JP2003248049A - Radar image simulator of apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a radar image simulator of apparatus, capable of highly accurately simulating a radar image targeted over a wide area. <P>SOLUTION: The radar image simulator of apparatus is provided with a track database for storing track data on a mobile body in which a radar is mounted, a sensor database for storing sensor data indicating the specifications of sensors onboard of the radar, an elevation database for dividing the ground surface of a region to be observed specific region by specific region and storing elevation data on each divided region, a database for land utilization for storing covering data on the ground surface of each divided region, an RCS database for irradiating the ground surface of each divided region with first radio waves by the radar, to make the first radar waves scatter at the ground surface and storing back-scattering cross section product values indicating the intensity of second radio waves received by the radar, and an RCS map creating means for creating an RCS map, two-dimensionally indicating the distribution of the back-scattering cross section product values in the region to be observed on the basis of the track data, the sensor data, the elevation data, and the covering data. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar image simulator for simulating an image obtained by observation using a radar.

[0002]

2. Description of the Related Art FIG. 16 shows, for example, "Y. Yang e.
t al. , "A GIS-drive inter
active radar images simul
ation using EMSARS mode
1, "IGARSS '94, vol.2 p857.
It is a block diagram which shows the conventional radar image simulation apparatus which is analogized from "-859".

In FIG. 16, a conventional radar image simulating apparatus includes an elevation database X58 for storing elevation data of a target area and a land feature amount database for storing land feature amount data such as surface roughness and water content. 59, a sensor database X60 that stores sensor data related to specifications of sensors mounted on the radar, and a trajectory database X61 of a platform that stores trajectory data of a moving body (platform) such as an aircraft equipped with the radar,
RCS map creating means 53 by calculation of a scattering model,
It is provided with an incident angle calculator 6, a backscattering calculator 55 based on a scattering model, and a simulated radar image storage area X57 for storing a simulated radar image.

Next, the operation of the conventional radar image simulator will be described. FIG. 17 is a flowchart showing the operation of the conventional radar image simulating device, and FIG. 18 is an explanatory view showing the operation of the incident angle calculator 6.

First, in step S1701, the elevation data, the orbit data of the platform, and the sensor data are input to the incident angle calculator 6 in the RCS map creating means by calculation of the scattering model.

In step S1702, as shown in FIG. 18, the incident angle calculator 6 considers that the ground surface of the observation target area (simulation target area) is divided into meshes, for example,
The positional relationship between each mesh and the radar is calculated.
Then, the incident angle of the microwave on the ground surface is calculated for each mesh from each positional relationship and the microwave irradiation angle data included in the sensor data.

Subsequently, in step S1703, the backscattering calculator 55 based on the scattering model calculates the incident angle obtained by the incident angle calculator 6 and the roughness of the ground surface of each mesh in the feature amount data of the land. From data such as water content,
The value of the backscattering cross section (RCS) is calculated based on the scattering model of the simulation target area.

Here, the backscattering cross section (RCS) is a value representing the intensity of backscattering (scattering in the direction in which the microwave is incident) of the object. This value varies depending on the type of object, and also varies depending on the microwave frequency and the angle of incidence of the same object.

Further, the scattering model is a calculation formula in which the intensity of scattering is modeled by using parameters that affect scattering such as permittivity, surface roughness, and incident angle of microwaves. It is prepared for each mesh.

Thus, RC for all meshes
By calculating the S value and plotting the RCS value corresponding to each mesh, it is possible to obtain a two-dimensional RCS value distribution on the ground surface of the simulation target region. In addition, this 2
A dimensional RCS value distribution is called an RCS map.

In step S1703, the RCS map is output to the simulated radar image storage area X57 as a simulated radar image.

[0012]

As described above, since the conventional radar image simulating device has a large amount of calculation of the RCS value based on the scattering model, it takes a lot of time to simulate the radar image. As a result, there is a problem that it is difficult to obtain a simulated radar image for a wide area because it is necessary to limit the range of the simulated target area.

Further, since the RCS value obtained by the scattering model is different from the RCS value obtained by the actual radar observation, there is a problem that the accuracy of simulating the radar image is lowered.

Further, there is a problem that the radar image cannot be simulated if there is no scattering model suitable for the simulation target area.

Further, in order to calculate the scattering model, there is a problem that detailed data such as the roughness of the ground surface and the dielectric constant in the simulation target area are required.

