CN113156429B - Imaging method, device and equipment based on millimeter wave and storage medium - Google Patents
Imaging method, device and equipment based on millimeter wave and storage medium Download PDFInfo
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- CN113156429B CN113156429B CN202110440740.7A CN202110440740A CN113156429B CN 113156429 B CN113156429 B CN 113156429B CN 202110440740 A CN202110440740 A CN 202110440740A CN 113156429 B CN113156429 B CN 113156429B
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- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
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Abstract
The invention is suitable for the technical field of radar imaging, and provides an imaging method, an imaging device, imaging equipment and a storage medium based on millimeter waves, wherein the imaging method based on the millimeter waves comprises the following steps: receiving an echo signal of a target to be imaged; traversing and calculating contrast functions of all preset three-dimensional coordinate points of the echo signals in a preset three-dimensional space region; the method comprises the steps that a preset three-dimensional space region is constructed on the basis of a preset frequency interval, a preset transmitting position interval and a preset receiving position interval, wherein the preset frequency interval is the frequency range of a transmitting signal of the imaging device, the preset transmitting position interval is the position interval of a transmitting antenna of the imaging device, and the preset receiving position interval is the position interval of a receiving antenna of the imaging device; summing the contrast functions of all the preset three-dimensional coordinate points to obtain a target contrast function of the target to be imaged; and generating an image of the target to be imaged according to the target contrast function. The invention can improve the imaging precision.
Description
Technical Field
The invention belongs to the technical field of radar imaging, and particularly relates to an imaging method, an imaging device, imaging equipment and a storage medium based on millimeter waves.
Background
With the rapid development of millimeter wave technology, the application field of millimeter wave technology is also wider and wider, such as the security inspection field. The millimeter wave human body security check instrument is a human body security check device which can utilize millimeter waves to image the penetrating capability of ordinary clothes so as to determine whether suspected articles are hidden on the body surface of a checked human body. In terms of antenna distribution, the millimeter wave human body security inspection instrument can be divided into a linear array scanning structure and an area array scanning structure, and at present, the linear array scanning structure is developed more at home and abroad.
The antenna layout in the linear array scanning structure generally adopts an arrangement mode of transmitting and receiving separation but close distance, so that the equivalent phase center can be used for replacing the antenna layout. To avoid aliasing in the image, the equivalent phase center is required to satisfy the nyquist sampling theorem. However, for high-band signals, this will cause the antenna spacing to be further reduced, resulting in poor transmit-receive isolation. For this problem, a sparse linear array mode is generally adopted for antenna layout arrangement, so as to increase the antenna spacing and improve the transmit-receive isolation. Therefore, when imaging processing is carried out, the antenna structure with separated transmitting and receiving can be subjected to single-station approximation by using the equivalent phase center, namely, the positions of the transmitting and receiving antennas are approximated to the same position, phase compensation is carried out on the single-station approximation, and then a universal near-field imaging algorithm is adopted to obtain a millimeter wave holographic imaging result.
However, for the millimeter wave human body security inspection instrument, since the human body is close to the antenna, it is difficult for the single-station approximation to perform phase compensation in a way of completely compensating for the phase error of the single-station approximation, resulting in low imaging accuracy.
Disclosure of Invention
In view of this, embodiments of the present invention provide an imaging method, an imaging device, an imaging apparatus, and a storage medium based on millimeter waves, so as to solve the problem in the prior art that the imaging accuracy of a millimeter wave human body security inspection apparatus is low.
