).

Hereinafter, the normal elevation correction point candidate selecting unit 23 will be described in detail with reference to FIG. 5.

As shown in (a), the candidate elevation correction point candidate selecting unit 23 is a candidate source having a radius of 2 m (center elevation correction point) at the center of the candidate search region (circle) set by the search region setting unit 22. Candidates) are generated. In this case, the radius of the candidate member is set to 2 m because an error occurring in the plane when the airborne laser scan data is acquired exists because the area that can cover the margin of error (0.3 to 0.6 m) is 2 m.

Then, as shown in (b), the candidate circle is extended along the center line that vertically bisects the circle. That is, 25 candidate members having a diameter of 4m are generated along the center line. At this time, the candidate member may be extended along the center line dividing the circle horizontally, or the candidate member may be extended in the horizontal and vertical directions.

6 is an exemplary view of a typical airborne laser scan image.

As shown in FIG. 6, a general airborne laser scan image is composed of a myriad of points, and each point has a planar coordinate value (x, y) and a height value (z) as shown in Table 1 below. .

Therefore, the airborne laser scan image may be represented by three-dimensional terrain as shown in FIG. 7.

Basically, the terrain condition of the elevation elevation point is as good as flat land without slope as much as possible, and the terrain condition should be satisfied based on a radius of 2m as an area where no step exists. That is, as shown in (c) of FIG. 8, a place marked with a box may be viewed as a suitable terrain. Here, (a) shows an airborne laser scan image of an inclined area, and (b) shows an airborne laser scan image of an area where a step is present.

Hereinafter, the elevation elevation correction point detector 24 will be described in detail with reference to FIGS. 9 to 11.

The normal elevation correction point detection unit 24 does not have a step for the candidate elevation correction point candidates (see FIG. 9) including a plurality of airborne laser scan data (indicated by points in the image) having plane coordinate values and height values. A normal elevation correction point at which the inclination satisfies a predetermined condition is detected.

That is, the normal elevation correction point detection unit 24 is for each candidate member, the difference between the minimum height value and the maximum height value among the airborne laser scan data included in the candidate member exceeds the first threshold (for example, 20cm) If the distance (horizontal distance) between the point having the minimum height value and the point having the maximum height value is less than the second threshold value (for example, 30 cm), it is determined that a step exists in the candidate member.

In addition, the normal elevation correction point detector 24 uses a basic concept of regression analysis to show a best-fitting line that best represents the relationship between two variables on a scatter diagram showing the relationship between the X and Y variables. ) Is calculated using the least-square method, which is a method of obtaining a straight line that minimizes the sum of squares of residuals.

That is, the normal elevation correction point detection unit 24 obtains a straight line having the distance and height from the center point of the candidate as variables for the airborne laser scan data in each candidate source as shown in FIG. The slope of the candidate member is calculated by calculating the slope. This may be expressed as in Equation 1 below.

는 X의 평균,

는 Y의 평균, n은 후보원내 점(에어본 레이저 스캔 데이터)의 수를 각각 의미한다. 아울러 i는 n개 점들의 순차를 나타낸다.Where X is the independent variable, distance from the center of the candidate circle, Y is the dependent variable, height is the intercept, b is the slope,

Is the mean of X,

Is the average of Y, and n is the number of points (airborne laser scan data) in the candidate source, respectively. In addition, i represents a sequence of n points.

Thereafter, the static elevation correction point detector 24 determines whether the calculated slope exceeds the third threshold.

As a result, the stationary height correction point detection unit 24 detects the candidate source having no step and whose slope does not exceed the third threshold as the stationary elevation correction point. This process is performed for all nodes in the target area.

Additionally, as shown in FIG. 11, the normal elevation correction point detection unit 24 has a plurality of normal elevation correction points 110, 120, and 130 that satisfy both the step condition and the slope condition in one candidate source. In addition, distance and inclination from the center point of the candidate search region are provided numerically so that the objective evaluation of the decision can be made.

