Beidou + InSAR corner reflector deformation monitoring data fusion method and precision evaluation method

Abstract

The invention discloses a Beidou + InSAR corner reflector deformation monitoring data fusion method and a new precision evaluation method, and the method comprises the steps: building a local rectangular coordinate system according to the center of a corner reflector as a coordinate origin, and decomposing a Beidou observation displacement vector into a vertical movement component and a horizontal movement component; according to vector superposition characteristics of four quadrants, a radar lifting rail side-looking geometrical relationship and a radar sight direction total deformation quantity of a single corner reflector, when a vertical movement component value difference obtained according to lifting rail observation inversion is smaller than a given threshold value, a result is used as correction of a Beidou vertical movement component; and when the point positions of the two corner reflectors have three-dimensional moving components, the relative vertical deformation of the two corner reflectors is solved by using the method. According to the method, deformation observation data obtained by two different technical means of the Beidou and the InSAR corner reflector can be well complemented and evaluated, so that the problem that high-precision data fusion is difficult to directly carry out in an observation value domain when the corner reflector and the Beidou are arranged side by side for monitoring is solved.

Description

Technical Field

[0001] The present invention belongs to the field of satellite navigation and satellite remote sensing engineering applications, and specifically relates to a Beidou + InSAR corner reflector deformation monitoring data fusion method and accuracy assessment method, which realizes the observation value domain fusion of Beidou and SAR satellite remote sensing displacement monitoring data. Background Art

[0002] Early high-precision deformation monitoring technology was implemented using traditional geodetic methods. Its horizontal deformation monitoring mainly relied on total stations (reference stations) and reflectors (monitoring stations), and vertical high-precision deformation monitoring mainly relied on leveling technology. Although the specific locations monitored by these two technologies are not completely consistent, such as reflectors and total stations measure the axis position of the forced centering device, and leveling is usually observed using level marks on the side or base of the observation pier, but since the accuracy of deformation monitoring is required to be several millimeters, the inconsistency of the observation center of these two observation methods does not affect the accuracy of their monitoring results.

[0003] With the rise of global satellite navigation and positioning technology, the price of GNSS terminals has gradually dropped, allowing them to gradually replace traditional total stations and levels. Due to the symmetry of GNSS antenna manufacturing, after fixing it on the forced centering axis of deformation monitoring, high-precision horizontal and vertical displacement monitoring can be achieved solely by GNSS observations. Many documents show that when the nominal performance of GNSS terminal equipment and antennas reaches 1mm-level phase observation accuracy, the actual deformation monitoring accuracy is also close to mm level. 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 of horizontal observation results. It is necessary to smooth the long-term time series observations to obtain accurate deformation monitoring results, which is a shortcoming in high-precision deformation monitoring applications.

[0004] At present, with the application and popularization of InSAR technology, the corresponding high-precision deformation monitoring application of corner reflectors has gradually emerged. Some literatures have estimated theoretically that when the signal-to-noise ratio of the corner reflector in the SAR image reaches more than 25dB, its vertical monitoring accuracy is better than 1mm. Therefore, without considering the atmospheric error, the vertical deformation results monitored by the corner reflector have a greater advantage than GNSS.

[0005] The existing practice of fusing Beidou and corner reflector deformation monitoring data is usually to calculate the Beidou deformation monitoring results, and then convert the Beidou monitoring results to the InSAR monitoring coordinate system through the geometric relationship of the SAR side-view projection for fusion calculation. Since the InSAR monitoring results are one-dimensional deformation monitoring results in the radar line of sight, how to calibrate the reliability of the InSAR monitoring results and how to fuse them into the Beidou observation values ​​are the current difficulties. The existing literature ignores the deformation component in the north-south direction and only converts the deformation in the east-west direction in the direction of the radar view. This approximate conversion affects the accuracy of corner reflector monitoring.

[0006] The present invention provides a new method for fusing InSAR monitoring results with Beidou deformation results in the deformation observation value domain. Through the geometric observation conditions of the satellite ascending and descending orbits, the deformation monitoring results of the artificial corner reflector under the left and right viewing conditions of the ascending and descending orbits are analyzed, thereby providing high-quality fused observation values ​​for high-precision monitoring of the GNSS elevation direction. Summary of the invention

[0007] In order to solve the current technical problems, the main purpose of the present invention is to provide a Beidou + InSAR corner reflector deformation monitoring data fusion method and accuracy evaluation method to solve the problem that when the corner reflector and GNSS are monitored side by side, the two deformation monitoring results are difficult to directly perform high-precision data fusion in the observation value domain, and to enable the deformation observation data obtained by two different technical means, GNSS and InSAR corner reflector, to be well complemented and evaluated, thereby realizing the accurate weighting and evaluation of redundant observation values.