A first aspect of an embodiment of the present invention provides a millimeter wave-based imaging method, which is applied to an imaging device employing a sparse linear array scanning antenna structure, and includes:
receiving an echo signal of a target to be imaged;
traversing and calculating contrast functions of all preset three-dimensional coordinate points of the echo signals in a preset three-dimensional space region; the method comprises the steps that a preset three-dimensional space region is constructed on the basis of a preset frequency interval, a preset transmitting position interval and a preset receiving position interval, wherein the preset frequency interval is the frequency range of a transmitting signal of the imaging device, the preset transmitting position interval is the position interval of a transmitting antenna of the imaging device, and the preset receiving position interval is the position interval of a receiving antenna of the imaging device;
summing the contrast functions of all the preset three-dimensional coordinate points to obtain a target contrast function of the target to be imaged;
and generating an image of the target to be imaged according to the target contrast function.
Optionally, traversing and calculating contrast functions of all preset three-dimensional coordinate points of the echo signal in the preset three-dimensional space region, including:
dividing the three-dimensional space area into a plurality of two-dimensional plane areas formed by a second dimension and a third dimension in the three-dimensional space area by taking a unit coordinate of the first dimension in the three-dimensional space area as a unit;
traversing and calculating contrast functions of all preset three-dimensional coordinate points corresponding to each two-dimensional plane area in the plurality of two-dimensional plane areas;
the first dimension, the second dimension and the third dimension are any one of the preset arrangement sets, and the preset arrangement sets are all arrangements formed by frequencies, transmitting positions and receiving positions.
Optionally, when the first dimension is frequency, the unit coordinate is a first preset proportion of a difference value between an upper limit value and a lower limit value in a preset frequency interval;
correspondingly, under the condition that the first dimension is the transmitting position, the unit coordinate is a second preset proportion of the difference value between the upper limit value and the lower limit value in the preset transmitting position interval;
correspondingly, when the first dimension is the receiving position, the unit coordinate is a third preset proportion of the difference value between the upper limit value and the lower limit value in the preset receiving position interval.
Optionally, generating an image of the target to be imaged according to the target contrast function includes:
and performing two-dimensional projection on the target contrast function to generate an image of the target to be imaged.
Optionally, performing two-dimensional projection on the target contrast function to generate an image of the target to be imaged, including:
carrying out maximum value projection along the direction vertical to the plane where the transmitting antenna and the receiving antenna are positioned to generate a two-dimensional image;
and determining the two-dimensional image as an image of the object to be imaged.
A second aspect of an embodiment of the present invention provides a millimeter wave-based imaging device, which employs a sparse linear array scanning antenna structure, and includes:
the receiving module is used for receiving an echo signal of a target to be imaged;
the calculating module is used for traversing and calculating contrast functions of all preset three-dimensional coordinate points of the echo signal in a preset three-dimensional space region; the method comprises the steps that a preset three-dimensional space region is constructed on the basis of a preset frequency interval, a preset transmitting position interval and a preset receiving position interval, wherein the preset frequency interval is the frequency range of a transmitting signal of the imaging device, the preset transmitting position interval is the position interval of a transmitting antenna of the imaging device, and the preset receiving position interval is the position interval of a receiving antenna of the imaging device;
the calculation module is also used for summing the contrast functions of all the preset three-dimensional coordinate points to obtain a target contrast function of the target to be imaged;
and the imaging module is used for generating an image of the target to be imaged according to the target contrast function.
Optionally, the calculation module is further configured to:
dividing the three-dimensional space area into a plurality of two-dimensional plane areas formed by a second dimension and a third dimension in the three-dimensional space area by taking a unit coordinate of the first dimension in the three-dimensional space area as a unit;
traversing and calculating contrast functions of all preset three-dimensional coordinate points corresponding to each two-dimensional plane area in the plurality of two-dimensional plane areas;
the first dimension, the second dimension and the third dimension are any one of the preset arrangement sets, and the preset arrangement sets are all arrangements formed by frequencies, transmitting positions and receiving positions.
Optionally, when the first dimension is frequency, the unit coordinate is a first preset proportion of a difference value between an upper limit value and a lower limit value in a preset frequency interval;
correspondingly, under the condition that the first dimension is the transmitting position, the unit coordinate is a second preset proportion of the difference value between the upper limit value and the lower limit value in the preset transmitting position interval;
correspondingly, when the first dimension is the receiving position, the unit coordinate is a third preset proportion of the difference value between the upper limit value and the lower limit value in the preset receiving position interval.