The present invention has been made to solve the above problems, and an object thereof is to obtain a radar image simulating device for simulating a radar image for a wide area with high accuracy.

[0017]

A radar image simulating apparatus according to the present invention includes a trajectory database for storing orbital data indicating orbital information of a moving body equipped with a radar, and a sensor for indicating specifications of a sensor mounted on the radar. A sensor database that stores data, an altitude database that divides the ground surface of the observation target area into predetermined areas and that stores altitude data that indicates the altitude information of each divided area, and a covering that indicates the ground surface coverage information in each divided area. The land use database that stores the data and the radar is used to
RCS database that stores the backscattering cross-section value that indicates the intensity of the second radio wave received by the radar due to the scattering of the first radio wave on the ground surface when the radio wave of Create an RCS map that two-dimensionally shows the distribution of backscattering cross-sectional area values in the observation area based on the data, elevation data, and coverage data R
And a CS map creating means.

The RCS map creating means of the radar image simulating apparatus according to the present invention comprises an incident angle calculator for calculating the incident angle of the first radio wave based on the orbit data, the sensor data and the altitude data, and the incident angle calculator. And a table look-up device that acquires a backscattering cross-sectional area value corresponding to each divided region by referring to the RCS database based on the coverage data.

The radar image simulating apparatus according to the present invention further includes an artifact structure database that stores structure data of a three-dimensional shape of an artifact existing on the ground surface of each divided area,
A position database that stores position data indicating position information of the artifact and the moving body, and based on the structure data and the position data, calculate the backscattering cross-sectional area value when the first radio wave is incident on the artifact, An artifact target adding means for adding a backscattering cross-sectional area value to the position of the RCS map corresponding to each divided region where an artifact exists is provided.

Further, the radar image simulating apparatus according to the present invention is based on the orbit data, the sensor data and the altitude data, and the first positional relationship of the ground surface obtained by observing the observation target area with the radar and the ground surface. The geometrical distortion indicating the deviation of the two-dimensional positional relationship from the second positional relationship of the ground surface obtained by observing is calculated, and the backscattering cross-sectional area values in the RCS map are rearranged based on the geometrical distortion. The geometric distortion adding means is provided.

Further, the radar image simulating apparatus according to the present invention calculates the point image response in the radar image obtained by observing with the radar based on the orbit data, the sensor data and the altitude data, and the point image response and the RCS map. And a point image response adding means for adding a point image response to the RCS map by performing a convolution calculation of and.

Further, the RCS database of the radar image simulator according to the present invention uses the covering data, the incident angle of the first radio wave, the polarization of the first radio wave, and the frequency of the first radio wave as parameters. And an extended RCS database that stores backscattering cross-section values.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. Hereinafter, Embodiment 1 of the present invention will be described in detail with reference to the drawings. 1 is a block diagram showing the first embodiment of the present invention. The same components as those described above (see FIG. 16) are designated by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 1, the radar image simulator stores an altitude database 1 which stores altitude data of a simulation target area (simulation target area) and orbit data of a moving body (platform) such as an aircraft equipped with radar. The orbit database 2 and the sensor database 3 storing the sensor data regarding the sensor specifications of the radar are provided.

Further, a land use database 4 storing land use data (coverage data) indicating the land cover of the target area, an RCS database 5 accumulating RCS data obtained by measurement by a radar, and an RCS value are calculated. An RCS map creating means 8 for creating a simulated radar image (RCS map) of the target area and a simulated radar image storage area A14 for storing the simulated radar image.
Further, the altitude database 1, the trajectory database 2, the sensor database 3, and the land use database 4 are divided for each simulation target area.

The RCS data is data showing the RCS value when a microwave is incident at N degrees on a certain land use area.

Further, the RCS map creating means 8 includes an incident angle calculator 6 for calculating the incident angle of microwaves on the ground surface,
And a table lookup unit 7 that acquires an RCS value for creating an RCS map.

Next, the operation according to the first embodiment of the present invention will be described. FIG. 2 is a flowchart showing the operation according to the first embodiment of the present invention.

In step S201, elevation data, platform orbit data, sensor data, and land use data, which are prepared in advance, are read from each database. These read data are R
It is transmitted to the CS map creating means 8.