[0008] The embodiment of the first aspect of the present invention provides a Beidou + InSAR corner reflector deformation monitoring data fusion method, comprising the following steps: establishing a local rectangular coordinate system with the center of the corner reflector as the coordinate origin, decomposing the corner reflector relative displacement vector observed by Beidou into a vertical movement component and a horizontal movement component in the plane rectangular coordinate system; obtaining the projection of the Beidou vertical and horizontal movement components in the radar sight line according to the side-view geometric relationship of the radar lifting track, and performing vector superposition according to the four quadrant characteristics to obtain the total deformation amount in the radar sight line inverted by Beidou; deducting the corresponding Beidou horizontal movement component projection from the radar corner reflector deformation amount, and then obtaining the vertical deformation component monitored by the radar corner reflector; when the difference in the vertical movement component value obtained by inversion according to the lifting track observation is less than a given threshold, the result is used as the correction of the GNSS vertical movement component. When there are three-dimensional movement components at both corner reflector points, the two corner reflector vertical movement components are obtained respectively, and when the difference between the two is less than a given threshold, the result is used to correct the GNSS baseline elevation difference of the two corner reflectors.

[0009] Optionally, a local rectangular coordinate system is established with the center of the corner reflector as the coordinate 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, including: 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 coordinate origin, the elevation direction as the vertical Z axis, the north direction as the Y axis, and the east direction as the X axis; projecting the three-dimensional movement vector obtained by Beidou measurement to the local rectangular coordinate system to obtain the vertical movement component and the horizontal movement component.

[0010] Optionally, the projections of the deformation of the vertical and horizontal movement components in the radar line of sight are obtained according to the side-view geometric relationship of the radar ascending and descending orbits, and vector superposition is performed according to the characteristics of the four quadrants to obtain the total deformation in the radar line of sight, including: according to the radar ascending orbit heading angle, the projection of the Beidou horizontal movement component on the horizontal pointing line of the radar ascending orbit is obtained; according to the left and right viewing incident angles of the radar ascending orbit, the vertical projection of the ascending orbit left view and the vertical projection of the ascending orbit right view are respectively obtained; according to the radar descending orbit heading angle, the projection of the Beidou horizontal movement component on the horizontal pointing line of the radar descending orbit is obtained; according to the left and right viewing incident angles of the radar descending orbit, the vertical projection of the descending orbit left view and the vertical projection of the descending orbit right view are respectively obtained; according to the projection results of the horizontal deformation projection in the four quadrants under the radar ascending and descending orbit conditions and the radar incident angle conditions, the deformation in the radar line of sight under the corresponding left and right viewing conditions is calculated; according to the four quadrants condition judgment conditions, the vector superposition of the horizontal deformation and the vertical deformation components in the radar line of sight is performed to obtain the total deformation in the radar line of sight inverted by GNSS under the ascending and descending orbit left and right viewing conditions.

[0011] Optionally, the projection of the corresponding Beidou horizontal motion component is deducted from the total deformation amount in the line of sight observed by the radar, and then the vertical deformation component monitored by the radar is obtained, including: calculating the radar line of sight deformation amount of the Beidou horizontal motion component according to the radar ascending and descending orbit heading angle and the local incident angle; deducting the corresponding Beidou horizontal motion component from the total deformation amount in the radar line of sight according to the vector superposition conditions corresponding to the left and right views of the radar ascending orbit and the four quadrants, and obtaining the vertical deformation component monitored by the radar ascending orbit; deducting the corresponding Beidou horizontal motion component from the total deformation amount in the radar line of sight according to the vector superposition conditions corresponding to the left and right views of the radar descending orbit and the four quadrants, and obtaining the vertical deformation component monitored by the radar descending orbit.

[0012] Optionally, when the difference in the vertical movement component value obtained by inversion based on the ascending and descending orbit observation is less than a given threshold, the result can be used as a correction of the GNSS vertical movement component, including: calculating the vertical deformation components respectively observed by the left and right views of the ascending and descending orbit; when the difference between the ascending and descending orbits is less than a given threshold, taking the average value of the vertical deformation components obtained by the left and right views of the ascending and descending orbits as the correction of the GNSS vertical movement component; Optionally, when both corner reflectors measure GNSS three-dimensional motion components, the above method is used to obtain the vector superposition value of the radar line-of-sight deformation of the two corner reflectors. 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, including: first, according to steps 2 to 3 of claims 2, the vertical deformation components of the two corner reflectors and the monitored radar are respectively obtained; secondly, according to the directions of the two deformation component vectors and the radar ascending and descending track conditions, vector superposition is performed to obtain the vertical elevation difference of the two corner reflectors; and according to whether the vertical elevation difference of the two corner reflectors exceeds a given threshold, it is determined whether the result can be used to correct the GNSS baseline elevation difference of the two corner reflectors.

[0013] The present 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 horizontal deformation monitoring accuracy of the radar corner reflector according to the SAR satellite geometric observation conditions; evaluating the GNSS vertical deformation monitoring accuracy by manually moving the corner reflector vertically, and evaluating the vertical deformation monitoring accuracy of the radar corner reflector according to the SAR satellite geometric observation conditions; based on the triangulated network formed by the Beidou corner reflector observation points, obtaining the relative deformation monitoring results of any two points in the network, and evaluating the GNSS baseline deformation monitoring accuracy and the corner reflector vertical deformation monitoring accuracy between the two points.

