JP4851212B2 - Radar reflection prediction map creation method - Google Patents

Description

  The present invention relates to a method of creating a radar reflection prediction map when radar is irradiated from an aircraft or the like, and more particularly to a method of continuously performing radar reflection prediction marking quantitatively on a two-dimensional map by a computer.

  When creating a flight plan for an aircraft or the like, an operation for creating a reflection prediction map based on topography when radar is irradiated from an airplane occurs. As a method for creating a radar coverage diagram when the radar irradiation source is fixed, there is a technique disclosed in Patent Document 1 below. Further, as a method for switching and displaying a radar range drawing from a radar mounted on an aircraft in time series, there is a technique disclosed in Patent Document 2 below.

However, there has been no appropriate technique for representing a reflection prediction map from a moving radar mounted on an aircraft or the like as a display having no time information such as a paper map.
The actual situation will be described below.
When creating a flight plan for an aircraft equipped with a mapping radar or the like, the reflection prediction of the radar wave with respect to the topography is often handwritten on a paper map such as an aerial chart. In this case, it has been difficult to set a clear writing method from information that can be read from a paper map. Therefore, since the radar reflection prediction marking is performed sensorily or empirically for each flight plan creator, it is impossible to create a quantitative prediction map.

  FIG. 13 is an example of a radar reflection prediction diagram written by hand. In FIG. 13, the aircraft is assumed to fly along the center dotted line from the left side to the right side of the figure. It can be seen from the contour lines on the map that there are two mountains on the flight path. Therefore, the pilot has marked the higher elevation on the front side of the hillside to match his sense based on his experience so that it is darker and more individual. It requires experience and skill.

  Therefore, we created a reflection prediction map on flight plan creation software using a computer such as a personal computer (PC), printed out a composite of the quantified reflection prediction on a digital map, and used it as a flight plan map. The need to use has arisen.

  However, in order to express the radar reflection by software, it is common to execute a real-time simulation. This is a method of displaying an image displayed on a display in a cockpit by simulating by a simulation.

  In a general method, the display is rewritten according to the update rate of the radar signal, and the beam scanning pattern is performed in a three-dimensional space. Returning to the 3D scanning pattern from all sides, and the reflection of each mesh area changes with the movement of the aircraft and the reflection intensity changes, so that most meshes are finally marked. It will be filled. As a result, the markings required as a flight plan cannot be identified on the map.

Problems in the above general method will be described in more detail with reference to FIGS.
FIG. 14 shows the level of radar reflection at the point B on the ground surface directly below the flight line when the flight position of the aircraft changes to positions A ₁ , A ₂ , and A _3. These are shown in three partial views (a) to (c) consisting of a right view and a right view. A rectangular area surrounded by a dotted line in the figure viewed from the vertical direction is an area displayed on the display device by a normal shadow display method, and the flight position of the aircraft changes to position A ₁ , position A ₂ , and position A ₃ . As a result, the aircraft moves in the traveling direction.

In FIG. 14 (a), the aircraft is at a position A _1, the distance 4 is large and the point B, and from a view from the horizontal direction, shallower reflections in exemplified, radar reflection point B are most shaded The concentration is low. In FIG. 14 (b), the aircraft is at a position A _2, the distance 3 between the point B is next to the distance 4, shading concentration of radar reflection point B has become darker. In FIG. 14 (c), the aircraft is in position A _3, the distance between the point B 2 is almost vertical also reflected short, shading concentration of radar reflection point B has become darkest.

  As described above, when the radar irradiation source moves in the case of normal radar echo display, as shown in FIGS. 14 (a) to (c), the reach distance and reflection of the beam to the ground surface in accordance with the movement. Corresponding to the conditions, the intensity of reflection from the ground surface occurs.

  Therefore, the shadow density simulating the radar reflection at each point in the display area always changes as the radar irradiation source moves. Usually, the change of the shadow is displayed on a display device or the like in real time.

  When radar reflection is marked on a paper map (the same applies to a digital map) by a normal general method, as described above, an image in which the radar irradiation area continuously moves on the map is obtained. Depending on the position of the aircraft, even at the same point on the map, the density of reflection shadows will vary. In order to display this on the map, the change of the shadow accompanying the movement of the aircraft is overlaid on the point on the map until the irradiation area passes that point. It is expressed by the shadow density at the time.

  FIG. 15 is a diagram for explaining a radar reflection marking method according to the normal general method. Fig.15 (a) is the figure which overlap | superposed the figure which looked at the ground surface of the left side of FIG.14 (a)-(c) from the horizontal direction, FIG.15 (b) is FIG.14 (a)-(c ) Is a diagram obtained by superimposing the diagrams of the right-side surface as viewed from the vertical direction.

The shadow density at the point B is obtained by superimposing radar reflections when the aircraft is at the position A ₁ , the position A ₂ , and the position A ₃ , and the shadow is determined with a density according to the strongest echo.
Since the same can be said for other points, as shown in FIG. 15 (c), most of the points in the area displaying the shadow on the map are filled with the density when a strong echo is returned. It will end up.

Therefore, with this method, the radar reflection cannot be continuously expressed on the map with a contrast that is easy to recognize.
Japanese Patent Laid-Open No. 4-21186 JP 2002-23619 A

  The present invention avoids this filling problem that occurs when a radar reflection prediction map is quantitatively generated using a computer, and displays a reflection prediction map from a moving radar as a display having no time information. The object is to provide a method for proper representation.

  That is, the present invention is an empirical marking method for processing in a human head, marking a radar reflection on a specified area on a two-dimensional map without being painted, taking into account continuous time passage. Is realized by a program, and the radar reflection prediction is expressed quantitatively.

