CN109711016B - Method and system for simulating imaging form and dynamically simulating two-sided SAR (synthetic Aperture Radar) satellite - Google Patents
Method and system for simulating imaging form and dynamically simulating two-sided SAR (synthetic Aperture Radar) satellite Download PDFInfo
- Publication number
- CN109711016B CN109711016B CN201811536014.XA CN201811536014A CN109711016B CN 109711016 B CN109711016 B CN 109711016B CN 201811536014 A CN201811536014 A CN 201811536014A CN 109711016 B CN109711016 B CN 109711016B
- Authority
- CN
- China
- Prior art keywords
- satellite
- cone
- tan
- points
- sar
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Landscapes
- Radar Systems Or Details Thereof (AREA)
- Image Processing (AREA)
Abstract
The invention discloses a method and a system for simulating imaging morphology and dynamically simulating a bilateral SAR satelliteThe specific imaging modality types of (1) specifically include: calculating f (x, y) ═ a1+a2*x+a3*y+a4*x2+a5X, wherein when x is tan (minimum elevation), the value obtained by calculating f (x, y) is f1When x is tan (maximum elevation), the value obtained by calculating f (x, y) is f2According to tan (forward exception) and f2、f1Determining the image form according to the size relationship; and finally, performing different simulations on different types of image forms according to the types of the imaging forms of the bilateral SAR satellites obtained through judgment. The method can effectively simulate the imaging form of the SAR satellite scanning area at two sides, and has good simulation effect and high response speed.
Description
Technical Field
The invention relates to the field of subject application of aerospace, earth information science and technology and the like, in particular to a method and a system for simulating imaging forms and dynamically simulating bilateral SAR satellites.
Background
In the current earth observation application of the remote sensing satellite, the remote sensing satellite provided with the SAR sensor is widely applied to disaster monitoring, environment monitoring, ocean monitoring, resource exploration, crop estimation, surveying and mapping and military affairs due to the characteristics of all-time and all-weather and certain ground surface penetrating capability, and is also valued by all countries in the world, so the imaging form of the SAR sensor needs to be further researched and developed. Compared with remote sensing satellites such as optics and electronics, the sensor form style of the SAR satellite is the most complex at most, and how to disclose the imaging form simulation method of the SAR satellite is not disclosed in the prior art, so that how to simulate the imaging form of the SAR satellite needs to be further developed and perfected urgently.
Disclosure of Invention
The invention aims to solve the technical problems that in the prior art, SAR satellites are multiple and complex in sensor forms, and imaging form simulation of SAR satellites is difficult to realize, and provides a method and a system for imaging form simulation and dynamic simulation of double-sided SAR satellites.
According to one aspect of the present invention, the technical solution adopted by the present invention to solve the technical problem is: a bilateral SAR satellite imaging morphological simulation method is constructed, and comprises the following steps:
s1, judging the specific imaging form type of the SAR satellite according to the given sensor parameters of the SAR satellite, wherein the judging method comprises the following steps:
s11, calculating f (x, y) ═ a1+a2*x+a3*y+a4*x2+a5X; wherein, y is the height from the satellite point to the ground point, the unit is kilometer, and the value f obtained by calculating f (x, y) when x is tan (minimum elevation) is obtained1When x is tan (maximum elevation), the value obtained by calculating f (x, y) is f2(ii) a In the formula, a1To a5Is a preset value, a1＝0.1729±5％，a2＝0.7444±5％，a3＝0.0002576±5％，a4＝0.07817±5％，a5＝0.07817±5％；
S12, judging whether tan (forward exception)>＝f2When the two-sided Sar satellite imaging modality is the two-leaf modality, when tan (forward exception)<＝f1When the imaging form of the two-sided Sar satellite is concentric, when f1<tan(forward exclusion)<f2Meanwhile, the imaging form of the Sar satellites on two sides is an ideal form;
wherein, minimum elevation and maximum elevation respectively represent the minimum elevation and the maximum elevation, and forward exception represents the along-track angle;
and S2, performing different simulations on different types of image forms according to the judged types of the imaging forms of the double-sided SAR satellite.
Further, in the simulation method of the bilateral SAR satellite imaging modality of the present invention, in the step S2, the simulation of the concentric circle modality includes the steps of:
s211, determining the opening angles of the tops of the inner cone and the outer cone according to minium elevation and maximum elevation respectively; wherein, the vertex of the cone is the position of the satellite;
s212, setting the height of the cone as the current height k of the satellite0Multiple, so that the inner and outer conical cones will intersect the earth;
s213, rendering the earth, the inner cone and the outer cone in sequence to enable the inner cone and the outer cone to be invisible and eliminated by the shielding part of the earth sphere, and accordingly obtaining the three-dimensional concentric circle form of the bilateral SAR satellite.