[0014] Optionally, the GNSS horizontal deformation monitoring accuracy is evaluated by manually moving the corner reflector horizontally, and the radar corner reflector horizontal deformation monitoring accuracy is evaluated according to the SAR satellite geometric observation conditions, including: manually moving the corner reflector horizontally in the east and west directions by no more than 1 / 2 of the radar wavelength; calculating the difference between the horizontal displacement monitored by Beidou and the model deformation, and performing accuracy evaluation; calculating the horizontal displacement component value corresponding to the deformation in the radar line of sight according to the side-view conditions of the radar lifting track, and performing accuracy evaluation; Optionally, the GNSS vertical deformation monitoring accuracy is evaluated by manually moving the corner reflector vertically, and the vertical deformation monitoring accuracy of the radar corner reflector is evaluated according to the SAR satellite geometric observation conditions, including: manually moving the corner reflector up and down in the vertical direction not exceeding 1 / 2 of the radar wavelength; calculating the difference between the horizontal displacement monitored by Beidou and the model deformation, and performing accuracy evaluation; calculating the horizontal displacement component value corresponding to the deformation in the radar line of sight according to the side-view conditions of the radar lifting track, and performing accuracy evaluation.

[0015] Optionally, based on the triangulated 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 GNSS baseline deformation monitoring accuracy between the two points and the corner reflector vertical deformation monitoring accuracy are evaluated, including: respectively calculating the artificially simulated horizontal and vertical displacement components of the two corner reflectors, and calculating the vector sum of the deformations of the two according to the vector direction of the line connecting the two corner reflectors; calculating the difference between the deformation vector and the simulated deformation vector between the two corner reflectors monitored by Beidou, and performing accuracy evaluation; comparing the difference between the artificially simulated deformation vector sum of the two corner reflectors and the deformation vector in the radar line of sight, and performing accuracy evaluation.

[0016] Therefore, the present invention has at least the following beneficial effects: The present invention solves the technical problem of calculating the geometric projection function of deformation variables in the fusion of Beidou and corner reflector monitoring data. By decomposing the Beidou deformation monitoring results into spatially orthogonal horizontal deformation components and vertical deformation components, a coordinate projection transformation method under radar side-view conditions is proposed to calculate the projection results of these two components respectively, thereby realizing the accurate distinction between Beidou vertical deformation components and horizontal deformation components in the corner reflector deformation monitoring domain. Since the monitoring accuracy of Beidou horizontal monitoring components is much higher than that of vertical components, based on the rigorous geometric transformation method of this model, this method has extremely high accuracy in decomposing and eliminating Beidou horizontal monitoring components under SAR side-view conditions, thereby providing the possibility for the fusion of Beidou deformation medium- and medium-elevation components with high-precision elevation results of SAR remote sensing monitoring.

[0017] Another application field of the present invention is the accurate evaluation and verification of the deformation monitoring accuracy of different SAR satellites. By artificially moving the corner reflector horizontally and vertically with high precision, when the simulation effect of the deformation micro-motion process is better than 1 mm, the corresponding ascending and descending orbit SAR satellite observation geometry can be used to provide a reliable and effective technical method for mm-level accuracy evaluation of GNSS deformation monitoring results and different SAR satellite interferometric phase deformation monitoring accuracy.

[0018] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the drawings of the embodiment are briefly introduced below.

[0020] Figure 1 The present invention is a flowchart of a BeiDou + InSAR corner reflector deformation monitoring data fusion method provided according to an embodiment of the present application.

[0021] Figure 2It is a schematic diagram of a three-dimensional decomposition projection of the deformation of a reflector of a lifting rail at the right viewing angle provided according to an embodiment of the present application.

[0022] Figure 3 It is a schematic diagram of a three-dimensional decomposition projection of the deformation of a reflector of a lifting rail from a left perspective provided according to an embodiment of the present application.

[0023] Figure 4 It is a schematic diagram of the decomposition projection of the deformation amount of the left and right viewing angle reflector of the ascending track provided according to an embodiment of the present application.

[0024] Figure 5 It is a schematic diagram of the decomposition projection of the reflector deformation amount of the descending orbit left and right viewing angles provided according to an embodiment of the present application.

[0025] Figure 6 It is a schematic diagram of the decomposition of the four-quadrant Beidou horizontal deformation components on the heading pointing line provided according to an embodiment of the present application.

[0026] Figure 7 This is a schematic diagram of the Beidou horizontal deformation components in the four-axis directions on the heading pointing line provided according to an embodiment of the present application.

[0027] Figure 8 The present invention provides a flow chart of a Beidou+InSAR corner reflector deformation monitoring data accuracy assessment method according to an embodiment of the present application.

[0028] Fig. 9 A schematic diagram of a radar sight line vector for moving a right-viewing angle reflector for an ascending orbit according to an embodiment of the present application.

[0029] Fig.10 A schematic diagram of a radar sight line vector for moving a descending right-viewing angle reflector according to an embodiment of the present application.

[0030] Fig.11 This is the BeiDou + InSAR horizontal displacement monitoring accuracy evaluation result provided according to the embodiment of the present application.

[0031] Fig.12 This is the BeiDou + InSAR vertical displacement monitoring accuracy evaluation result provided according to the embodiment of the present application. DETAILED DESCRIPTION

[0032] In order to explain the technical method and implementation scheme of the present invention in detail and to highlight the technical objectives, technical advantages and results that can be achieved by the present invention, the present invention is described in detail below with reference to the accompanying drawings and examples.

