BeiDou + InSAR corner reflector deformation monitoring data fusion method and accuracy assessment method

Abstract

This application discloses a novel method for fusing deformation monitoring data from BeiDou and InSAR corner reflectors and a new method for accuracy evaluation. The method includes: establishing a local rectangular coordinate system with the corner reflector center as the origin; decomposing the BeiDou observation displacement vector into vertical and horizontal movement components; based on the superposition characteristics of the four quadrant vectors and the side-view geometry of the radar's ascending and descending orbits, calculating the total radar line-of-sight deformation of a single corner reflector; when the difference in the vertical movement component value obtained from the ascending and descending orbit observations is less than a given threshold, this result is used as a correction for the BeiDou vertical movement component; when both corner reflector locations have three-dimensional movement components, the relative vertical deformation of the two corner reflectors is calculated using the above method. This invention enables the deformation observation data obtained from BeiDou and InSAR corner reflectors—two different technologies—to be effectively complementary and evaluated, solving the problem that it is difficult to directly perform high-precision data fusion in the observation domain when corner reflectors and BeiDou are monitored side-by-side.

Description

Technical Field

[0001] This disclosure pertains to the field of satellite navigation and satellite remote sensing engineering applications, specifically involving a BeiDou + InSAR corner reflector deformation monitoring data fusion method and accuracy evaluation method, which realizes the fusion of observation value domains of BeiDou and SAR satellite remote sensing displacement monitoring data. Background Technology

[0002] Early high-precision deformation monitoring technologies employed traditional geodetic methods. Horizontal deformation monitoring primarily relied on total stations (base stations) and reflectors (monitoring stations), while vertical high-precision deformation monitoring relied mainly on leveling techniques. Although the specific locations monitored by these two technologies are not entirely consistent—for example, reflectors and total stations measure the axis of the forced centering device, while leveling typically uses leveling marks on the side or base of observation piers—the discrepancy in observation centers does not affect the accuracy of the monitoring results because deformation monitoring requires precision on the order of millimeters.

[0003] With the rise of global satellite navigation and positioning technology, the price of GNSS terminals has gradually decreased, enabling them to gradually replace traditional total stations and levels. Due to the symmetrical characteristics of GNSS antenna construction, after being fixed to the forced alignment axis of deformation monitoring, high-precision horizontal and vertical displacement monitoring can be achieved solely based on GNSS observations. Many studies show that when the nominal performance of GNSS terminal equipment and antennas reaches 1mm-level phase observation accuracy, their actual deformation monitoring accuracy is also close to the millimeter level. However, due to the influence of the troposphere, the accuracy of GNSS deformation monitoring results in the elevation direction is usually several times lower than that in the horizontal direction. Accurate deformation monitoring results can only be obtained after smoothing long-term time-series observations, which is a drawback for high-precision deformation monitoring applications.

[0004] Currently, with the application and popularization of InSAR technology, the corresponding high-precision deformation monitoring application of corner reflectors is also gradually emerging. Some literature has theoretically estimated that when the signal-to-clutter ratio of a corner reflector in SAR imagery reaches 25dB or higher, its vertical monitoring accuracy is better than 1mm. Therefore, without considering atmospheric errors, the vertical deformation results monitored by corner reflectors have a significant advantage over GNSS.

[0005] Current methods for fusing BeiDou and corner reflector deformation monitoring data typically involve calculating the BeiDou deformation monitoring results and then transforming them into the InSAR monitoring coordinate system using the geometric relationship of SAR side-view projection before performing the fusion calculation. Since InSAR monitoring results are one-dimensional deformation monitoring results along the radar line of sight, verifying the reliability of InSAR monitoring results and integrating them into BeiDou observations are current challenges. Existing literature ignores the north-south deformation component, only converting the east-west deformation amount according to the radar viewpoint direction. This approximate conversion affects the accuracy of corner reflector monitoring.

[0006] This invention provides a novel method for fusing InSAR monitoring results with BeiDou deformation results in the deformation observation domain. By analyzing the geometric observation conditions of the satellite's ascent and descent orbits, the deformation monitoring results of the artificial corner reflector under the left and right viewing conditions of the ascent and descent orbits are obtained, thereby providing high-quality fused observation values ​​for high-precision monitoring in the GNSS elevation direction. Summary of the Invention

[0007] To address the existing technical problems, the main objective of this invention is to provide a BeiDou + InSAR corner reflector deformation monitoring data fusion method and accuracy evaluation method. This method solves the problem that when corner reflectors and GNSS are monitored side-by-side, it is difficult to directly perform high-precision data fusion of the two deformation monitoring results in the observation domain. It also enables the deformation observation data obtained by GNSS and InSAR corner reflectors, two different technical means, to be well complementary and evaluated, and achieves accurate weighting and evaluation of redundant observation values.

[0008] An embodiment of the first aspect of the present invention provides a method for fusing BeiDou + InSAR corner reflector deformation monitoring data, comprising the following steps: establishing a local rectangular coordinate system with the center of the corner reflector as the origin; decomposing the relative displacement vector of the corner reflector observed by BeiDou into a vertical movement component and a horizontal movement component in the plane rectangular coordinate system; calculating the projection of the BeiDou vertical and horizontal movement components onto the deformation along the radar line of sight based on the side-looking geometry of the radar's ascent and descent rails; performing vector superposition based on the features of the four quadrants to obtain the total deformation along the radar line of sight retrieved by BeiDou; subtracting the corresponding BeiDou horizontal movement component projection from the deformation of the radar corner reflector to obtain the vertical deformation component monitored by the radar corner reflector; when the difference between the vertical movement component values ​​retrieved from the ascent and descent rail observations is less than a given threshold, this result is used as a correction for the GNSS vertical movement component. When both corner reflector locations have three-dimensional movement components, the vertical movement components of the two corner reflectors are calculated separately; when the difference between the two is less than a given threshold, this result is used to correct the GNSS baseline elevation difference between the two corner reflectors.