In step S202, the incident angle calculator 6 in the RCS map creating means calculates the positional relationship between the ground surface and the radar from the altitude data of the simulation target area and the orbit data of the platform. Then, the incident angle of the microwave on the ground surface is calculated from the positional relationship and the microwave irradiation angle data included in the sensor data.

In step S203, the table look-up device 7 calculates the RC from the incident angle of the microwave on the ground surface and the land use data indicating the land cover on the ground surface.
The corresponding RCS value is acquired by referring to the RCS data in the S database 5. Here, since the RCS value is acquired by table lookup (table reference), the RCS value is not calculated based on the scattering model. In this way, all RCS values on the ground surface of the simulation target area are acquired.

In step S203, the RCS map showing the distribution of RCS values in the simulated target area is output to the simulated radar image storage area A14 as a simulated radar image, and the processing routine of FIG. 2 ends. This simulated radar image is a simulated radar image that does not include the point image response of the observation system and the geometric distortion of the radar image.

As described above, the radar image simulation device creates a simulated radar image from the altitude database 1, the platform orbit database 2, the sensor database 3, the land use database 4, and the RCS database 5. You can

Further, since the RCS value is acquired by the table lookup by the table lookup unit 7, the calculation based on the scatter model can be reduced and the radar image can be simulated at high speed. As a result, a simulated radar image for a wide area can be obtained.

Further, since the RCS database 5 stores the RCS value obtained by the actual measurement by the radar, the simulation accuracy of the radar image can be improved by using the RCS data based on the actual measurement value.

Data calculated by a scattering model may be used as the RCS data in the RCS database 5. By accumulating RCS data calculated by the scattering model in an area where there is no actual measurement value of RCS data,
The target area that can be simulated can be increased and the simulation accuracy can be improved.

Embodiment 2. In the first embodiment, the radar image is simulated for the area consisting of natural objects, but artificial structures may exist in the simulation target area.

FIG. 3 is a block diagram showing the second embodiment of the present invention. In FIG. 3, the above (FIG. 1, FIG.
6)), the same symbols are attached,
Detailed description is omitted.

In FIG. 3, the radar image simulating device shows an artificial object target adding means 11 for adding scattering of an artificial object (artificial structure) to the simulated radar image, and a three-dimensional shape of the artificial object existing in the target area. The structure database 12 for storing the structure data of the artifact, the position database 13 for the position of the artifact showing the position relationship between the artifact and the platform, and the natural object and the artifact. And a simulated radar image storage area B17 for storing a simulated radar image of the area including it. In addition, the structure database 12 of the artifact and the position database 13 of the artifact are divided for each simulation target area.

Next, the operation according to the second embodiment of the present invention will be described. FIG. 4 is a flow chart showing the operation according to the second embodiment of the present invention, and FIG. 5 is an explanatory diagram explaining the operation according to the second embodiment of the present invention.
Note that steps S403 and S404 in FIG.
It corresponds to step S202 and step S203 of FIG. 2, respectively, and a detailed description thereof will be omitted.

In step S401, the elevation data of the target area, the orbital data of the platform, the sensor data, the land use data, the structure data of the artifact,
The position data of the artifact and each database are read.

In step S402, it is determined whether or not the data is about natural objects, and if the input data is elevation data, platform orbit data, sensor data, or land use data (that is, YES),
Input to RCS map creation 8, structure data of artifacts,
Alternatively, in the case of the position data of the artifact (that is, NO), it is input to the artifact target adding unit 11.

In steps S402 to S403, a mesh (see Embodiment 1) in which a natural object exists is targeted.
The RCS value is calculated as described above (see Embodiment 1), and the RCS map is created.

In step S405, the artifact target adding means 11 determines the incident angle of the microwave to the artifact for each mesh in which the artifact exists based on the structure data of the artifact and the position data of the artifact. To calculate.

In step S406, the RCS value of the artificial structure when the microwave is reflected and scattered by the artificial object is calculated based on the incident angle of the microwave and the structural data of the artificial object. The calculation of the scattering from the artificial structure takes into consideration that the scattering of the artificial object depends on its structure and the like, and thus GTD (Geometrical Theo) is considered.
An analysis method such as ry of Diffraction) is used.

In step S407, an RCS value is calculated based on the RCS value of the artificial structure, taking into account the contribution of scattering that occurs between the artificial object and the surrounding natural object.
This is because the scattering of the artificial object is strong, and considering that the reflected wave of the artificial object is further incident on the surrounding natural object and the scattering of the natural object is changed, as shown in FIG. 5, it is reflected by the artificial object. An RCS value when an object is further reflected by a natural object on the ground surface and observed by a radar, and an RCS value when the object is observed by a reverse route are calculated by using, for example, the ray tracing method.