[0033] The following describes a Beidou + InSAR corner reflector deformation monitoring data fusion method and accuracy assessment method of an embodiment of the present application with reference to the accompanying drawings.

[0034] Embodiment 1: In view of the problems mentioned in the above background technology, the present application provides a Beidou + InSAR corner reflector deformation monitoring data fusion method, in which: Specifically, Figure 1 A flow chart of a BeiDou + InSAR corner reflector deformation monitoring data fusion method provided in an embodiment of the present application.

[0035] like Figure 1 As shown, the Beidou + InSAR corner reflector deformation monitoring data fusion method includes the following steps: In step S1, the geographic coordinates of the Beidou corner reflector are obtained; a local rectangular coordinate system is established with the center point of the Beidou corner reflector as the coordinate origin, the elevation direction as the vertical Z axis, the north direction as the Y axis, and the east direction as the X axis, such as Figure 2 As shown; the three-dimensional motion vector obtained by Beidou measurement Projected to the local rectangular coordinate system, the vertical movement component is obtained and the horizontal translation component . The horizontal component The projection in the east direction (X axis) is , the projection in the north direction (Y axis) is .

[0036] In step S2, the projection of the deformation of the vertical and horizontal movement components in the radar line of sight is obtained according to the side-view geometric relationship of the radar lifting track, and vector superposition is performed according to the characteristics of the four quadrants to obtain the total deformation in the radar line of sight.

[0037] It is understandable that if Figure 2 The figure shows the three-dimensional deformation vector (located in the second horizontal quadrant) obtained by GNSS monitoring in the right-view mode of the lifting orbit. The projection vector of the three-dimensional deformation vector in the horizontal direction (east-west coordinate axis) is We define it as the GNSS horizontal movement component; the projection of the three-dimensional deformation vector in the vertical direction is We define it as the GNSS vertical motion component. For the ascending right view, the projection of the vertical motion component in the radar line of sight can be recorded as , and the projection of the horizontal motion component on the horizontal pointing line of the ascending orbit (the straight line perpendicular to the ascending orbit heading and passing through the origin 0 is called the horizontal pointing line of the ascending orbit) is ,refer to Figure 4 As shown, it can be seen The line of sight displacement to the right of the radar ascending orbit is , and the line of sight displacement to the right of the radar ascending orbit is .

[0038] According to the radar orbit raising heading angle, the projection of the Beidou horizontal motion component on the radar orbit raising horizontal pointing line is obtained. The specific calculation method is as follows: according to Figure 2 The second quadrant where the deformation vector obtained by Beidou monitoring is located and the heading angle of the related satellite ascending and descending orbit are shown and the angle of incidence , , , From the angle information, we can know that the horizontal movement component of Beidou The projection of the horizontal pointing line on the radar ascending orbit can be calculated using the following formula: ; in, is the projection of the Beidou horizontal motion component under the radar ascending right-looking condition, It is the projection of the Beidou horizontal motion component under the radar ascending orbit left-looking condition. Beidou horizontal motion component In the azimuth of the second quadrant, is the heading angle of the ascending and descending track, is the radar local side-view inclination angle under the right-view condition of ascending orbit, is the radar local side-view inclination angle under the condition of left-viewing on ascending orbit. Figure 4 It can be seen that in the second quadrant, the Beidou horizontal motion component is positive for the radar's right-hand view when ascending, that is, close to the radar's line of sight, while for the left-hand view when ascending, its deformation is negative (that is, away from the radar's line of sight).

[0039] According to the left and right incident angles of the radar ascending orbit, the left vertical projection of the ascending orbit and the right vertical projection of the ascending orbit are calculated respectively. The specific calculation method is as follows: according to Figure 4 The example shown shows the projection of the Beidou vertical deformation component under the right-looking condition and the local incident angle under the right-looking condition. Similarly, the local incident angle under the right-view projection and left-view conditions of the ascending orbit is The following formula can be used to calculate: ; in, is the projection of the Beidou vertical motion component under the radar ascending right-looking condition, It is the projection of the Beidou vertical motion component under the radar ascending orbit and left-looking condition. is the radar local side-view inclination angle under the right-view condition of ascending orbit, is the radar local side-view inclination angle under the condition of left-viewing on ascending orbit. Figure 4 It can be seen from the figure that the projection of the Beidou vertical motion component on the left and right views of the radar orbit is the same, either upward or downward, and is only affected by the local incident angle and has nothing to do with the radar heading angle.

[0040] According to the radar descending track heading angle, the projection of the Beidou horizontal motion component on the radar descending track horizontal pointing line is obtained. The specific calculation method is as follows: It is understandable that if Figure 3 As shown, the three-dimensional deformation vector (located in the second horizontal quadrant) obtained by GNSS monitoring in the left-view mode of the lifting orbit is shown. The projection vector of the three-dimensional deformation vector in the horizontal direction (east-west coordinate axis) is We define it as the GNSS horizontal movement component; the projection of the three-dimensional deformation vector in the vertical direction is We define it as the GNSS vertical motion component. For the left view of the descending orbit, the projection of the vertical motion component in the radar line of sight can be recorded as , and the projection of the horizontal motion component on the horizontal pointing line of the ascending orbit (the straight line perpendicular to the ascending orbit heading and passing through the origin 0 is called the horizontal pointing line of the ascending orbit) is ,refer to Figure 5 The schematic diagram of the decomposition projection of the reflector deformation at the left and right viewing angles of the descending orbit shows that The line of sight displacement to the right of the radar ascending orbit is , and the line of sight displacement to the right of the radar ascending orbit is .