Optionally, the imaging module is further configured to:
and carrying out two-dimensional projection on the target contrast function to generate an image of the target to be imaged.
Optionally, the imaging module is further configured to:
carrying out maximum value projection along the direction vertical to the plane where the transmitting antenna and the receiving antenna are positioned to generate a two-dimensional image;
and determining the two-dimensional image as an image of the object to be imaged.
A third aspect of embodiments of the present invention provides a terminal device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the method according to the first aspect when executing the computer program.
A fourth aspect of embodiments of the present invention provides a computer-readable storage medium storing a computer program which, when executed by a processor, performs the steps of the method according to the first aspect.
Compared with the prior art, the embodiment of the invention has the following beneficial effects:
in the embodiment of the invention, after the echo signal of the target to be imaged is received, the contrast function of all the preset three-dimensional coordinate points of the echo signal in the preset three-dimensional space region can be calculated in a traversing manner; then, summing the contrast functions of all the preset three-dimensional coordinate points to obtain a target contrast function of the target to be imaged; finally, an image of the target to be imaged may be generated according to the target contrast function. Therefore, the problem of solving the target contrast function can be decomposed into the calculation results of a plurality of independent calculation units, the independent calculation units can calculate the contrast functions of a certain frequency point, a certain transmitting position and a certain receiving position, and then the three dimensions are traversed and summed, so that the final target contrast function, namely the imaging result, can be obtained. Because no approximation is used in the calculation process, errors caused by interpolation calculation used in a conventional range migration algorithm are avoided, and the imaging precision is improved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
Fig. 1 is a schematic structural diagram of a sparse linear array scanning antenna provided in an embodiment of the present invention;
FIG. 2 is a schematic diagram illustrating a calculation process of a target contrast function according to an embodiment of the present invention;
fig. 3 is a flowchart illustrating steps of a millimeter wave-based imaging method according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a millimeter wave-based imaging device according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a terminal device according to an embodiment of the present invention.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
In order to explain the technical means of the present invention, the following description will be given by way of specific examples.
As shown in fig. 1, fig. 1 shows a sparse linear array scanning antenna structure, which includes two dimensions of X and Y, where X represents a linear array direction, Y represents a mechanical movement direction of a linear array, and a dotted line represents a position where the linear array moves along with the mechanical movement.
As described in the related art, for an imaging device that performs antenna layout arrangement in a sparse linear array manner, it is necessary to perform single-station approximation on a transmit-receive separated antenna structure using an equivalent phase center and use a range migration algorithm to improve imaging efficiency by means of a fast fourier algorithm. However, when the range migration algorithm is used for processing a scene in a sparse array mode, phase compensation needs to be performed on a single-station approximation so as to ensure good focusing of an image. However, for the millimeter wave human body security check instrument, since the human body is close to the antenna, it is difficult for the single-station approximation to completely compensate the phase error of the single-station approximation by using a phase compensation method, resulting in low imaging accuracy.
In order to solve the problems in the prior art, embodiments of the present invention provide an imaging method, an imaging device, imaging equipment, and a storage medium based on millimeter waves. The millimeter wave-based imaging method provided by the embodiment of the invention is first described below.
The imaging device which adopts the sparse linear array mode to carry out antenna layout arrangement can send out millimeter waves to a target to be imaged through an antenna, and therefore millimeter wave signals, namely echo signals, returned by a template to be imaged can be received.
By taking fig. 1 as an example, a technical concept of the millimeter wave-based imaging method provided by the embodiment of the invention is introduced. Assuming that the transmit and receive antennas have the same y-coordinate, denoted as y ', the x-coordinates of the transmit and receive antennas are x't、x′rThe coordinate of the plane in the z direction is z0Then, for an echo with a wavenumber k, the following equation can be expressed:
where ρ (x, y, z) is the target contrast function of the target to be imaged.