Further, in the simulation method of the imaging modality of the bilateral SAR satellite of the present invention, in step S2, the simulation of the biplate modality is a simulation of the imaging modality of two unilateral SAR satellites, and the simulation of the imaging modality of each unilateral SAR satellite includes the following steps:
s221, respectively calculating boundaries of an inner circle and an outer circle according to the minimum clock angle and the maximum clock angle, and respectively and uniformly taking out N points in the boundaries to form a 2N-sided polygon serving as a fan ring; wherein N is a positive integer greater than or equal to 3; the coordinate calculation formula of each point in the satellite observation coordinate system is as follows:
for points on the outer circle of the sector ring:
x＝h*tan(outerhalfangle)*cos(minclockangle*(N-1-i)/(N-1)+i*maxclockangle/(N-1))；
y＝-h*tan(outerhalfangle)*sin(minclockangle*(N-1-i)/(N-1)+i*maxclockangle/(N-1))；
for points on the outer circle of the sector ring:
x＝h*tan(innerhalfangle)*cos(maxclockangle*(N-1-i)/(N-1)+i*minclockangle/(N-1))；
y＝-h*tan(innerhalfangle)*sin(maxclockangle*(N-1-i)/(N-1)+i*minclockangle/(N-1))；
wherein h represents the height of the satellite from the ground0Outerhalfang and innerhalfang respectively represent half of the included angle of the outer cone and half of the included angle of the inner cone, minicrockangle and maxcrockangle respectively represent the minimum clock angle and the maximum clock angle, i is 0,10Is a constant greater than 1; wherein, for the right side of the satellite heading: the minicloskangle value is forward exception, the mxclockkangle value is 180-forward exception, for the left side of the satellite advancing direction, the minicloskangle value is-forward exception, and the maxcloskangle value is forward exception-180;
s222, transforming the 2N points and the coordinate points of the satellite from a satellite observation coordinate system to a geocentric coordinate system, and intersecting connecting lines of the 2N points and the points of the satellite with an earth model to obtain a coordinate set of ground points after transformation;
s223, respectively taking out two adjacent points from the obtained ground point coordinate set to form a triangular surface with a coordinate point of the satellite;
s224, drawing the combination of the triangular surfaces to obtain the three-dimensional shape simulation of the unilateral SAR satellite.
Further, in the simulation method of the bilateral SAR satellite imaging modality of the present invention, in the step S2, the simulation of the ideal modality includes the following steps:
s231, bottom surface of image form projected on earth: comprises an inner cone projection, an outer cone projection and an intersection line projection of an oblique cone and the outer cone; wherein, the vertex of the cone is the position of the satellite, and the intersecting line of the oblique cone and the external cone is a hyperbola;
s232, dispersing the projection circle of the outer cone on the earth according to the obtained outer cone, wherein 2N points are adopted for approximation during dispersion, and N is a positive integer greater than 1; the coordinates of the discrete points are calculated by the following formula:
x＝r*cos(i*π/N)，
y＝r*sin(i*π/N)；
wherein r is the radius of the projection circle, i is the serial number of the discrete point, and i is 0,1, …, 2N-1;
s233, when the 2N points fall in (F1, F2) or (G1, G2), using points on the hyperbola instead of discrete points; here, when the discrete point is located in (F1, F2) or (G1, G2), it means that the abscissa of the discrete point is located between the abscissas of F1 and F2 or between the abscissas of (G1, G2).
And S234, respectively connecting the 2N points obtained in the step S232 with points where the satellites are located, respectively intersecting the obtained straight lines with the spherical surface of the earth to obtain 2N ground points, respectively forming triangular surfaces with the vertexes where the satellites are located by the ground points in a pairwise manner according to an adjacent sequence, respectively rendering the triangular surfaces, and combining the triangular surfaces with an internal cone to obtain the final three-dimensional simulation of the image morphology.
Further, in the bilateral SAR satellite imaging modality simulation method of the present invention, the hyperbola is:
wherein a ═ h2/((tan(θ)+tan(α)-tan(θ1))*(tan(θ)+tan(α)-tan(θ1)))，
b＝(h2*(-2*(cos(θ)-cos(θ1))-(cos(θ)-cos(θ1))2))/((1+cos(θ)-cos(θ1))2*(tan(α)+tan(θ)-tan(θ1))2-tan2(α)；P1And P2The highest point of intersection of the front cone and the rear cone with the outer cone is P1And P2The projection with the bottom surface is respectively K1And K2P on the left and right sides in the direction of satellite advance1、P2Projecting the light beam on the ground to obtain the intersection point F of the bottom surfaces of the front cone, the rear cone and the external cone1、F2、G1、G2(ii) a Wherein, P1、K1A point in front of the satellite, P2、K2The point behind the satellite is theta, the included angle between the connecting line of P2 and the center of the bottom surface of the large cone and the ground is theta, α refers to the bottom angle of the large cone, and theta is theta1Means minimum elevation, theta2Means maximum elevation, c ═ h, h represents height k of satellite from ground0，k0Is a constant greater than 1; that the discrete points are located in (F1, F2) or (G1, G2) means that the abscissa of the discrete point is located
Within the range.
Further, in the simulation method of the dual-side SAR satellite imaging modality of the present invention, in step S231, the obtaining of the internal cone projection and the external cone projection includes the following steps:
s2311, determining the opening angles of the tops of the inner cone and the outer cone according to minium elevation and maximum elevation respectively; wherein, the vertex of the cone is the position of the satellite;
s2312, setting the height of the cone as k of the current satellite height0And multiplying the inner and outer cones to intersect with the earth, wherein the intersection line is the inner cone projection and the outer cone projection.