[0041] according to Figure 3 The second quadrant where the deformation vector obtained by Beidou monitoring is located and the heading angle of the related satellite ascending and descending orbit are shown and the local angle of incidence , , , Angle information, combined with Figure 5 From the geometric relationship, we can know that the Beidou horizontal motion component The projection of the horizontal pointing line on the radar descending orbit can be calculated using the following formula: ; in, is the projection of the Beidou horizontal motion component under the radar descending right-looking condition, It is the projection of the Beidou horizontal motion component under the radar descending left-looking condition. Beidou horizontal motion component In the azimuth of the second quadrant, is the heading angle of the ascending and descending track, is the radar local incident angle under descending right-looking conditions, is the radar local incident angle under the descending left-looking condition. Figure 5 It can be seen that in the second quadrant, the Beidou horizontal motion component is positive for the radar right view, and its deformation is negative for the radar left view.

[0042] According to the left and right incident angles of the radar descending track, the left vertical projection of the descending track and the right vertical projection of the descending track are calculated respectively. The specific calculation method is as follows: according to Figure 5 The example shown shows that the projection of the Beidou vertical deformation component in the descending orbit right view and the local incident angle Similarly, the projection of the right view in the descending orbit is related to the local incident angle The following formula can be used to calculate: ; in, is the projection of the Beidou vertical motion component under the radar descending right-looking condition, It is the projection of the Beidou vertical motion component under the radar ascending orbit and left-looking condition. is the radar local incident angle under descending right-looking conditions, is the radar local incident angle under the descending left-looking condition. Figure 4 It can be seen from the figure that for the projection of the Beidou vertical motion component on the left and right viewing directions of the radar's descending orbit, the projection of the radar's line of sight is the same, either upward or downward, and is only affected by the local incident angle and has nothing to do with the radar heading angle.

[0043] According to the projection results of the horizontal deformation projection in the four quadrants under the radar ascending and descending orbit conditions and the radar incident angle conditions, the radar line of sight deformation under the corresponding left and right viewing conditions is calculated. The calculation method is as follows: Figure 6 The calculation angles of the Beidou horizontal deformation components projected onto the radar route pointing line in the four quadrants are given. Referring to formulas 1 to 4, the deformation of the Beidou horizontal deformation projection in each quadrant on the radar line of sight can be obtained.

[0044] According to the four quadrant conditions, the horizontal deformation and vertical deformation components are vector-superimposed in the radar line of sight, and the total deformation in the radar line of sight under the conditions of left and right viewing of the ascending and descending orbits is obtained. Figure 4 and Figure 5 The positive and negative calculation method of the drawn horizontal deformation in the radar line of sight direction is that the direction close to the radar antenna is positive and the direction away from the radar antenna is negative.

[0045] According to the four quadrant conditions, the vector superposition of the horizontal deformation and vertical deformation components in the radar line of sight is performed to obtain the total deformation in the radar line of sight under the left and right viewing conditions of the ascending and descending orbits.

[0046] If the vertical deformation component of Beidou is positive upward and negative downward on the vertical coordinate axis, similarly, we define the deformation toward the radar antenna as positive and the deformation away from the radar antenna as negative. Then the positive and negative directions of Beidou's vertical deformation have nothing to do with the horizontal four quadrants, but only with its direction on the vertical coordinate axis.

[0047] Based on this, the projections of Beidou horizontal deformation and Beidou vertical deformation in the radar line of sight can be vector superimposed to obtain the total deformation variable in the radar line of sight under the conditions of ascending and descending orbits and left and right viewing.

[0048] It is understandable that, because Beidou can obtain three-dimensional deformation, while SAR can only obtain one-dimensional deformation in the line of sight, the deduction of step S2 belongs to forward modeling, and its geometric relationship is clear and accurate. From step S2, it can be seen that if the GNSS horizontal deformation component can be accurately eliminated from the deformation in the radar line of sight, 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 deducting the Beidou horizontal deformation component to obtain the vertical deformation monitoring result of the corner reflector, and then use it to correct the Beidou vertical deformation result.

[0049] In step S3, the corresponding Beidou horizontal movement component projection is deducted from the radar corner reflector deformation, and then the vertical deformation component monitored by the radar is obtained. In the usual precision GNSS deformation monitoring system, the horizontal displacement measured by GNSS is relatively accurate, and its accuracy can reach more than 1mm in a small range, but its vertical accuracy is relatively low. Therefore, this step eliminates the deformation of the corner reflector horizontal deformation in the radar line of sight from the deformation observed by the radar, thereby obtaining the vertical deformation measured by the radar. The specific calculation method is as follows: In some examples, the radar line of sight deformation of the Beidou horizontal motion component is calculated based on the radar elevation track heading angle and the local incident angle. Figure 2 Taking the deformation vector R monitored by GNSS as an example, its vertical projection is , the projection on the horizontal plane (horizontal deformation component) is , located in the second quadrant of the horizontal plane, in the case of ascending orbit and right view, the horizontal deformation component The projection on the horizontal pointing line of the ascending orbit is , according to the local incident angle of the ascending orbit right view ,refer to Figure 4 It can be obtained that the deformation in the right-looking radar line of sight of the ascending orbit is . Similarly, in Figure 2 Under the descending right-viewing condition shown in The projection on the horizontal pointing line of the ascending orbit is , according to the local incident angle of the descending orbit right view ,refer to Figure 5 It can be obtained that the deformation in the right-looking radar line of sight of the descending orbit is .

