A phase unwrapping method based on random shortest path optimization

Abstract

The present invention proposes a phase unwrapping method based on random shortest path optimization, including: obtaining an interference phase map, initializing a set of lateral distance scale scaling factors and a set of neighborhood scattering point numbers: traversing the set of lateral distance scale scaling factors and the set of neighborhood scattering point numbers, and determining the corresponding phase unwrapping sequence for each lateral scale scaling factor and the corresponding number of neighborhood scattering points; using the phase unwrapping sequence, determining the three-dimensional image of the corresponding target; determining the variance of the three-dimensional image in turn, and the three-dimensional image corresponding to the minimum variance, and its corresponding phase unwrapping sequence is determined as the final unwrapping phase. The present invention overcomes the problem of being unable to obtain the true position of the scattering and unable to calculate the distance between the scattering points by selecting the scattering point with the smallest phase difference in the neighborhood of the scattering point as the next scattering point of the path integral, and constructing a highly robust phase unwrapping method with variance as an evaluation index, which does not rely on prior information and is applicable to various scenarios.

Description

Technical Field

[0001] The invention relates to the technical field of interferometric inverse synthetic aperture radar, and in particular to a phase unwrapping method based on random shortest path optimization. Background Art

[0002] Interferometric Inverse Synthetic Aperture Radar (InISAR) imaging is an extension of traditional Inverse Synthetic Aperture Radar (ISAR). It can perform three-dimensional imaging of non-cooperative targets all day and all weather, and can obtain important information such as the three-dimensional structure and attitude of the imaging target. It has extremely high civil and military value. InISAR relies on the interference phase difference of the target scattering points in different radar channels to solve the position information of the scattering points, thereby obtaining the three-dimensional structure of the target. The interference phase in the signal is entangled in a period, so unwrapping the phase and obtaining the correct interference phase is the key to InISAR imaging. In addition, the phase entanglement problem also exists in Interferometric Synthetic Aperture Radar (InSAR) imaging. However, due to the differences between InISAR and InSAR in imaging principles and imaging targets, the phase unwrapping method of InSAR (hereinafter referred to as "unwrapping") is mature but cannot be directly used in InISAR. InISAR phase unwrapping is still a difficult problem to be solved.

[0003] In existing InISAR imaging, phase unwrapping is often avoided by controlling the baseline length, or additional prior knowledge is used to assist phase unwrapping, which greatly limits the actual application scenarios of InISAR. Summary of the invention

[0004] The technical problem to be solved by the present invention is how to perform phase unwrapping with high robustness without relying on prior knowledge and baseline restrictions; in view of this, the present invention provides a phase unwrapping method based on random shortest path optimization.

[0005] The technical solution adopted by the present invention is a phase unwrapping method based on random shortest path optimization, comprising:

[0006] Step 1, obtaining an interference phase map, initializing a set of lateral distance scale scaling factors and a set of neighborhood scattering point numbers, wherein the interference phase map is obtained by:

[0007] In a first radar channel, a second radar channel, and a third radar channel of an InISAR imaging radar, a signal of the first radar channel is used as a reference signal, in a world coordinate system, a distance between the second radar channel and the first radar channel is a first baseline, a distance between the third radar channel and the first radar channel is a second baseline, the first baseline and the second baseline are orthogonal to each other and have equal lengths, the interference phase map is an interference phase map further obtained by using an ISAR image formed by the first radar channel and the second radar channel, or the interference phase map is an interference phase map further obtained by using an ISAR image formed by the second radar channel and the third radar channel;

[0008] Step 2, traversing the set of transverse distance scale scaling factors and the set of neighborhood scattering point numbers, and determining corresponding phase unwrapping sequences for each transverse scale scaling factor and corresponding number of neighborhood scattering points;

[0009] Step 3, using the phase unwrapping sequence to determine a three-dimensional image of the corresponding target;

[0010] Step 4: determine the variance of the three-dimensional image in turn, and the phase unwrapping sequence corresponding to the three-dimensional image corresponding to the minimum variance is determined as the final unwrapping phase.