According to the present invention, in a radar reflection prediction map creation method for predicting the strength of reflection from the ground surface when a radar is irradiated to the ground surface from a flying aircraft by a computer, the calculation control unit of the computer Reads out map data to be marked from a map database storing map data, and sets various meshes on the map from the radar specifications, the irradiation direction, and the flight plan of the airplane input by the input device. Based on the original, a process for determining only one radar irradiation beam and a process for marking each mesh based on the determined irradiation beam are performed. Direction determined by the sum of the irradiation angle of the radar and a predetermined angle within the vertical scanning line width which is the vertical scanning range of the radar A process in which a virtual fan-shaped irradiation beam is used, and the arithmetic control unit determines a mesh range for marking on the map and calculates a marking altitude threshold based on the flight altitude of the aircraft and the irradiation distance of the radar In the process of performing the marking, the arithmetic control unit performs marking on a mesh having an altitude equal to or higher than the marking altitude threshold, and the arithmetic control unit applies to the mesh having an altitude equal to or higher than the marking altitude threshold. A process for obtaining a distance between the virtual position of the aircraft that irradiates the irradiation beam of the single radar determined and the mesh, and a process for setting the luminance in the scanning line distance direction of the mesh based on the distance. And a process for obtaining a virtual position of the aircraft, and a position vector from the obtained position to the mesh A process of calculating an angle formed by the normal vector of the mesh, a process of setting a luminance with respect to the reflectance of the radar wave on the mesh based on the angle, a luminance in the scanning line distance direction, and a reflection of the radar wave A radar reflection prediction map creation method is provided, which performs a process of marking with the coloring of the mesh based on luminance with respect to a rate .

  The amount of radar reflection on a mesh on a map always changes with the movement of the aircraft because the radar emits a three-dimensional scan line, but the radar reflection prediction map creation method of the present invention uses a three-dimensional scan line. By pseudo-converting into a two-dimensional sector, even if the aircraft moves, the reflected beam (radar wave) of each mesh is limited to one. Thereby, a fixed value is given to the amount of reflection for each mesh.

  Therefore, the radar reflection prediction map creating method of the present invention is characterized in that the radar reflection amount for each terrain mesh is obtained as a fixed value. Also, the present invention is characterized in that it is configured to include a method for matching the shape of the reflection marking thus obtained and the shadow with the image assumed by the creator.

  Further, according to the present invention, the virtual position of the aircraft assigned to each mesh is calculated according to the scanning line condition defined by converting into a two-dimensional sector, and the scanning line length from the mesh is obtained. Then, the marking luminance with respect to the scanning line distance direction is determined by comparing the set longest scanning line length with the scanning line length from the mesh. Further, the vector direction of the beam is obtained from the calculated virtual position of the aircraft, and the brightness is set by making the angle formed with the normal vector of the mesh correspond to the reflectance. By setting these two luminances to overlap each mesh and changing the minimum threshold value and the minimum marking height for each luminance, it is possible to obtain a diagram assumed by the reflection prediction creator. Furthermore, it is possible to obtain a quantitative output by setting the optimum setting as the drawing reference value.

  In the present invention, only one radar irradiation beam is determined for each mesh on the map to be marked, and each mesh is marked based on the irradiation beam, so that radar reflection prediction of the target region is programmed. The problem of filling does not occur even if determined and displayed by. Thereby, it is possible to appropriately perform quantitative reflection prediction marking without individual differences. In addition, the reflection prediction marking is automatically determined by the program with only the initial settings, so there is no restriction due to the complexity of the terrain, and the drawing work time is greatly reduced. It is.

  Further, by fixing the reflected beam of each mesh, the beam irradiation angle to the mesh is limited, and it is possible to easily calculate whether or not the reflected beam reaches the virtual position of the aircraft (line of sight).

FIG. 1 is a diagram for explaining a processing flow of radar reflection prediction (REP: Radar Echo Prediction) according to the present invention.
First, in the first step S10, specifications set from radar specifications, irradiation direction, and flight plan are input.

  Next, in step S11, the display area width on the map to be marked is determined. As will be described in detail later, a virtual two-dimensional fan-shaped surface (virtual fan-shaped surface) of the radar scan line is set based on the input specifications and the flight line of the aircraft according to the flight plan, and the surface at an altitude of 0 meters above sea level To determine.

  Next, in step S12, a marking altitude threshold is calculated from the radar irradiation distance and the virtual fan-shaped surface. A mesh with an altitude that is below the marking altitude threshold need not be subject to the following calculations.

  The above processing from step S10 to step S12 is the initial setting processing based on the area on the two-dimensional map to be marked and the flight plan, and designates the target mesh on the map in the following processing. is there. Accordingly, the following steps S13 to S16 are repeatedly executed for each mesh designated by the initial setting.

In step S13, the luminance is set for the scanning line distance direction, and in step S14, the luminance is set for the reflectance of the radar wave.
Next, a line-of-sight calculation is performed in step S15 to obtain a portion that is a shadow of the radar wave.
Finally, in step S16, the mesh is colored based on the luminance obtained in steps S13 and S14, except for the mesh that was found to be a shadow in step S15.

  By repeating the processes from step S13 to step S16 for the mesh on the map to be marked, a quantitative radar reflection prediction map can be created by the computer.