In addition, when there are a plurality of elevation elevation correction points that satisfy both the step condition and the slope condition at one node, the elevation elevation correction point detection unit 24 detects the candidate source closest to the node as the optimal elevation elevation correction point. You may. In FIG. 11, a candidate member corresponding to '110' is detected as an optimal normal elevation correction point.

Meanwhile, a method for detecting a normal elevation correction point according to the present invention will be described.

First, the node generator 21 generates a first virtual boundary line that is 5 km away from the boundary line of the target area in the direction of the center of the target area, and is further separated from the first virtual boundary line by 5 km in the center direction of the target area. Create a second virtual boundary.

Thereafter, the node generator 21 generates nodes at the boundary line and each virtual boundary line. That is, after defining a random starting point (starting node) on the boundary line and each virtual boundary line, nodes are generated at intervals of 5 km in a clockwise or counterclockwise direction.

Thereafter, the search area setting unit 22 sets a candidate search area having a radius of 50m around each node.

Thereafter, the normal height correction point candidate selecting unit 23 generates a candidate circle (normal height correction point candidate) having a radius of 2 m at the center of the candidate search area (circle) set by the search area setting unit 22, Candidates are extended along a centerline that vertically bisects the candidate search area.

Thereafter, the normal height correction point detection unit 24 performs the difference between the minimum height value and the maximum height value among the points in the candidate circles generated by the normal elevation correction point candidate selection unit 23 while exceeding a first threshold value. A candidate member whose distance between the point having the maximum value and the point having the maximum height value is less than the second threshold and the inclination does not exceed the third threshold is detected as the normal elevation correction point.

In addition, when there are a plurality of fixed elevation correction points detected, the normal elevation correction point detection unit 24 may detect the normal elevation correction point that is closest to the corresponding node as the optimum elevation correction point.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

21: node generation unit 22: search area setting unit
23: candidate height correction point candidate selection unit 24: normal elevation correction point detection unit

Claims (2)

An apparatus for detecting an elevation elevation point in a target area to detect an elevation elevation point in an aerial laser scan image including a plurality of points consisting of plane coordinate values and three-dimensional coordinate values having a height value,
Generating at least one virtual boundary line having the same shape as the boundary line of the target area and having different magnifications in the target area, and on the boundary line and the virtual boundary line, the shortest distance between a predetermined center point set in the target area and the boundary line; A node generator configured to set a plurality of nodes at a constant straight line or a curved interval with a point of the boundary line and the virtual boundary line which meet the line extending by connecting the shortest point on the boundary line with the center point;
A search area setting unit connected to the node generation unit and configured to set a plurality of elevation elevation candidate search areas having a circle shape having a predetermined first radius around each of the plurality of nodes generated by the node generation unit;
An elevation elevation point candidate selection unit connected to the search area setting unit and configured to set one or more circular candidates having a predetermined second radius on a center line that vertically bisects the plurality of elevation elevation candidate search areas into semicircles. ; And
Regarding a plurality of points connected to the normal elevation correction point candidate selecting unit and having a three-dimensional coordinate value constituting the aerial laser scan image respectively belonging to the one or more candidate sources generated by the normal elevation correction point candidate selecting unit, Iii) the difference between the minimum height value and the maximum height value exceeds the first threshold, ii) the horizontal distance between the point having the minimum height value and the point having the maximum height value is less than the second threshold value, and iii) the candidate Candidate circle to which points satisfying three conditions that the slope of the candidate circle obtained through Equation A does not exceed the third threshold are calculated from the slope of the straight line obtained by using the distance and the height from the center point of the circle as parameters. A normal elevation correction point detection unit for detecting a as an elevation elevation correction point,
[Equation A] is

,
In Equation A, X is an independent variable, and the distance between the planar coordinate values from the center point in the candidate circle, Y is the dependent variable, the height value among the three-dimensional coordinate values, and a is the intercept of the straight line. b is the slope of the straight line,

Is the mean of X , and

Is the average of the Y , n is the number of the plurality of points belonging to each of the plurality of candidate members, i represents the order as the n- th point,
And the peak elevation correction point detection unit detects, as an optimum peak elevation correction point, the closest distance from the corresponding node among the peak elevation correction points being 2 or more as an optimum peak elevation correction point. delete

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