[0011] In one embodiment, step 2 comprises:

[0012] Normalizing the range and Doppler coordinates of the ISAR image, scaling the range using the lateral scaling factor, and performing random initial scattering points;

[0013] Find the scattering points of the number of neighborhood scattering points closest to the p-th scattering point through the L2 distance, and select the scattering point with the smallest phase difference with the p-th point as the p+1-th scattering point;

[0014] Perform phase unwrapping on the p+1th scattering point;

[0015] Repeat the above steps until the maximum number of scattering points is reached, and save the unwrapped phase sequence, which is the phase unwrapped sequence.

[0016] In one embodiment, step 3 comprises:

[0017] Using the phase unwrapping sequence, sequentially determine the three-dimensional coordinates of the corresponding targets;

[0018] The three-dimensional coordinates corresponding to all the phase unwrapping sequences are determined as the three-dimensional image corresponding to the target.

[0019] In one embodiment, step 4 comprises:

[0020] Based on a preset three-dimensional image scattering point variance algorithm, sequentially determining the variance of the three-dimensional image;

[0021] The minimum value among the variance values ​​corresponding to the three-dimensional image and the phase unwrapping sequence corresponding to the three-dimensional image are determined as the final unwrapping phase.

[0022] Another aspect of the present invention further provides an InISAR phase winding resolution device based on random shortest path optimization, comprising:

[0023] An acquisition unit is configured to acquire an interference phase image and initialize a set of lateral distance scale scaling factors and a set of neighborhood scattering point numbers, wherein the interference phase image is acquired in the following manner:

[0024] In a first radar channel, a second radar channel, and a third radar channel of an InISAR imaging radar, a signal of the first radar channel is used as a reference signal, in a world coordinate system, a distance between the second radar channel and the first radar channel is a first baseline, a distance between the third radar channel and the first radar channel is a second baseline, the first baseline and the second baseline are orthogonal to each other and have equal lengths, the interference phase map is an interference phase map further obtained by using an ISAR image formed by the first radar channel and the second radar channel, or the interference phase map is an interference phase map further obtained by using an ISAR image formed by the second radar channel and the third radar channel;

[0025] A phase unwrapping unit is configured to traverse the set of transverse distance scale scaling factors and the set of neighborhood scattering point numbers, and determine a corresponding phase unwrapping sequence for each transverse scale scaling factor and the corresponding number of neighborhood scattering points;

[0026] a target imaging unit configured to determine a three-dimensional image of a corresponding target using the phase unwrapping sequence;

[0027] The output unit is configured to determine the variance of the three-dimensional image in sequence, and the phase unwrapping sequence corresponding to the three-dimensional image corresponding to the minimum variance is determined as the final unwrapping phase.

[0028] In one embodiment, the phase unwrapping unit is further configured to:

[0029] Normalizing the range and Doppler coordinates of the ISAR image, scaling the range using the lateral scaling factor, and performing random initial scattering points;

[0030] Find the scattering points of the number of neighborhood scattering points closest to the p-th scattering point through the L2 distance, and select the scattering point with the smallest phase difference with the p-th point as the p+1-th scattering point;

[0031] Perform phase unwrapping on the p+1th scattering point;

[0032] Repeat the above steps until the maximum number of scattering points is reached, and save the unwrapped phase sequence, which is the phase unwrapped sequence.

[0033] In one embodiment, the target imaging unit is further configured as:

[0034] Using the phase unwrapping sequence, sequentially determine the three-dimensional coordinates of the corresponding targets;

[0035] The three-dimensional coordinates corresponding to all the phase unwrapping sequences are determined as the three-dimensional image corresponding to the target.

[0036] In one embodiment, the output unit is further configured as:

[0037] Based on a preset three-dimensional image scattering point variance algorithm, sequentially determining the variance of the three-dimensional image;

[0038] The minimum value among the variance values ​​corresponding to the three-dimensional image and the phase unwrapping sequence corresponding to the three-dimensional image are determined as the final unwrapping phase.

[0039] Another aspect of the present invention provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the phase unwrapping method based on random shortest path optimization as described in any one of the above items.

[0040] Another aspect of the present invention further provides a computer storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the phase unwrapping method based on random shortest path optimization as described in any one of the above items are implemented.