[0009] Optionally, a local rectangular coordinate system is established with the center of the corner reflector as the origin, and the relative displacement vector of the corner reflector observed by BeiDou is decomposed into a vertical movement component and a horizontal movement component in the plane rectangular coordinate system. This includes: obtaining the geographic coordinates of the BeiDou corner reflector; establishing a local rectangular coordinate system with the center point of the BeiDou corner reflector as the origin, the elevation direction as the vertical Z-axis, the north direction as the Y-axis, and the east direction as the X-axis; and projecting the three-dimensional movement vector obtained by BeiDou measurement onto the local rectangular coordinate system to obtain the vertical movement component and the horizontal movement component.

[0010] Optionally, the projections of the vertical and horizontal movement components onto the radar line-of-sight deformation are obtained based on the radar's elevating and lowering orbit side-looking geometry. Vector superposition is then performed based on the characteristics of the four quadrants to obtain the total deformation along the radar line-of-sight, including: obtaining the projection of the BeiDou horizontal movement component onto the radar's elevating orbit horizontal pointing line based on the radar's elevating orbit heading angle; obtaining the left and right vertical projections of the elevating orbit based on the left and right angles of incidence; obtaining the projection of the BeiDou horizontal movement component onto the radar's lowering orbit horizontal pointing line based on the radar's lowering orbit heading angle; obtaining the left and right vertical projections of the lowering orbit based on the left and right angles of incidence; calculating the corresponding radar line-of-sight deformation under left and right looking conditions based on the projection results of the horizontal deformation projection in the four quadrants and the radar incident angle conditions; and performing vector superposition of the horizontal and vertical deformation components along the radar line-of-sight based on the four quadrant conditions to obtain the total deformation along the radar line-of-sight retrieved by GNSS under elevating and lowering orbit left and right looking conditions.

[0011] Optionally, the vertical deformation component monitored by the radar is obtained by subtracting the corresponding BeiDou horizontal movement component projection from the total deformation of the line-of-sight observed by the radar, including: calculating the radar line-of-sight deformation of the BeiDou horizontal movement component based on the radar ascent / elevation heading angle and the local incident angle; subtracting the corresponding BeiDou horizontal movement component from the total deformation of the line-of-sight observed by the radar based on the vector superposition conditions corresponding to the left and right views and the four quadrants of the radar ascent, and obtaining the vertical deformation component monitored by the radar ascent; and subtracting the corresponding BeiDou horizontal movement component from the total deformation of the line-of-sight observed by the radar based on the vector superposition conditions corresponding to the left and right views and the four quadrants of the radar descent, and obtaining the vertical deformation component monitored by the radar descent.

[0012] Optionally, when the difference in the vertical motion component values ​​obtained from the observations of the ascending and descending rails is less than a given threshold, the result can be used as a correction for the GNSS vertical motion component, including: calculating the vertical deformation components observed by the left and right views of the ascending and descending rails respectively; when the difference between the ascending and descending rails is less than a given threshold, using the average value of the vertical deformation components obtained by the left and right views of the ascending and descending rails as a correction for the GNSS vertical motion component.

[0013] Optionally, when both corner reflectors measure the GNSS three-dimensional motion component, the vector superposition value of the radar line-of-sight deformation of the two corner reflectors is obtained using the above method. When the difference in the vertical motion component is less than a given threshold, the result can be used to correct the GNSS baseline elevation difference between the two corner reflectors. This includes: firstly, obtaining the vertical deformation components of the two corner reflectors and the monitored radar according to steps 2-3; secondly, performing vector superposition based on the direction of the two deformation component vectors and the radar ascent / descent conditions to obtain the vertical elevation difference between the two corner reflectors; and thirdly, determining whether the result can be used to correct the GNSS baseline elevation difference between the two corner reflectors based on whether the vertical elevation difference between the two corner reflectors exceeds a given threshold.

[0014] This invention also provides a method for evaluating the accuracy of BeiDou + InSAR corner reflector deformation monitoring data, comprising the following steps: evaluating the GNSS horizontal deformation monitoring accuracy by manually moving the corner reflector horizontally, and evaluating the radar corner reflector horizontal deformation monitoring accuracy based on SAR satellite geometric observation conditions; evaluating the GNSS vertical deformation monitoring accuracy by manually moving the corner reflector vertically, and evaluating the radar corner reflector vertical deformation monitoring accuracy based on SAR satellite geometric observation conditions; and obtaining the relative deformation monitoring results between any two points in the triangular network formed by BeiDou corner reflector observation points, and evaluating the GNSS baseline deformation monitoring accuracy and the corner reflector vertical deformation monitoring accuracy between the two points.

[0015] Optionally, the accuracy of GNSS horizontal deformation monitoring can be evaluated by manually moving the corner reflector horizontally, and the accuracy of radar corner reflector horizontal deformation monitoring can be evaluated based on SAR satellite geometric observation conditions, including: the manual horizontal movement of the corner reflector along the due east and due west directions should not exceed 1 / 2 of the radar wavelength; the difference between the horizontal displacement monitored by BeiDou and the model deformation can be calculated to evaluate the accuracy; and the horizontal displacement component value corresponding to the radar line-of-sight deformation can be calculated based on the radar rise and fall rail side-looking conditions to evaluate the accuracy.

