CN111880181B

CN111880181B - Weak trace processing method and device, and detection method and device

Info

Publication number: CN111880181B
Application number: CN202010761626.XA
Authority: CN
Inventors: 胡利平; 李胜; 周峰; 吴皓; 王超
Original assignee: Beijing Institute of Environmental Features
Current assignee: Beijing Institute of Environmental Features
Priority date: 2020-07-31
Filing date: 2020-07-31
Publication date: 2021-11-30
Anticipated expiration: 2040-07-31
Also published as: CN111880181A

Abstract

The invention discloses a weak trace processing method, a weak trace processing device, a weak trace detection method and a weak trace detection device, wherein the processing method comprises the following steps: testing the trace sample under the background of the manufactured ground object, and acquiring RCS test data of the scattering cross section of the omnibearing sweep frequency radar of the trace sample under different ground wiping angles; performing two-dimensional high-resolution inverse synthetic aperture radar ISAR imaging on the RCS test data to obtain omnibearing ISAR image data under different ground wiping angles; fusing ISAR image data of the trace sample at a plurality of azimuth angles under a preset ground wiping angle to obtain a multi-angle fusion enhancement result image of the weak trace; comparing fusion result images of the omnibearing ISAR image data under different ground wiping angles; and determining the optimal wiping angle data for performing target enhancement on the weak traces in the ground object background. The invention can realize the discovery, detection and identification of weak trace targets.

Description

Weak trace processing method and device, and detection method and device

Technical Field

The invention relates to the technical field of weak trace target detection, in particular to a weak trace processing method, a weak trace processing device, a weak trace detection method and a weak trace detection device.

Background

Accurate acquisition and identification of sensitive targets is one of effective ways for timely discovery and timely response of terrorist people, vehicles, mules and horses in complex environments. Therefore, the detection and classification technology of sensitive target traces such as researchers, mules, horses and vehicles has very important significance. However, trace targets such as people, mules, vehicles and the like belong to weak targets due to small structures and dimensions, and are difficult to be found in low-resolution radar images and even high-resolution radar images with single view angles.

Therefore, a need exists for a targeted enhancement method of weak traces.

Disclosure of Invention

The invention aims to provide a weak trace processing method, a weak trace processing device, a weak trace detection method and a weak trace detection device, and realizes the discovery, detection and identification of a weak trace target.

The invention discloses a weak trace processing method, which comprises the following steps: testing the trace sample under the background of the manufactured ground object, and acquiring RCS test data of the scattering cross section of the omnibearing sweep frequency radar of the trace sample under different ground wiping angles;

performing two-dimensional high-resolution inverse synthetic aperture radar ISAR imaging on the RCS test data to obtain omnibearing ISAR image data under different ground wiping angles;

fusing ISAR image data of the trace sample at a plurality of azimuth angles under a preset ground wiping angle to obtain a multi-angle fusion enhancement result image of the weak trace;

comparing the fusion enhancement result images of the omnibearing ISAR image data under different ground rubbing angles; and determining the angle data of the ground rubbing angle for performing target enhancement on the weak trace under the ground feature background.

Preferably, before fusing the ISAR image data of the trace sample at a plurality of azimuth angles under the predetermined rubbing angle, the method further includes:

ISAR images at multiple azimuth angles at a predetermined scrub angle are registered and multi-view averaged.

Preferably, the acquiring of the omnibearing swept frequency RCS test data of the trace sample under different ground wiping angles comprises the following steps:

under the preset radar working parameters, calibrating the radar by using a calibration body with a known RCS value to realize the frequency response error calibration of the radar;

and carrying out omnibearing sweep frequency RCS measurement on the trace sample under different ground-wiping angles by using the calibrated radar to obtain omnibearing sweep frequency RCS test data under different ground-wiping angles.

Preferably, the two-dimensional high resolution ISAR imaging of the RCS test data comprises:

and carrying out two-dimensional high-resolution ISAR imaging on the omnibearing frequency sweep RCS test data of the trace sample by adopting a filtering-inverse projection imaging algorithm.