[0041] Compared with the prior art, the present invention has at least the following advantages:

[0042] This application overcomes the problem of being unable to obtain the true position of the scattering and unable to calculate the distance between two scattering points by selecting the scattering point with the smallest phase difference in the neighborhood of the scattering point as the next scattering point of the path integral; using the variance of the InISAR imaging result as the evaluation index, combined with the strategy of random initial scattering points, traversing the set of lateral distance scale scaling factors, and traversing the set of neighborhood scattering points, a highly robust phase unwrapping optimization method is constructed; it does not rely on additional prior information and can be applied to various scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of the "L" type interferometric antenna configuration;

[0044] Figure 2A schematic diagram of a process flow of a method for resolving winding of InISAR phases based on random shortest path optimization according to an embodiment of the present invention;

[0045] Figure 3 A logical schematic diagram of a method for resolving winding of InISAR phases based on random shortest path optimization according to an embodiment of the present invention;

[0046] Figure 4 is a schematic diagram of a target model according to an embodiment of the present invention;

[0047] Figure 5 Schematic diagram of the comparison of InISAR imaging results using different unwrapping methods;

[0048] Figure 6 It is a schematic diagram of the structure of a device for solving the winding of InISAR phase based on random shortest path optimization according to an embodiment of the present invention;

[0049] Figure 7 FIG. 1 is a schematic diagram of an electronic device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0050] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined purpose, the present invention is described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0051] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined in this article.

[0052] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0053] For ease of understanding, necessary explanations are given below on the relevant technologies involved in the present invention.

[0054] 1) InISAR imaging

[0055] ISAR imaging uses radar to emit a wide bandwidth signal to obtain a one-dimensional range image of the target and then form a range resolution capability. The Doppler resolution capability is formed by the Doppler difference of different scattering points generated by the effective rotation of the target. Range resolution and Doppler resolution constitute the two-dimensional resolution capability of ISAR imaging. Therefore, the most commonly used ISAR imaging method is called the range-Doppler method. Different from the range-Doppler method of ISAR imaging, InISAR imaging increases the number of radar channels. There are differences in the spatial positions of different radar channels, which will produce a small phase difference in the ISAR image. The phase difference carries the position information of the scattering point. The position information of the scattering point can be restored by phase calculation, forming a resolution capability beyond the range-Doppler, and then three-dimensional imaging can be achieved. This method of measuring distance using phase is called interferometry. The three-dimensional imaging method using the interferometry principle combined with ISAR imaging is InISAR imaging. Compared with ISAR imaging, InISAR imaging can obtain a three-dimensional image of the target, but its technology is also more complicated. Among them, InISAR phase unwrapping is one of the key technologies that determine the success of imaging.

[0056] The basic concept of InISAR imaging is explained using the most common "L" interferometric antenna configuration in Figure 1. Assume that the InISAR imaging radar has three radar channels, A, B, and C. The signal of radar A is used as the reference signal in the world coordinate system. In the example, the distances from radar B and radar C to reference radar A are called baseline lengths. Baseline AB and baseline AC are orthogonal to each other and have a length of ; Point M is the midpoint of AB, From point M to the target scattering point p The distance can be used for the final interference distance calculation. The ISAR images formed by radar A and radar B can obtain a set of interference phase diagrams The ISAR images formed by radar A and radar C can obtain another set of interference phase images . use and The coordinates of the scattering points along the two baseline directions can be calculated, and then combined with the distance coordinates of the scattering points to form the three-dimensional coordinates of the scattering points.

[0057] 2) InISAR phase entanglement / ambiguity problem

[0058] Assuming that there are two radar channels A and B, and ISAR imaging is performed on a non-cooperative target at the same time, two ISAR images can be obtained. In addition to amplitude information, ISAR images also include phase information. The phases of the ISAR images formed by radar A and radar B are recorded as and , and Both The interference phase diagram can be obtained by subtracting the phases of different channels. , the position information of the target scattering point is contained in the interference phase diagram.

[0059] (1)

[0060] middle, The interference phase of the position scattering point is recorded as , Also known as the winding phase, the non-winding absolute phase is denoted by ,and Satisfaction relationship:

[0061] (2)

[0062] in, It is a fuzzy number, which takes an integer value and describes the multiple of phase winding.

[0063] is the final phase that can be used for interferometric distance calculation. Errors will lead to errors in interferometric distance calculation and imaging errors, so phase unwrapping is crucial. However, in InISAR imaging, most of the research is based on simulation and simple scene testing, usually by controlling the length of the baseline to avoid phase unwrapping, that is, It is always 0 and no phase ambiguity occurs, which greatly limits the use scenarios of InISAR imaging.