Further, the method for simulating the imaging form of the bilateral SAR satellite further comprises two-dimensional simulation of the imaging form, wherein the two-dimensional simulation comprises the steps of converting coordinates of points in an intersection line of a cone and the ground into longitudes and latitudes, and sequentially connecting the points of the longitudes and latitudes into polygons in the projection of a two-dimensional map of the earth, so that the two-dimensional form simulation is obtained.
According to another aspect of the invention, in order to solve the technical problem, the invention further provides a double-sided SAR satellite imaging form simulation system, and the double-sided SAR satellite imaging form simulation method is adopted to simulate the double-sided SAR satellite imaging form. /
According to another aspect of the present invention, to solve the technical problem, the present invention further provides a method for dynamically simulating a bilateral SAR satellite imaging modality, comprising the following steps:
a1, simulating the imaging form of the double-sided SAR satellite according to the simulation method of the imaging form of the double-sided SAR satellite at the beginning time when the satellite is in a static state;
a2, sequentially mapping to real time according to the simulation refreshing frequency when the satellite moves;
a3, calculating an attitude transformation matrix of the satellite in the real time;
a4, multiplying the three-dimensional form entity simulated by the starting time simulation by a transformation matrix to obtain a new three-dimensional form, thereby obtaining the position and the attitude of the satellite at the current moment;
a5, taking a new three-dimensional bottom surface point set, and intersecting the new three-dimensional bottom surface point set with the earth to obtain a new bottom surface point set;
a5, constructing the three-dimensional and/or two-dimensional form by using the new set of bottom surface points.
According to the last aspect of the invention, in order to solve the technical problem, the invention also provides a bilateral SAR satellite imaging form dynamic simulation system, and the bilateral SAR satellite imaging form dynamic simulation is carried out by adopting the bilateral SAR satellite imaging form dynamic simulation method.
The imaging form simulation and dynamic simulation method and system of the double-side SAR satellite can effectively simulate the imaging form of the scanning area of the double-side SAR satellite, and have good simulation effect and high response speed.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a schematic diagram of a single-sided SAR satellite during scanning;
FIG. 2 is a schematic view of a ground fan ring during scanning by a single-sided SAR satellite;
FIG. 3 is a schematic diagram of a two-sided SAR satellite when scanning;
FIG. 4 is a schematic diagram of the front and back cones of a two-sided SAR satellite during scanning;
FIG. 5 is a schematic diagram of the ground area as scanned by a two-sided SAR satellite;
FIG. 6 is a flow chart of a bilateral SAR satellite imaging modality simulation method;
FIG. 7 is a schematic view of a scanning situation when a tilted cone is small when scanning is performed by a double-sided SAR satellite;
FIG. 8 is a schematic view of scanning of a double-sided SAR satellite in an ideal case;
FIG. 9 is a schematic view of a scanning situation when a tilted cone is large in scanning by a double-sided SAR satellite;
fig. 10 and 11 are schematic diagrams of 3D and 2D scenes of a dual-fan shape;
fig. 12 and 13 are schematic diagrams of concentric 3D and 2D scenes;
fig. 14 and 15 are schematic diagrams of 3D and 2D scenes in an ideal form;
FIG. 16 is a schematic view of the intersection of two cones with the ground;
FIG. 17 is a schematic cross-sectional view of a cone surface;
FIG. 18 is a schematic view of the intersection of the forward and aft cones with the large cone;
FIG. 19 is a schematic view of the intersection projection of the anterior-posterior cone with the large cone;
FIG. 20 is a schematic representation of points on a hyperbola instead of discrete points;
fig. 21 is a fan-ring coordinate solving diagram when a unilateral SAR satellite performs scanning.
Detailed Description
For a more clear understanding of the technical features, objects and effects of the present invention, embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
A single-sided SAR satellite typically performs a ground area scan in the following manner, as shown in fig. 1 below. The satellite moves forward along the direction of X, the ground area scanned by the instantaneous antenna is two concentric circles projected to the ground by cones made by taking the position point of the satellite as a vertex and being vertical to the direction of the subsatellite point, the included angle of the inner circular cone, namely the minimum altitude angle, is innerHalfAngle X2, the included angle of the outer circular cone, namely the maximum altitude angle, is the middle part (circular ring) of the outlerHalfAngle X2, the intersection part with the outer circular sector (maxcyclockangle-minclockangle, the sector part clamped by the maximum clock angle and the minimum clock angle, the circle center corresponding to the sector is the center of the orthographic projection of the satellite on the earth) is taken out from the circular ring, and the finally formed sector ring is the scanning area of the antenna on the earth as shown in the following figure 2.
Also for bi-directional SAR, there are projections of two cones (at the top included angles innerangle and outerangle, respectively) onto the ground, as shown in fig. 3. In contrast, the bi-directional sar takes the ground projection of the intersection of the front and back cones of the satellite heading direction and the two cones. The two cones at the front and back are shown in fig. 4 below. The resulting ground area (ideally) is shown in figure 5 below.