Then, the RCS value calculated by the RCS map creating means 8 due to the scattering of the natural object, and the RCS value calculated by the artificial object target adding means 11 due to the scattering of the artificial object and the contribution between the artificial object and the natural object. Is added to the RCS map created by the RCS map creating means 8 to obtain an RCS map in the entire simulation target.

The created RCS map is output to the simulated radar image storage area B17 as a simulated radar image, and the processing routine of FIG. 4 is terminated.

As described above, the artificial target adding means 11
By including the artifact structure database 12 and the artifact position database 13, it is possible to simulate a radar image when an artifact is present in the target area.

For natural objects, the table lookup means 7 is used to suppress an increase in the amount of calculation required for RCS map calculation as described above, and at the same time for artificial objects in which scattering depends on the structure or the like. By performing the scattering calculation of the artificial object, the simulation accuracy of the radar image can be improved.

Embodiment 3. In addition, the first embodiment,
In 2, the geometric distortion is not mentioned, but the effect of the geometric distortion may be added to the simulated radar image.

FIG. 6 is a block diagram showing a third embodiment of the present invention. In FIG. 6, the above-mentioned (FIG. 1, FIG. 3, FIG. 16)
The same reference numerals are given to the same components as those of the reference), and the detailed description thereof will be omitted.

In FIG. 6, a geometric distortion adding means 9 for calculating a geometric distortion and a simulated radar image storage area C18 for storing a simulated radar image containing the geometric distortion are provided.

Next, the operation according to the third embodiment of the present invention will be described. FIG. 7 is a flowchart showing the operation according to the third embodiment of the present invention, and FIGS.
FIG. 9 is an explanatory diagram illustrating an operation according to the third embodiment of the present invention. In addition, step S701 to step S of FIG.
707 is step S401 to step S407 in FIG.
, And detailed description thereof will be omitted.

In steps S701 to S707, the RCS map creating means 8 and the artificial target adding means 1
1 is the RCS value of the simulation target area calculated for each mesh by calculating the RCS value in consideration of the scattering in the natural object and the artificial object.
Create a map.

First, the geometric distortion will be described. In FIG. 8, for example, when observing a mountain on the ground surface,
As shown in (a), when the radar actually observes the ground surface, the distance (slant range distance) between the radar and the observation point on the ground surface is the distance in the topographic map as shown in FIG. 8 (b). A deviation occurs between the (ground range distance) and the distance observed by a radar as shown in FIG. 8 (c).

At the point A on the ground surface, this deviation is
Difference between the distance SR0 and the distance GR0 (distance SR0-distance G
R0), at point B, there is a difference between the distance SR1 and the distance GR0 (distance SR1−distance GR1), and this deviation is called geometric distortion.

Further, the geometric distortion has deviations due to the effects of for shortening, layover, and shadow.

First, points A and B on the ground surface shown in FIG. 8A are displayed on the radar image at positions proportional to the distance from the radar as shown in FIG. 8C. . As a result, the slope facing the radar is inevitably compressed, and this effect is called for shortening.

Next, in FIG. 8A, when the altitude of the point B on the ground surface is high and is closer to the radar than the point A on the bottom surface (that is, SR1 <SR0), the radar image shows
Point B is displayed in front of point A (on the radar side), and this effect is called layover.

Subsequently, as shown in FIG. 9, the surface on the opposite side illuminated by the radar becomes a shadow, and an area without observation data is formed. This effect is called a shadow.

Such geometric distortion is caused by the radar observing the uneven ground surface, and the geometric distortion adding means 9 uses the RCS value in the RCS map as follows.
The RCS value is rearranged at a position considering the influence of this geometric distortion and added to the simulated radar image.

In step S708 of FIG. 7, the geometric distortion adding means 9 actually observes the ground surface with a radar, as shown in FIG. 8A, from the altitude data, the platform trajectory data, and the sensor data. The RC is calculated by calculating the distance in the case, and plotting the RCS values of all points on the ground surface at the positions in consideration of the distance when actually observed by the radar.
An SCS value distribution is created to obtain an RCS map to which geometric distortion is added.