[0064] In the phase unwrapping theory of InSAR imaging, the phase in the two-dimensional image is required to strictly satisfy the Itoh condition (phase continuity assumption), that is, the phase difference between a pixel and its adjacent pixels must be within To ensure the correctness of the two-dimensional unwrapping, the InISAR image only has physical meaning for the pixels at the scattering point. The phase difference between adjacent pixels does not satisfy the Itoh condition, which brings great difficulties to the phase unwrapping of InISAR imaging.

[0065] To solve this problem, we can assume that the two closest scattering points in the ISAR image meet the Itoh condition. The scattering point is compared with the nearest scattering point (marked as ) satisfies the interference phase:

[0066] (3)

[0067] in, For the The interference phase of the scattering points is For the The interferometric phase of each scattering point. Although the scattering points of InISAR imaging are sparse and discrete, the assumption that the two closest scattering points meet the Itoh condition is very loose, as long as the distance between the two scattering points in the baseline direction is less than the unambiguous distance, and the unambiguous distance is usually equivalent to the target size, so this assumption is reasonable. The correct unwrapped phase can be obtained by unwrapping the scattering points one by one according to the principle of the closest distance, and the phase unwrapping problem of InISAR is converted into a shortest path integral problem.

[0068] The InISAR phase entanglement problem can be solved by performing one-dimensional linear integral unwrapping in the shortest path sequence, but how to calculate the distance between two scattering points and find the two scattering points with the smallest distance has become another difficult problem. Only the distance of the scattering points and the lateral Doppler can be obtained through ISAR images. The lateral Doppler can only provide lateral relative position information. The third dimension coordinate of the vertical imaging plane is unknown, so the real position of the scattering points cannot be obtained, and therefore the distance between two scattering points cannot be calculated.

[0069] Analyze the relationship between the target structure and imaging. Two scattering points that are adjacent in the ISAR image are not necessarily adjacent in the geometric structure, but two scattering points that are adjacent in the target geometric structure must be adjacent in the ISAR image. Therefore, the “distance” in the ISAR image can be The closest scattering point The scattering point with the smallest phase difference is selected as the first scattering point. This method can replace the shortest distance calculation to find the nearest point, thus solving the problem of being unable to calculate the distance between two scattering points.

[0070] In addition, through the analysis of the InISAR imaging results of unwrapping failure, the target in the InISAR imaging results of unwrapping failure will be split into multiple parts, and most of these split parts will be scattered in the imaging space instead of being gathered together. The overall InISAR imaging of unwrapping failure is scattered and poorly aggregated, so the variance of the reconstructed coordinates of the scattering points can be used as an evaluation index. The InISAR imaging result with the smallest variance is most likely to be the result of successful unwrapping. Variance is a reasonable evaluation index, so it is possible to consider reasonably expanding the search range to increase the probability of successful unwrapping. Three strategies for reasonably expanding the search range include:

[0071] 1. Random initial scattering point. The first scattering point will affect the unwrapping result. If the first scattering point is an incorrect non-scattering point, the unwrapping result will be wrong.

[0072] 2. Scaling the lateral distance at different scales. When scaling the lateral distance at different scales, there is always a scale that is closest to the calibration scale of the ISAR image. Then, the unwrapping at this scale will have a greater probability of success.

[0073] 3. Use multiple sets of values. It will make the search strategy more "conservative" or "aggressive", so different values ​​can be used and different strategies can be used to make it easier to find the optimal solution.

[0074] Based on this, the present invention provides a phase unwrapping method based on random shortest path optimization, which is as follows:

[0075] The first embodiment of the present invention is a phase unwrapping method based on random shortest path optimization, such as Figure 2 As shown, including:

[0076] Step 1, obtain the interference phase map, initialize the lateral distance scale scaling factor set and the number set of neighborhood scattering points;

[0077] Step 2, traversing the set of transverse distance scale scaling factors and the set of neighborhood scattering point numbers, and determining corresponding phase unwrapping sequences for each transverse scale scaling factor and corresponding number of neighborhood scattering points;

[0078] Step 3, using the phase unwrapping sequence to determine a three-dimensional image of the corresponding target;

[0079] Step 4: determine the variance of the three-dimensional image in turn, and the phase unwrapping sequence corresponding to the three-dimensional image corresponding to the minimum variance is determined as the final unwrapping phase.