[0016] Optionally, the accuracy of GNSS vertical deformation monitoring can be evaluated by manually moving the corner reflector vertically, and the accuracy of radar corner reflector vertical deformation monitoring can be evaluated based on SAR satellite geometric observation conditions, including: manually moving the corner reflector vertically up and down by no more than 1 / 2 of the radar wavelength; calculating the difference between the horizontal displacement monitored by BeiDou and the model deformation to evaluate the accuracy; and calculating the horizontal displacement component value corresponding to the radar line-of-sight deformation based on the radar rise and fall rail side-view conditions to evaluate the accuracy.

[0017] Optionally, based on the triangular network formed by the BeiDou corner reflector observation points, the relative deformation monitoring results of any two points in the network are obtained, and the accuracy of GNSS baseline deformation monitoring and vertical deformation monitoring of the corner reflectors between the two points is evaluated. This includes: calculating the artificially simulated horizontal and vertical displacement components of the two corner reflectors respectively; calculating the vector sum of the deformations of the two corner reflectors according to the vector direction of the line connecting the two corner reflectors; calculating the difference between the deformation vector monitored by BeiDou and the simulated deformation vector to evaluate the accuracy; and comparing the difference between the artificially simulated deformation vector sum of the two corner reflectors and the deformation vector along the radar line of sight to evaluate the accuracy.

[0018] Therefore, the present invention has at least the following beneficial effects:

[0019] This invention solves the technical problem of calculating the geometric projection function of deformation in the fusion of BeiDou and SAR corner reflector monitoring data. By decomposing the BeiDou deformation monitoring results into spatially orthogonal horizontal and vertical deformation components, a coordinate projection transformation method under radar side-looking conditions is proposed to calculate the projection results of these two components separately, achieving accurate differentiation between the BeiDou vertical and horizontal deformation components in the corner reflector deformation monitoring domain. Since the monitoring accuracy of the BeiDou horizontal monitoring component is much higher than that of the vertical component, the rigorous geometric transformation method based on this model results in extremely high accuracy for the decomposition and elimination of the BeiDou horizontal monitoring component under SAR side-looking conditions. This provides the possibility for high-precision elevation fusion of the elevation component in BeiDou deformation with SAR remote sensing monitoring results.

[0020] Another application area of ​​this invention is the accurate evaluation and verification of deformation monitoring accuracy of different SAR satellites. By using artificial high-precision horizontal and vertical moving corner reflectors, when the simulation effect of the deformation micro-motion process is better than 1mm, the corresponding ascending and descending orbit SAR satellite observation geometry can provide a reliable and effective technical method for evaluating GNSS deformation monitoring results with mm-level accuracy and the deformation monitoring accuracy of different SAR satellite interferometric phases.

[0021] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below.

[0023] Figure 1 This is a flowchart of a BeiDou + InSAR corner reflector deformation monitoring data fusion method provided according to an embodiment of this application.

[0024] Figure 2This is a schematic diagram of the three-dimensional decomposition projection of the right-view reflector deformation of the lifting rail according to an embodiment of this application.

[0025] Figure 3 This is a schematic diagram of the three-dimensional decomposition projection of the shape of the left-view reflector of the lifting rail according to an embodiment of this application.

[0026] Figure 4 This is a schematic diagram of the decomposition projection of the shape of the left and right view reflector of the lifting track according to the embodiments of this application.

[0027] Figure 5 This is a schematic diagram of the decomposition projection of the shape of the left and right viewing angle reflector according to an embodiment of this application.

[0028] Figure 6 This is a schematic diagram showing the decomposition of the four-quadrant BeiDou horizontal deformation components on the heading line according to the embodiments of this application.

[0029] Figure 7 This is a schematic diagram of the horizontal deformation components of the four-axis BeiDou system provided in the embodiments of this application on the heading line.

[0030] Figure 8 This is a flowchart of a method for evaluating the accuracy of deformation monitoring data of a BeiDou + InSAR corner reflector, according to an embodiment of this application.

[0031] Figure 9 This is a schematic diagram of the line-of-sight vector of a right-view reflector moving radar according to an embodiment of this application.

[0032] Figure 10 This is a schematic diagram of the line-of-sight vector of a right-view reflector mobile radar according to an embodiment of this application.

[0033] Figure 11 The results are the accuracy assessment results of BeiDou + InSAR horizontal displacement monitoring provided in the embodiments of this application.

[0034] Figure 12 The results are the accuracy assessment results of BeiDou + InSAR vertical displacement monitoring provided according to the embodiments of this application. Detailed Implementation

[0035] To illustrate the technical methods and implementation schemes of the present invention in detail, and to demonstrate the technical objectives, advantages and results that the present invention can achieve, the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0036] The following describes, with reference to the accompanying drawings, a BeiDou + InSAR corner reflector deformation monitoring data fusion method and accuracy evaluation method according to an embodiment of this application.

[0037] Example 1:

[0038] To address the problems mentioned in the background section, this application provides a BeiDou + InSAR corner reflector deformation monitoring data fusion method, in which:

[0039] Specifically, Figure 1 This is a flowchart of a BeiDou + InSAR corner reflector deformation monitoring data fusion method provided in an embodiment of this application.

[0040] like Figure 1 As shown, the BeiDou + InSAR corner reflector deformation monitoring data fusion method includes the following steps:

[0041] In step S1, the geographic coordinates of the Beidou angle reflector are obtained; a local rectangular coordinate system is established with the center point of the Beidou angle reflector as the origin, the elevation direction as the vertical Z-axis, the north direction as the Y-axis, and the east direction as the X-axis, as shown below. Figure 2 As shown; the three-dimensional movement vector obtained by BeiDou measurement Projecting onto a local rectangular coordinate system yields the vertical translation component. and horizontal translation component The horizontal component The projection in the east direction (X-axis) is The projection in the north direction (Y-axis) is .