According to the backprojection algorithm, the target contrast function can be expressed as follows:
considering the complexity of the summation over wavenumber k in equation (2), the target contrast function can be further expressed as:
that is, the following formula:
thus, the key to imaging is how to solve for ρk(x,y,z)。
The following expression may be defined:
then, the above equation (4) can be expressed as:
further, equation (6) may be written as to x'tThe form of summation of (a):
wherein the content of the first and second substances,
thus, as can be derived from equations (3) and (7), the solution of the target contrast function can be translated into a solution of different emission locations x'tAt different wavenumbers k
In fact, equation (8) can be expressed in terms of a convolution with y, i.e.:
fourier transform on y is performed on both sides of equation (9) and we can obtain:
wherein the content of the first and second substances,
and
are respectively
And
fourier transform on y.
Then, formula (10) may be represented as relating to x'rThe discrete summation form of (a):
thus, it is possible to obtain:
further, equation (12) can be expressed as:
wherein the content of the first and second substances,
thus, the final target contrast function can be expressed as:
the formula (14) shows that the solution of the target contrast function can be decomposed into a plurality of independent computing units for computing respectively, and then the computing results of the independent computing units are summed. The formula (14) can show that the calculation does not need to use interpolation processing in a range migration algorithm, and the method has the characteristic of high parallelization. As shown in FIG. 2, FIG. 2 is a schematic diagram of the calculation process of equation (14), where each small square in FIG. 2 corresponds to one calculation unit PU, that is, equation (14)
As can be seen from fig. 2, the solution problem of the target contrast function can be decomposed into a plurality of calculation units to independently calculate and then sum the calculation processes.
It should be noted that the computations of these PUs are independent from each other, so that the imaging time can be shortened by parallel computation.
In summary, the problem of solving the target contrast function can be decomposed into calculation results of a plurality of independent calculation units, the independent calculation units can calculate the contrast functions at a certain frequency point, a certain transmitting position and a certain receiving position, and then the three dimensions are traversed and summed to obtain the final target contrast function, namely the imaging result. Because the algorithm does not use any approximation, errors caused by interpolation calculation used in the conventional range migration algorithm are avoided.
Taking imaging of a human body as an example, in the process of imaging and scanning a certain person, the three dimensions of the frequency point, the transmitting position and the receiving position of the transmitting signal can determine a specific traversal range according to the actual situation, and referring to fig. 2 again, the transmitting frequency can correspond to the wave number, and the number of points is m; the number of the emission positions is n; the number of points for a receiving location is p points. Thus, three dimensions form a three-dimensional coordinate system, each grid unit corresponds to a calculation unit, and in a specific calculation process, traversal can be performed according to the sequence of frequency, transmitting antennas and receiving antennas, so that a result determined by three dimensions (frequency, transmitting antennas and receiving antennas) can be obtained, and then all the results are superposed, namely a final result, namely a target contrast function of the target to be imaged.
The following describes an execution subject of the millimeter wave-based imaging method.
The subject of execution of the millimeter wave based imaging method may be a millimeter wave based imaging device, which may be a terminal device having a processor and a memory, for example an imaging device employing millimeter wave technology, such as a millimeter wave human body security tester.
As shown in fig. 3, the millimeter wave-based imaging method provided in the embodiment of the present invention may include the following steps:
and step S310, receiving an echo signal of the target to be imaged.
Step S320, traversing and calculating contrast functions of all the preset three-dimensional coordinate points of the echo signal in the preset three-dimensional space region.
The preset three-dimensional space area is constructed based on a preset frequency interval, a preset transmitting position interval and a preset receiving position interval, the preset frequency interval is a frequency range of a transmitting signal of the imaging device, the preset transmitting position interval is a position interval of a transmitting antenna of the imaging device, and the preset receiving position interval is a position interval of a receiving antenna of the imaging device.