Hereinafter, each step will be described in detail.
First, in step S10, as input setting specifications, radar irradiation distance: R, which is the maximum practical reach distance of the radar, horizontal scanning line width: Ψ, which is the horizontal scanning angle of the radar, and radar vertical direction. A vertical scanning line width that is a scanning angle: θ _V , a radar irradiation angle: θ, and an aircraft flight altitude: h are input. These input specifications are stored in a storage means such as a work area or a register, read out in subsequent processing, and used for calculation or the like.

Next, the determination of the display area width in step S11 will be described with reference to FIGS.
FIG. 2 is a diagram showing a display area in which radar reflection prediction is performed and marking is to be performed. A region surrounded by a rectangular dotted line in the figure is a display region. By line of flight of the aircraft derived from the flight plan information to select the display area for marking so as to pass through the center of the display area as a radar reflector prediction area designation line map, to determine the display area width R _W, Map The mesh to be marked among the upper meshes is first selected.

For this purpose, a radar reflection prediction area designation line (flight line) is input on the map based on the flight plan.
Next, a virtual two-dimensional fan-shaped surface is set by radar scanning lines.
FIG. 3 is a diagram for explaining the virtual sector surface and the display area width. As mentioned earlier, R represents radar irradiation distance was set at step S10, theta, is theta _V is likewise set irradiation angle and vertical scanning line width of the radar, respectively. 3A and 3B are views seen from the horizontal direction. FIG. 3A shows the case where the radar irradiation direction is upward from the horizontal plane, and FIG. 3B is the case where the radar irradiation direction is downward from the horizontal plane. When the angle in the clockwise direction with respect to the horizontal direction is positive, θ + θ _V / 2 ≦ 0 ° and θ + θ _V / 2> 0 °, respectively.
A plane in the direction of θ + θ _V / 2 indicated by a thick line in FIGS. 3A and 3B is set as a virtual sector surface of the radar scanning line. Then, the reflection prediction is performed using only the reflection of the radar scanning line in the virtual fan-shaped plane.

In the above description, the direction of the virtual fan-shaped surface is the direction of θ + θ _V / 2, that is, the lowermost surface of the surface formed by the actual radar scanning line, but this surface is closest to the ground surface. This is because appropriate marking can be performed as a warning when the flight altitude is lowered during flight, and the reflection from the lowermost surface is strong even in actual radar reflection. However, if the range of the vertical scan line width, it is also possible to employ any angle of the surface, even in this case, by setting the angle as theta _V, the following calculation is quite similar.

Next, determination of the display area width by the set virtual fan-shaped surface will be described.
FIG.3 (c) is the figure which looked at the virtual sector surface from the perpendicular direction. In the figure, Ψ is the horizontal scanning line width set in step S10. R _W0 is the maximum value of the display area width _{R W,} equal to R · sin (Ψ / 2) . R _Wshita is described in more detail below, a display area width R _W when the irradiation beam of the radar has reached advanced 0 meters below sea level.

Figure 3 In the case of (a), i.e. when the virtual sector faces upward from a horizontal plane, display area width R _W assumes the maximum value _{R W0 = R · sin (Ψ} / 2).
In the case of FIG. 3 (b), that is, when the virtual fan-shaped surface is downward from the horizontal plane, and when the flight altitude of the aircraft is high and the radar irradiation distance R does not reach the sea level altitude 0, the case of FIG. Similarly, the display area width _{R W} is assumed as the maximum value _{R W0 = R · sin (Ψ} / 2).

As illustrated in FIG. 3 (b), the aircraft is in flight altitude h, or the virtual sector surface is dive into the ground, the irradiation is up Altitude 0, display area width R _W is Limited to _RWθ .

Assuming that the height from the tip of the virtual fan-shaped surface to the altitude h is h_R and θ + θ _V / 2 is expressed as θ _{plus, as} is apparent from FIG. 3C, h_R = R · sin θ _plus . Further, from the similar relationship between the two right triangles on the vertical plane where the hypotenuses coincide and the two right triangles on the virtual fan _plane , the ratio of R _W0 and R _Wθ is equal to the ratio of h_R and h.
Then, the display area width _{R W} is obtained with _{R Wθ = R W0 · h /} h_R = h / h_R · R · sin (Ψ / 2).

4, the irradiation direction of the radar, i.e. one in which the virtual sector surface showing a display area width R _W due to the flight altitude when downward from the horizontal plane. FIG. 4A shows a case where the beam does not reach the altitude 0 line at the altitude 0 from the relationship between the flight altitude of the aircraft and the irradiation angle of the radar beam. In this case, the display area width is R _W = R. _It is constant at _Wθ . FIG. 4 (b), when the beam reaches the following altitude, display area width R _W indicates to be limiting.

  Next, the marking height threshold value calculation process in step S12 will be described with reference to FIG. The processing for calculating the marking altitude threshold is basically processing for excluding from the marking target altitude mesh that the radar beam does not reach, regardless of whether the irradiation direction of the radar is upward or downward from the horizontal plane.

When the beam is upward and θ + θ _V / 2 ≦ 0 °, h_R = Rsin | θ _plus |, so the marking altitude threshold value h_marking = h + h_R. When the beam is downward and θ + θ _V / 2> 0 °, h_marking = h−h_R.

  The processing flow for determining the display area width and calculating the marking height threshold will be described with reference to FIG. Steps S60 to S65 correspond to step S11 for determining the display area width shown in FIG. 1, and steps S66 to S68 correspond to step S12 for calculating the marking height threshold.

  First, in step S60, setting parameters input in step S10 of FIG. 1 and held in storage means such as a work area or a register are acquired. Specifically, the data may be copied to the storage means dedicated to the program, or the address of the storage means that holds the input setting parameters may be simply given.