[0042] In step S2, the projections of the vertical and horizontal movement components onto the radar line of sight are obtained based on the side-view geometry of the radar elevator rail. The total deformation along the radar line of sight is obtained by vector superposition based on the features of the four quadrants.

[0043] It is understandable that if Figure 2 The image shows the 3D deformation vector (located in the second horizontal quadrant) obtained by GNSS monitoring in the right-view mode of the ascending rail. The projection vector of this 3D deformation vector in the horizontal direction (east-west coordinate axis) is: We define it as the GNSS horizontal movement component; the projection of this three-dimensional deformation vector in the vertical direction is... We define it as the GNSS vertical movement component. For the right-looking trajectory of the ascending orbit, the projection of the vertical movement component onto the radar line of sight can be denoted as... The projection of the horizontal translation component onto the horizontal pointing line of the ascending orbit (we define the straight line perpendicular to the ascending orbit's heading and passing through the origin 0 as the horizontal pointing line of the ascending orbit) is: ,refer to Figure 4 As shown, it can be seen that The line-of-sight displacement when looking to the right during radar ascent is: The line-of-sight displacement to the right of the radar's ascent orbit is... .

[0044] Based on the radar's ascent heading angle, the projection of the BeiDou horizontal movement component onto the radar's horizontal pointing line is obtained. The specific calculation method is as follows:

[0045] according to Figure 2 The image shows the second quadrant where the deformation vector obtained from BeiDou monitoring is located, as well as the related satellite ascent and descent orbit heading angles. and angle of incidence , , , Angle information reveals the horizontal movement component of the BeiDou system. The projection of the horizontal pointing line of the radar's ascending trajectory can be calculated using the following formula:

[0046] ;

[0047] in, This is the projection of the BeiDou horizontal movement component under radar orbit raising and right-looking conditions. This is the projection of the BeiDou horizontal movement component under the radar's left-looking orbital ascent condition. For BeiDou horizontal movement components Azimuth in the second quadrant, The heading angle of the elevator rail. This refers to the radar's local side-looking tilt angle under right-looking conditions during ascent. This refers to the radar's local side-looking tilt angle under the condition of left-looking while in ascending orbit. From Figure 4 As can be seen, for the right-looking direction of the radar ascent orbit in the second quadrant, the deformation of the BeiDou horizontal movement component is defined as positive (i.e., close to the radar line of sight), while for the left-looking direction of the ascent orbit, the deformation is negative (i.e., away from the radar line of sight).

[0048] Based on the left and right view incident angles of the radar ascending orbit, the left-view vertical projection and the right-view vertical projection of the ascending orbit are calculated respectively. The specific calculation method is as follows:

[0049] according to Figure 4 The example shown illustrates the projection of the BeiDou vertical deformation component onto the right-looking orbit and the local incident angle under right-looking conditions. Similarly, the local angle of incidence under the conditions of projection on the right and left sides of the ascending orbit is related. The relevant information can be calculated using the following formula:

[0050] ;

[0051] in, This represents the projection of the vertical movement component of the BeiDou system under right-looking conditions during radar orbit ascent. This is the projection of the vertical movement component of BeiDou under the left-looking condition of radar orbit ascent. This refers to the radar's local side-looking tilt angle under right-looking conditions during ascent. This refers to the radar's local side-looking tilt angle under the left-looking condition of ascending orbit. From Figure 4 As can be seen from this, the projection of the BeiDou vertical movement component onto the radar's left and right views of the orbit ascent is either upward or downward, and is only affected by the local incident angle, and is unrelated to the radar's heading angle.

[0052] Based on the radar's reduced orbit heading angle, the projection of the BeiDou horizontal movement component onto the radar's reduced orbit horizontal pointing line is obtained. The specific calculation method is as follows:

[0053] It is understandable that if Figure 3 As shown, the image shows the 3D deformation vector (located in the second horizontal quadrant) obtained by GNSS monitoring in the left-view mode of the ascending rail. The projection vector of this 3D deformation vector in the horizontal direction (east-west coordinate axis) is... We define it as the GNSS horizontal movement component; the projection of this three-dimensional deformation vector in the vertical direction is... We define it as the GNSS vertical movement component. For a down-orbit left-look configuration, the projection of the vertical movement component onto the radar line of sight can be denoted as: The projection of the horizontal translation component onto the horizontal pointing line of the ascending orbit (we define the straight line perpendicular to the ascending orbit's heading and passing through the origin 0 as the horizontal pointing line of the ascending orbit) is: ,refer to Figure 5 The diagram shows the decomposition projection of the reflector's shape from the left and right viewing angles of the descending track. It can be seen that... The line-of-sight displacement when looking to the right during radar ascent is: The line-of-sight displacement to the right of the radar's ascent orbit is... .

[0054] according to Figure 3 The image shows the second quadrant where the deformation vector obtained from BeiDou monitoring is located, as well as the related satellite ascent and descent orbit heading angles. and local angle of incidence , , , Angular information, and combined with Figure 5 According to the geometric relationship, the horizontal movement component of Beidou can be determined. The projection of the radar's horizontal pointing line during its descent can be calculated using the following formula:

[0055] ;

[0056] in, This is the projection of the BeiDou horizontal movement component under radar-lowered right-look conditions. This is the projection of the BeiDou horizontal movement component under radar-lowered left-looking conditions. BeiDou horizontal movement component Azimuth in the second quadrant, The heading angle of the elevator rail. The local incident angle of the radar under the condition of right-looking orbit reduction. This is the local incident angle of the radar under the condition of reduced orbit and left look-ahead. From Figure 5 As can be seen, for the right-looking direction of the radar descent, the deformation of the BeiDou horizontal movement component in the second quadrant is defined as positive (i.e., close to the right-looking direction of the radar descent), while for the left-looking direction of the descent, the deformation is negative (i.e., far from the left-looking direction of the radar descent).