In some embodiments, the three-dimensional spatial region may be divided into a plurality of two-dimensional plane regions made up of a second dimension and a third dimension in the three-dimensional spatial region in units of unit coordinates of the first dimension in the three-dimensional spatial region. And then, traversing and calculating the contrast function of all preset three-dimensional coordinate points corresponding to each two-dimensional plane area in the plurality of two-dimensional plane areas. The first dimension, the second dimension and the third dimension are any one of the preset arrangement sets, and the preset arrangement sets are all arrangements formed by frequencies, transmitting positions and receiving positions.
Specifically, in the case where the first dimension is frequency, the unit coordinate may be a first preset proportion of a difference between an upper limit value and a lower limit value in a preset frequency interval, for example, parts per million. In the case where the first dimension is the transmission position, the unit coordinate may be a second preset ratio of a difference between an upper limit value and a lower limit value in the preset transmission position interval. In the case where the first dimension is the receiving position, the unit coordinate may be a third preset proportion of a difference between an upper limit value and a lower limit value in a preset receiving position interval.
The first preset proportion, the second preset proportion and the third preset proportion may be the same proportion or different proportions, and are not limited herein.
And S330, summing the contrast functions of all the preset three-dimensional coordinate points to obtain a target contrast function of the target to be imaged.
And step S340, generating an image of the target to be imaged according to the target contrast function.
In some embodiments, since the imaging result is generally displayed as a two-dimensional image, after the target contrast function is obtained, the target contrast function may be subjected to two-dimensional projection to generate an image of the target to be imaged.
Specifically, maximum value projection may be performed along a direction perpendicular to a plane in which the transmitting antenna and the receiving antenna are located, that is, a z direction, and thus, a two-dimensional image result, that is, an imaging result of an object to be imaged may be obtained.
In the embodiment of the invention, after the echo signal of the target to be imaged is received, the contrast function of all the preset three-dimensional coordinate points of the echo signal in the preset three-dimensional space region can be calculated in a traversing manner; then, summing the contrast functions of all the preset three-dimensional coordinate points to obtain a target contrast function of the target to be imaged; finally, an image of the target to be imaged may be generated according to the target contrast function. Therefore, the problem of solving the target contrast function can be decomposed into the calculation results of a plurality of independent calculation units, the independent calculation units can calculate the contrast functions of a certain frequency point, a certain transmitting position and a certain receiving position, and then the three dimensions are traversed and summed, so that the final target contrast function, namely the imaging result, can be obtained. Because no approximation is used in the calculation process, errors caused by interpolation calculation used in a conventional range migration algorithm are avoided, and the imaging precision is improved.
Based on the millimeter wave-based imaging method provided by the above embodiment, correspondingly, the invention further provides a specific implementation manner of the millimeter wave-based imaging device applied to the millimeter wave-based imaging method. Please see the examples below.
As shown in fig. 4, there is provided a millimeter wave based imaging device 400, which employs a sparse linear array scanning antenna structure, the device comprising:
a receiving module 410, configured to receive an echo signal of a target to be imaged;
the calculating module 420 is configured to traverse and calculate contrast functions of all preset three-dimensional coordinate points of the echo signal in a preset three-dimensional space region; the method comprises the steps that a preset three-dimensional space region is constructed on the basis of a preset frequency interval, a preset transmitting position interval and a preset receiving position interval, wherein the preset frequency interval is the frequency range of a transmitting signal of the imaging device, the preset transmitting position interval is the position interval of a transmitting antenna of the imaging device, and the preset receiving position interval is the position interval of a receiving antenna of the imaging device;
the calculating module 420 is further configured to sum the contrast functions of all the preset three-dimensional coordinate points to obtain a target contrast function of the target to be imaged;
and the imaging module 430 is configured to generate an image of the target to be imaged according to the target contrast function.
