KR102523092B1 - Method for decisioning line of sight on 3d map - Google Patents

Abstract

The present invention relates to a method for determining a line of sight in a 3D map, comprising the steps of forming a bounding box; performing a test whether the test point of the bounding box is located inside the triangular plane; Acquiring DTED (Digital Terrain Elevation Data) height point information corresponding to the test point when the test point is inside the triangular plane; calculating a distance reference value from the DTED height point to a line-of-sight triangle plane; and determining that the line of sight is blocked when the maximum value of the distance reference value is greater than 0.

Description

Method and system for determining line of sight in 3D map {METHOD FOR DECISIONING LINE OF SIGHT ON 3D MAP}

The present invention relates to a method and system for determining a line of sight in a 3D map, and more particularly, to a new method and system for determining a line of sight reflecting 3D DTEC for modeling an electromagnetic warfare propagation environment.

Since radar, which detects objects using the electromagnetic spectrum, has appeared on the battlefield, information obtained through detection and reconnaissance of radar-equipped aircraft can give allies an advantage in war. The importance of gathering information through the electromagnetic (EM) spectrum is increasing day by day. Along with this, technologies that can thwart adversary attempts to gather information across the electromagnetic spectrum are also becoming increasingly important. The above two types of technologies of information collection and information collection obstruction are continuously evolving with each other through mutual competition.

Modeling and simulation (M&S) technology can provide an experimental environment in virtual space that can predict and confirm situations that are difficult or impossible to reproduce in reality. Modeling and simulation techniques can be particularly useful in the defense sector where evaluation of systems can be risky and costly. One such example could be the modeling of an electronic warfare (EW) environment that may contain continent-sized fields, harmful electromagnetic radiation, and the like. Therefore, significant efforts are underway to develop electronic warfare simulators to incorporate the advantages of modeling and simulation.

Accurate environmental modeling and rapid calculations may be required for the modeling and simulation techniques to be useful. Therefore, the problem of reducing the calculation time can be one of the important problems in electronic warfare simulation.

A technical problem to be solved by the present invention is to provide a method and system for determining a line of sight in a 3D map that can have a faster calculation algorithm than in an electronic warfare environment.

A method for determining a line of sight in a 3D map according to an embodiment of the present invention includes forming a bounding box; performing a test whether the test point of the bounding box is located inside the triangular plane; Acquiring DTED (Digital Terrain Elevation Data) height point information corresponding to the test point when the test point is inside the triangular plane; calculating a distance reference value from the DTED height point to a line-of-sight triangle plane; and determining that the line of sight is blocked when the maximum value of the distance reference value is greater than 0.

In the line-of-sight determination method in a 3D map according to an embodiment of the present invention, the step of testing whether the test point of the bounding box is located inside the triangular plane is the triangle vertex with the test point as the origin. Checking the sign of; calculating a sign change range of the vertex of the triangle; and determining that the test point is inside the triangle according to the sign change range.

In the method for determining the line of sight in a 3D map according to an embodiment of the present invention, in the step of determining that the test point is inside the triangle according to the sign change range, if the sign change range exceeds 2, calculating a cross product of vectors from the test point to the vertex; The method may include determining that the test point is inside the triangle when the cross product value of the vector is a positive number.

In the method for determining the line of sight in a 3D map according to an embodiment of the present invention, the sign change range is a value obtained by summing the sign changes when moving the vertices of the triangle, and the sign change value is a value obtained by moving in the same quadrant. It can be 0 when moving to an adjacent quadrant, 1 when moving to an adjacent quadrant, or 2 when moving to a diagonal quadrant.

In the method for determining the line of sight in a 3D map according to an embodiment of the present invention, the three vertexes of the triangular plane may be a jammer point in a 3D space and two virtual points near an object reflecting DTED information.

In the method for determining the line of sight in a 3D map according to an embodiment of the present invention, the two virtual points may be generated at a predetermined distance δ from an object in a direction perpendicular to a line of sight path.

In the method for determining a line of sight in a 3D map according to an embodiment of the present invention, the DTED (Digital Terrain Elevation Data) height point information may be standard digital data representing an altitude above sea level.

In the method for determining the line of sight in a 3D map according to an embodiment of the present invention, when the test point is inside the triangular plane, the height of the test point from the sea level is determined by Equation 1 below,

[Equation 1]

과

는 가시선 결정 삼각형 내의 포인트일 수 있다.here,

class

may be a point within the line-of-sight determination triangle.