[0080] refer to Figure 3 , the method provided in this embodiment will be described in detail step by step below.

[0081] Step 1: Obtain the interference phase map and initialize the lateral distance scale scaling factor set and the number of neighborhood scattering points.

[0082] In this embodiment, the interference phase diagram is obtained by the following method:

[0083] Among the first radar channel A, the second radar channel B, and the third radar channel C of the InISAR imaging radar, the signal of the first radar channel A is used as a reference signal. In the figure, the distance between the second radar channel B and the first radar channel A is the first baseline AB, the distance between the third radar channel C and the first radar channel A is the second baseline AC, the first baseline AB and the second baseline AC are orthogonal to each other and have the same length (for example, both are L), and the interferometric phase map is the interferometric phase map further obtained by using the ISAR image formed by the first radar channel A and the second radar channel B. Alternatively, the interferometric phase image is an interferometric phase image further obtained by using the ISAR image formed by the second radar channel B and the third radar channel C. .

[0084] For example, for the interference phase diagram or , initialize the horizontal distance scale scaling factor set , the number of neighborhood scattering points . Can be set to , Can be set to .

[0085] Step 2: traverse the set of transverse distance scale scaling factors and the set of neighborhood scattering point numbers, and determine the corresponding phase unwrapping sequence for each transverse scale scaling factor and the corresponding number of neighborhood scattering points.

[0086] That is to say, traversal and , for a certain horizontal scaling factor and the number of neighborhood scattering points , perform the following steps:

[0087] Step 2-1: Normalize the range and Doppler coordinates of the ISAR image. Scaling, random initial scattering point, the initial scattering point sequence number is The distance-Doppler coordinates of the scattering points in the ISAR image are represented as , the normalized distance-Doppler coordinate is , the distance coordinate after scaling is marked as , the coordinate normalization operation and distance scaling operation are expressed by formula (4) and formula (5) respectively:

[0088] (4)

[0089] (5)

[0090] Step 2-2: Find the distance by L2 distance The closest scatter point scattering points, select the one with The scattering point with the smallest phase difference is taken as the first scattering points. The L2 distance calculation formula between two scattering points is:

[0091] (6)

[0092] Step 2-3: Phase unwrapping of scattering points:

[0093] (7)

[0094] Step 2-4: Repeat steps 2-1 to 2-3 until Reach the maximum number of scatter points , save the unwrapped phase sequence .

[0095] Step 3: Use the phase unwrapping sequence to determine the three-dimensional image of the corresponding target.

[0096] For all unwrapped phase sequences ; Calculate the three-dimensional coordinates of the target , and then get the target three-dimensional image. Among them, is the scattering point in the baseline direction of A and B radar channels coordinate, is the scattering point in the baseline direction of A and C radar channels coordinate, Scattering point The range image coordinates (in InISAR imaging, this coordinate can be obtained directly without interferometry).

[0097] Taking two radar channels A and B as an example, a scattering point The coordinates along the AB baseline are:

[0098] (8)

[0099] in, Scattering point The interference phase of channels A and B after unwrapping is also A phase in is the speed of light; is the radar signal carrier frequency; From the midpoint M of the AB baseline to the scattering point distance; is the baseline length; The calculation method and same.

[0100] Step 4, determining the variance of the three-dimensional image in turn, and the phase unwrapping sequence corresponding to the three-dimensional image corresponding to the minimum variance is determined as the final unwrapping phase.

[0101] Specifically, the variance of each InISAR 3D image is calculated, and the 3D image with the smallest variance is the final 3D image, corresponding to the unwrapped phase sequence This is the unwrapping result of the phase unwrapping method based on random shortest path optimization. The variance of the InISAR three-dimensional image can be calculated from the coordinates of each scattering point, and the formula is:

[0102] (9)

[0103] in, The unwrapped phase sequence The variance corresponding to the resulting InISAR 3D image.

[0104] Figure 4 It is a three-dimensional scattering point model of a satellite target. Figure 4 Comparison of InISAR imaging results under different unwrapping methods. The dots are marked as the actual positions of the scattering points, and the asterisks are marked as the InISAR imaging results.