Optionally, the calculation module is further configured to:
dividing the three-dimensional space region into a plurality of two-dimensional plane regions consisting of a second dimension and a third dimension in the three-dimensional space region by taking a unit coordinate of the first dimension in the three-dimensional space region as a unit;
traversing and calculating contrast functions of all preset three-dimensional coordinate points corresponding to each two-dimensional plane area in the plurality of two-dimensional plane areas;
the first dimension, the second dimension and the third dimension are any one of the preset arrangement sets, and the preset arrangement sets are all the arrangements formed by the frequency, the transmitting position and the receiving position.
Optionally, when the first dimension is frequency, the unit coordinate is a first preset proportion of a difference value between an upper limit value and a lower limit value in a preset frequency interval;
correspondingly, under the condition that the first dimension is the transmitting position, the unit coordinate is a second preset proportion of the difference value between the upper limit value and the lower limit value in the preset transmitting position interval;
correspondingly, when the first dimension is the receiving position, the unit coordinate is a third preset proportion of the difference value between the upper limit value and the lower limit value in the preset receiving position interval.
Optionally, the imaging module is further configured to:
and carrying out two-dimensional projection on the target contrast function to generate an image of the target to be imaged.
Optionally, the imaging module is further configured to:
carrying out maximum value projection along the direction vertical to the plane where the transmitting antenna and the receiving antenna are positioned to generate a two-dimensional image;
and determining the two-dimensional image as an image of the object to be imaged.
In the embodiment of the invention, after the echo signal of the target to be imaged is received, the contrast functions of all the preset three-dimensional coordinate points of the echo signal in the preset three-dimensional space region can be calculated in a traversing manner; then, summing the contrast functions of all the preset three-dimensional coordinate points to obtain a target contrast function of the target to be imaged; finally, an image of the target to be imaged may be generated according to the target contrast function. Therefore, the problem of solving the target contrast function can be decomposed into the calculation results of a plurality of independent calculation units, the independent calculation units can calculate the contrast functions of a certain frequency point, a certain transmitting position and a certain receiving position, and then the three dimensions are traversed and summed, so that the final target contrast function, namely the imaging result, can be obtained. Because no approximation is used in the calculation process, errors caused by interpolation calculation used in a conventional range migration algorithm are avoided, and the imaging precision is improved.
Fig. 5 is a schematic diagram of a terminal device according to an embodiment of the present invention. As shown in fig. 5, the terminal device 5 of this embodiment includes: a processor 50, a memory 51 and a computer program 52 stored in said memory 51 and executable on said processor 50. The processor 50 implements the steps in the various millimeter wave based imaging method embodiments described above when executing the computer program 52. Alternatively, the processor 50 implements the functions of the modules/units in the above-described device embodiments when executing the computer program 52.
Illustratively, the computer program 52 may be partitioned into one or more modules/units that are stored in the memory 51 and executed by the processor 50 to implement the present invention. The one or more modules/units may be a series of computer program instruction segments capable of performing specific functions, which are used to describe the execution process of the computer program 52 in the terminal device 5. For example, the computer program 52 may be divided into a receiving module, a calculating module, and an imaging module, and the specific functions of the modules are as follows:
the receiving module is used for receiving an echo signal of a target to be imaged;
the calculating module is used for traversing and calculating contrast functions of all preset three-dimensional coordinate points of the echo signals in a preset three-dimensional space region; the method comprises the steps that a preset three-dimensional space region is constructed on the basis of a preset frequency interval, a preset transmitting position interval and a preset receiving position interval, wherein the preset frequency interval is the frequency range of a transmitting signal of the imaging device, the preset transmitting position interval is the position interval of a transmitting antenna of the imaging device, and the preset receiving position interval is the position interval of a receiving antenna of the imaging device;
the calculation module is also used for summing the contrast functions of all the preset three-dimensional coordinate points to obtain a target contrast function of the target to be imaged;
and the imaging module is used for generating an image of the target to be imaged according to the target contrast function.