Preferably, the two-dimensional high-resolution ISAR imaging of the omni-directional swept frequency RCS test data of the trace sample by using a filter-backprojection imaging algorithm comprises:

determining a range of synthetic aperture angles;

under a preset ground wiping angle, carrying out coherent processing on RCS test data of each azimuth angle within the range of synthetic aperture teaching;

and detecting whether the resolution meets the requirement, and if not, interpolating the distance resolution and the azimuth resolution by adopting a linear interpolation method to obtain the ideal resolution.

Preferably, registering and multi-view averaging the ISAR images at a plurality of azimuth angles at a predetermined scrub angle comprises:

carrying out conversion from an oblique distance map to a ground distance map on ISAR images in different directions under a preset ground wiping angle, and rotating the ISAR images to a preset angle according to azimuth angle information;

and carrying out amplitude average processing on the registered ISAR images of all azimuth angles under the preset ground rubbing angle to obtain a multi-azimuth angle fusion enhancement result image.

In a second aspect, the present invention provides a weak trace detection method, including:

acquiring RCS data of the scattering cross section of the omnibearing sweep frequency radar of the trace to be identified within a preset ground-wiping angle range;

performing two-dimensional high-resolution inverse synthetic aperture radar ISAR imaging on the RCS data to obtain omnibearing ISAR image data in the range of the ground rubbing angle;

fusing ISAR image data of the trace to be recognized in a plurality of azimuth angles in the preset ground wiping angle range to obtain a multi-angle fusion enhancement result image of the weak trace;

detecting and identifying the trace to be identified by utilizing the omnibearing ISAR multi-angle fusion enhancement result image under the range of the ground rubbing angle;

wherein the range of the preset floor mopping angle is determined by the weak trace processing method.

In a third aspect, the present invention provides a weak trace processing apparatus, including:

the test data acquisition module is used for testing the trace sample under the manufactured ground object background and acquiring RCS test data of the scattering cross section of the omnibearing sweep frequency radar of the trace sample under different ground wiping angles;

the image processing module is used for carrying out two-dimensional high-resolution inverse synthetic aperture radar ISAR imaging on the RCS test data to obtain omnibearing ISAR image data under different ground wiping angles;

the multi-angle fusion module is used for fusing ISAR image data of the trace sample at a plurality of azimuth angles under a preset ground wiping angle to obtain a multi-angle fusion enhancement result image of the weak trace;

and the fusion effect determining module is used for comparing fusion enhancement result images of the omnibearing ISAR image data under different ground wiping angles and determining ground wiping angle data for target enhancement of weak traces under the ground object background.

Preferably, the weak trace processing apparatus further includes a calibration module configured to calibrate the radar by using a calibration object with a known RCS value under a predetermined radar operating parameter, so as to calibrate a frequency response error of the radar.

In a fourth aspect, the present invention provides a weak trace detection apparatus, including:

the detection data acquisition module is used for acquiring RCS data of the scattering cross section of the omnibearing sweep frequency radar of the trace to be identified in a preset ground wiping angle range;

the imaging processing module is used for carrying out two-dimensional high-resolution inverse synthetic aperture radar ISAR imaging on the RCS data to obtain omnibearing ISAR image data in the range of the ground rubbing angle;

the data fusion module is used for fusing ISAR image data of the trace to be identified at a plurality of azimuth angles in the preset ground wiping angle range to obtain a multi-angle fusion enhancement result image of the weak trace;

the detection recognition module is used for performing detection recognition on the trace to be recognized by utilizing the omnibearing ISAR multi-angle fusion enhancement result image in the range of the ground rubbing angle;

wherein the range of the preset floor mopping angle is determined by the weak trace processing method. Compared with the prior art, the invention has the following advantages:

the method verifies that the high-resolution imaging measurement system is feasible to realize weak trace enhancement and detection identification in the multi-angle fusion treatment of a specific ground wiping angle through the trace sample making, the high-resolution imaging test, the multi-angle fusion and other treatments, provides a weak trace target enhancement method based on the multi-angle fusion, summarizes that the weak trace target can realize trace enhancement through the multi-angle fusion treatment under the small ground wiping angle, and provides a range suitable for the ground wiping angle with a better weak trace multi-angle fusion effect, so that the method is more beneficial to the detection and identification of the weak trace, and has important guiding significance for the detection and identification of the weak trace target by the actual high-resolution imaging radar system.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the example serve to explain the principles of the invention and not to limit the invention.