In the line-of-sight determination method in a 3D map according to an embodiment of the present invention, when the test point is inside the triangular plane, the distance reference value between the test point and the triangular plane is determined by Equation 2 below,

[Equation 2]

는 DTED에서 (

,

)에 해당하는 고도 데이터일 수 있다.here

in DTED (

,

) may be altitude data corresponding to

According to one embodiment of the present invention, a computer program stored in a medium is included to execute the method of any one of claims 1 to 9 using a computer device.

An apparatus for determining a line of sight in a 3D map according to an embodiment of the present invention includes a memory for storing DTED data, UTM coordinates, triangle plane data, and sign change values; and forming a bounding box for the triangular plane data, performing a test whether a test point of the bounding box is located inside the triangular plane, and if the test point is inside the triangular plane, the test point is located inside the triangular plane. DTED (Digital Terrain Elevation Data) height point information corresponding to the point is acquired, a distance reference value from the DTED height point to the visible line triangular plane is calculated, and if the maximum value of the distance reference value is less than 0, it is determined as a visible line, and the and at least one processor determining that the line of sight is blocked when the maximum value of the distance reference value is greater than zero.

The present invention provides a line-of-sight determination method that can have a fast calculation algorithm in performing real-time simulation so that appropriate and accurate judgment can be made even in a changing environment. It is possible to perform a line-of-sight judgment for an area.

The technical effects of the present invention are not limited to those mentioned above, and other technical effects not mentioned will be clearly understood by those skilled in the art from the description below.

1 is a view showing how an aircraft equipped with a jammer emits a jamming signal toward an enemy object in an electronic warfare scenario.
2 is a view showing an example of a grid-post terrain format of DTED according to an embodiment of the present invention.
3 is a table showing data information according to each level in DTED.
Figure 4 (a) is a diagram showing the appearance of the Korean Peninsula in the UTM coordinate system. 4(b) is a diagram showing an elevation representation using DTED level 0.
5 is a diagram illustrating a decision triangle and a bounding box for determining a line of sight according to an embodiment of the present invention.
6 is a diagram showing six cases for determining test points.
7 is a flow chart for an algorithm according to one embodiment of the present invention.
8 is a table showing randomly selected positions of jammers and objects for comparison with the prior art.
9 is a table showing the time taken for calculation when calculated by sign counting and conventional interpolation methods.

While the present invention is susceptible to various modifications and variations, specific embodiments thereof are shown by way of illustration in the drawings and will be described in detail below. However, it is not intended to limit the present invention to the particular form disclosed, but rather the present invention includes all modifications, equivalents and substitutions consistent with the spirit of the present invention as defined by the claims.

It will be appreciated that when an element such as a layer, region or substrate is referred to as being “on” another element, it may be directly on the other element or intervening elements may exist. .

Although the terms first, second, etc. may be used to describe various elements, components, regions, layers and/or regions, these elements, components, regions, layers and/or regions It will be understood that one should not be limited by these terms.

Terms such as "part", "element", "means", and "component" may be used broadly, and the components of the present invention are not limited to mechanical and physical components. The term may include a meaning of a series of software routines in association with a processor or the like.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in more detail. Hereinafter, the same reference numerals are used for the same components in the drawings, and redundant descriptions of the same components are omitted.

1 shows a state in which an aircraft equipped with a jammer emits a jamming signal toward an enemy object in an electronic warfare scenario.

Referring to FIG. 1 , the strength and delay of a jamming signal can be easily calculated in a line-of-sight path. However, complex physical phenomena such as diffraction and reflection may occur if the interfering signal is blocked by an obstacle such as a mountain. NLOS (Non Line of Sight) calculation is performed in a separate subroutine, and the depth and complexity of modeling can be determined according to the modeling purpose. Therefore, in an electronic warfare scenario, the priority part to check may be to determine whether an obstacle exists in the line-of-sight path of the jamming signal.

Actual three-dimensional terrain data may be required to determine whether a signal is on the line-of-sight path. All line-of-sight decision algorithms can make decisions based on specific terrain data. According to an embodiment of the present invention, a line of sight may be determined based on Digital Terrain Elevation Data (DTED) terrain data.

DTED can use a grid-post terrain data format.

2 is a view showing an example of a grid-post terrain format of DTED according to an embodiment of the present invention.

As shown in FIG. 2 , each 2D coordinate plane may have height information corresponding to a grid. DTED data may be standard digital data representing altitude above sea level.