The terminal device 5 may be a desktop computer, a notebook, a palm computer, a cloud server, or other computing devices. The terminal device may include, but is not limited to, a processor 50, a memory 51. Those skilled in the art will appreciate that fig. 5 is merely an example of a terminal device 5 and does not constitute a limitation of terminal device 5 and may include more or fewer components than shown, or some components may be combined, or different components, e.g., the terminal device may also include input-output devices, network access devices, buses, etc.
The Processor 50 may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic, discrete hardware components, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The memory 51 may be an internal storage unit of the terminal device 5, such as a hard disk or a memory of the terminal device 5. The memory 51 may also be an external storage device of the terminal device 5, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), and the like, provided on the terminal device 5. Further, the memory 51 may also include both an internal storage unit and an external storage device of the terminal device 5. The memory 51 is used for storing the computer program and other programs and data required by the terminal device. The memory 51 may also be used to temporarily store data that has been output or is to be output.
It should be clear to those skilled in the art that, for convenience and simplicity of description, the foregoing division of the functional units and modules is only used for illustration, and in practical applications, the above function distribution may be performed by different functional units and modules as needed, that is, the internal structure of the apparatus may be divided into different functional units or modules to perform all or part of the above described functions. Each functional unit and module in the embodiments may be integrated in one processing unit, or each unit may exist alone physically, or two or more units are integrated in one unit, and the integrated unit may be implemented in a form of hardware, or in a form of software functional unit. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present application. The specific working processes of the units and modules in the system may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the embodiments provided in the present invention, it should be understood that the disclosed apparatus/terminal device and method may be implemented in other ways. For example, the above-described embodiments of the apparatus/terminal device are merely illustrative, and for example, the division of the modules or units is only one logical division, and there may be other divisions when actually implemented, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated modules/units, if implemented in the form of software functional units and sold or used as separate products, may be stored in a computer readable storage medium. Based on such understanding, all or part of the flow of the method according to the embodiments of the present invention may also be implemented by a computer program, which may be stored in a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the method embodiments may be implemented. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, Read-Only Memory (ROM), Random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution medium, and the like. It should be noted that the computer readable medium may contain content that is subject to appropriate increase or decrease as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, computer readable media does not include electrical carrier signals and telecommunications signals as is required by legislation and patent practice.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.
Claims (10)
1. An imaging method based on millimeter waves is characterized in that the method is applied to imaging equipment adopting a sparse linear array scanning antenna structure, and the method comprises the following steps:
receiving an echo signal of a target to be imaged;
traversing and calculating contrast functions of all preset three-dimensional coordinate points of the echo signals in a preset three-dimensional space region; the preset three-dimensional space region is constructed based on a preset frequency interval, a preset transmitting position interval and a preset receiving position interval, wherein the preset frequency interval is a frequency range of a transmitting signal of the imaging device, the preset transmitting position interval is a position interval of a transmitting antenna of the imaging device, and the preset receiving position interval is a position interval of a receiving antenna of the imaging device;
summing the contrast functions of all the preset three-dimensional coordinate points to obtain a target contrast function of the target to be imaged;
generating an image of the target to be imaged according to the target contrast function;
wherein the contrast function of the preset three-dimensional coordinate point is as follows:
the echo waveThe wave number of the signal is k, the y coordinates of the transmitting antenna and the receiving antenna are both y ', and the x coordinates of the transmitting antenna and the receiving antenna are x't、x′rThe x coordinate is the linear array direction, the y coordinate is the mechanical motion direction of the linear array, and the z coordinate of the plane where the transmitting antenna and the receiving antenna are located is z0，
And
is a fourier transform with respect to y.