[0105] Figure 5 (a) is the result without phase unwrapping. One scattering point is obviously deviated from the main body. The reason is that the phase wrapping leads to the miscalculation of the three-dimensional position of the scattering point.

[0106] Figure 5 Method 1 in (b) is the InISAR imaging result that directly uses the range-Doppler coordinates of the ISAR image to calculate the shortest path. The InISAR image of the target is split into multiple pieces and the unwrapping fails. The reason is that the scattering point distance calculated by range-Doppler is not the actual scattering point distance.

[0107] Figure 5 Method 2 in (c) is the InISAR imaging result after phase unwrapping by the method proposed in the present invention. The imaging result basically coincides with the position of the scattering point, verifying the effectiveness of the method proposed in the present invention.

[0108] It can be seen from the above that compared with the prior art, this embodiment has at least the following effects:

[0109] 1) The present invention overcomes the problem of being unable to obtain the true position of the scattering and unable to calculate the distance between two scattering points by selecting the scattering point with the smallest phase difference in the neighborhood of the scattering point as the next scattering point of the path integral.

[0110] 2) The present invention improves the success rate of disentanglement by taking the variance of InISAR imaging results as the evaluation index and combining strategies such as random initial scattering points, traversing the lateral distance scale scaling factor set, and traversing the neighborhood scattering point number set.

[0111] 3) This paper proposes to use variance as the evaluation index of InISAR imaging results, which provides an optimization target for converting the InISAR phase unwrapping problem into an optimization problem.

[0112] 4) The present invention overcomes the influence of initial point selection on InISAR phase unwrapping through a random initial scattering point strategy.

[0113] 5) The present invention overcomes the drawback that the lateral Doppler can only provide lateral relative information by traversing the lateral range scale scaling factor set, thus avoiding lateral calibration of ISAR images.

[0114] 6) The present invention improves the robustness of the phase unwrapping method by traversing the number set of neighborhood scattering points.

[0115] In summary, compared with the existing methods, the method proposed in the present invention does not rely on prior knowledge and does not need to adjust the baseline length. It is widely applicable to various scenarios and can achieve effective InISAR phase unwrapping.

[0116] The second embodiment of the present invention corresponds to the first embodiment. Figure 6 As shown, this embodiment introduces a phase unwrapping device based on random shortest path optimization, including the following components:

[0117] An acquisition unit is configured to acquire an interference phase image and initialize a set of lateral distance scale scaling factors and a set of neighborhood scattering point numbers, wherein the interference phase image is acquired in the following manner:

[0118] In a first radar channel, a second radar channel, and a third radar channel of an InISAR imaging radar, a signal of the first radar channel is used as a reference signal, in a world coordinate system, a distance between the second radar channel and the first radar channel is a first baseline, a distance between the third radar channel and the first radar channel is a second baseline, the first baseline and the second baseline are orthogonal to each other and have equal lengths, the interference phase map is an interference phase map further obtained by using an ISAR image formed by the first radar channel and the second radar channel, or the interference phase map is an interference phase map further obtained by using an ISAR image formed by the second radar channel and the third radar channel;

[0119] A phase unwrapping unit is configured to traverse the set of transverse distance scale scaling factors and the set of neighborhood scattering point numbers, and determine a corresponding phase unwrapping sequence for each transverse scale scaling factor and the corresponding number of neighborhood scattering points;

[0120] a target imaging unit configured to determine a three-dimensional image of a corresponding target using the phase unwrapping sequence;

[0121] The output unit is configured to determine the variance of the three-dimensional image in sequence, and the phase unwrapping sequence corresponding to the three-dimensional image corresponding to the minimum variance is determined as the final unwrapping phase.

[0122] In one embodiment, the phase unwrapping unit is further configured to:

[0123] Normalizing the range and Doppler coordinates of the ISAR image, scaling the range using the lateral scaling factor, and performing random initial scattering points;

[0124] Find the scattering points of the number of neighborhood scattering points closest to the p-th scattering point through the L2 distance, and select the scattering point with the smallest phase difference with the p-th point as the p+1-th scattering point;

[0125] Perform phase unwrapping on the p+1th scattering point;

[0126] Repeat the above steps until the maximum number of scattering points is reached, and save the unwrapped phase sequence, which is the phase unwrapped sequence.