The data set can be used in many military system applications that require terrain elevation information. In DTED, a specified level may exist according to resolution. Levels can be divided into levels 0, 1, and 2, and the higher the number, the higher the resolution. Horizontal and vertical resolutions can be about 900 meters, 90 meters and 30 meters at levels 0, 1 and 2, respectively. In addition, higher-resolution data may be used in High-Resolution Terrain Information (HRTI) data, and the HRTI data may be designated as levels 3 to 5 in FIG. 3 .

3 is a table showing data information according to each level in DTED. Referring to FIG. 3 , the resolution of level 3 may be up to 10 meters, the resolution of level 4 up to 3 meters, and the resolution of level 5 up to 1 meter.

Algorithms according to embodiments of the present invention may be applicable to all grid-post terrain types, and high-level data sets may be required to obtain accurate results. However, in most cases, these data are not available to the public because they contain data critical to national security. Therefore, an algorithm according to an embodiment of the present invention, which will be described later, can be confirmed using actual terrain information obtained at level 0 that can be checked in the global step.

Figure 4 (a) is a diagram showing the appearance of the Korean Peninsula in the UTM coordinate system. 4(b) is a diagram showing an elevation representation using DTED level 0. Where Latitude is latitude, Longitude is longitude, and Elevation is altitude.

An intuitive way to determine if a signal path is a line-of-sight might be to connect the jammer and the object to form a line and check the DTED data to see if there are higher points along the line created. As shown in FIG. 2 , the grid-post terrain data may store only height information of intersections with a desired resolution. Thus, the line connecting the jammer and the object may not pass through the grid replacement points.

In this case, line-of-sight determination may be performed using point reconstruction techniques that generate new points using nearest point, interpolation techniques such as bilinear or bilinear interpolation.

Although this method is intuitive, it may not be suitable for application to radar signals with beam widths because it only calculates straight-line signal paths. Also, if the resolution is high, calculating the path can take a significant amount of time.

For example, regions 51T, 52T, 51S, and 52S in the UTM coordinate system of FIG. 4(a) may be represented by 961 data points between 124 and 132 degrees and 1921 data points between latitudes 31 and 47 degrees. Even in the lowest resolution DTED level 0 data set, a total of 1,846,081 data points may need to be processed for each jammer-object line-of-sight determination. Therefore, an algorithm that can immediately process about 2 million data points may be needed to compute a real-time simulation.

Thus, for a given jammer-object location, it is not necessary to use all points in the data set. To reduce the number of points available for line-of-sight determination, a triangular plane containing the line-of-sight path can be formed. If one of the data points within the triangular area is higher than the triangular plane, the jammer-to-object path may be considered non-line-of-sight (NLOS).

5 is a diagram illustrating a decision triangle and a bounding box for determining a line of sight according to an embodiment of the present invention.

Referring to FIG. 5 , the three vertexes of the triangular plane may be a jammer point in a 3D space and two virtual points near an object reflecting DTED information. The two points may be created at a preset distance δ from the object in a direction perpendicular to the line-of-sight path.

The preset distance δ may be set in consideration of the beam width of the jammer antenna. The equation of the plane including the triangle can be expressed as Equation 1 below.

[Equation 1]

)에 대해, 수학식 1의 4개의 계수는 하기 수학식 2에 의해 결정될 수 있다.three points (

), the four coefficients of Equation 1 can be determined by Equation 2 below.

[Equation 2]

Three vertices can give a bounding box whose sides are parallel to the UTM axes. Points outside this bounding box may be excluded from the line-of-sight determination calculation. Points may be determined to be within a bounding box if the points are within a triangular region, referred to as the line of sight decision triangle. To determine if points are within a triangle, a sign counting method described below may be used.

6 is a diagram showing six cases for determining test points.

Referring to the code counting method with reference to FIG. 6, it is first assumed that a point is within a bounding box. At this time, the point may be temporarily set as the origin. Four quadrants may be defined based on the origin. In this case, each quadrant may be provided with two code pairs as shown in FIG. 6 . The positions of the three vertices can be determined in a four-quadrant space. It is possible to calculate the sign change starting from one of the three vertices and moving to the second vertex. The sign change may be calculated while moving from the second vertex to the third vertex and from the third vertex to the first vertex. The change range of the sign can be from 0 to 2.

At this time, when the sign changes in a quadrant, the sign change range can be 0 when moving within the same quadrant, 1 when moving to an adjacent quadrant, and 2 when moving to a diagonal quadrant. For a hypothesized point to be included within the bounding box, at least two sign changes may be required. Cases in which the hypothesized point is included in the bounding box are shown in (c) to (f) of FIG. 6 . When the sign change range is 0, 1, or 2, as shown in (a) and (b) of FIG. 6 , the point is disposed outside the bounding box and thus can be excluded from the line-of-sight determination calculation.