2. The millimeter wave-based imaging method according to claim 1, wherein the step of traversing the contrast function of all the preset three-dimensional coordinate points of the echo signal in the preset three-dimensional spatial region comprises:
dividing the three-dimensional space region into a plurality of two-dimensional plane regions formed by a second dimension and a third dimension in the three-dimensional space region by taking the unit coordinate of the first dimension in the three-dimensional space region as a unit;
traversing and calculating contrast functions of all preset three-dimensional coordinate points corresponding to each two-dimensional plane area in the plurality of two-dimensional plane areas;
the first dimension, the second dimension and the third dimension are any one of a preset arrangement set, and the preset arrangement set is all arrangements formed by frequencies, transmitting positions and receiving positions.
3. The millimeter wave-based imaging method according to claim 2, wherein:
under the condition that the first dimension is frequency, the unit coordinate is a first preset proportion of a difference value between an upper limit value and a lower limit value in the preset frequency interval;
under the condition that the first dimension is the transmitting position, the unit coordinate is a second preset proportion of the difference value between the upper limit value and the lower limit value in the preset transmitting position interval;
and under the condition that the first dimension is the receiving position, the unit coordinate is a third preset proportion of the difference value between the upper limit value and the lower limit value in the preset receiving position interval.
4. The millimeter wave-based imaging method according to claim 1, wherein the generating an image of the object to be imaged according to the object contrast function comprises:
and performing two-dimensional projection on the target contrast function to generate an image of the target to be imaged.
5. The millimeter wave-based imaging method according to claim 4, wherein the two-dimensional projection of the target contrast function to generate the image of the target to be imaged comprises:
carrying out maximum value projection along the direction vertical to the plane where the transmitting antenna and the receiving antenna are located to generate a two-dimensional image;
and determining the two-dimensional image as the image of the target to be imaged.
6. An imaging device based on millimeter waves, the device employing a sparse linear array scanning antenna structure, the device comprising:
the receiving module is used for receiving an echo signal of a target to be imaged;
the calculating module is used for traversing and calculating contrast functions of all preset three-dimensional coordinate points of the echo signal in a preset three-dimensional space region; the preset three-dimensional space region is constructed based on a preset frequency interval, a preset transmitting position interval and a preset receiving position interval, wherein the preset frequency interval is a frequency range of a transmitting signal of the imaging device, the preset transmitting position interval is a position interval of a transmitting antenna of the imaging device, and the preset receiving position interval is a position interval of a receiving antenna of the imaging device;
the calculation module is further configured to sum the contrast functions of all the preset three-dimensional coordinate points to obtain a target contrast function of the target to be imaged;
the imaging module is used for generating an image of the target to be imaged according to the target contrast function;
wherein the contrast function of the preset three-dimensional coordinate point is as follows:
the wave number of the echo signal is k, the y coordinates of the transmitting antenna and the receiving antenna are y ', and the x coordinates of the transmitting antenna and the receiving antenna are x't、x′rThe x coordinate is the linear array direction, the y coordinate is the mechanical motion direction of the linear array, and the z coordinate of the plane where the transmitting antenna and the receiving antenna are located is z0，
And
is a fourier transform with respect to y.
7. The millimeter-wave based imaging device of claim 6, wherein the computation module is further configured to:
dividing the three-dimensional space region into a plurality of two-dimensional plane regions formed by a second dimension and a third dimension in the three-dimensional space region by taking the unit coordinate of the first dimension in the three-dimensional space region as a unit;
traversing and calculating contrast functions of all preset three-dimensional coordinate points corresponding to each two-dimensional plane area in the plurality of two-dimensional plane areas;
the first dimension, the second dimension and the third dimension are any one of a preset arrangement set, and the preset arrangement set is all arrangements formed by frequencies, transmitting positions and receiving positions.
8. The millimeter-wave based imaging device of claim 6, wherein the imaging module is further configured to:
and performing two-dimensional projection on the target contrast function to generate an image of the target to be imaged.
9. A terminal device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor implements the steps of the method according to any of claims 1 to 5 when executing the computer program.
10. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 5.
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