Referring to fig. 6, the double-sided SAR satellite imaging morphological simulation method includes the following steps:
and S1, judging the specific three-dimensional imaging form type of the SAR satellite according to the given sensor parameters of the SAR satellite.
As can be seen from the above-described principle of the bidirectional SAR imaging modality, there are three different SAR imaging modalities, which are different according to given angles (given parameters, three angle values are: outer cone (outer cone) elevation angle (minimum elevation), inner cone (inner cone) elevation angle (maximum elevation), and oblique cone opening angle (two angles of forward or aft inclination are generally equal).
When the flare angle (forward exclusion) of the oblique cone is small, the intersection of the oblique cone and the right outer cone falls completely within the outer cone profile, as shown in fig. 7. Ideally, only the upper half of the oblique cone intersects the external cone, as shown in FIG. 8. When the flare angle (forward exclusion) of the oblique cone is large, the projection of the intersection point of the oblique cone and the outer cone falls within the inner cone, as shown in fig. 9.
S11, it can be seen that the projection form of SAR is related to the minimum elevation, maximum elevation, and forward exception, and the determination formula is given by calculation as follows:
f(x,y)＝0.1729+0.7444*x+0.0002576*y+0.07817*x2+0.0782*x*x
in the formula, the value y is the satellite point-to-ground point height (SO in kilometers in the drawing), the value obtained by calculating f (x, y) when the value x is tan (minimum elevation) is f1, and the value obtained by calculating f (x, y) when the value x is tan (maximum elevation) is f 2.
S12, the following judgment is made: when tan (forward exception)>＝f2Meanwhile, the three-dimensional/two-dimensional imaging form of the Sar satellite is a two-leaf form, as shown in fig. 10 and 11. When tan (forward exception)<＝f1Meanwhile, the three-dimensional/two-dimensional imaging form of the Sar satellite presents a concentric circle form, as shown in fig. 12 and 13. When f is1<tan(forward exclusion)<f2Meanwhile, the three-dimensional/two-dimensional imaging modality of the Sar satellite presents an ideal modality, as shown in fig. 14 and fig. 15:
in step S2, the simulation of the concentric circle shape includes the steps of:
s211, determining the opening angles of the tops of the inner cone and the outer cone respectively according to the minimum elevation and the maximum elevation, wherein the vertex of the cone is the position of the satellite;
s212, setting the height of the cone as the current height k of the satellite0Multiple such that the inner and outer cones intersect the earth, k0Is a constant greater than 1, e.g. k01.5, as shown in fig. 16:
s213, rendering the earth (sphere) and the inner and outer cones in sequence, so that the parts of the inner and outer cones, which are shielded by the earth entity (sphere), are naturally eliminated due to invisibility, and the three-dimensional concentric circle form of the Sar satellite is obtained.
In step S2, the simulation of the biplate form is essentially the simulation of two cones, i.e. the combination of two single-sided SAR satellite imaging forms (one for each of the left and right sides), so the specific three-dimensional form simulation can refer to the simulation of the subsequent single-sided SAR satellite imaging form.
In step S2, the simulation of the ideal form includes the steps of:
s231, the bottom of the ideal-form sar three-dimensional body consists of three parts: internal cone projection, external cone projection, oblique cone and external cone section intersection line projection. Since the determination of the inner and outer cones can refer to the simulation of the imaging form of the subsequent unilateral SAR satellite, what needs to be determined first is the intersection line of the oblique cone and the outer cone and the union of the projection of the oblique cone and the outer cone.
Referring to fig. 17, since the intersection line of the two cones in this application case is a hyperbolic equation, only the point on the hyperbolic curve needs to be determined to solve the hyperbolic equation.
● let the hyperbolic equation be:
the coordinates of two points need to be determined to solve the equation. Get the front point P1And P2As in fig. 18.
As can be seen from FIG. 18, if the positive direction of the x-axis is taken out of the plane of the paper, P is1And P2The highest point of the front and back cones intersected with the big cone (namely the outer cone, and the other parts are also the same), and the projections with the bottom surface are respectively K1And K2The radius of the large cone
To obtain
From which P can be obtained1、P2、K1、K2The coordinates of (a).
P on the left and right sides of the satellite in the advancing direction1、P2Projected on the ground and projected on the ground, as shown in the following FIG. 19, the front and back cones intersect with the bottom surface of the big cone to obtain F1、F2、G1、G2The distances from the four intersection points to D are all the length of the large cone radius R. From this can be obtained F1、F2、G1、G2The coordinates of (a). Assume that the cone vertex coordinates are (0,0, 0). Then: c-h (likewise, h can be 1.5 times the height of the satellite from the satellite's nadir)
However, the angle theta is limited (theta)1、θ2Respectively correspond to f1And f2) And the value can not be obtained between 0 and 90 degrees, so that the value of the coordinates of the point is limited. Therefore, corrections are made so that the angle theta is at (theta)1、θ2) In the time of change, F1、F2、K1Can approach 0. With the denominator of the abscissa of the three points unchanged, we obtain the corrected coordinates as follows:
take two points k1,f1The hyperbolic equation can be solved.
a＝h2/((tan(θ)+tan(α)-tan(θ1))*(tan(θ)+tan(α)-tan(θ1)))
b＝(h2*(-2*(cos(θ)-cos(θ1))-(cos(θ)-cos(θ1))2))/((1+cos(θ)-cos(θ1))2
*(tan(α)+tan(θ)-tan(θ1))2-tan2(α)
Wherein, P1、K1A point in front of the satellite, P2、K2The point behind the satellite is theta, the included angle between the connecting line of P2 and the center of the bottom surface of the large cone and the ground is theta, α refers to the bottom angle of the large cone, and theta is theta1Is referred to as minimum elevation, theta2Referred to as maximum energy.