If the sign change range exceeds 2, the cross product of the vectors from the test point to the vertex can be calculated. In this case, when the cross product value of the vector is a positive number, the test point may be determined to be within the triangle.

If the point is determined to be within the triangle, the height of the point at sea level can be determined by Equation 3 below.

[Equation 3]

과

는 가시선 결정 삼각형 내의 포인트 들이 될 수 있다. 삼각형 평면으로부터의 거리 참조값은 하기 수학식 4에서 구할 수 있다.here,

class

can be points in the line-of-sight decision triangle. A distance reference value from the triangular plane can be obtained from Equation 4 below.

[Equation 4]

는 DTED에서 (

,

)에 해당하는 고도 데이터가 될 수 있다.here

in DTED (

,

) may be altitude data corresponding to

If this distance reference value D is a positive number, the line of sight can be obstructed. This can be repeated for every point in the triangular plane. If the max(D(x, y)) of all points is less than 0 then the path is a line of sight. The x, y points that produce the maximum value max(D(x,y)) can be the most cut-off points that create the invisible line.
Any planar expression can be expressed as (ax + by + cz + d = 0). Therefore, the values of a, b, c, and d can be determined using the coordinates of the three vertices ((x1, y1, z1), (x2, y2, z2), (x3, y3, z3)) that define the line-of-sight triangle plane. there is. That is, the variables a, b, c, and d can be seen as coefficients for x, y, and z in the plane equation defining the line-of-sight triangular plane. The distance reference value (D) is the formula defined above from the plane and the test point (x _in , y _in , z _in ), and the absolute value of the distance reference value (D) can be a positive distance value between the plane and the point there is.
Since the line of sight triangular plane is a plane, the entire three-dimensional space can be divided into two. Therefore, the sign of the distance reference value D may be determined depending on where the test point is located in the two spaces separated by the triangular plane of the line of sight. In this embodiment, if the test point is positive, the test point is above the visible triangle plane, and if the test point is negative, the test point is below the visible triangle plane.

By applying the above-described code counting algorithm and comparing DTED data only in the extracted region to determine whether the line of sight exists, the line of sight can be determined much faster than comparing the entire region. An algorithm for determining a line of sight according to an embodiment of the present invention is summarized in FIG. 7 . 7 is a flow chart for an algorithm according to one embodiment of the present invention.

Referring to FIG. 7 , a method for determining a line of sight in a 3D map according to an embodiment of the present invention includes forming a bounding box (S100), and testing whether a point of the bounding box is located inside a triangular plane. Step of performing (S200), step of acquiring DTED height information corresponding to the confirmed interior point (S300), step of calculating a distance reference value from the DTED height point to the line of sight triangular plane (S400), maximum of the distance reference value If the value is less than 0, it is determined as a line of sight, and if the maximum value of the distance reference value is greater than 0, it is determined that the line of sight is blocked (S500).

At this time, the step of performing a test on whether the point of the bounding box is located inside the triangle plane (S200) is the step of checking the sign of the triangle vertex from the origin of the test point (S210), according to the movement of the triangle vertex Calculating the sign change range (S220), if the sign change range exceeds 2, calculating the cross product of the vector from the test point to the vertex (S230), and if the cross product value of the vector is positive, the test point is a triangle It may include a step (S240) determined to be within.

As in the embodiment of the present invention, when the sign counting method is applied to the DTED level 0 data set in the 51T, 52T, 51S, and 52S regions in the UTM coordinate system, it can be compared with the conventional interpolation method calculated directly. 8 is a table showing randomly selected positions of jammers and objects for comparison with the prior art.

The positions of jammers and objects were converted to UTM-k coordinates. The UTM-k coordinates are similar to the existing UTM coordinates, but the false north and false trends are slightly different depending on the curvature of the earth where the Korean peninsula is located. The positions of the randomly secured jammers and objects are positions where the line of sight is not secured.

9 is a table showing the time taken for calculation when calculated by sign counting and conventional interpolation methods.

Referring to FIG. 9 , line-of-sight determination was performed according to an algorithm according to the present embodiment, and positions of points obstructing line-of-sight were calculated. The position calculation was calculated through a total of 10 simulations, and FIG. 9 discloses the time and average time taken during the 10 simulations.