[0057] Based on the left and right view incident angles of the radar's reduced trajectory, the left-view vertical projection and the right-view vertical projection of the reduced trajectory are calculated separately. The specific calculation method is as follows:

[0058] according to Figure 5 The example shown illustrates that the projection of the BeiDou vertical deformation component onto the right-side view during orbit descent is related to the local incident angle. Similarly, the projection of the right-viewed object on the descending orbit is related to the local angle of incidence. The relevant information can be calculated using the following formula:

[0059] ;

[0060] in, This represents the projection of the vertical movement component of the BeiDou system under radar-lowered right-looking conditions. This is the projection of the vertical movement component of BeiDou under the left-looking condition of radar orbit ascent. The local incident angle of the radar under the condition of right-looking orbit reduction. This is the local incident angle of the radar under the condition of reduced orbit and left look-ahead. From Figure 4 As can be seen, the projection of the BeiDou vertical movement component onto the left and right viewing directions of the radar's orbit descent is either upward or downward, and is only affected by the local incident angle, and is unrelated to the radar's heading angle.

[0061] Based on the projection results of the horizontal deformation projection in the four quadrants under the radar rising and falling rail conditions and the radar incident angle conditions, the radar line-of-sight deformation under the corresponding left and right looking conditions is calculated as follows:

[0062] Figure 6 The calculation angles of the BeiDou horizontal deformation component projected onto the radar flight path in the four quadrants are given. Referring to formulas 1 to 4, the deformation of the BeiDou horizontal deformation projection in each quadrant as it is projected onto the radar line of sight can be obtained.

[0063] Based on the four quadrant conditions, the horizontal and vertical deformation components are vector-superimposed along the radar line of sight to calculate the total deformation along the radar line of sight under the left and right looking conditions of the elevator and ascent rails. (Reference) Figure 4 and Figure 5 The method for calculating the positive and negative values ​​of the horizontal deformation in the radar line of sight is as follows: the direction closer to the radar antenna is positive, and the direction farther away from the radar antenna is negative.

[0064] Based on the four quadrant conditions, the horizontal and vertical deformation components are vector-superimposed in the radar line-of-sight direction to obtain the total deformation in the radar line-of-sight direction under the left and right look conditions of the elevator rail.

[0065] If the vertical deformation component of BeiDou is positive upwards and negative downwards on the vertical coordinate axis, similarly, we define deformation towards the radar antenna as positive and deformation away from the radar antenna as negative. Then, the positive and negative directions of BeiDou's vertical deformation are independent of the four horizontal quadrants, and only depend on its direction on the vertical coordinate axis.

[0066] Based on this, the projections of BeiDou's horizontal deformation and vertical deformation onto the radar line of sight can be vector-superimposed to obtain the total deformation of the radar line of sight under the left and right look conditions of the ascent and descent orbits.

[0067] Understandably, because BeiDou can obtain three-dimensional deformation data, while SAR can only obtain one-dimensional deformation data along the line of sight, the derivation in step S2 is a forward modeling process, with clear and accurate geometric relationships. Step S2 shows that if the GNSS horizontal deformation component can be accurately eliminated from the radar line-of-sight deformation, the corresponding GNSS vertical deformation component can be obtained. Considering that the accuracy of vertical monitoring in BeiDou deformation monitoring is usually lower than that of horizontal monitoring, it is reasonable to use the method of subtracting the BeiDou horizontal deformation component to obtain the corner reflector vertical deformation monitoring results, and then use this to correct the BeiDou vertical deformation results.

[0068] In step S3, the corresponding BeiDou horizontal displacement component projection is subtracted from the radar corner reflector deformation to obtain the vertical deformation component monitored by the radar. Since the horizontal displacement measured by GNSS in typical precision GNSS deformation monitoring systems is relatively accurate, achieving an accuracy of over 1mm in a small range, but its vertical accuracy is lower, this step eliminates the horizontal deformation of the corner reflector along the radar line of sight from the radar-observed deformation to obtain the vertical deformation measured by the radar. The specific calculation method is as follows:

[0069] In some examples, the radar line-of-sight deformation of the BeiDou horizontal movement component is calculated based on the radar elevation and yaw angles and the local incident angle. Figure 2 Taking the deformation vector R detected by GNSS as an example, its projection in the vertical direction is: The projection onto the horizontal plane (horizontal deformation component) is Located in the second quadrant of the horizontal plane, with the right-looking orbit, the horizontal deformation component... The projection on the horizontal pointing line of the ascending orbit is According to the local angle of incidence when viewed from the right of the ascending orbit ,refer to Figure 4The deformation along the right-looking radar line of sight in the ascending orbit can be obtained as follows: Similarly, in Figure 2 The horizontal deformation component under the right-look condition of the descending orbit shown in the figure. The projection onto the horizontal pointing line of the ascending orbit is According to the local incident angle of the right-side view of the descending orbit ,refer to Figure 5 The deformation along the right-looking radar line of sight during the descent can be obtained as follows: .

[0070] Since BeiDou and the corner reflector are co-located, the radar line-of-sight deformation measured by the corner reflector is denoted as d. Under the corresponding right-looking condition in ascending orbit, the measured radar corner reflector deformation is denoted as... Subtract the value obtained by inversion using GNSS horizontal deformation components This allows us to obtain the vertical deformation component of the radar line of sight as measured by the radar corner reflector. Then we have the following formula:

[0071] (5);

[0072] In the formula, The line-of-sight deformation of the radar detected by the corner reflector (the reference point is a stable point, i.e., the reference point has no displacement). This represents the contribution of the corner reflector's vertical displacement in the radar line-of-sight direction. The contribution of the horizontal displacement of the corner reflector in the radar line of sight (obtained by inversion from BeiDou observations).