S231, from the above, first we can easily calculate the outer cone, and its base circle. By discretizing the ground circle, e.g. by approximating it with 32 points, the coordinates in this base circle can be calculated as follows: r is the radius of the bottom circle, i is the serial number of the discrete points i is 0,1
x＝r*cos(i*π/16)
y＝r*sin(i*π/16)
S233, the hyperbolic equation, and the coordinates of F1, F2, G1, and G2 have been found. Therefore, when some of the 32 points fall in (F1, F2) or (G1, G2), the corresponding points on the hyperbola are used instead, resulting in fig. 20. Wherein the discrete point located in (F1, F2) or (G1, G2) means that the discrete point isThe abscissa lies between the abscissas of F1 and F2 or (G1, G2), i.e. between the abscissas of (F1 and F2), i.e. between the (G1, G2)
Within the range.
And S234, respectively connecting the 32 points obtained in the last step with the vertexes where the satellites are located, respectively intersecting the obtained straight lines with the spherical surface of the earth to obtain 32 sar ground points, respectively forming triangular surfaces by pairwise points and the vertexes where the satellites are located, respectively rendering the triangular surfaces, and combining the triangular surfaces with the inner cone to obtain the final three-dimensional simulation of the image form.
Regarding the three-dimensional simulation of the imaging form of the unilateral SAR satellite, the method comprises the following steps:
s1, determining the fan-ring position of the unilateral SAR satellite: determining whether a fan ring appears on the left side or the right side of the satellite advancing direction according to the left side scanning or the right side scanning of the single-side SAR satellite, wherein the circle center position corresponding to the fan ring is the circle center corresponding to the fan and is the center of the orthographic projection of the satellite on the earth;
s2, calculating boundaries of the inner circle and the outer circle according to the minimum clock angle and the maximum clock angle, and uniformly taking out N points inside the boundaries to form a 2N-sided polygon as a fan ring, which may be referred to fig. 4 (taking right-side SAR as an example); wherein N is a positive integer greater than or equal to 3, in this embodiment N ═ 7; the coordinate calculation formula of each point in the satellite observation coordinate system (the origin is the point where the satellite is located, and the Z-axis points to the projection point of the satellite on the ground, i.e. the subsatellite point) is as follows:
for points on the outer circle of the sector ring:
x＝h*tan(outerhalfangle)*cos(minclockangle*(N-1-i)/(N-1)+i*maxclockangle/(N-1))；
y＝-h*tan(outerhalfangle)*sin(minclockangle*(N-1-i)/(N-1)+i*maxclockangle/(N-1))；
for points on the outer circle of the sector ring:
x＝h*tan(innerhalfangle)*cos(maxclockangle*(N-1-i)/(N-1)+i*minclockangle/(N-1))；
y＝-h*tan(innerhalfangle)*sin(maxclockangle*(N-1-i)/(N-1)+i*minclockangle/(N-1))；
wherein h represents the height of the satellite from the ground0Outerhalfang and innerhalfang respectively represent half of the included angle of the outer cone and half of the included angle of the inner cone, minicrockangle and maxcrockangle respectively represent the minimum clock angle and the maximum clock angle, i is 0,10Is a constant greater than 1 to ensure that the cone intersects the earth, e.g. k0＝1.5；
S3, transforming the 2N points and the coordinate points of the satellite from a satellite observation coordinate system to a geocentric coordinate system (namely transforming the coordinates of the 2N points and the points of the satellite obtained from the top from the satellite observation coordinate system to the geocentric coordinate system, wherein a transformation matrix of the transformation can be obtained, and is changed by rotating and translating, namely rotating the vector direction formed by the coordinates of the satellite in the geocentric coordinate system from the coordinates of the satellite in the geocentric coordinate system to the subsatellite point to the vertical upward (0,0,1) direction of the geocentric coordinate system), and obtaining a coordinate set of ground points by intersecting the connecting lines of the 2N points and the points of the satellite with an earth model after transformation;
s4, respectively extracting two adjacent points in the obtained ground point coordinate set to form a triangular surface with the coordinate point of the satellite;
and S5, drawing the combination of the triangular surfaces to obtain the three-dimensional shape simulation of the unilateral SAR satellite.
When two-dimensional simulation is performed, the coordinates of each point in the coordinate set in step S3 are converted into longitude and latitude, and the points of the longitude and latitude are sequentially connected into a polygon in the two-dimensional map projection of the earth, so that two-dimensional morphological simulation is obtained.