[0127] In one embodiment, the target imaging unit is further configured as:

[0128] Using the phase unwrapping sequence, sequentially determine the three-dimensional coordinates of the corresponding targets;

[0129] The three-dimensional coordinates corresponding to all the phase unwrapping sequences are determined as the three-dimensional image corresponding to the target.

[0130] In one embodiment, the output unit is further configured as:

[0131] Based on a preset three-dimensional image scattering point variance algorithm, sequentially determining the variance of the three-dimensional image;

[0132] The minimum value among the variance values ​​corresponding to the three-dimensional image and the phase unwrapping sequence corresponding to the three-dimensional image are determined as the final unwrapping phase.

[0133] A third embodiment of the present invention is an electronic device, which can be understood as a physical device, such as Figure 7 As shown, it includes a processor and a memory storing instructions executable by the processor. When the instructions are executed by the processor, the following operations are performed:

[0134] Step 1, obtaining an interference phase map, initializing a set of lateral distance scale scaling factors and a set of neighborhood scattering point numbers, wherein the interference phase map is obtained by:

[0135] In a first radar channel, a second radar channel, and a third radar channel of an InISAR imaging radar, a signal of the first radar channel is used as a reference signal, in a world coordinate system, a distance between the second radar channel and the first radar channel is a first baseline, a distance between the third radar channel and the first radar channel is a second baseline, the first baseline and the second baseline are orthogonal to each other and have equal lengths, the interference phase map is an interference phase map further obtained by using an ISAR image formed by the first radar channel and the second radar channel, or the interference phase map is an interference phase map further obtained by using an ISAR image formed by the second radar channel and the third radar channel;

[0136] Step 2, traversing the set of transverse distance scale scaling factors and the set of neighborhood scattering point numbers, and determining corresponding phase unwrapping sequences for each transverse scale scaling factor and corresponding number of neighborhood scattering points;

[0137] Step 3, using the phase unwrapping sequence to determine a three-dimensional image of the corresponding target;

[0138] Step 4: determine the variance of the three-dimensional image in turn, and the phase unwrapping sequence corresponding to the three-dimensional image corresponding to the minimum variance is determined as the final unwrapping phase.

[0139] The fourth embodiment of the present invention, the process of the phase unwrapping method based on random shortest path optimization in this embodiment is the same as that of the first, second or third embodiment, the difference is that in engineering implementation, this embodiment can be implemented by means of software plus a necessary general hardware platform, of course, it can also be implemented by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the method of the present invention can be embodied in the form of a computer software product, which is stored in a storage medium (such as ROM / RAM, disk, CD), including a number of instructions for a device to execute the method described in the embodiment of the present invention.

[0140] Through the description of the specific implementation methods, a deeper and more specific understanding of the technical means and effects adopted by the present invention to achieve the predetermined purpose should be obtained. However, the accompanying drawings are only for reference and illustration purposes and are not intended to limit the present invention.

Claims

1. A phase unwrapping method based on random shortest path optimization, characterized in that: include: Step 1, obtaining an interference phase map, initializing a set of lateral distance scale scaling factors and a set of neighborhood scattering point numbers, wherein the interference phase map is obtained by: In a first radar channel, a second radar channel, and a third radar channel of an InISAR imaging radar, a signal of the first radar channel is used as a reference signal, in a world coordinate system, a distance between the second radar channel and the first radar channel is a first baseline, a distance between the third radar channel and the first radar channel is a second baseline, the first baseline and the second baseline are orthogonal to each other and have equal lengths, the interference phase map is an interference phase map further obtained by using an ISAR image formed by the first radar channel and the second radar channel, or the interference phase map is an interference phase map further obtained by using an ISAR image formed by the second radar channel and the third radar channel; Step 2, traversing the set of transverse distance scale scaling factors and the set of neighborhood scattering point numbers, and determining corresponding phase unwrapping sequences for each transverse distance scale scaling factor and corresponding number of neighborhood scattering points; Step 3, using the phase unwrapping sequence to determine a three-dimensional image of the corresponding target; Step 4, determining the variance of the three-dimensional image in turn, and the phase unwrapping sequence corresponding to the three-dimensional image corresponding to the minimum variance is determined as the final unwrapping phase; Wherein, the step 2 comprises: Normalizing the range and Doppler coordinates of the ISAR image, scaling the range using the lateral range scale scaling factor, and randomly initializing scattering points; Find the scattering points of the number of neighborhood scattering points closest to the p-th scattering point through the L2 distance, and select the scattering point with the smallest phase difference with the p-th point as the p+1-th scattering point; Perform phase unwrapping on the p+1th scattering point; Repeat the above steps until the maximum number of scattering points is reached, and save the unwrapped phase sequence, which is the phase unwrapped sequence.