[0073] Under the corresponding right-looking down-orbit condition, the measured radar corner reflector deformation is denoted as: Subtract the value obtained by inversion using GNSS horizontal deformation components This allows us to obtain the vertical deformation component of the radar line of sight as measured by the radar corner reflector. Then we have the following formula:

[0074] (6);

[0075] In the formula, The line-of-sight deformation of the radar detected by the corner reflector (the reference point is a stable point, i.e., the reference point has no displacement). This represents the contribution of the corner reflector's vertical displacement in the radar line-of-sight direction. The contribution of the horizontal displacement of the corner reflector in the radar line of sight (obtained by inversion from BeiDou observations).

[0076] In some examples, based on the left and right lookouts of the radar during orbit ascent and the vector superposition conditions corresponding to the four quadrants, the corresponding BeiDou horizontal movement component is subtracted from the deformation of the radar corner reflector to obtain the vertical deformation component monitored by the radar during orbit ascent. (Reference) Figure 6 and Figure 7 The projection of the GNSS horizontal displacement component and the corresponding incident angle conditions of the rising and falling rails under different quadrant conditions shown can be used to obtain the radar vertical deformation monitoring results for the four quadrants.

[0077] In some examples, based on the left and right lookouts of the radar during orbit reduction and the vector superposition conditions corresponding to the four quadrants, the vertical deformation component monitored by the radar during orbit reduction is obtained after subtracting the corresponding BeiDou horizontal movement component from the deformation of the radar corner reflector. For example... Figure 2 Under the right-view condition of the rising and falling rail shown, the projection of the vertical deformation measured by the radar falling rail on the line of sight can be obtained. And the projection of the vertical deformation measured by the radar's right-side ascent along the line of sight. .

[0078] In step S4, when the difference in the vertical motion component values ​​obtained from the inversion of the rising and falling orbit observations is less than a given threshold, this result can be used as a correction for the GNSS vertical motion component. The specific calculation method is as follows:

[0079] First, calculate the vertical deformation components observed from the left and right views of the radar elevator rail. Following the method in step 3, obtain the four radar line-of-sight projection values ​​corresponding to the vertical deformation of the corner reflector under left and right view conditions of the radar elevator rail. , , , .

[0080] The vertical deformation component of the corner reflector measured by the radar is calculated based on the local incident angle:

[0081] ;

[0082] In some examples, when the difference between the lifting and lowering rails is less than a given threshold, the average value of the vertical deformation components obtained from the left and right views of the lifting and lowering rails is used as a correction for the GNSS vertical movement component.

[0083] Given a threshold, in some examples, the horizontal monitoring accuracy of BeiDou is taken as this threshold. Then, by subtracting the horizontal displacement phase measured by the corner reflector from this accuracy, a high-precision vertical displacement phase of the corner reflector can be obtained. If... Then the average of the two can be taken. This serves as the vertical displacement component of the BeiDou system. Similarly, when there are three or four redundant SAR vertical observations, they can be differentiated by calculating their differences, removing those exceeding the tolerance limit. The result is then averaged for the vertical displacement of the diagonal reflector, and used to correct the vertical deformation result of BeiDou.

[0084] In step S5, when both corner reflectors measure the GNSS three-dimensional motion component, the vector superposition value of the radar line-of-sight deformation of the two corner reflectors is obtained using the above method. When the difference in the vertical motion component is less than a given threshold, the result can be used to correct the GNSS baseline elevation difference between the two corner reflectors.

[0085] In some examples, such as Figure 9 The BeiDou baseline formed by points 04 and 07, as shown, has a horizontal displacement component of 14mm westward and an elevation component of 10mm. The radar line-of-sight deformation measured using corner reflector deformation is 15.7mm. By subtracting the horizontal displacement component of 7.2mm, the vertical deformation of the corner reflector corresponding to the 04-07 baseline is 8.5mm. This is combined with the incident angle viewed from the right during the ascent. After inverse calculation using Formula 7, it can be determined that the vertical deformation of the Beidou 04-07 baseline is 10mm.

[0086] Example 2:

[0087] like Figure 8 As shown, the accuracy evaluation method for BeiDou + InSAR corner reflector deformation monitoring data includes the following steps:

[0088] In step S101, the accuracy of GNSS horizontal deformation monitoring is evaluated by manually moving the corner reflector horizontally, and the accuracy of radar corner reflector horizontal deformation monitoring is evaluated based on SAR satellite geometric observation conditions; the method is as follows.

[0089] like Figure 9 The diagram shows a network of 11 BeiDou angle reflectors. Points 04 and 06 were manually moved 14 mm westward and monitored using X-band SAR satellites at an incident angle of 32° and a satellite heading angle of 12°. Using the above formula, when a stable point is used as a reference for calculation, the radar line-of-sight deformation of these two points observed by InSAR is 7.2 mm.

[0090] The baseline observation results obtained from BeiDou calculations are compared with the horizontal simulated deformation to evaluate the accuracy of BeiDou deformation monitoring. However, for InSAR results, it is necessary to refer to Formula 1 to calculate the phase to vertical displacement, unifying the calculation results to the vertical deformation amount for easier comparison and analysis.

[0091] Figure 11The results show the BeiDou monitoring results, InSAR monitoring results, and corresponding artificially simulated horizontal deformation results at points 04 and 06. The results show that the horizontal deformation monitoring accuracy of BeiDou is better than 1 mm, while the horizontal deformation monitoring accuracy of InSAR is approximately 2 mm.