FIG. 1 is a flow chart of a faint trace processing method according to one embodiment of the present application;

FIG. 2 is a flow chart of a faint trace detection method according to another embodiment of the present application;

FIG. 3 is a schematic structural diagram of a weak trace processing apparatus according to another embodiment of the present application;

FIG. 4 is a schematic structural diagram of a weak trace detection apparatus according to another embodiment of the present application;

FIG. 5 is a block diagram of a computing device according to another embodiment of the present application;

FIG. 6 is a diagram of a computer readable storage medium structure according to another embodiment of the present application;

FIG. 7 is a schematic view of a model of a feature background holding device according to another embodiment of the present application;

FIG. 8 is a schematic view of a surface feature background holding device according to another embodiment of the present application;

FIG. 9 is a sample view of a footprint against a sand background according to another embodiment of the present application;

FIG. 10 is a schematic diagram of an external structure of a satellite remote sensing surface feature spectrum according to another embodiment of the present application;

FIG. 11 is an omnidirectional ISAR image of a footprint sample at a 20 deg. scrub angle according to another embodiment of the present application; wherein FIG. 11(a) is an ISAR image at-180 °; FIG. 11(b) is an ISAR image at-90 °; fig. 11(c) is an ISAR image of 0 °; fig. 11(d) is an ISAR image of 90 °;

FIG. 12 is a graph of the results of an omni-directional ISAR image fusion at a 20 deg. scrub angle for a footprint sample according to another embodiment of the present application;

FIG. 13 is a graph of the results of an omni-directional ISAR image fusion of a footprint sample at different scrub angles according to another embodiment of the present application; wherein, fig. 13(a) is an ISAR fusion result image of 20 °; fig. 13(b) is an ISAR fusion result image of 30 °; fig. 13(c) is an ISAR fusion result image of 40 °; fig. 13(d) is an ISAR fusion result image of 50 °;

FIG. 14 is a graph of the results of an omni-directional ISAR image fusion of a groove mark sample at different scrub angles according to another embodiment of the present application; wherein, fig. 14(a) is an ISAR fusion result image of 30 °; fig. 14(b) is an ISAR fusion result image of 40 °; fig. 14(c) is an ISAR fusion result image of 50 °;

FIG. 15 is a graph of the results of an omni-directional ISAR image fusion of a pit mark sample at different scrub angles according to another embodiment of the present application; wherein, fig. 15(a) is an ISAR fusion result image of 30 °; fig. 15(b) is an ISAR fusion result image of 40 °; fig. 15(c) is an ISAR fusion result image of 50 °.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

The steps illustrated in the flow charts of the figures may be performed in a computer system such as a set of computer-executable instructions. Also, while a logical order is shown in the flow diagrams, in some cases, the steps shown or described may be performed in an order different than here.

Example one

As shown in fig. 1, an embodiment of the present invention provides a weak trace processing method, which may include steps S101 to S104:

s101, testing the trace sample under the background of the manufactured ground object, and acquiring RCS test data of the scattering cross section of the omnibearing frequency-sweeping radar of the trace sample under different ground-wiping angles;

s102, performing two-dimensional high-resolution inverse synthetic aperture radar ISAR imaging on the RCS test data to obtain omnibearing ISAR image data under different ground wiping angles;

s103, fusing ISAR image data of the trace sample at a plurality of azimuth angles under a preset ground wiping angle to obtain a multi-angle fusion enhancement result image of the weak trace;

s104, comparing fusion enhancement result images of the omnibearing ISAR image data under different ground rubbing angles; and determining the angle data of the ground rubbing angle for performing target enhancement on the weak trace under the ground feature background.