2. The phase unwrapping method based on random shortest path optimization according to claim 1, characterized in that: The step 3 comprises: Using the phase unwrapping sequence, sequentially determine the three-dimensional coordinates of the corresponding targets; The three-dimensional coordinates corresponding to all the phase unwrapping sequences are determined as the three-dimensional image corresponding to the target.

3. The phase unwrapping method based on random shortest path optimization according to claim 2, characterized in that: The step 4 comprises: Based on a preset three-dimensional image scattering point variance algorithm, sequentially determining the variance of the three-dimensional image; The minimum value among the variance values ​​corresponding to the three-dimensional image and the phase unwrapping sequence corresponding to the three-dimensional image are determined as the final unwrapping phase.

4. A phase unwrapping device based on random shortest path optimization, characterized in that: include: An acquisition unit is configured to acquire an interference phase image and initialize a set of lateral distance scale scaling factors and a set of neighborhood scattering point numbers, wherein the interference phase image is acquired in the following manner: In a first radar channel, a second radar channel, and a third radar channel of an InISAR imaging radar, a signal of the first radar channel is used as a reference signal, in a world coordinate system, a distance between the second radar channel and the first radar channel is a first baseline, a distance between the third radar channel and the first radar channel is a second baseline, the first baseline and the second baseline are orthogonal to each other and have equal lengths, the interference phase map is an interference phase map further obtained by using an ISAR image formed by the first radar channel and the second radar channel, or the interference phase map is an interference phase map further obtained by using an ISAR image formed by the second radar channel and the third radar channel; A phase unwrapping unit is configured to traverse the set of transverse distance scale scaling factors and the set of neighborhood scattering point numbers, and determine a corresponding phase unwrapping sequence for each transverse distance scale scaling factor and the corresponding number of neighborhood scattering points; a target imaging unit configured to determine a three-dimensional image of a corresponding target using the phase unwrapping sequence; An output unit is configured to determine the variance of the three-dimensional image in sequence, and the phase unwrapping sequence corresponding to the three-dimensional image corresponding to the minimum variance is determined as the final unwrapping phase; Wherein, the phase unwrapping unit is further configured as: Normalizing the range and Doppler coordinates of the ISAR image, scaling the range using the lateral range scale scaling factor, and randomly initializing scattering points; Find the scattering points of the number of neighborhood scattering points closest to the p-th scattering point through the L2 distance, and select the scattering point with the smallest phase difference with the p-th point as the p+1-th scattering point; Perform phase unwrapping on the p+1th scattering point; Repeat the above steps until the maximum number of scattering points is reached, and save the unwrapped phase sequence, which is the phase unwrapped sequence.

5. The phase unwrapping device based on random shortest path optimization according to claim 4, characterized in that: The target imaging unit is further configured as: Using the phase unwrapping sequence, sequentially determine the three-dimensional coordinates of the corresponding targets; The three-dimensional coordinates corresponding to all the phase unwrapping sequences are determined as the three-dimensional image corresponding to the target.

6. The phase unwrapping device based on random shortest path optimization according to claim 5, characterized in that: The output unit is further configured as: Based on a preset three-dimensional image scattering point variance algorithm, sequentially determining the variance of the three-dimensional image; The minimum value among the variance values ​​corresponding to the three-dimensional image and the phase unwrapping sequence corresponding to the three-dimensional image are determined as the final unwrapping phase.

7. An electronic device, characterized in that: The electronic device comprises: a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the phase unwrapping method based on random shortest path optimization as claimed in any one of claims 1 to 3.

8. A computer storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the phase unwrapping method based on random shortest path optimization as claimed in any one of claims 1 to 3.

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