Further, as shown in FIG. 9, by observing the uneven ground surface, a shadowed portion is produced. The geometric distortion adding means 9 calculates the position of this shadowed portion from the altitude data, the platform trajectory data, and the sensor data, and sets the RCS value of this position to 0.

The RCS map to which the geometric distortion has been added is output to the simulated radar image storage area C18 as a simulated radar image, and the processing routine of FIG. 7 ends.

As described above, it is possible to improve the simulation accuracy of the radar image by adding the geometric distortion that is generated when the radar is observed, similar to the image actually observed by the radar.

Fourth Embodiment In addition, the above-described first to first embodiments
In 3, the point image response actually measured by the radar is not mentioned, but the RCS map may include the point image response.

FIG. 10 is a block diagram showing a fourth embodiment of the present invention. In FIG. 10, the above (FIG. 1,
The same components as those in FIGS. 3, 6, and 16) are designated by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 10, the radar image simulation device is
A simulated radar image storage area D19 for storing a simulated radar image including a point image response of the observation system, and a point image response adding means 20 after geometric transformation for adding the point image response of the observation system to the simulated radar image are provided. There is.

Next, the operation according to the fourth embodiment of the present invention will be described. FIG. 11 shows the fourth embodiment of the present invention.
6 is a flowchart showing the operation of the above. Note that FIG.
Steps S1101 to S1107 correspond to steps S401 to S407 of FIG. 4, respectively, and detailed description thereof will be omitted.

Steps S1101 to S1107
In the above, the RCS map creating means 8 and the artificial target adding means 11 calculate the RCS value in consideration of the scattering in the natural object and the artificial object, and create the RCS map in which the RCS value corresponding to each mesh is plotted.

First, the point image response of the observation system will be described. The point image response appears by performing image reproduction processing on the received data obtained by observing one point scatterer on the ground surface with a radar. During the image reproduction processing, the signal from a certain point scatterer is not concentrated at one point but affects the surrounding area and the image is blurred. This blur phenomenon is called point image response.

In step S1108 of FIG. 11, the point image response adding means 20 after the geometric conversion uses the altitude data, the platform orbit data, and the sensor data as the basis.
The point image response when one point scatterer is observed is calculated.
This point image response is converted to a point image response on the ground range because it is a point image response on the slant range.

The point image response on the ground range and the RCS map obtained from the scattering of natural objects and artificial objects are convoluted to obtain an RCS map including the point image response.

In the case of radar images, RCS of points on the ground surface
The value is displayed at a position proportional to the distance between the radar and a point on the ground surface, as shown in FIG. 8C, and this display is called a slant range display. The point image response in the actual radar image is in principle convolved with the RCS map of this slant range display.

On the other hand, as shown in FIG. 8 (b), a display of a point on the ground surface at the position of the distance (ground range distance) on the ground surface is called a ground range display. After geometrically converting the point image response on the slant range into the point image response on the ground range, convolution is performed on the RCS map on the ground range.

The convolution calculation is performed by the following equation (1).

[0078]   G (m, n) = ∬M (p, q) H (m−p, n−q) dpdq                                                     ... (1)

In the equation (1), M (m, n) is RC
The S map, H (m, n), shows the point image response.

The RCS map after the addition of the point image response is output to the simulated radar image storage area D19 as a simulated radar image, and the processing routine of FIG. 11 ends.

As described above, by adding the point image response of the observation system similar to the image actually observed by the radar,
A simulated radar image closer to an actual radar image can be created, and the simulation accuracy of the radar image can be improved.

Also, including the point spread response of the observation system, at the same time,
It is possible to obtain a simulated radar image in which the geometric distortion caused by the radar observing the uneven ground surface is corrected.

Embodiment 5. In the third embodiment, geometric distortion is added to the RCS map, and point image response is added in the fourth embodiment. However, both geometric distortion and point image response may be added.

FIG. 12 is a configuration diagram showing a fifth embodiment of the present invention. In FIG. 12, the same components as those described above (see FIGS. 1, 3, 6, and 10) are designated by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 12, the radar image simulator is
The RCS map is provided with a point image response adding means 10 for convoluting the point image response and a simulated radar image storage area E21 for storing a simulated radar image to which geometric distortion and point image response are added.

FIG. 13 is a flow chart showing the operation according to the fifth embodiment of the present invention. Note that steps S1301 to S1307 and step S13 in FIG.
08 indicates steps S401 to S407 in FIG.
This corresponds to step S708 in FIG. 7, and detailed description thereof will be omitted.