In the embodiment of the invention, the trace sample is subjected to the omnibearing RCS test under a typical incident angle, wherein the RCS test can be carried out by utilizing millimeter waves, and omnibearing sweep frequency RCS test data of the trace sample under different ground wiping angles are obtained.

The RCS test is a relative calibration of free space reflections. In order to keep the repeatability and stability of the test and minimize the influence of manual operation in the test process, the measuring radar is kept in a continuous measuring and uninterrupted power state, and the target does not perform other operations on the rotary table except the rotation of the control direction in the test process.

In this embodiment of the present invention, before the step S103 of fusing the ISAR image data of the trace sample at a plurality of azimuth angles under the predetermined scrub angle, the method further includes:

In the embodiment of the invention, the omnibearing ISAR images under different ground-wiping angles are obtained, and the ISAR images of a plurality of azimuth angles under the same ground-wiping angle are subjected to registration and multi-view averaging to obtain a multi-angle fusion result image of a trace sample under a certain ground-wiping angle.

In the embodiment of the present invention, the acquiring of the omnibearing sweep frequency RCS test data of the trace sample under different ground-wiping angles in step S101 includes:

The RCS test of the embodiment of the invention adopts a relative calibration method of free space reflection to carry out measurement. And under the conditions of determined radar working frequency, polarization mode and the like, calibrating the radar by using a calibration body with an accurately known RCS value to finish frequency response error calibration of the measurement system. And the calibrated radar can carry out RCS precision measurement.

In the embodiment of the present invention, the performing two-dimensional high resolution ISAR imaging on the RCS test data in step S102 includes:

In the embodiment of the invention, the two-dimensional high-resolution ISAR imaging of the omnibearing frequency sweep RCS test data of the trace sample by adopting a filtering-inverse projection imaging algorithm comprises the following steps:

determining a range of synthetic aperture angles;

The synthetic aperture angle determined in the embodiments of the present invention generally ranges from an angle of 10 to 20.

In the embodiment of the invention, the filtering-inverse projection imaging algorithm directly carries out coherent processing in the azimuth direction, in order to ensure the coherent processing effect in the imaging process and simultaneously give consideration to higher imaging resolution ratio so as to be beneficial to subsequent multi-angle fusion processing, when carrying out high-resolution imaging on omnidirectional sweep RCS test data, a synthetic aperture angle is selected to be a certain angle range. If the resolution is required to be further improved, the distance direction resolution and the azimuth direction resolution are interpolated to the ideal resolution by adopting a linear interpolation method.

In the embodiment of the present invention, the registering and multi-view averaging the ISAR images at a plurality of azimuth angles under a predetermined scrub angle includes:

The registration processing is to convert the ISAR images in different directions under a certain wiping angle from a slope distance image to a ground distance image, and then rotate the ISAR images to a certain fixed angle according to azimuth angle information, wherein in the embodiment of the invention, the ISAR images in all directions can be rotated to 0 degree.

And the multi-view average processing is to perform amplitude average processing on the registered ISAR images of all azimuth angles under a certain ground rubbing angle to obtain a multi-direction angle fusion result image. In order to achieve a better fusion effect, in the embodiment of the invention, a plurality of high-resolution ISAR images are selected for multi-view averaging.

The embodiment of the invention verifies that weak traces can be enhanced by fusing the data under a plurality of azimuth angles on one hand, and determines the range of the ground rubbing angle which is beneficial to detection and identification on the other hand.

Example two

As shown in fig. 2, an embodiment of the present invention further provides a weak trace detection method, which may include steps S201 to S204:

s201, acquiring RCS data of an omnibearing sweep frequency radar scattering cross section of a trace to be identified in a preset ground wiping angle range;

s202, performing two-dimensional high-resolution Inverse Synthetic Aperture Radar (ISAR) imaging on the RCS data to acquire omnibearing ISAR image data within the range of the ground rubbing angle;

s203, fusing ISAR image data of the trace to be recognized in a plurality of azimuth angles in the preset ground wiping angle range to obtain a multi-angle fusion enhancement result image of the weak trace;

s204, detecting and identifying the trace to be identified by utilizing the omnibearing ISAR multi-angle fusion enhancement result image under the ground-wiping angle range;

The embodiment of the invention utilizes the floor wiping angle data determined by the weak trace processing method to find, detect and identify the weak trace target.