[0092] In step S102, the accuracy of GNSS vertical deformation monitoring is evaluated by manually moving the corner reflector vertically, and the accuracy of radar corner reflector vertical deformation monitoring is evaluated based on SAR satellite geometric observation conditions. An example is shown below:

[0093] like Figure 9 The diagram shows a network containing 11 BeiDou angle reflectors. Point 07 was manually moved upwards by 10mm, and point 09 by 15mm, while the radar incident angle and wavelength remained the same. When using a stable point as a reference for calculation, formula 2 shows that the displacement of point 07 along the radar line of sight is 8.5mm, and the displacement of point 09 along the radar line of sight is 12.7mm. It should be noted that if the deformation of these two points is calculated using the stable point as a reference, the results are positive; however, if the deformation is calculated relative to the stable point using these two points as references, the results are negative. Figure 9 The relevant illustrations are provided in the text.

[0094] The baseline observation results calculated by BeiDou are compared with the simulated vertical deformation to evaluate the accuracy of BeiDou's vertical deformation monitoring. Based on the radar's elevating orbit side-looking conditions, the vertical displacement value corresponding to the radar line-of-sight deformation is calculated to evaluate the accuracy of InSAR's vertical deformation monitoring.

[0095] Figure 12 The results show the BeiDou monitoring results at 07 and 09, the InSAR monitoring results, and the corresponding artificially simulated horizontal deformation results. The results show that the vertical deformation monitoring accuracy of BeiDou is approximately 3 mm, while the vertical deformation monitoring accuracy of InSAR is approximately 1 mm.

[0096] In step S103, based on the triangular network formed by the BeiDou corner reflector observation points, the relative deformation monitoring results between any two points in the network are obtained, and the GNSS baseline deformation monitoring accuracy and the corner reflector vertical deformation monitoring accuracy between the two points are evaluated. An example is shown below:

[0097] like Figure 9 The diagram shows a network of 11 BeiDou angle reflectors. The radar is a right-looking, down-orbit system, using the X-band, with an incident angle of 26° and a satellite heading angle of 12°.

[0098] When points 04 and 07 form a BeiDou baseline, point 04 experiences a 14mm westward horizontal displacement, while point 07 moves upward by 10mm. The BeiDou calculation results for this segment can be used to assess the baseline's accuracy in both the horizontal and vertical directions. However, in the InSAR monitoring results, the deformation caused by the horizontal displacement between points 04 and 07 needs to be deducted using the above method. The remaining vertical component is then used for comparison and accuracy assessment of the InSAR corner reflector's vertical monitoring accuracy. Referring to Formula 7, if the difference between the observations under the four conditions of left and right views of the ascent and descent rails is less than a given threshold (BeiDou horizontal deformation monitoring accuracy index), the InSAR multi-view monitoring results are averaged and used to correct the vertical deformation of the BeiDou baseline between 04 and 07.

[0099] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for fusing BeiDou + InSAR corner reflector deformation monitoring data, characterized in that, include: A local rectangular coordinate system is established with the center of the corner reflector as the origin. The relative displacement vector of the corner reflector observed by BeiDou is decomposed into the vertical and horizontal displacement components of the plane rectangular coordinate system. The projection of the vertical and horizontal movement components of BeiDou onto the radar line of sight deformation is obtained based on the side-looking geometry of the radar riser and riser. Vector superposition is performed based on the characteristics of the four quadrants to obtain the total deformation of the radar line of sight retrieved by BeiDou. The vertical deformation component monitored by the radar corner reflector is obtained by subtracting the corresponding BeiDou horizontal movement component projection from the radar corner reflector deformation. When the difference in the vertical motion component values ​​obtained from the inversion of observations on the ascending and descending orbits is less than a given threshold, this result is used as a correction for the GNSS vertical motion component. When both corner reflector points have three-dimensional movement components, the vertical movement components of the two corner reflectors are calculated separately. When the difference between the two is less than a given threshold, the result is used to correct the GNSS baseline elevation difference between the two corner reflectors.

2. The BeiDou + InSAR corner reflector deformation monitoring data fusion method according to claim 1, characterized in that, A local rectangular coordinate system is established with the center of the corner reflector as the origin. The relative displacement vector of the corner reflector observed by BeiDou is decomposed into a vertical displacement component and a horizontal displacement component in the plane rectangular coordinate system, including: Obtain the geographic coordinates of the BeiDou angle reflector; A local rectangular coordinate system is established with the center point of the Beidou corner reflector as the origin, the elevation direction as the vertical Z-axis, the north direction as the Y-axis, and the east direction as the X-axis. The three-dimensional movement vector obtained by BeiDou measurement is projected onto a local rectangular coordinate system to obtain the vertical and horizontal movement components.

3. The BeiDou + InSAR corner reflector deformation monitoring data fusion method according to claim 1, characterized in that, The projections of the BeiDou vertical and horizontal movement components onto the radar line-of-sight deformation are obtained based on the radar's rise and fall orbit side-look geometry. Vector superposition is then performed based on the characteristics of the four quadrants to obtain the total deformation of the radar line-of-sight retrieved from GNSS; including: Based on the radar's ascent heading angle, calculate the projection of the BeiDou horizontal movement component onto the radar's horizontal pointing line. Based on the left and right view incidence angles of the radar ascending rail, the left view vertical projection and the right view vertical projection of the ascending rail are obtained respectively. Based on the radar's descent heading angle, calculate the projection of the BeiDou horizontal movement component onto the radar's descent horizontal pointing line. Based on the left and right view incidence angles of the radar's reduced orbit, the left-view vertical projection and the right-view vertical projection of the reduced orbit are obtained respectively. Based on the projection results of the horizontal deformation projection in the four quadrants under the radar rising and falling rail conditions and the radar incident angle conditions, the radar line-of-sight deformation under the corresponding left and right looking conditions is calculated. Based on the four quadrant conditions, the horizontal and vertical deformation components are vector-superimposed in the radar line-of-sight direction to obtain the total radar line-of-sight deformation under the left and right look conditions of the ascending and descending orbits.