In step S61, among the setting parameters acquired in step S60, θ _plus = θ + θ _V / 2 is obtained from the irradiation angle θ of the radar and the vertical scanning line width θ _V that is the vertical scanning angle of the radar, Whether the value is positive or negative is determined. Semantically, as described above, it is determined whether the radar beam in the virtual fan-shaped plane is upward or downward.

If _{θ + θ V / 2 ≦ 0} ° is satisfied branches to step S65, the display area width R _W is determined to be the maximum width _{R W = R · sin (Ψ} / 2) by using the set specifications.
If θ + θ _V / 2 ≦ 0 ° is not satisfied, h_R = R · sin θ _plus is calculated in step S62, and it is determined whether h ≧ h_R is satisfied in step S63. Semantically, it is determined whether the irradiation beam from the radar has reached an altitude of 0 meters or less above sea level.

Branches to step S65 if the condition is satisfied, the display area width R _W and that of the maximum width. If satisfied, at step _S64, it determines a display area width _{R W} by the formula _{R W = h / h_R · R} · sin (Ψ / 2).

While the display area width R _W is determined by the above, the value for use in subsequent processing, are stored in the storage means such as a work area or a register. Similarly, θ _plus and h_R are also held.
Subsequent to step S65, step S66 to step S68 of FIG. 1 are performed to calculate the marking altitude threshold value.

In step S66, it is determined again that θ + θ _V / 2 ≦ 0 °. If the condition is satisfied, the marking altitude threshold is calculated by the equation h_marking = h + h_R in step S68. If the condition is not satisfied, the equation h_marking = Calculated by h−h_R. The marking altitude threshold calculated here is also stored in a storage means such as a work area or a register for use in later processing.

By determining the display area width, the width of the display area shown in FIG. 2 is determined, and a primary selection criterion for the mesh to be marked on the map is obtained. Further, a secondary selection target mesh for marking is obtained by the marking height threshold.
Next, the luminance setting for the mesh on the display area in step S13 and step S14 will be described with reference to FIGS.

  FIG. 7 is a flow of processing for setting the luminance with respect to the scanning line distance direction corresponding to step S13 in FIG. 1, and FIG. 8 is for setting the luminance with respect to the reflectance of the radar wave corresponding to step S14 in FIG. It is a flow of processing. FIG. 9 is an xy plan view and a vertical sectional view showing a mesh whose luminance is to be determined and the position of the aircraft relative to the mesh. FIG. 10 is a diagram illustrating a geometric relationship on the xy plane.

  In FIG. 7, in step S70, the same input setting parameters as in step 60 of FIG. 6 are acquired, and the marking height threshold h_marking obtained earlier is acquired. It should be noted that even if not specifically mentioned, when the calculation is performed first and the retained data is used, the data is naturally acquired.

Next, in step S71, the display area of the determined 2 display area width R _W, successively selected mesh coordinates _{(x 1, y 1, z} 1). Some mesh coordinates on the map are generally provided as a database and can be used.

Next, in step S72, it is determined whether z ₁ > h_marking is satisfied. This semantically determines whether the altitude of the mesh selected in step S71 exceeds the marking altitude threshold. If the condition of step S72 is not satisfied, the process returns to step S71 to select the next mesh coordinate. Although not shown in the figure, if there is no mesh coordinate to be selected, the processing is of course ended. In addition, it is obvious to those skilled in the art that various methods can be adopted in what order the meshes are selected. Also, although not shown in the figure, after executing the process up to mesh coloring in step S16 following step S13, the brightness is again set in the scanning line distance direction in step S13 for the next mesh process. It goes without saying that the mesh selection in step S71 of FIG. 7 is performed.

If the altitude of the mesh exceeds the marking altitude threshold and the condition of step S72 is satisfied, the distance R _{min — 3d} between the aircraft and the mesh is obtained by R _min — _3d = h−z ₁ / sin θ _plus in step S731.

This calculation will be described with reference to FIG. If B ′ shown in FIG. 9B is a mesh whose luminance is to be set, B ′ is on the virtual sector surface of the radar beam irradiated by the aircraft at position A in the figure. (Hereinafter, the position A is sometimes referred to as the virtual position of the aircraft with respect to the mesh B ′.)
Assuming that a point B ′ is projected onto the xy plane of FIG. 9A, which is a horizontal plane at the flight altitude h of the aircraft, is B, the angle between the side BA and the side B′A of the right triangle ABB ′ is θ + θ _V / 2 = θ _plus , and the length of the side BB ′ is equal to h−z ₁ because the coordinates of B ′ are (x ₁ , y ₁ , z ₁ ).

Accordingly, R _min — _3d · sin θ _plus = h−z ₁ , that is, R _min — _3d = h−z ₁ / sin θ _plus .
Since it is clear that the luminance is affected by the distance between the radar irradiation source and the reflection source, R _{min — 3d} can be used as a parameter for setting the luminance. Since 0 ≦ R _{min — 3d} ≦ R, for example, it is defined as luminance k ₁ = R / R _min — _3d −1, and the value of 10 or more is adjusted to 10 to adjust the range of luminance k ₁ to a value between 0 and 10 It can be.

Therefore, in step S74 in FIG. 7, the luminance k ₁ can be obtained as k ₁ = R / R _min — _3d −1 and k ₁ ≦ 10.
Next, FIG. 8 will be used to explain the flow of processing for setting the luminance with respect to the reflectance of the radar wave corresponding to step S14 in FIG. 1, but before that, the concept behind the processing flow in FIG. 8 will be explained. To do.

It is clear that radar wave reflectivity is greatly affected by the direction of the ground surface of the mesh with respect to the traveling direction of the radar wave. The method according to the present invention is performed based on the traveling direction of the radar wave at the angle and the normal vector angle of the ground surface at the mesh.
The normal vector in the mesh can be obtained from an existing map database.

  Regarding the radar wave vector, the virtual position A of the aircraft in FIG. 9, that is, the coordinates of the position A where the mesh B ′ for setting the luminance is on the virtual sector surface of the radar beam irradiated by the aircraft is If it is obtained for the mesh B ′, it can be easily obtained as the difference between the position vectors.

  Then, in order to obtain the coordinates of A, Δy, which is the distance between BCs, is obtained, where C is the perpendicular foot drawn from the point B on the xy plane in FIG. 9A to the flight line, Based on this, the angle φ between the side AC and the side AB is obtained to obtain the length of the side AC, and further, the xy coordinate of C is obtained from the coordinates of B and the distance Δy, and from this and the length of the side AC, A The coordinates are obtained from the contents of the processing from step S80 to step S86 in FIG.

  First, in step S80, an equation ax + by + c = 0 in which an aircraft flight line obtained from flight plan information serving as a reflection prediction (REP) reference line is expressed in a mesh coordinate system is acquired. This can be obtained from two known mesh coordinates on the flight line, etc., but it may be calculated inside the computer by inputting the two mesh coordinates, or separately calculated and the coefficients a, b, and c are input. You may make it do.

  In step S81, | Δy | is calculated by the formula of the distance between the point and the straight line on the plane.

Ask for.
In step S82, the distance _{Rmin_2d} between A and B is determined as _{Rmin_2d} = _{Rmin_3d} · _{cosθ plus} by _{Rmin_3d} determined in step S73 of FIG.

Next, in step S83, Δy / R _min — _2d = _sinφ for the angle φ formed between the side AB and the side BC of the right triangle ABC in FIG. 9A, so the angle φ is changed to φ = sin ⁻¹ (Δy / R _{min_2d} ), and in step S84, the length of the side AC, that is, the distance | AC | between ACs is obtained by | AC | = | R _{min_2d} · cosφ |.

Next, in step S85, the coordinates (x ₂ , y ₂ ) of the point C are obtained by x ₂ = a + x ₁ and y ₂ = b + y ₁ . This calculation will be described with reference to FIG. Suppose that a perpendicular is dropped from point B (x ₁ , y ₁ ) to point C on a straight line connecting point A (x ₃ , y ₃ ) and point C (x ₂ , y ₂ ) on the xy plane. . Then, the contact point between the circle having the radius Δy centered on the point B and the straight line AC is the coordinates of C. The tangent equation at C (x ₂ , y ₂ ) on the circle is
(x ₂ −x ₁ ) (x−x ₁ ) + (y ₂ −y ₁ ) (y−y ₁ ) = Δy ² , and transforming it gives (x ₂ −x ₁ ) x−x ₁ ( x ₂ −x ₁ ) + (y ₂ −y ₁ ) y−y ₁ (y ₂ −y ₁ ) = Δy ²
It becomes.

On the other hand, the equation representing the flight line of the aircraft acquired in step S80 in the mesh coordinate system is ax + by + c = 0, so that by comparing the coefficients, a = x ₂ −x ₁ , b = y ₂ −y ₁ , Therefore, x ₂ = a + x ₁ and y ₂ = b + y ₁ are obtained.

In step S86, the coordinates of point A are calculated from the distance between ACs obtained in step S84 and the coordinates of point C obtained in step S85. The coordinates (x ₃ , y ₃ ) of the virtual position A of the aircraft can be easily obtained by the simultaneous equations of the distance formula between ACs and the formula representing the flight line.

The three-dimensional coordinates (x ₃ , y ₃ , h) of the point A are held in storage means such as a work area and a register, and are also used in later line-of-sight calculations.
In step S87, the irradiation direction vector α = (αx, αy, αz) of the radar is obtained based on the difference between the three-dimensional coordinates (x ₃ , y ₃ , h) of the point A and the coordinates of the mesh B ′.

In step S88, the normal vector of the mesh B ′ is acquired from the map database. Let the acquired normal vector be β = (βx, βy, βz).
In step S89, the angle γ formed by the vector α and the vector β is calculated as follows.

The inner product of the vector α and the vector β is expressed as follows: α · β = | α | · where the length of the vector α is | α |, the length of the vector β is | β |, and the angle between the vector α and the vector β is γ. | Β | cosγ. Therefore, γ = cos ⁻¹ (α · β / | α | · | β |) is used to calculate γ as a luminance setting parameter. Since 0 ° ≦ γ ≦ 90 ° and the luminance is large in the case of 0 °, the luminance k ₂ with respect to the reflectance of the radar wave is adjusted to k ₂ = 10 (1-sinγ), for example, as in step S90. Then, it can be in the range of 0 to 10 as in the case of the luminance k ₁ .

Next, the line-of-sight calculation in step S15 in FIG. 1 will be described with reference to FIG.
The line-of-sight calculation in step S15 is sequentially executed for the mesh B ′ for which the luminance has been set in steps S13 and S14. That is, it is executed as a continuation of the processing shown in FIG.

FIG. 11 is a diagram showing a vertical plane _{PAB ′} including the mesh B ′ and the virtual position A of the aircraft. '"When, linear AB" mesh should consider prospects against B and the angle of the horizontal plane, the straight line AB' mesh B with small such B than an angle formed between the line of flight "plane P _{AB '} If it exists above, the mesh B ′ cannot be seen from A, and will be excluded from the target of mesh coloring in step S16.

If the coordinates of B ″ are B ″ (x _{b ″} , y _{b ″} , h _{b ″} ), the distance of the virtual position A of the aircraft | AB ″ | The height difference H _{b ″} is also obtained as h−h _{b ″} . When the angle between the straight line AB ″ and the horizontal plane is θ _{AB ″} , sin θ _{AB ″} is obtained as sin θ _{AB ″} = H _{b ″} / | AB ″ |. Therefore, by comparing the magnitude of θ _{AB ″} and θ _plus , it can be determined whether or not it can be seen.

  In step S16 of FIG. 1, the visible mesh is colored based on the luminance set in steps S13 and S14, and marking for radar reflection prediction is executed.

The coloring is performed by setting the color density based on the combination of the luminance k ₁ with respect to the scanning line distance direction and the luminance k ₂ of the reflectance of the radar wave. For example, the product of k ₁ and k ₂ or k ₁ weighted sum such as k ₂ are possible adopted, it is possible to continue to adjust to the optimum fit and feeling of the plurality of markings experience. In the above example, the range of k ₁ and k ₂ is set to 0 to 10. However, a threshold value may be provided as a parameter for the luminance to be colored, and marking may be performed by coloring only the mesh having luminance higher than the threshold value. it can.

  In addition to the previously determined marking altitude threshold, the altitude threshold for coloring in step S16 can be set as a parameter so that meshes at altitudes below the altitude threshold for coloring are not colored. Is also possible.

In some cases, it is also possible to use only one luminance.
The colors used for coloring are preferable because the primary colors are conspicuous, but are not limited thereto, and are not limited to one color.

  As described above, according to the present invention, various options are possible for marking of radar reflection prediction, and these are set so as to obtain a figure assumed by the reflection prediction map creator, and quantitatively optimal radar reflection can be obtained. Predictive charts can be created.

  When the process of step S16 is completed, as described above, it is determined whether or not the mesh to be processed remains. If not, the marking process is terminated, and if it remains, the process returns to step S13 to select the next mesh. Then, the processing below the setting of the luminance with respect to the scanning line processing direction is repeated.

FIG. 12 explains the environment in which the radar reflection prediction map creation method of the present invention described in detail above is implemented and the operation of the flight plan related to radar reflection prediction map creation.
The present invention is implemented using a computer such as a personal computer (PC), and includes a processing device 10 as a main body of the computer and an input device 20 as a peripheral device thereof, a map database 30, a display device 40, and printing. This is performed as part of the flight plan creation in the system environment including the device 50.

  The processing apparatus 10 will be schematically described with reference to functional blocks for carrying out the present invention. The processing apparatus 10 includes an input specification setting area 11, a flight line data setting area 12, a mesh data storage unit 13, various work areas 14, The calculation control unit 15 includes a marking map storage unit 16.

The input item setting area 11 is storage means for setting the input item input from the input device 20 in step S10 described in FIG. 1, and is a radar irradiation distance: R, which is a practical maximum reach distance of the radar. The horizontal scanning line width that is the horizontal scanning angle of the radar: Ψ, the vertical scanning line width that is the vertical scanning angle of the radar: θ _V , the irradiation angle of the radar: θ, and the flight altitude of the aircraft: h Is set.

  In the flight line data setting area 12, flight line data based on the flight plan is held based on the input from the input device 20. This flight line data is input by inputting the (x, y) coordinates of the mesh on the map of the planned flight course, and calculating and maintaining the coefficients of the linear flight line equation of the region to be marked in the flight path. Alternatively, the coefficient of the flight line equation may be separately calculated and the coefficient may be input.

  When a plurality of radar reflection prediction maps are created with one flight plan, data of a plurality of flight lines are input and held, and a radar reflection prediction map is sequentially generated based on each data. If there is no change in the input specifications in the middle, the second and subsequent steps may be started from step S11.

  The mesh data storage unit 13 reads and stores the mesh data of the area where the marking process is executed from the map database 30. The mesh data to be read is for the mesh in the range determined by the display area width determination in step S11.

The various work areas 14 store data such as marking altitude threshold values obtained in the calculation process and various parameters and threshold values that are set, and are used for various calculation processes.
The calculation control unit 15 executes various calculations and controls processes according to the present invention.
The marking map storage unit 16 stores the density of the color to be colored, which is the result of the color processing of each mesh in step S16 according to the present invention.

The input device 20 is, for example, a keyboard, and inputs flight specifications such as the flight altitude of the aircraft and radar specifications as described above.
The map database 30 only needs to have data of the three-dimensional coordinates of the mesh and the normal vector of the mesh.

The display device 40 displays a map of the display area where the radar reflection prediction is marked based on the coloring data of each mesh stored in the marking map storage unit 16.
The printing device 50 prints the same marked map as the map displayed on the display device 40 to create a marked paper map.

  In the operation example shown in FIG. 12, first, specifications are input based on the original flight plan, the radar reflection prediction map according to the present invention is generated and other processing is performed, and the result is output to the display device 40 or the printing device 50. If there is a need to correct the plan after confirming with the output of, correct the original flight plan, input data again, repeat the creation of the radar reflection prediction map, etc. FIG. 60 is output as a paper map. The output radar reflection prediction map is referred to on the plane during flight by an aircraft navigator, for example.

  As described above in detail, according to the present invention, a radar reflection prediction map with quantitative marking can be created. Therefore, it is not limited to use by human eyes as a paper map, but it can also be used as a digital map on a computer on an aircraft for comparison of actual radar reflections on a virtual fan-shaped surface during actual flight, for confirmation of flight paths, etc. Applicable.

(Appendix 1)
In a radar reflection prediction map creation method for predicting the strength of reflection from the surface when radar is irradiated to the ground surface from a flying aircraft by a computer, and marking the strength of the reflection on a map,
For each mesh on the marking target map, define only one irradiation beam of the radar,
A radar reflection prediction map creation method, wherein marking of each mesh is performed based on the irradiation beam.
(Appendix 2)
The single determined radar irradiation beam is placed in a virtual fan-shaped plane in a direction determined by the sum of the irradiation angle of the radar and a predetermined angle within a vertical scanning line width that is a scanning range of the radar in the vertical direction. The radar reflection prediction map creation method according to appendix 1, wherein the irradiation beam is an irradiation beam.
(Appendix 3)
The range of the mesh to be marked on the map is determined from the flight altitude of the aircraft and the irradiation distance of the radar, and the marking altitude threshold is calculated,
The radar reflection prediction map creation method according to appendix 2, wherein marking is performed on a mesh having an altitude equal to or higher than the marking altitude threshold.
(Appendix 4)
For meshes with altitudes above the marking altitude threshold,
Determining a distance between the virtual position of the aircraft that irradiates the irradiation beam of the single radar determined and the mesh;
Based on the distance, set the brightness in the scanning line distance direction of the mesh,
Further, a virtual position of the aircraft is obtained,
Calculating an angle formed by a position vector from the obtained position to the mesh and a normal vector of the mesh;
Based on the angle, setting the luminance for the reflectance of the radar wave in the mesh,
4. The radar reflection prediction map creation method according to appendix 3, wherein marking is performed by coloring the mesh based on the luminance in the scanning line distance direction and the luminance with respect to the reflectance of the radar wave.
(Appendix 5)
Item 5. The supplementary note 4, wherein the line-of-sight calculation from the virtual position of the aircraft to the mesh is performed based on the single radar irradiation beam defined, and the mesh that can be lined is marked by coloring. Radar reflection prediction map creation method.
(Appendix 6)
The radar according to appendix 4 or appendix 5, wherein a threshold is provided for the luminance in the scanning line distance direction and the luminance with respect to the reflectance of the radar wave, and marking is performed only on a mesh having a luminance equal to or higher than the threshold. Reflection prediction map creation method.
(Appendix 7)
6. The radar reflection prediction map creation method according to appendix 4 or appendix 5, wherein a threshold is provided at an altitude of a mesh for performing marking by coloring, and marking is performed by coloring only for an altitude higher than the threshold.
(Appendix 8)
The radar reflection prediction map creation method according to appendix 2, wherein the virtual fan-shaped surface is a lowermost surface within the vertical scanning line width.
(Appendix 9)
In a program that causes a computer to execute a radar reflection prediction map creation method that predicts the intensity of reflection from the ground surface when the radar is irradiated from a flying aircraft and marks on the map,
On the computer,
Display width determining step for determining a mesh range to be marked on the map based on the radar reach distance set in the input specification setting area, the flight altitude of the aircraft, and the flight line of the aircraft set in the flight line data setting area When,
Based on the radar reach distance, the flight altitude of the aircraft, the radar irradiation angle set in the input specification setting area, and a predetermined angle within the vertical scanning line width which is the vertical scanning range of the radar A marking altitude threshold calculation step for calculating a marking altitude threshold which is an arrival limit altitude of the radar;
A mesh selection step of selecting a mesh in the range determined in the display width determination step;
It is determined whether the altitude of the selected mesh is equal to or higher than the marking altitude threshold, and if the condition is not satisfied, the process returns to the mesh selection step, and if the condition is met, the mesh altitude determining step proceeds to the next step;
Based on the difference between the irradiation angle of the radar and the predetermined angle, and the difference between the flight altitude of the aircraft and the altitude of the selected mesh, the aircraft irradiates the selected mesh on the flight line with the radar. The distance between the virtual position of the aircraft that irradiates the radar scanning line with the sum of the angle and the predetermined angle and the selected mesh is obtained, and the brightness with respect to the scanning line distance direction of the selected mesh using the distance as a parameter Scanning line distance direction luminance setting step for setting,
From the coordinates of the virtual position of the aircraft and the coordinates of the position of the selected mesh, a vector of the radar scanning line in the selected mesh is obtained, and the vector of the radar scanning line and the normal line in the selected mesh A radar wave reflectance luminance setting step for obtaining an angle formed by the vector, and further setting a luminance with respect to the radar wave reflectance of the selected mesh using the angle as a parameter;
A line-of-sight calculation step for calculating whether a line-of-sight from the virtual position of the aircraft to the selected mesh is possible based on the coordinates of the virtual position of the aircraft and the coordinates of the position of the selected mesh;
Based on the luminance set in the scanning line distance direction luminance setting step and the luminance set in the radar wave reflectance luminance setting step when a line-of-sight from the virtual position of the aircraft is possible And executing a mesh coloring step for coloring the selected mesh.
(Appendix 10)
In a radar reflection prediction map creation device that predicts the strength of reflection from the surface when a radar is irradiated to the ground surface from a flying aircraft by a computer and marks the strength of the reflection on a map,
For each mesh on the marking target map, define only one irradiation beam of the radar,
A radar reflection prediction map creating apparatus, wherein marking of each mesh is performed based on the irradiation beam.

It is a figure explaining the flow of processing of radar reflection prediction by the present invention. It is a figure which shows the display area which performs radar reflection prediction and performs marking. It is a figure explaining a virtual sector surface and a display area width. Virtual sector surface is a diagram showing a display area width R _W due to the flight altitude when downward from the horizontal plane. It is a figure for demonstrating the process of marking height threshold value calculation. It is a figure explaining the processing flow of determination of a display area width, and marking height threshold value calculation. It is a figure explaining the processing flow which sets the brightness | luminance with respect to a scanning line distance direction. It is a figure explaining the processing flow which sets the brightness | luminance with respect to the reflectance of a radar wave. FIG. 4 is an xy plan view and a vertical sectional view showing a mesh whose luminance is to be determined and a virtual position of the aircraft with respect to the mesh. It is a figure explaining the geometric relationship on an xy plane. It is a figure which shows the vertical plane containing the mesh of marking object, and the virtual position of an aircraft. It is a figure explaining the environment where this invention is implemented. It is a figure which shows an example of the radar reflection prediction figure written by handwriting. It is the figure which showed the strength of the radar reflection in the point of the ground surface right under the flight line for every flight position when the flight position of an aircraft changes. It is a figure explaining the marking method of the radar reflection by the normal general method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Processing apparatus 11 Input specification setting area 12 Flight line data setting area 13 Mesh data memory | storage part 14 Various work areas 15 Computation control part 16 Marking map memory | storage part 20 Input device 30 Map database 40 Display apparatus 50 Printing apparatus 60 Radar reflection prediction figure

Claims (3)

In a radar reflection prediction map creation method for predicting the strength of reflection from the surface when radar is irradiated to the ground surface from a flying aircraft by a computer, and marking the strength of the reflection on a map,
The arithmetic control unit of the computer,
The map data to be marked is read from a map database storing map data, and set for each mesh on the map from the specifications of the radar, the irradiation direction, and the flight plan of the airplane input by the input device. A process of determining only one irradiation beam of the radar based on the specifications;
A process for marking each mesh based on the defined irradiation beam;
The execution,
The single determined radar irradiation beam is placed in a virtual fan-shaped plane in a direction determined by the sum of the irradiation angle of the radar and a predetermined angle within a vertical scanning line width that is a scanning range of the radar in the vertical direction. As an irradiation beam,
The calculation control unit executes a process of determining a marking altitude threshold while determining a mesh range for marking on a map based on a flight altitude of the aircraft and an irradiation distance of the radar,
In the process of performing the marking, the arithmetic control unit performs marking on a mesh having an altitude equal to or higher than the marking altitude threshold,
The arithmetic control unit is
For meshes with altitudes above the marking altitude threshold,
A process for obtaining a distance between the virtual position of the aircraft that irradiates the irradiation beam of the radar to be determined and the mesh;
A process of setting the luminance in the scanning line distance direction of the mesh based on the distance;
A process for obtaining a virtual position of the aircraft;
A process of calculating an angle formed by a position vector from the obtained position to the mesh and a normal vector of the mesh;
A process for setting the luminance with respect to the reflectance of the radar wave on the mesh based on the angle;
Based on the luminance in the scanning line distance direction and the luminance with respect to the reflectance of the radar wave, a process of marking by coloring the mesh;
Radar return prediction map creation method, characterized by the execution. In the processing in which the calculation control unit performs the line-of-sight calculation from the virtual position of the aircraft to the mesh based on the irradiation beam of the single radar that is defined, the calculation control unit includes: The radar reflection prediction map creation method according to claim 1 , wherein marking is performed by coloring a mesh that can be used. In a program that causes a computer to execute a radar reflection prediction map creation method that predicts the intensity of reflection from the ground surface when the radar is irradiated from a flying aircraft and marks on the map,
On the computer,
Display width determining step for determining a mesh range to be marked on the map based on the radar reach distance set in the input specification setting area, the flight altitude of the aircraft, and the flight line of the aircraft set in the flight line data setting area When,
Based on the radar reach distance, the flight altitude of the aircraft, the radar irradiation angle set in the input specification setting area, and a predetermined angle within the vertical scanning line width which is the vertical scanning range of the radar A marking altitude threshold calculation step for calculating a marking altitude threshold which is an arrival limit altitude of the radar;
A mesh selection step of selecting a mesh in the range determined in the display width determination step;
It is determined whether the altitude of the selected mesh is equal to or higher than the marking altitude threshold, and if the condition is not satisfied, the process returns to the mesh selection step, and if the condition is met, the mesh altitude determining step proceeds to the next step;
Based on the difference between the irradiation angle of the radar and the predetermined angle, and the difference between the flight altitude of the aircraft and the altitude of the selected mesh, the aircraft irradiates the selected mesh on the flight line with the radar. The distance between the virtual position of the aircraft that irradiates the radar scanning line with the sum of the angle and the predetermined angle and the selected mesh is obtained, and the brightness with respect to the scanning line distance direction of the selected mesh using the distance as a parameter Scanning line distance direction luminance setting step for setting,
A radar scanning line vector in the selected mesh is obtained from the virtual position coordinates of the aircraft and the selected mesh position coordinates, and the radar scanning line vector and the normal vector in the selected mesh are obtained. A radar wave reflectance luminance setting step for setting the luminance with respect to the radar wave reflectance of the selected mesh using the angle as a parameter, and
A line-of-sight calculation step for calculating whether a line-of-sight from the virtual position of the aircraft to the selected mesh is possible based on the coordinates of the virtual position of the aircraft and the coordinates of the position of the selected mesh;
Based on the luminance set in the scanning line distance direction luminance setting step and the luminance set in the radar wave reflectance luminance setting step when a line-of-sight from the virtual position of the aircraft is possible And executing a mesh coloring step for coloring the selected mesh.