EXAMPLE III

As shown in fig. 3, an embodiment of the present invention further provides a weak trace processing apparatus, including:

The weak trace processing device in the embodiment of the invention further comprises a calibration module which is set to calibrate the radar by using a calibration body with a known RCS value under the preset radar working parameters, so as to realize the frequency response error calibration of the radar.

Example four

As shown in fig. 4, an embodiment of the present invention further provides a weak trace detection apparatus, including:

the preset floor mopping angle data are determined by the weak trace processing method.

EXAMPLE five

Embodiments also provide a computing device, referring to fig. 5, comprising a memory 1120, a processor 1110 and a computer program stored in said memory 1120 and executable by said processor 1110, the computer program being stored in a space 1130 for program code in the memory 1120, the computer program, when executed by the processor 1110, implementing the method steps 1131 for performing any of the methods according to the invention.

The embodiment of the application also provides a computer readable storage medium. Referring to fig. 6, the computer readable storage medium comprises a storage unit for program code provided with a program 1131' for performing the steps of the method according to the invention, which program is executed by a processor.

EXAMPLE six

The embodiment of the invention discloses a weak trace target enhancement method based on multi-angle fusion, which comprises the following steps:

first, constructing a weak trace target enhancement system based on multi-angle fusion

Weak trace object enhancement system based on multi-angle fusion includes: designing and manufacturing a trace sample module, a trace sample RCS test data acquisition module and a two-dimensional high-resolution ISAR imaging and multi-angle fusion processing module under a sand background; the following steps:

the function of designing and manufacturing the trace sample module under the sand background is as follows: designing and manufacturing a trace sample which can be tested in a laboratory;

the trace sample test data acquisition module has the functions of: developing trace sample test in a satellite remote sensing ground object spectrum characteristic laboratory to obtain all-directional sweep frequency RCS test data of the trace sample under different ground-rubbing angles;

the two-dimensional high-resolution ISAR imaging and multi-angle fusion processing module has the functions of: and performing two-dimensional high-resolution ISAR imaging on the test data to obtain all-dimensional ISAR images under a plurality of ground-rubbing angles, and performing registration and multi-view averaging on the all-dimensional ISAR images under the specific ground-rubbing angles to obtain a multi-angle fusion result image of the trace sample under the specific ground-rubbing angles.

Designing and manufacturing a trace sample under the sand background

Because the ground environment is various and complex and most of the ground environment is difficult to simulate in a laboratory, according to the principle that the ground environment is relatively easy to operate and control, the trace is relatively easy to realize and is relatively obvious and stable, when the ground scene and the trace sample are designed, sand is selected as the type of the ground scene, and the foot print is trampled on the sand or the pit or the ditch of a shovel is used as the type of the trace sample.

Since the sand has loose characteristics, a special containing device needs to be designed. In addition, in order to reduce the influence of the containing device on the laboratory measurement result as much as possible, the containing device is made of glass fiber reinforced plastic materials with good wave permeability and strong rigidity. The tray is designed to be 2000mm in diameter and 50mm thick according to the maximum measurable target size requirement of the laboratory. Because sand has great weight, need hoist and mount in the testing process, designed 8 hoist and mount buttons in the bottom of glass steel tray, guaranteed the reliability of hoist and mount in the testing process. The schematic view and the size and structure of the glass fiber reinforced plastic pallet are shown in fig. 7 and 8.

And paving sand in a glass fiber reinforced plastic tray, and treading foot prints with different sizes and depths on a flat sand ground or digging pits or grooves by using a shovel, so that the design and the manufacture of the trace sample are completed. A photograph of a sample of traces of the footprint against a sand background is shown in fig. 9.