[0050] Since Beidou and the corner reflector are co-located, the radar line of sight deformation measured by the corner reflector is marked as d. Under the corresponding ascending orbit right-view condition, the measured radar corner reflector deformation is recorded as , minus the inversion of the horizontal deformation component obtained by GNSS , we can get the vertical deformation component of the radar line of sight measured by the radar corner reflector , then we have the following formula: (5); In the formula, is the radar line of sight deformation detected by the corner reflector (the reference datum is a stable point, that is, the reference datum does not have displacement), is the contribution of the vertical displacement of the corner reflector in the radar line of sight, is the contribution of the horizontal displacement of the corner reflector in the radar line of sight (obtained by inverting Beidou observations).

[0051] Under the right-looking condition of the corresponding descending orbit, the measured deformation of the radar corner reflector is recorded as , minus the inversion of the horizontal deformation component obtained by GNSS , we can get the vertical deformation component of the radar line of sight measured by the radar corner reflector , then we have the following formula: (6); In the formula, is the radar line of sight deformation detected by the corner reflector (the reference datum is a stable point, that is, the reference datum does not have displacement), is the contribution of the vertical displacement of the corner reflector in the radar line of sight, is the contribution of the horizontal displacement of the corner reflector in the radar line of sight (obtained by inverting Beidou observations).

[0052] In some examples, according to the vector superposition conditions corresponding to the left and right views of the radar orbit raising and the four quadrants, the corresponding Beidou horizontal movement component is deducted from the radar corner reflector deformation to obtain the vertical deformation component of the radar orbit raising monitoring. Figure 6 and Figure 7 The projection of the GNSS horizontal displacement components under different quadrant conditions and the corresponding ascending and descending orbit incident angle conditions are shown, and the radar vertical deformation monitoring results corresponding to the four quadrants can be obtained.

[0053] In some examples, according to the vector superposition conditions corresponding to the left and right views of the radar and the four quadrants, the corresponding Beidou horizontal movement component is deducted from the radar corner reflector deformation to obtain the vertical deformation component of the radar descending orbit monitoring. Figure 2 Under the right-viewing condition of the ascending and descending orbit shown in the figure, the projection of the vertical deformation measured by the descending orbit right-viewing radar in the line of sight direction can be obtained. , and the projection of the vertical deformation measured by the radar ascending track rightward in the line of sight .

[0054] In step S4, when the difference in the vertical motion component value obtained by inversion based on the ascending and descending orbit observations is less than a given threshold, the result can be used as a correction of the GNSS vertical motion component. The specific calculation method is as follows: First, calculate the vertical deformation components observed by the left and right views of the lifting track. According to the method in step 3, the four radar line of sight projection values ​​corresponding to the vertical deformation of the corner reflector under the left and right viewing conditions of the radar lifting track can be obtained: , , , .

[0055] Calculate the vertical deformation component of the corner reflector measured by the radar according to the local incident angle: ; In some examples, when the difference between the ascending and descending orbits is less than a given threshold, the average value of the vertical deformation components obtained from the left and right views of the ascending and descending orbits is used as a correction to the GNSS vertical movement component.

[0056] is a given threshold. In some examples, the horizontal monitoring accuracy of Beidou is taken as the threshold. Then, the horizontal displacement phase measured by the corner reflector can be deducted from the accuracy to obtain the high-precision vertical displacement phase of the corner reflector. , then the average of the two , as the vertical displacement component of BeiDou. Similarly, when there are 3 or 4 redundant SAR vertical observation results, they can be distinguished by the method of mutual difference, and the ones larger than the limit difference can be removed. The result is then used to correct the Beidou vertical deformation result after averaging the vertical displacement of the diagonal reflector.

[0057] In step S5, when both corner reflectors measure the GNSS three-dimensional motion components, the above method is used to obtain the vector superposition value of the radar line of sight deformation of the two corner reflectors. 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.

[0058] In some examples, such as Fig. 9 The Beidou baseline composed of points 04 and 07 shown in the figure has a horizontal movement component of 14mm to the west and 10mm up. The radar line of sight vertical deformation measured by the corner reflector deformation is 15.7mm. By deducting the horizontal movement component of 7.2mm, it can be known that the vertical deformation of the corner reflector corresponding to the vertical deformation of the 04-07 baseline is 8.5mm. Combined with the incident angle of the right view of the ascending orbit , after back-calculation by formula 7, it can be known that the vertical deformation of the Beidou 04-07 baseline is 10mm.

[0059] Embodiment 2: like Figure 8 As shown in the figure, the accuracy evaluation method of Beidou + InSAR corner reflector deformation monitoring data includes the following steps: In step S101, the GNSS horizontal deformation monitoring accuracy is evaluated by manually moving the corner reflector horizontally, and the radar corner reflector horizontal deformation monitoring accuracy is evaluated according to the SAR satellite geometric observation conditions; the method is as follows.

[0060] like Fig. 9 The network shown contains 11 Beidou corner reflectors, where point 04 and point 06 are manually moved 14 mm in the due west direction, and monitored by X-band SAR satellite, with an incident angle of 32° and a satellite heading angle of 12°. According to the above formula, when the stable point is used as the reference for calculation, it can be seen that the radar line of sight deformation of the two points observed by InSAR is 7.2 mm. The baseline observation results calculated by BeiDou 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 and unify the calculation results to the vertical deformation for easy comparison and analysis.

[0061] Fig.11 The Beidou monitoring results, InSAR monitoring results and corresponding artificial simulation horizontal deformation results at points 04 and 06 are displayed. The results show that the horizontal deformation monitoring accuracy of Beidou is better than 1mm, and the horizontal deformation monitoring accuracy of InSAR is about 2mm.

[0062] In step S102, the GNSS vertical deformation monitoring accuracy is evaluated by manually moving the corner reflector vertically, and the vertical deformation monitoring accuracy of the radar corner reflector is evaluated according to the SAR satellite geometric observation conditions. An embodiment is shown as follows: like Fig. 9 The network shown contains 11 Beidou corner reflectors. Point 07 is moved upward by 10mm and point 09 is moved upward by 15mm by artificial means. The radar incident angle and wavelength are the same as above. When the stable point is used as the reference for calculation, the displacement of point 07 in the radar line of sight is 8.5mm and the displacement of point 09 in the radar line of sight is 12.7mm using Formula 2. It should be pointed out that if the deformation of these two points is calculated from the stable point as the reference, the results are positive. If the deformation of these two points with respect to the stable point is calculated from the two points as the reference, the result is negative. Fig. 9 A related illustration is given in .

[0063] The baseline observation results calculated by BeiDou are compared with the vertical simulated deformation to evaluate the accuracy of BeiDou vertical deformation monitoring. According to the side-view conditions of the radar elevation track, the vertical displacement value corresponding to the deformation in the radar line of sight is calculated to evaluate the vertical deformation monitoring accuracy of InSAR.

[0064] Fig.12 The Beidou monitoring results, InSAR monitoring results and corresponding artificially simulated horizontal deformation results at 07 and 09 points are displayed. The results show that the vertical deformation monitoring accuracy of Beidou is about 3mm, and the vertical deformation monitoring accuracy of InSAR is about 1mm.

[0065] In step S103, based on the triangulated 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 GNSS baseline deformation monitoring accuracy between the two points and the corner reflector vertical deformation monitoring accuracy are evaluated. An embodiment is shown below: like Fig. 9 A network of 11 Beidou corner reflectors is shown. The radar is in descending orbit and right-looking, using X-band, with an incidence angle of 26° and a satellite heading angle of 12°.

[0066] When point 04 and point 07 form a Beidou baseline, point 04 has a horizontal displacement of 14mm to the west, and point 07 has moved upward by 10mm. The Beidou calculation results of this line segment can convert the baseline to the horizontal and vertical directions for separate accuracy assessments. However, in the InSAR monitoring results, it is necessary to first use the above method to deduct the deformation caused by the horizontal displacement component between points 04-07, and the remaining vertical component is used for the comparison and accuracy assessment of the vertical monitoring accuracy of the InSAR corner reflector. Referring to Formula 7, if the difference between the observation values ​​under the four conditions of the ascending and descending orbit and the left and right views is less than the 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 04-07 Beidou baseline.

[0067] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A BeiDou + InSAR corner reflector deformation monitoring data fusion method, characterized in that: include: 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; According to the side-view geometric relationship of the radar ascending and descending orbits, the projection of the vertical and horizontal movement components of Beidou on the radar line of sight is obtained, and the total deformation of the radar line of sight inverted by Beidou is obtained by vector superposition based on the characteristics of the four quadrants. Deduct the corresponding Beidou horizontal movement component projection from the radar corner reflector deformation to obtain the vertical deformation component monitored by the radar corner reflector; When the difference in the vertical motion component value obtained from the inversion of ascending and descending orbit observations is less than a given threshold, the result is used as a correction of the GNSS vertical motion component; When there are three-dimensional motion components at both corner reflector positions, the vertical motion components of the two corner reflectors are calculated respectively. 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, and the relative displacement vector of the corner reflector observed by Beidou is decomposed into the vertical movement component and the horizontal movement component in the plane rectangular coordinate system, including: Get the geographic coordinates of the Beidou corner reflector; A local rectangular coordinate system is established with the center point of the Beidou corner reflector as the coordinate 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 motion vector obtained by Beidou measurement is projected into the local rectangular coordinate system to obtain the vertical motion component and the horizontal motion component.

3. The BeiDou + InSAR corner reflector deformation monitoring data fusion method according to claim 1, characterized in that: According to the side-view geometric relationship of the radar ascending and descending orbits, the projection of the vertical and horizontal movement components of Beidou in the radar line of sight is obtained, and the vector superposition is performed according to the characteristics of the four quadrants to obtain the total deformation of the radar line of sight inverted by GNSS; including: According to the radar orbit raising heading angle, the projection of Beidou horizontal motion component on the radar orbit raising horizontal pointing line is obtained; According to the left and right incident angles of the radar ascending orbit, the left vertical projection and the right vertical projection of the ascending orbit are calculated respectively; According to the radar descending track heading angle, the projection of the Beidou horizontal motion component on the radar descending track horizontal pointing line is obtained; According to the left and right incident angles of the radar descending orbit, the left vertical projection of the descending orbit and the right vertical projection of the descending orbit are calculated respectively; According to the projection results of the horizontal deformation projection in the four quadrants under the radar ascending and descending orbit conditions and the radar incident angle conditions, the radar line of sight deformation under the corresponding left and right viewing conditions is calculated; According to the four quadrant conditions, the vector superposition of the horizontal deformation and vertical deformation components in the radar line of sight is performed to obtain the total deformation in the radar line of sight inverted by GNSS under the conditions of left and right viewing of the ascending and descending orbits.

4. The Beidou + InSAR corner reflector deformation monitoring data fusion method according to claim 1, characterized in that: Deduct the corresponding Beidou horizontal motion component projection from the radar corner reflector deformation, and then obtain the vertical deformation component monitored by the radar corner reflector; including: According to the heading angle of the radar ascending and descending track and the local incident angle, the radar line of sight deformation of the Beidou horizontal movement component is calculated; According to the vector superposition conditions corresponding to the left and right views of the radar orbit raising and the four quadrants, the corresponding Beidou horizontal movement component is deducted from the total deformation of the radar line of sight to obtain the vertical deformation component monitored by the radar orbit raising; According to the vector superposition conditions corresponding to the left and right views of the radar and the four quadrants, the corresponding Beidou horizontal movement component is deducted from the total deformation of the radar line of sight to obtain the vertical deformation component monitored by the radar.

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 value obtained from the inversion of the ascending and descending orbit observations is less than a given threshold, the result is used as the correction of the GNSS vertical motion component, including: Calculate the vertical deformation components observed from the left and right views of the ascending and descending orbits; When the difference between the ascending and descending orbits is less than a given threshold, the average value of the vertical deformation components obtained from the left and right views of the ascending and descending orbits is used as the correction of the GNSS vertical movement component.

6. The Beidou + InSAR corner reflector deformation monitoring data fusion method according to claim 1, characterized in that: When there are three-dimensional motion components at both corner reflector positions, the vertical motion components of the two corner reflectors are calculated respectively. 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: Firstly, the vertical deformation components of the two corner reflectors and the monitored radar are obtained; Secondly, according to the directions of the two deformation component vectors and the radar ascending and descending track conditions, vector superposition is performed to obtain the vertical elevation difference of the two corner reflectors; According to whether the vertical elevation difference between the two corner reflectors exceeds a given threshold, it is determined whether the result can be used to correct the GNSS baseline elevation difference between the two corner reflectors.

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

8. The accuracy assessment method of BeiDou+InSAR corner reflector deformation monitoring data according to claim 7 is characterized in that: The GNSS horizontal deformation monitoring accuracy is evaluated by manually moving the corner reflector horizontally. The radar corner reflector horizontal deformation monitoring accuracy is evaluated based on the SAR satellite geometric observation conditions, including: In the east or west direction, the artificial horizontal movement of the corner reflector should not exceed 1 / 2 of the radar wavelength; Calculate the difference between the horizontal displacement monitored by Beidou and the model deformation to evaluate the accuracy; According to the side-view conditions of the radar lifting rail, the horizontal displacement component value corresponding to the deformation of the radar line of sight is calculated to conduct accuracy evaluation.

9. The accuracy assessment method of Beidou+InSAR corner reflector deformation monitoring data according to claim 7 is characterized in that: The vertical deformation monitoring accuracy of GNSS is evaluated by manually moving the corner reflector vertically. The vertical deformation monitoring accuracy of radar corner reflector is evaluated according to the geometric observation conditions of SAR satellite, including: The vertical manual movement of the corner reflector should not exceed 1 / 2 of the radar wavelength; Calculate the difference between the horizontal displacement monitored by Beidou and the model deformation to evaluate the accuracy; According to the side-view conditions of the radar lifting rail, the horizontal displacement component value corresponding to the deformation of the radar line of sight is calculated to conduct accuracy evaluation.

10. The accuracy assessment method of Beidou+InSAR corner reflector deformation monitoring data according to claim 7, characterized in that: Based on the triangulated network formed by Beidou corner reflector observation points, the relative deformation monitoring results of any two points in the network are obtained, and the GNSS baseline deformation monitoring accuracy between the two points and the vertical deformation monitoring accuracy of the corner reflector are evaluated, including: The artificially simulated horizontal and vertical displacement components of the two corner reflectors are calculated respectively, and the vector sum of the deformations of the two corner reflectors is calculated according to the vector direction of the line connecting the two corner reflectors; Calculate the difference between the deformation vector of the two corner reflectors monitored by Beidou and the simulated deformation vector to evaluate the accuracy; The difference between the artificially simulated deformation vectors of the two corner reflectors and the deformation vectors in the radar line of sight is compared to evaluate the accuracy.

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