Steps S1301 to S1307
In the above, the RCS map creating means 8 and the artificial target adding means 11 calculate the RCS value in consideration of the scattering in the natural object and the artificial object, and create the RCS map in which the RCS value corresponding to each mesh is plotted.

In step S1308, the geometric distortion adding means 9 calculates the geometric distortion based on the altitude data, the platform trajectory data, and the sensor data, and the RCS value is calculated at the position (each mesh) in consideration of the geometric distortion. Plot.

In step S1309, the point image response adding means 10 calculates the point image response based on the altitude data, the platform trajectory data, and the sensor data, and the equation (1) described above (see Embodiment 4) is used. )On the basis of,
The point image response and the RCS map to which the geometric distortion is added are convolutionally calculated to obtain an RCS map including the point image response.

In the equation (1), M (m, n)
Indicates an RCS map to which geometric distortion is added, and H (m, n) indicates a point image response.

Then, the RCS map to which the geometric distortion and the point image response are added is output to the simulated radar image storage area E21 as a simulated radar image, and the processing routine of FIG. 13 ends.

As described above, by adding the geometric distortion and the point image response similar to those of the actual radar image to the RCS map, an image similar to the radar image actually observed by the radar can be obtained. The simulation accuracy of the radar image can be improved.

Sixth Embodiment In addition, although the land use data and the incident angle data are provided as the parameters of the RCS database in the fifth embodiment, the frequency and the polarization may be further added to the parameters.

FIG. 14 is a configuration diagram showing a sixth embodiment of the present invention. 14, the same components as those described above (see FIGS. 1, 3, 6, 10, and 12) are designated by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 14, in addition to land use data and incident angle data, which are parameters of the RCS database 5, parameters of microwave frequency and polarization are added, and the RCS database 5 is expanded to include parameters. Extended RCS database 15 that stores the corresponding RCS values
And an extended RCS map creating means 68 for creating an RCS map using the extended database.

Further, the extended RCS map creating means 68 is
In addition to the incident angle calculator 6 and the table look-up device 7 described above (see FIGS. 1, 3, 6, 10, and 12),
A database selector 64 that refers to the extended RCS database based on specifications such as frequency and polarization is provided.

Next, the operation of the sixth embodiment of the present invention will be described. FIG. 15 is a flow chart for explaining the operation according to the sixth embodiment of the present invention. Note that steps S1501 to S1503 and step S150 in FIG.
1505 to step S1508, step S1509,
Step S1510 is step S401 to step S403, step S404 to step S407 of FIG.
Step S708 of FIG. 7 and step S1309 of FIG.
The detailed description is omitted.

In step S1503, the incident angle calculator 6 of the expanded RCS map creating means 68, based on the altitude data of the target area and the orbit data of the platform,
The positional relationship between the ground surface and the radar is calculated. Then, based on this positional relationship and the microwave irradiation angle data included in the sensor data, the incident angle of the microwave on the ground surface is calculated.

In step S1504, the database selector 68 uses the parameters such as the microwave frequency used by the radar and the specifications such as polarization as parameters.
The CS database 15 is referred to and the corresponding RCS data is selected.

[0100] In step S1505, the table lookup unit 7 uses the selected RCS data as parameters with the microwave incident angle on the ground surface and the land use data on the ground surface as parameters.
The database 15 is referenced and the corresponding RCS value is acquired.

Steps S1506 to S1508
In, the artifact target adding means 11 calculates the RCS value in consideration of the scattering in the artifact.

In this way, the extended RCS map creating means 8
The artificial object target adding unit 11 calculates the RCS value in consideration of the scattering in the natural object and the artificial object, and creates the RCS map in which the RCS value corresponding to each mesh is plotted.

In step S1509, the geometric distortion adding means 9 calculates the geometric distortion based on the altitude data, the platform trajectory data, and the sensor data, and the RCS is set at the position (each mesh) in consideration of the geometric distortion.
Plot the values.

In step S1510, the point image response adding means 10 calculates a point image response based on the altitude data, the platform trajectory data, and the sensor data, and adds this point image response and geometric distortion. The obtained RCS map is subjected to a convolution calculation to obtain a RCS map including a point image response in addition to the geometric distortion.

Then, the RCS map to which the geometric distortion and the point image response are added is output to the simulated radar image storage area E21 as a simulated radar image, and the processing routine of FIG. 15 is terminated.

As described above, the extended RCS database 1
In addition to the land use data and incident angle data, the parameters of frequency data and polarization are added to the parameter of No. 5, so that radar images with different frequencies and polarizations can be simulated. Can be improved.

[0107]

As described above, according to the present invention, a trajectory database that stores trajectory data indicating trajectory information of a radar-equipped moving body and sensor data indicating specifications of sensors mounted on the radar are stored. The sensor database, the ground surface of the observation area is divided into predetermined areas, and the altitude database that stores the altitude data that indicates the altitude information of each divided area, and the covering data that indicates the covering information of the ground surface in each divided area are stored. When the radar irradiates the ground surface in each of the divided areas with the first radio wave, the intensity of the second radio wave received by the radar can be determined by scattering the first radio wave on the ground surface. Based on the RCS database that stores the backscattering cross-section values shown, and orbital data, sensor data, elevation data, and coverage data, Since the RCS map creating means for creating the RCS map showing the distribution of the backscattering cross-sectional area values in a two-dimensional manner is provided, the radar image can be simulated at a high speed to obtain a wide range simulated radar image. There is an effect that a radar image simulating device capable of improving the simulation accuracy can be obtained.

Further, according to the present invention, the RCS map creating means includes an incident angle calculator for calculating the incident angle of the first radio wave based on the orbit data, the sensor data and the altitude data, and the incident angle and the covering data. Based on the RCS database, a table lookup device for obtaining the backscattering cross-sectional area value corresponding to each divided region is provided, so that the radar image simulation can be performed at high speed to obtain a wide range simulated radar image. There is an effect that a radar image simulation device capable of performing the above can be obtained.

Further, according to the present invention, the structure database of the artifact which stores the structure data of the three-dimensional shape of the artifact existing on the ground surface of each divided area and the position information of the artifact and the moving body are shown. The backscattering cross-sectional area value when the first radio wave is incident on the artifact is calculated based on the position database that stores the position data and the structure data and the position data, and the backscattering cross-sectional area value corresponding to each divided area where the artifact exists Since the artificial object target adding means for adding the backscattering cross-sectional area value is provided at the position of the RCS map, the radar image can be simulated in the presence of the artificial object, and the radar image simulation accuracy can be improved. There is an effect that an image simulation device can be obtained.

Further, according to the present invention, based on the orbit data, the sensor data and the altitude data, the first positional relationship of the ground surface obtained by observing the observation target area with the radar and the observation on the ground surface are performed. Geometric distortion indicating the deviation of the two-dimensional positional relationship between the obtained ground surface and the second positional relationship is calculated, and geometric distortion is added to rearrange the backscattering cross-sectional area value in the RCS map based on the geometric distortion. Since the means is provided, there is an effect that a radar image simulation device capable of improving the simulation accuracy of the radar image can be obtained.

Further, according to the present invention, the point image response in the radar image obtained by the radar observation is calculated based on the orbit data, the sensor data and the altitude data, and the point image response and the RCS map are convoluted. Since the point image response adding means for adding the point image response to the RCS map is provided,
There is an effect that a simulated radar image that is close to an actual radar image can be created, and a radar image simulation device that can improve the simulation accuracy of the radar image can be obtained.

Further, according to the present invention, the RCS database includes the coverage data, the incident angle of the first radio wave, and the first radio wave.
Since it is composed of the extended RCS database that stores the backscattering cross-sectional area value using the polarization of the radio wave and the frequency of the first radio wave as parameters, it is possible to simulate radar images of different frequencies and polarizations. There is an effect that a radar image simulation device capable of improving the simulation accuracy of the radar image can be obtained.

[Brief description of drawings]

FIG. 1 is a block configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a flowchart showing an operation according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing a second embodiment of the present invention.

FIG. 4 is a flowchart showing an operation according to the second embodiment of the present invention.

FIG. 5 is an explanatory diagram illustrating an operation according to the second embodiment of the present invention.

FIG. 6 is a block diagram showing a third embodiment of the present invention.

FIG. 7 is a flowchart showing an operation according to the third embodiment of the present invention.

FIG. 8 is an explanatory diagram illustrating an operation according to the third embodiment of the present invention.

FIG. 9 is an explanatory diagram illustrating an operation according to the third embodiment of the present invention.

FIG. 10 is a block diagram showing a fourth embodiment of the present invention.

FIG. 11 is a flowchart showing an operation according to the fourth embodiment of the present invention.

FIG. 12 is a block diagram showing a fifth embodiment of the present invention.

FIG. 13 is a flowchart showing an operation according to the fifth embodiment of the present invention.

FIG. 14 is a block diagram showing a sixth embodiment of the present invention.

FIG. 15 is a flowchart showing an operation according to the sixth embodiment of the present invention.

FIG. 16 is a block diagram showing a conventional radar image simulation device.

FIG. 17 is a flowchart showing the operation of a conventional radar image simulation device.

FIG. 18 is an explanatory diagram illustrating an operation of a conventional radar image simulation device.

[Explanation of symbols]

1 elevation database, 2 platform orbit database, 3 sensor database, 4 land use database, 5 RCS database, 6 incident angle calculator, 7 table lookup device, 8 RCS map creating means, 9 geometric distortion adding means, 10 point image Response adding means, 11 Artificial target adding means, 12 Artificial structure database, 13 Artificial position database, 14
Simulated radar image storage area A, 15 Extended RCS database, 17 Simulated radar image storage area B, 18 Simulated radar image storage area C, 19 Simulated radar image storage area D, 20 Point image response adding means after geometric conversion, 21
Simulated radar image storage area E, 64 database selector, 68 extended RCS map creation means.

Continued front page    (72) Inventor Masafumi Iwamoto             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. (72) Inventor Tetsuro Kirimoto             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. F-term (reference) 5J070 AJ14 AK22

Claims (6)

[Claims] 1. A trajectory database for storing orbital data indicating orbital information of a moving body equipped with a radar, a sensor database for storing sensor data indicating specifications of a sensor mounted on the radar, and a ground of an observation target area. A surface is divided by a predetermined area, an altitude database that stores altitude data indicating altitude information of each divided area, a land use database that stores covering data indicating covering information of the ground surface in each of the divided areas, and the radar Backscattering indicating the intensity of the second radio wave received by the radar when the first radio wave is scattered on the ground surface when the ground surface in each of the divided areas is irradiated with the first radio wave. An RCS database that stores cross-sectional area values, based on the orbital data, the sensor data, the elevation data, and the coverage data, RC that indicates the distribution of the backscatter cross section value in the serial observation target region two-dimensionally
A radar image simulation device, comprising: an RCS map creating means for creating an S map. 2. The RCS map creation means, an incident angle calculator that calculates an incident angle of the first radio wave based on the orbit data, the sensor data, and the altitude data, the incident angle and the coating. Based on the data, the RC
The radar image simulation device according to claim 1, further comprising a table lookup device that refers to an S database and acquires the backscattering cross-sectional area value corresponding to each of the divided areas. 3. A structure database of an artifact which stores structure data of a three-dimensional shape of an artifact existing on the ground surface of each of the divided areas, and position data indicating position information of the artifact and the moving body. A position database for storing, and based on the structure data and the position data, the backscattering cross-section value when the first radio wave is incident on the artifact is calculated, and each of the artifacts is present. The radar image simulation device according to claim 1 or 2, further comprising: an artifact target adding unit that adds the backscattering cross-sectional area value to a position of the RCS map corresponding to a divided region. 4. A first positional relationship of the ground surface obtained by observing the observation area with the radar based on the orbit data, the sensor data, and the altitude data,
Geometric distortion indicating a deviation of a two-dimensional positional relationship from the second positional relationship of the ground surface obtained by observing on the ground surface is calculated, and based on the geometric distortion, the backward direction in the RCS map. The radar image simulator according to claim 1, further comprising a geometric distortion adding unit that rearranges the scattering cross-section values. 5. A point image response in a radar image obtained by observing with the radar is calculated based on the orbit data, the sensor data, and the altitude data, and a convolution calculation of the point image response and the RCS map is performed. Then, the RCS
The radar image simulator according to any one of claims 1 to 4, further comprising point image response adding means for adding the point image response to a map. 6. The backscattering using the coverage data, the incident angle of the first radio wave, the polarization of the first radio wave, and the frequency of the first radio wave as parameters, in the RCS database. Extended RCS to store cross-sectional area value
The radar image simulation device according to claim 1, wherein the radar image simulation device comprises a database.