Third, trace sample test data acquisition

And carrying out the omnibearing millimeter wave RCS test on the trace sample at a typical incidence angle in a satellite remote sensing ground feature spectrum characteristic laboratory, and acquiring the omnibearing sweep frequency RCS test data of the trace sample at different ground wiping angles.

The satellite remote sensing ground feature spectrum characteristic laboratory adopts a structure form of combining a sphere and a column, a main body consists of a sphere part and a cylinder part, a circular arc track is arranged at the combining part of the sphere and the cylinder, and an equipment vehicle capable of sliding along the circular arc track is arranged on the track. The laboratory setup is shown in fig. 10. Two sets of radar transmitting and receiving equipment are respectively arranged on two equipment vehicles. A15-meter-long linear track is arranged on the ground perpendicular to the plane of the arc-shaped track, a rotary table capable of translating integrally is arranged on the track, and a tested object is supported on the rotary table through a foam support. Wave-absorbing materials are coated on all wall surfaces in the laboratory, so that the influence of multipath effect and background scattering on the test is reduced.

RCS is measured by adopting a free space reflection relative calibration method according to GJB 5022-2001 indoor field scaling target radar scattering cross section test method. And under the conditions of determined radar working frequency, polarization mode and the like, calibrating by using a calibration body with an RCS value accurately known to finish frequency response error calibration of the measurement system. The RCS precision measurement can be carried out by the calibrated system.

In order to maintain the repeatability and stability of the test system and minimize the influence of manual operation in the test process, the test system is kept in a continuous measurement and uninterrupted power state, and the target does not perform other operations on the rotary table except the rotation of the control direction in the test process.

During measurement, a small metal ball is placed at a certain position of the edge of the sand table in order to select a reference point.

Four-dimensional and two-dimensional high-resolution ISAR imaging and multi-angle fusion processing

The method comprises the steps of carrying out two-dimensional high-resolution ISAR imaging on omnibearing sweep RCS test data of a trace sample by adopting a back-projection (BP) imaging algorithm to obtain omnibearing ISAR images under different ground-rubbing angles, and then carrying out registration and multi-view averaging on ISAR images of a plurality of azimuth angles under the same ground-rubbing angle to obtain a multi-angle fusion result image of the trace sample under a certain ground-rubbing angle.

The filtering-inverse projection imaging algorithm is to directly perform coherent processing in the azimuth direction, in order to ensure the coherent processing effect in the imaging process and simultaneously give consideration to higher imaging resolution so as to be beneficial to subsequent multi-angle fusion processing, when high-resolution imaging is performed on all-directional frequency sweep RCS test data (frequency: 32-36 GHz, interval 10MHz, azimuth angle-180 DEG- +180 DEG, interval 0.1 DEG), a synthetic aperture angle is selected to be a certain angle between 10 DEG and 20 deg. If the resolution is required to be further improved, the distance direction resolution and the azimuth direction resolution are interpolated to the ideal resolution by adopting a linear interpolation method.

The registration is to convert the ISAR images in different directions under a certain ground wiping angle from a slope distance image to a ground distance image, and then rotate the ISAR images to a certain fixed angle according to azimuth angle information, wherein in the embodiment of the invention, the ISAR images in all directions are rotated to 0 degree.

And the multi-view average processing is to perform amplitude average processing on the registered ISAR images of all azimuth angles under a certain ground rubbing angle to obtain a multi-direction angle fusion result image. In order to achieve a better fusion effect, 37 high-resolution ISAR images are selected in the embodiment of the invention to perform multi-view averaging, the azimuth angle ranges from minus 180 degrees to plus 180 degrees, and the interval is 10 degrees.

Figure 11 shows an omnidirectional ISAR image of a footprint sample at a 20 deg. scrub angle. It can be seen that it is difficult to find footprint traces from ISAR images at a single azimuth angle. FIG. 12 shows the results of the fusion of the omnidirectional ISAR images of the footprint sample at a 20 deg. scrub angle. It can be seen that after ISAR images under a plurality of azimuth angles are fused, footprint traces are obviously highlighted.