The invention also provides a bilateral SAR satellite imaging form simulation system, and because the satellite points are changed all the time and the postures of the satellites are changed constantly, the essence of the imaging form simulation of the SAR satellite during motion is to constantly adjust and simulate the two-three-dimensional imaging form of the SAR according to the track and posture change of the satellites. The method comprises the following steps:
a1, simulating two three-dimensional forms of the SAR satellite sensor at the starting time (in a static state).
A2, during movement, sequentially mapping to real time according to the simulation refresh frequency (1/60 seconds).
A3, calculating a satellite 4 x 4 transformation matrix in the real time.
A4, multiplying the three-dimensional form entity simulated by the starting time simulation by a transformation matrix (changing the satellite observation coordinate system to the transformation matrix of the geocentric coordinate system through the transformation matrix) to obtain a new three-dimensional form, thereby obtaining the position and the attitude of the satellite at the current moment; the three-dimensional entity refers to a coordinate point where the satellite is located and each vertex under the combined form of the triangular surface;
a5, extracting a new three-dimensional bottom point set (i.e. removing satellite points from the vertex set of the three-dimensional simulation entity), and then intersecting the new bottom point set with the earth to obtain a new bottom point set.
A6, constructing the three-dimensional and/or two-dimensional form by using the new set of bottom surface points.
While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (9)
1. A bilateral SAR satellite imaging morphological simulation method is characterized by comprising the following steps:
s1, judging the specific imaging form type of the SAR satellite according to the given sensor parameters of the SAR satellite, wherein the judging method comprises the following steps:
s11, calculating f (x, y) ═ a1+a2*x+a3*y+a4*x2+a5X; wherein, y is the height from the satellite point to the ground point, the unit is kilometer, and the value f obtained by calculating f (x, y) when x is tan (minimum elevation) is obtained1When x is tan (maximum elevation), the value obtained by calculating f (x, y) is f2(ii) a In the formula, a1To a5Is a preset value, a1＝0.1729±5％，a2＝0.7444±5％，a3＝0.0002576±5％，a4＝0.07817±5％，a5＝0.07817±5％；
S12, judging whether tan (forward exception)>＝f2When the two-sided Sar satellite imaging modality is the two-leaf modality, when tan (forward exception)<＝f1When the imaging form of the two-sided Sar satellite is concentric, when f1<tan(forward exclusion)<f2Meanwhile, the imaging form of the Sar satellites on two sides is an ideal form;
wherein, minimum elevation and maximum elevation respectively represent the minimum elevation and the maximum elevation, and forward exception represents the along-track angle;
and S2, performing different simulations on different types of image forms according to the judged types of the imaging forms of the double-sided SAR satellite.
2. The method for simulating the imaging modality of the bilateral SAR satellite according to claim 1, wherein in the step S2, the simulation of the concentric circle modality comprises the following steps:
s211, determining the opening angles of the tops of the inner cone and the outer cone according to minium elevation and maximum elevation respectively; wherein, the vertex of the cone is the position of the satellite;
s212, setting the height of the cone as the current height k of the satellite0Multiple such that the inner and outer cones intersect the earth, k0Is a constant greater than 1;
s213, rendering the earth, the inner cone and the outer cone in sequence to enable the inner cone and the outer cone to be invisible and eliminated by the shielding part of the earth sphere, and accordingly obtaining the three-dimensional concentric circle form of the bilateral SAR satellite.
3. The method for simulating the imaging modality of the bilateral SAR satellite according to claim 1, wherein in the step S2, the simulation of the biplate modality is a simulation of two unilateral SAR satellite imaging modalities, and the simulation of each unilateral SAR satellite imaging modality includes the following steps:
s221, respectively calculating boundaries of an inner circle and an outer circle according to the minimum clock angle and the maximum clock angle, and respectively and uniformly taking out N points in the boundaries to form a 2N-sided polygon serving as a fan ring; wherein N is a positive integer greater than or equal to 3; the coordinate calculation formula of each point in the satellite observation coordinate system is as follows:
for points on the outer circle of the sector ring:
x＝h*tan(outerhalfangle)*cos(minclockangle*(N-1-i)/(N-1)+i*maxclockangle/(N-1))；
y＝-h*tan(outerhalfangle)*sin(minclockangle*(N-1-i)/(N-1)+i*maxclockangle/(N-1))；
for points on the outer circle of the sector ring:
x＝h*tan(innerhalfangle)*cos(maxclockangle*(N-1-i)/(N-1)+i*minclockangle/(N-1))；
y＝-h*tan(innerhalfangle)*sin(maxclockangle*(N-1-i)/(N-1)+i*minclockangle/(N-1))；
wherein h represents the height of the satellite from the ground0Outerhalfang and innerhalfang respectively represent half of the included angle of the outer cone and half of the included angle of the inner cone, minicrockangle and maxcrockangle respectively represent the minimum clock angle and the maximum clock angle, i is 0,10Is a constant greater than 1; wherein, for the right side of the satellite heading: the minicloskangle value is forward exception, the mxclockkangle value is-forward exception and the maxcloskangle value is-forward exception-180 for the left side of the satellite advancing direction;
s222, transforming the 2N points and the coordinate points where the satellites are located from a satellite observation coordinate system to a geocentric coordinate system, and intersecting connecting lines of the 2N points and the points where the satellites are located with an earth model after transformation to obtain a coordinate set of ground points;
s223, respectively taking out two adjacent points from the obtained ground point coordinate set to form a triangular surface with a coordinate point of the satellite;
s224, drawing the combination of the triangular surfaces to obtain the three-dimensional shape simulation of the unilateral SAR satellite.