4. The BeiDou + InSAR corner reflector deformation monitoring data fusion method according to claim 1, characterized in that, The vertical deformation component monitored by the radar corner reflector is obtained by subtracting the corresponding BeiDou horizontal movement component projection from the radar corner reflector deformation; including: Based on the radar ascent and descent angles and the local incident angle, the radar line-of-sight deformation of the BeiDou horizontal movement component is calculated. Based on the left and right views of the radar and the vector superposition conditions corresponding to the four quadrants, the corresponding BeiDou horizontal movement component is subtracted from the total deformation from the radar line of sight to obtain the vertical deformation component monitored by the radar. Based on the left and right views of the radar's reduced orbit and the vector superposition conditions corresponding to the four quadrants, the corresponding BeiDou horizontal movement component is subtracted from the total deformation from the radar line of sight to obtain the vertical deformation component monitored by the radar's reduced orbit.

5. The BeiDou + InSAR corner reflector deformation monitoring data fusion method according to claim 1, characterized in that, When the difference in the vertical motion component values ​​obtained from the inversion of observations on the ascending and descending orbits is less than a given threshold, this result is used as a correction for the GNSS vertical motion component, including: Calculate the vertical deformation components observed from the left and right views of the lifting rail; When the difference between the lifting and lowering rails is less than a given threshold, the average value of the vertical deformation components obtained from the left and right views of the lifting and lowering rails is used as the correction for the GNSS vertical movement component.

6. The BeiDou + InSAR corner reflector deformation monitoring data fusion method according to claim 1, characterized in that, When both corner reflector locations have three-dimensional movement components, the vertical movement components of the two corner reflectors are calculated separately. When the difference between the two is less than a given threshold, the result is used to correct the GNSS baseline elevation difference between the two corner reflectors, including: First, the vertical deformation components of the two corner reflectors and the monitored radar are calculated; Secondly, based on the directions of the two deformation component vectors and the radar elevation and levitation conditions, vector superposition is performed to obtain the vertical elevation difference between the two corner reflectors; Whether the result can be used to correct the GNSS baseline elevation difference between the two corner reflectors is determined based on whether the vertical elevation difference between the two corner reflectors exceeds a given threshold.

7. A method for evaluating the accuracy of BeiDou + InSAR corner reflector deformation monitoring data, characterized in that, A method for fusing BeiDou + InSAR corner reflector deformation monitoring data according to any one of claims 1 to 6; Accuracy assessment methods include: The accuracy of GNSS horizontal deformation monitoring was evaluated by manually moving the corner reflector horizontally, and the accuracy of radar corner reflector horizontal deformation monitoring was evaluated based on SAR satellite geometric observation conditions. The accuracy of GNSS vertical deformation monitoring was evaluated by manually moving the corner reflector vertically, and the accuracy of radar corner reflector vertical deformation monitoring was evaluated based on SAR satellite geometric observation conditions. Based on the triangular network formed by the BeiDou corner reflector observation points, the relative deformation monitoring results of any two points in the network are obtained, and the accuracy of GNSS baseline deformation monitoring and corner reflector vertical deformation monitoring between the two points are evaluated.

8. The method for evaluating the accuracy of BeiDou + InSAR corner reflector deformation monitoring data according to claim 7, characterized in that, The accuracy of GNSS horizontal deformation monitoring is evaluated by manually moving the corner reflector horizontally, and the accuracy of radar corner reflector horizontal deformation monitoring is evaluated based on SAR satellite geometric observation conditions, including: Along the due east or due west direction, the artificial horizontal movement of the corner reflector shall not exceed 1 / 2 of the radar wavelength; The difference between the horizontal displacement detected by BeiDou and the model deformation is calculated to assess the accuracy. Based on the side-view conditions of the radar lifting rail, the horizontal displacement component corresponding to the deformation in the radar line of sight is calculated, and the accuracy is evaluated.

9. The method for evaluating the accuracy of BeiDou + InSAR corner reflector deformation monitoring data according to claim 7, characterized in that, The accuracy of GNSS vertical deformation monitoring was evaluated by manually moving the corner reflector vertically, and the accuracy of radar corner reflector vertical deformation monitoring was evaluated based on SAR satellite geometric observation conditions, including: The vertical movement of the corner reflector should not exceed 1 / 2 of the radar wavelength; The difference between the horizontal displacement detected by BeiDou and the model deformation is calculated to assess the accuracy. Based on the side-view conditions of the radar lifting rail, the horizontal displacement component corresponding to the deformation in the radar line of sight is calculated, and the accuracy is evaluated.

10. The method for evaluating the accuracy of BeiDou + InSAR corner reflector deformation monitoring data according to claim 7, characterized in that, Based on a triangular network formed by BeiDou corner reflector observation points, the relative deformation monitoring results between any two points in the network are obtained, and the accuracy of GNSS baseline deformation monitoring and corner reflector vertical deformation monitoring between the two points is evaluated, including: Calculate the horizontal and vertical displacement components of the two corner reflectors in the artificial simulation, and calculate the vector sum of their deformations based on the vector direction of the line connecting the two corner reflectors; The difference between the deformation vector detected by BeiDou and the simulated deformation vector is calculated to evaluate the accuracy. Accuracy assessment is performed by comparing the artificially simulated deformation vectors of the two corner reflectors with the deformation vectors along the radar line of sight.

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