As shown in FIG. 9 , through the algorithm according to the present embodiment, the line of sight can be accurately determined with an average of 0.026 seconds for 1.8 million data, which is about 1.5 times more efficient than the prior art interpolation method. Since the calculation method using the algorithm according to the present embodiment vectorizes and calculates given data, even if the data increases, time may not increase linearly by a multiple of the data. Therefore, in an electronic warfare situation, it is possible to determine line-of-sight in real time even with higher levels of DTED.

In order to make a specific decision by simulating the electronic warfare environment, real-time simulation may be performed so that an appropriate and accurate decision can be made even in a changing environment. Therefore, terrain data and object modeling may be reflected for accurate determination, and a fast calculation algorithm as in the present embodiment may be required for real-time simulation.

According to this embodiment, it is possible to have an algorithm capable of calculating within 0.03 seconds for about 2 million data sets in an electronic warfare environment in which DTED is reflected. The terrain data used for algorithm verification is a UTM coordinate system data set covering the entire Korean peninsula, and can show 50% improved efficiency compared to the existing interpolation method. The algorithm according to the present embodiment may have an advantage in that it is faster than other techniques because it tests points included in the line-of-sight triangle area to determine only sign or bit unit operations.

When the line-of-sight determination technique according to the present embodiment is used, it is possible to determine the line-of-sight of a desired area in real time for a situation in which an aircraft equipped with a radar moves in a specific scenario. Using this sign counting method, a path from a jammer to an object can be accurately identified, and a loss factor and jammer to signal ratio (J/S) can be calculated based on the method.

In the above, the configuration and characteristics of the present invention have been described based on the embodiments according to the present invention, but the present invention is not limited thereto. Various changes or modifications can be made by those skilled in the art within the spirit and scope of the present invention, and thus such changes or modifications fall within the scope of the appended claims.

Claims (11)

forming a bounding box;
performing a test as to whether the test point of the bounding box is located inside the visible triangular plane;
acquiring DTED (Digital Terrain Elevation Data) height point information corresponding to the test point when the test point is inside the line of sight triangular plane;
calculating a distance reference value from the DTED height point to a line-of-sight triangle plane; and
and determining that the line of sight is blocked when the maximum value of the distance reference value is greater than 0. According to claim 1,
The step of testing whether the test point of the bounding box is located inside the visible triangle plane,
Checking the sign of the triangle vertex with the test point as the origin;
calculating a sign change range of the vertex of the triangle; and
and determining that the test point is inside the triangle according to the sign change range. According to claim 2,
The step of determining that the test point is inside the triangle according to the sign change range,
calculating a cross product of vectors from the test point to a vertex when the sign change range exceeds 2;
and determining that the test point is inside the triangle when the extrinsic value of the vector is a positive number. According to claim 3,
The sign change range is a sum of sign changes when moving the vertices of the triangle,
The sign change value is 0 when moving in the same quadrant, 1 when moving in an adjacent quadrant, and 2 when moving in a diagonal quadrant. According to claim 1,
The method of determining the line of sight in a 3D map, wherein the three vertices of the line of sight triangular plane are a jammer point in a 3D space and two virtual points near an object reflecting DTED information. According to claim 5,
The method of determining the line of sight in a 3D map in which the two virtual points are generated at a preset distance (δ) from an object in a direction perpendicular to a line of sight path. According to claim 1,
The DTED (Digital Terrain Elevation Data) height point information is a method of determining a line of sight in a 3D map, which is standard digital data representing an altitude above sea level. According to claim 1,
When the test point is inside the line of sight triangular plane, the height of the test point from the sea level is determined by Equation 1 below,
[Equation 1]

here,

class

A method for determining the line of sight in a 3D map where is a point in the line of sight triangular plane.
According to claim 1,
When the test point is inside the line of sight triangle plane, the distance between the test point and the line of sight triangle plane is determined by Equation 2 below,
[Equation 2]

here

in DTED (

,

), a method for determining the line of sight in a 3D map, which is the altitude data corresponding to A computer program stored in a medium to execute the method of any one of claims 1 to 9 using a computer device. memory for storing DTED data, UTM coordinates, visible triangle plane data, and sign change values; and
forming a bounding box for the line of sight triangle plane data;
Perform a test whether the test point of the bounding box is located inside the line of sight triangular plane;
When the test point is inside the line of sight triangular plane, obtain DTED (Digital Terrain Elevation Data) height point information corresponding to the test point,
Calculate a distance reference value from the DTED height point to the line of sight triangular plane;
and at least one processor determining that the line of sight is blocked if the maximum value of the distance reference value is less than 0 and determining that the line of sight is blocked if the maximum value of the distance reference value is greater than 0.

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