4. The bilateral SAR satellite imaging modality simulation method according to claim 1, wherein in the step S2, the simulation of the ideal modality comprises the following steps:
s231, bottom surface of image form projected on earth: comprises an inner cone projection, an outer cone projection and an intersection line projection of an oblique cone and the outer cone; wherein, the vertex of the cone is the position of the satellite, and the intersecting line of the oblique cone and the external cone is a hyperbola;
s232, dispersing the projection circle of the outer cone on the earth according to the obtained outer cone, wherein 2N points are adopted for approximation during dispersion, and N is a positive integer greater than 1; the coordinates of the discrete points are calculated by the following formula:
x＝r*cos(i*π/N)，
y＝r*sin(i*π/N)；
wherein r is the radius of the projection circle, i is the serial number of the discrete point, and i is 0,1, …, 2N-1;
s233, when the 2N points fall in (F1, F2) or (G1, G2), using points on the hyperbola instead of discrete points; wherein, when the discrete point is located in (F1, F2) or (G1, G2), it means that the abscissa of the discrete point is located between the abscissas of F1 and F2 or between the abscissas of (G1, G2);
s234, respectively connecting the 2N points obtained in the step S232 with points where satellites are located, respectively intersecting the obtained straight lines with the spherical surface of the earth to obtain 2N ground points, respectively forming triangular surfaces with the vertexes where the satellites are located by the ground points in a pairwise manner according to an adjacent sequence, respectively rendering the triangular surfaces, and then combining the triangular surfaces with an internal cone to obtain the final three-dimensional simulation of the image form;
the hyperbola is:
wherein a ═ h2/((tan(θ)+tan(α)-tan(θ1))*(tan(θ)+tan(α)-tan(θ1)))，
b＝(h2*(-2*(cos(θ)-cos(θ1))-(cos(θ)-cos(θ1))2))/((1+cos(θ)-cos(θ1))2*(tan(α)+tan(θ)-tan(θ1))2-tan2(α)；P1And P2The highest point of intersection of the front cone and the rear cone with the outer cone is P1And P2The projection with the bottom surface is respectively K1And K2P on the left and right sides in the direction of satellite advance1、P2Projecting the light beam on the ground to obtain the intersection point F of the bottom surfaces of the front cone, the rear cone and the external cone1、F2、G1、G2(ii) a Wherein, P1、K1A point in front of the satellite, P2、K2The point behind the satellite is theta, the included angle between the connecting line of P2 and the center of the bottom surface of the large cone and the ground is theta, α refers to the bottom angle of the large cone, and theta is theta1Means minimum elevation, theta2Means maximum elevation, c ═ h, h represents height k of satellite from ground0，k0Is a constant greater than 1; that the discrete points are located in (F1, F2) or (G1, G2) means that the abscissa of the discrete point is located
Within the range.
5. The simulation method of the imaging modality of the bilateral SAR satellite according to claim 4, wherein in the step S231, the obtaining of the internal cone projection and the external cone projection comprises the following steps:
s2311, determining the opening angles of the tops of the inner cone and the outer cone according to minium elevation and maximum elevation respectively; wherein, the vertex of the cone is the position of the satellite;
s2312, setting the height of the cone as k of the current satellite height0And multiplying the inner and outer cones to intersect with the earth, wherein the intersection line is the inner cone projection and the outer cone projection.
6. The bilateral SAR satellite imaging modality simulation method according to any one of claims 4 to 5, further comprising two-dimensional simulation of the imaging modality, comprising converting coordinates of points in the intersection of the cone and the ground into longitudes and latitudes, and connecting the longitudes and latitudes in turn into polygons in the two-dimensional map projection of the earth, thereby obtaining the two-dimensional modality simulation.
7. A simulation system of the imaging form of the bilateral SAR satellite is characterized in that the simulation method of the imaging form of the bilateral SAR satellite according to any one of claims 1 to 5 is adopted to simulate the imaging form of the bilateral SAR satellite.
8. A dynamic simulation method for bilateral SAR satellite imaging forms is characterized by comprising the following steps:
a1, simulating the imaging form of the bilateral SAR satellite according to the simulation method of the imaging form of the bilateral SAR satellite of any claim 1-5 when the satellite is in a static state at the starting time;
a2, sequentially mapping to real time according to the simulation refreshing frequency when the satellite moves;
a3, calculating an attitude transformation matrix of the satellite in the real time;
a4, multiplying the three-dimensional form entity simulated by the starting time simulation by a transformation matrix to obtain a new three-dimensional form, thereby obtaining the position and the attitude of the satellite at the current moment;
a5, taking a new three-dimensional bottom surface point set, and intersecting the new three-dimensional bottom surface point set with the earth to obtain a new bottom surface point set;
a5, constructing the three-dimensional and/or two-dimensional form by using the new set of bottom surface points.
9. A bilateral SAR satellite imaging modality dynamic simulation system is characterized in that the bilateral SAR satellite imaging modality dynamic simulation method is adopted to carry out bilateral SAR satellite imaging modality dynamic simulation according to the claim 8.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811536014.XA CN109711016B (en) | 2018-12-14 | 2018-12-14 | Method and system for simulating imaging form and dynamically simulating two-sided SAR (synthetic Aperture Radar) satellite |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811536014.XA CN109711016B (en) | 2018-12-14 | 2018-12-14 | Method and system for simulating imaging form and dynamically simulating two-sided SAR (synthetic Aperture Radar) satellite |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109711016A CN109711016A (en) | 2019-05-03 |
| CN109711016B true CN109711016B (en) | 2020-09-04 |
Family
ID=66256556
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201811536014.XA Expired - Fee Related CN109711016B (en) | 2018-12-14 | 2018-12-14 | Method and system for simulating imaging form and dynamically simulating two-sided SAR (synthetic Aperture Radar) satellite |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109711016B (en) |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102073035B (en) * | 2010-12-13 | 2012-10-10 | 中国人民解放军国防科学技术大学 | Method for evaluating simulation performance of spaceborne interferometric synthetic aperture radar system |
| CN105512479B (en) * | 2015-12-03 | 2018-09-14 | 中国地质大学（武汉） | A kind of evaluation method and device of more star earth observation mission planning algorithms |
| CN106054145B (en) * | 2016-05-19 | 2018-10-23 | 杭州电子科技大学 | A kind of scouting discrimination method of satellite-borne synthetic aperture radar operating mode |
| CN106408587B (en) * | 2016-09-19 | 2018-11-09 | 辽宁工程技术大学 | Regard SAR image segmentation method and device more |
| CN106767705B (en) * | 2016-11-22 | 2019-12-13 | 航天恒星科技有限公司 | Imaging attitude modeling method in optical remote sensing satellite point target observation task |
-
2018
- 2018-12-14 CN CN201811536014.XA patent/CN109711016B/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN109711016A (en) | 2019-05-03 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US20170221226A1 (en) | Camera calibration | |
| US11187790B2 (en) | Laser scanning system, laser scanning method, movable laser scanning system, and program | |
| EP1895472B1 (en) | System and method for 3D radar image rendering | |
| WO2015096806A1 (en) | Attitude determination, panoramic image generation and target recognition methods for intelligent machine | |
| US9709673B2 (en) | Method and system for rendering a synthetic aperture radar image | |
| CN109801374B (en) | Method, medium, and system for reconstructing three-dimensional model through multi-angle image set | |
| CN105869167A (en) | High-resolution depth map acquisition method based on active and passive fusion | |
| US20140125774A1 (en) | Apparatus for synthesizing three-dimensional images to visualize surroundings of vehicle and method thereof | |
| US7301497B2 (en) | Stereo display for position sensing systems | |
| CN107329116B (en) | Airborne radar three-dimensional motion scene display method | |
| CN112001926A (en) | RGBD multi-camera calibration method and system based on multi-dimensional semantic mapping and application | |
| CN110930508A (en) | Two-dimensional photoelectric video and three-dimensional scene fusion method | |
| Aykin et al. | On 3-D target reconstruction from multiple 2-D forward-scan sonar views | |
| US11704825B2 (en) | Method for acquiring distance from moving body to at least one object located in any direction of moving body by utilizing camera-view depth map and image processing device using the same | |
| CN109597074A (en) | A kind of SAR image geometry positional parameter bearing calibration and system | |
| US10664947B2 (en) | Image processing apparatus and image processing method to represent part of spherical image in planar image using equidistant cylindrical projection | |
| CN115690336A (en) | Satellite beam coverage area visualization method, server and storage medium | |
| CN114761997A (en) | Target detection method, terminal device and medium | |
| CN116051766A (en) | External planet surface environment reconstruction method based on nerve radiation field | |
| CN115023736A (en) | Method for measuring environmental topography | |
| Jones et al. | Marine vehicles simulated SAR imagery datasets generation | |
| CN109711016B (en) | Method and system for simulating imaging form and dynamically simulating two-sided SAR (synthetic Aperture Radar) satellite | |
| US20220070433A1 (en) | Method and apparatus for 3d reconstruction of planes perpendicular to ground | |
| CN112927294B (en) | Satellite orbit and attitude determination method based on single sensor | |
| CN109581374B (en) | Method and system for simulating imaging form and dynamic simulation of unilateral SAR (synthetic Aperture Radar) satellite |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| CB03 | Change of inventor or designer information |
Inventor after: Yu Xiangyu Inventor after: Duan Lequan Inventor after: Chen Xin Inventor before: Yu Xiangyu |
|
| CB03 | Change of inventor or designer information | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20200904 Termination date: 20211214 |
|
| CF01 | Termination of patent right due to non-payment of annual fee |