In order to compare multidirectional fusion effects under different ground wiping angles, the ground wiping angles are selected from 20-50 degrees or 30-50 degrees at intervals of 10 degrees in the embodiment of the invention, as shown in fig. 13, the comprehensive ISAR image fusion results of foot print trace samples under different ground wiping angles are given, and it can be seen that when the ground wiping angles are small, such as 20 degrees and 30 degrees, the weak trace fusion effect is obvious, the ground wiping angles are increased, traces in the fusion result image are more and more unobvious, and when the ground wiping angles are 50 degrees, the traces cannot be highlighted even through multi-angle fusion processing. This is because the dihedral angle effect formed in the horizontal and vertical directions in the track structure is more pronounced when the ground-wiping angle is small, and the dihedral angle effect is reduced when the ground-wiping angle is large. The comparison of different types of traces can also be seen, because the edge vertical structure in the trace structure of the footprint is regular and the dihedral angle effect is obvious, the footprint trace in the fusion result is more obvious and regular and the edge is clear; as shown in fig. 14 and 15, the omnibearing ISAR image fusion results of the groove trace sample and the pit trace sample under different ground wiping angles are shown, and since the groove and the pit are dug by a shovel laterally, the edge vertical structure is not very regular, and the depth is shallow and deep, the edge of the groove and the pit in the fusion result image of the groove and the pit is not particularly clear compared with the footprint; by combining the results, the conclusion can be drawn that when a multi-angle fusion mode is adopted to strengthen weak traces, better fusion results can be obtained only by selecting multi-angle data of small ground wiping angles as much as possible.

Therefore, a weak trace target enhancement process based on multi-angle fusion is determined.

It will be understood by those of ordinary skill in the art that all or some of the steps of the methods, systems, and functional modules/units in the devices disclosed in the embodiments of the present invention may be implemented as software, firmware, hardware, and suitable combinations thereof. In a hardware implementation, the division between functional modules/units mentioned in the above description does not necessarily correspond to the division of physical components; for example, one physical component may have multiple functions, or one function or step may be performed by several physical components in cooperation. Some or all of the components may be implemented as software executed by a processor, such as a digital signal processor or microprocessor, or as hardware, or as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on computer readable media, which may include computer storage media (or non-transitory media) and communication media (or transitory media). The term computer storage media includes volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data, as is well known to those of ordinary skill in the art. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, Digital Versatile Disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can accessed by a computer. In addition, communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media as known to those skilled in the art.

Claims

1. A weak trace processing method is characterized by comprising the following steps:

testing the trace sample under the background of the manufactured ground object, and acquiring RCS test data of the scattering cross section of the omnibearing sweep frequency radar of the trace sample under different ground wiping angles;

2. The faint trace processing method according to claim 1, wherein before fusing ISAR image data of the trace sample at a plurality of azimuth angles under a predetermined scrub angle, further comprising:

3. The weak trace processing method according to claim 1 or 2, wherein the obtaining of the all-dimensional swept-frequency RCS test data of the trace sample under different ground-rubbing angles comprises:

4. The faint trace processing method of claim 3, wherein performing two-dimensional high resolution ISAR imaging on the RCS test data comprises:

5. The faint trace processing method of claim 4, wherein performing two-dimensional high resolution ISAR imaging on the omni-directional swept frequency RCS test data of the trace sample by using a filter-backprojection imaging algorithm comprises:

determining a range of synthetic aperture angles;

6. The faint trace processing method of claim 2, wherein registering and multi-view averaging the ISAR images at a plurality of azimuths under a predetermined scrub angle comprises:

7. A weak trace detection method is characterized by comprising the following steps:

wherein the predetermined scrub angle range is determined by the weak mark processing method of any one of claims 1 to 6.

8. A faint trace processing apparatus, comprising:

9. The faint trace processing apparatus of claim 8, further comprising a calibration module configured to calibrate the radar with a calibration volume having a known RCS value under predetermined radar operating parameters to achieve a frequency response error calibration of the radar.

10. A faint trace detecting apparatus, comprising: