Disclosure of Invention
Based on this, there is a need to provide a scanning-free single-channel terahertz radar forward-looking three-dimensional imaging method, system, computer device and storage medium capable of simplifying a radar imaging system while satisfying the requirement of high-resolution high-frame-rate imaging.
A scanning-free single-channel terahertz radar forward-looking three-dimensional imaging method, the method comprising:
Respectively controlling a single-shot terahertz radar receiving and transmitting signal through two paths of synchronous clock signals to obtain a one-dimensional range profile of a detection scene, controlling a time-of-flight camera to acquire a signal to obtain a three-dimensional depth image corresponding to the detection scene, and further obtaining a training set consisting of a plurality of groups of one-dimensional range profile and three-dimensional depth image pairs through changing the gesture and the position of a target in the detection scene;
Converting a one-dimensional range profile in a training set into a column vector, inputting the column vector into a pre-designed neural network model, and training the neural network model by taking the column vector obtained by flattening a three-dimensional depth image corresponding to the one-dimensional range profile as output to obtain a trained neural network model;
And obtaining a one-dimensional range profile of the scene to be detected, converting the one-dimensional range profile into a column vector, inputting the column vector into the trained neural network model, and obtaining a three-dimensional image of the scene to be detected according to the column vector output by the trained neural network model.
In one embodiment, the method further comprises the steps of controlling the single-shot terahertz radar to acquire signals in a trigger mode through a first clock signal, so that the single-shot terahertz radar can receive and transmit signals and store data when detecting one falling edge, and a one-dimensional range profile of a detection scene is obtained;
the method comprises the steps of controlling a time-of-flight camera to acquire signals in a trigger mode through a second clock signal, so that the time-of-flight camera acquires and stores data when detecting a falling edge, and obtaining a three-dimensional depth image corresponding to a detection scene, wherein the three-dimensional depth image comprises the abscissa and the ordinate of each point in the detection scene and depth information;
the first clock signal is kept synchronized with the second clock signal.
In one embodiment, the method further comprises the steps of converting a one-dimensional range profile in a training set into column vectors, inputting the column vectors into a pre-designed neural network model, training the neural network model by taking the column vectors obtained by flattening the three-dimensional depth image corresponding to the one-dimensional range profile as output, and obtaining a trained neural network model, wherein the neural network is a neural network of a multi-layer perceptron, the neural network of the multi-layer perceptron comprises an input layer, three fully connected layers and an output layer, the fully connected layers are used for connecting each point of input data with each point of output data, and an activation function layer is arranged behind each fully connected layer.
In one embodiment, the method further comprises the steps of converting one-dimensional range profiles in a training set into column vectors and inputting the column vectors into a pre-designed neural network model;
Flattening M multiplied by N dimensions of the three-dimensional depth image corresponding to the one-dimensional distance image in the transverse and longitudinal directions into a column vector with the length of MN;
And training the neural network model by taking the column vector with the length of MN as the output of the neural network model to obtain a trained neural network model.
In one embodiment, the method further comprises the step of recovering the column vector with the length of MN output by the trained neural network model into M multiplied by N dimensions to obtain the three-dimensional image of the scene to be detected.
A scanless single channel terahertz radar forward-looking three-dimensional imaging system, the system comprising:
the data collection module is used for respectively controlling the single-shot terahertz radar receiving and transmitting signals to obtain a one-dimensional range profile of a detection scene through two paths of synchronous clock signals, controlling the time-of-flight camera to acquire signals to obtain a three-dimensional depth image corresponding to the detection scene, and further obtaining a training set formed by a plurality of groups of one-dimensional range profile and three-dimensional depth image pairs through changing the gesture and the position of a target in the detection scene;
The model training module is used for converting one-dimensional range profiles in a training set into column vectors, inputting the column vectors into a pre-designed neural network model, and training the neural network model by taking the column vectors obtained by flattening the three-dimensional depth image corresponding to the one-dimensional range profiles as output to obtain a trained neural network model;
The model application module is used for acquiring a one-dimensional distance image of the scene to be detected, converting the one-dimensional distance image into a column vector, inputting the column vector into the trained neural network model, and obtaining a three-dimensional image of the scene to be detected according to the column vector output by the trained neural network model.
A computer device comprising a memory storing a computer program and a processor which when executing the computer program performs the steps of:
Respectively controlling a single-shot terahertz radar receiving and transmitting signal through two paths of synchronous clock signals to obtain a one-dimensional range profile of a detection scene, controlling a time-of-flight camera to acquire a signal to obtain a three-dimensional depth image corresponding to the detection scene, and further obtaining a training set consisting of a plurality of groups of one-dimensional range profile and three-dimensional depth image pairs through changing the gesture and the position of a target in the detection scene;
Converting a one-dimensional range profile in a training set into a column vector, inputting the column vector into a pre-designed neural network model, and training the neural network model by taking the column vector obtained by flattening a three-dimensional depth image corresponding to the one-dimensional range profile as output to obtain a trained neural network model;
And obtaining a one-dimensional range profile of the scene to be detected, converting the one-dimensional range profile into a column vector, inputting the column vector into the trained neural network model, and obtaining a three-dimensional image of the scene to be detected according to the column vector output by the trained neural network model.
A computer readable storage medium having stored thereon a computer program which when executed by a processor performs the steps of:
Respectively controlling a single-shot terahertz radar receiving and transmitting signal through two paths of synchronous clock signals to obtain a one-dimensional range profile of a detection scene, controlling a time-of-flight camera to acquire a signal to obtain a three-dimensional depth image corresponding to the detection scene, and further obtaining a training set consisting of a plurality of groups of one-dimensional range profile and three-dimensional depth image pairs through changing the gesture and the position of a target in the detection scene;
Converting a one-dimensional range profile in a training set into a column vector, inputting the column vector into a pre-designed neural network model, and training the neural network model by taking the column vector obtained by flattening a three-dimensional depth image corresponding to the one-dimensional range profile as output to obtain a trained neural network model;
And obtaining a one-dimensional range profile of the scene to be detected, converting the one-dimensional range profile into a column vector, inputting the column vector into the trained neural network model, and obtaining a three-dimensional image of the scene to be detected according to the column vector output by the trained neural network model.
The scanning-free single-channel terahertz radar forward-looking three-dimensional imaging method and system are characterized in that a one-dimensional range profile of a detection scene is obtained through receiving terahertz radar receiving and transmitting signals in a single mode, three-dimensional depth images are acquired through a time-of-flight camera to obtain a training set formed by one-dimensional range profile and three-dimensional depth image data pairs, a large number of one-dimensional range profiles are taken as input, corresponding three-dimensional depth images are taken as output, a neural network model is trained to obtain a trained neural network model, the one-dimensional range profile of the scene to be detected is obtained, the one-dimensional range profile of the scene to be detected is input into the trained neural network model, and a three-dimensional image of the scene to be detected is obtained according to the output of the trained neural network model. The invention only uses single-shot single-received single-channel terahertz radar, avoids the use of an antenna array and wave front modulation, realizes scanning-free single-channel forward-looking three-dimensional imaging without relying on aperture accumulation or relative movement, greatly simplifies the system and reduces the cost, and provides a forward-looking three-dimensional imaging algorithm based on deep learning, thereby improving the imaging efficiency of the system and meeting the imaging requirement of high resolution and high frame rate.
Detailed Description
The present application will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present application more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.
The scanning-free single-channel terahertz radar forward-looking three-dimensional imaging method provided by the application can be applied to an application environment shown in fig. 1. Under the forward-looking imaging condition, the terahertz radar system transmits a linear frequency modulation pulse waveform and acquires a one-dimensional range profile of a scene, and the time-of-flight camera is used for simultaneously acquiring depth information of the whole scene, namely a real three-dimensional image of the scene. And controlling the terahertz radar system and the time-of-flight camera to synchronously work by controlling two paths of synchronous clock signals separated from the processing terminal, so as to obtain a one-dimensional range profile-depth image pair, wherein the former serves as input for training a neural network model, and the latter serves as output. The control and processing terminal may be, but is not limited to, various personal computers, notebook computers, tablet computers, and portable wearable devices.
In one embodiment, as shown in fig. 2, a scanning-free single-channel terahertz radar forward-looking three-dimensional imaging method is provided, and the method is applied to the control and processing terminal in fig. 1 for illustration, and includes the following steps:
step 202, respectively controlling a single-shot terahertz radar receiving and transmitting signal to obtain a one-dimensional range profile of a detection scene through two paths of synchronous clock signals, controlling a time-of-flight camera to acquire a signal to obtain a three-dimensional depth image corresponding to the detection scene, and further obtaining a training set formed by a plurality of groups of one-dimensional range profile and three-dimensional depth image pairs through changing the gesture and the position of a target in the detection scene.
The invention only uses single-shot single-received single-channel terahertz radar, can avoid the use of an antenna array and wave front modulation, realizes scanning-free single-channel forward-looking three-dimensional imaging without relying on aperture accumulation or relative movement, and greatly simplifies the system and reduces the cost.
The terahertz radar transmits a linear frequency modulation pulse signal to a target scene, and the general expression form of the signal is as follows:
Where w (t) is the real envelope, The phase is modulated for the signal. For standard LFM signals, there are:
where T p denotes the pulse width of the signal and K denotes the tone frequency.
Let the received echo delay be t 0, then the echo expression is:
sr(t)=s(t-t0)=rect((t-t0)/Tp)exp(jπK(t-t0)2) (3)
the spectrum is in the form of:
According to the set chirp characteristics, the time domain and frequency domain responses of the matched filter can be obtained as follows:
after matched filtering, the frequency domain expression of the output signal is:
The Fourier transform of the rectangular window function is converted into a sine function, and the time domain expression of the output signal after matched filtering can be obtained according to the property of the Fourier transform, wherein the time domain expression is as follows:
sout(t)=IFFT[Sout(f)]=Tpsinc[πKTp(t-t0)] (7)
By observing the above equation, it can be known that the output signal has a peak at time t=t 0 according to the property of the sinc function, and the position information of the detected target, that is, the one-dimensional distance profile can be obtained by multiplying t 0 by c/2.
The time-of-flight camera may measure distances between itself and objects within the detection scene, thereby obtaining 3D information of the scene.
And 204, converting the one-dimensional range profile in the training set into a column vector, inputting the column vector into a pre-designed neural network model, and training the neural network model by taking the column vector obtained by flattening the three-dimensional depth image corresponding to the one-dimensional range profile as output to obtain a trained neural network model.
Neural network models are typically trained using back-propagation algorithms. And by adjusting the parameters, the loss function is reduced to obtain an optimal network model.
And 206, obtaining a one-dimensional range profile of the scene to be detected, converting the one-dimensional range profile into a column vector, inputting the column vector into a trained neural network model, and obtaining a three-dimensional image of the scene to be detected according to the column vector output by the trained neural network model.
Because the radar imaging system of the array system and the wavefront space modulation system has complex structure, the cost is higher, and aiming at the defect, the invention uses the radar system with single-shot and no wavefront modulation, thereby greatly simplifying the system and reducing the cost; the radar imaging system of the scanning system needs a long-time data accumulation process, and high-frame-rate imaging is difficult to realize, and aiming at the defect, the invention provides a forward-looking three-dimensional imaging algorithm based on deep learning. The invention realizes a scanning-free single-channel terahertz radar forward-looking three-dimensional imaging system which has the advantages of simple and small system and low cost and can meet the imaging requirement of high resolution and high frame rate.
In the scanning-free single-channel terahertz radar forward-looking three-dimensional imaging method, a one-dimensional range profile of a detection scene is obtained through receiving terahertz radar receiving and transmitting signals in a single mode, a three-dimensional depth image is acquired through a time-of-flight camera to obtain a training set formed by one-dimensional range profile and three-dimensional depth image data pairs, a large number of one-dimensional range profiles are taken as input, corresponding three-dimensional depth images are taken as output, a neural network model is trained to obtain a trained neural network model, the one-dimensional range profile of the scene to be detected is obtained, the one-dimensional range profile of the scene to be detected is input into the trained neural network model, and a three-dimensional image of the scene to be detected is obtained according to the output of the trained neural network model. The invention only uses single-shot single-received single-channel terahertz radar, avoids the use of an antenna array and wave front modulation, realizes scanning-free single-channel forward-looking three-dimensional imaging without relying on aperture accumulation or relative movement, greatly simplifies the system and reduces the cost, and provides a forward-looking three-dimensional imaging algorithm based on deep learning, thereby improving the imaging efficiency of the system and meeting the imaging requirement of high resolution and high frame rate.
In one embodiment, the method further comprises the steps of controlling the single-shot terahertz radar to acquire signals in a trigger mode through a first clock signal, enabling the single-shot terahertz radar to transmit and receive a signal and store data when detecting one falling edge, obtaining a one-dimensional range profile of a detection scene, controlling the time-of-flight camera to acquire signals in the trigger mode through a second clock signal, enabling the time-of-flight camera to acquire and store data when detecting one falling edge, obtaining a three-dimensional depth image corresponding to the detection scene, wherein the three-dimensional depth image comprises the horizontal coordinates, the vertical coordinates and depth information of each point in the detection scene, and the first clock signal and the second clock signal are kept synchronous.
In one embodiment, the method further comprises the steps of converting one-dimensional range profiles in a training set into column vectors, inputting the column vectors into a pre-designed neural network model, training the neural network model by taking the column vectors obtained by flattening three-dimensional depth images corresponding to the one-dimensional range profiles as output, and obtaining a trained neural network model, wherein the neural network is a neural network of a multi-layer perceptron, the neural network of the multi-layer perceptron comprises an input layer, three full-connection layers and an output layer, the full-connection layers are used for connecting each point of input data with each point of output data, the number of nodes of the three full-connection layers is 1024,512,256, an activation function layer is arranged behind each full-connection layer, and an activation function used is a tanh function.
In particular, the multi-layer perceptron model framework used in the present invention is shown in FIG. 3. The multi-layer perceptron (Multilayer Perceptron, MLP) is an artificial neural network (ARTIFICIAL NEURAL NETWORK, ANN) in the form of a forward structure that maps a set of input vectors into a set of output vectors. It can be abstracted into a directed graph, which is composed of multiple well-defined layers of nodes, each layer of nodes being fully connected to the next adjacent layer of nodes. In MLP, each node of the remaining layers, except the input layer, is provided with an activation function, which is typically trained using a back propagation algorithm. Analyzing its structure, it can be known that it can connect each point of input data with each point of output data. And each distance unit for acquiring the one-dimensional distance image by the single-shot single-received terahertz radar contains information from all imaging grids of the three-dimensional scene. It can be seen that the two have some similarity in structure.
In one embodiment, the method further comprises the steps of converting one-dimensional distance images in a training set into column vectors and inputting the column vectors into a pre-designed neural network model, flattening M multiplied by N dimensions of a three-dimensional depth image corresponding to the one-dimensional distance images in the transverse and longitudinal directions into column vectors with the length of MN, and training the neural network model by taking the column vectors with the length of MN as output of the neural network model to obtain a trained neural network model.
Specifically, data acquired by the single-shot terahertz radar and the time-of-flight camera are subjected to certain preprocessing to acquire main information of the data. Then, each one-dimensional range profile is stored in the form of a column vector, each depth image (with the dimension of MxN) is flattened into a column vector (with the dimension of 1 xMN) in the same way, the two are in one-to-one correspondence, and each pair of data is a group. 90% of all data sets were randomly chosen as training set, the remaining 10% as test set. And taking the one-dimensional range profile in each group of data as an input of a training neural network, and taking a column vector generated by the depth image as an output. And by adjusting the parameters, the loss function is reduced to obtain an optimal network model.
In one embodiment, the method further comprises the step of recovering column vectors with the length of MN output by the trained neural network model into M multiplied by N dimensions to obtain a three-dimensional image of the scene to be detected.
It should be understood that, although the steps in the flowchart of fig. 2 are shown in sequence as indicated by the arrows, the steps are not necessarily performed in sequence as indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least some of the steps in fig. 2 may include multiple sub-steps or stages that are not necessarily performed at the same time, but may be performed at different times, nor do the order in which the sub-steps or stages are performed necessarily performed in sequence, but may be performed alternately or alternately with at least a portion of the sub-steps or stages of other steps or other steps.
In one embodiment, as shown in FIG. 5, a scanless single-channel terahertz radar forward-looking three-dimensional imaging system is provided, comprising a data collection module 502, a model training module 504, and a model application module 506, wherein:
the data collection module 502 is configured to control the single-shot terahertz radar transceiver signal to obtain a one-dimensional range profile of the detection scene through two paths of synchronous clock signals, control the time-of-flight camera to acquire a signal to obtain a three-dimensional depth image corresponding to the detection scene, and further obtain a training set formed by a plurality of groups of one-dimensional range profile and three-dimensional depth image pairs through changing the gesture and the position of a target in the detection scene;
The model training module 504 is configured to convert a one-dimensional distance image in the training set into a column vector, input the column vector into a pre-designed neural network model, and train the neural network model by using the column vector obtained by flattening a three-dimensional depth image corresponding to the one-dimensional distance image as an output to obtain a trained neural network model;
The model application module 506 is configured to obtain a one-dimensional distance image of the scene to be detected, convert the one-dimensional distance image into a column vector, input the column vector into a trained neural network model, and obtain a three-dimensional image of the scene to be detected according to the column vector output by the trained neural network model.
The data collection module 502 is further configured to control the single-shot terahertz radar to collect signals in a trigger mode through a first clock signal, so that the single-shot terahertz radar can collect signals and store data when detecting a falling edge, and obtain a one-dimensional range profile of a detection scene, and control the time-of-flight camera to collect signals in the trigger mode through a second clock signal, so that the time-of-flight camera can collect and store data when detecting a falling edge, and obtain a three-dimensional depth image corresponding to the detection scene, wherein the three-dimensional depth image comprises the horizontal coordinates, the vertical coordinates and the depth information of each point in the detection scene, and the first clock signal and the second clock signal are kept synchronous.
The model training module 504 is further configured to convert a one-dimensional distance image in the training set into a column vector, input the column vector into a pre-designed neural network model, train the neural network model by using the column vector obtained by flattening a three-dimensional depth image corresponding to the one-dimensional distance image as an output, and obtain a trained neural network model, where the neural network is a neural network of a multi-layer perceptron, the neural network of the multi-layer perceptron includes an input layer, three full-connection layers and an output layer, the full-connection layers are used to connect each point of input data with each point of output data, and an activation function layer is located behind each full-connection layer.
The model training module 504 is further configured to convert a one-dimensional distance image in the training set into a column vector, input the column vector into a pre-designed neural network model, flatten m×n dimensions of a three-dimensional depth image corresponding to the one-dimensional distance image in a transverse direction and a longitudinal direction into a column vector with a length of MN, and train the neural network model by taking the column vector with the length of MN as an output of the neural network model to obtain a trained neural network model.
The model training module 504 is further configured to train the neural network model through a back propagation algorithm, so as to obtain a trained neural network model.
The model application module 506 is further configured to restore the column vector with the length MN output by the trained neural network model to m×n dimensions, so as to obtain a three-dimensional image of the scene to be detected.
Specific limitations regarding the scanning-free single-channel terahertz radar forward-looking three-dimensional imaging system can be found in the above description of the scanning-free single-channel terahertz radar forward-looking three-dimensional imaging method, and are not repeated here. The modules in the scanning-free single-channel terahertz radar forward-looking three-dimensional imaging system can be all or partially realized by software, hardware and a combination thereof. The above modules may be embedded in hardware or may be independent of a processor in the computer device, or may be stored in software in a memory in the computer device, so that the processor may call and execute operations corresponding to the above modules.
In one embodiment, a computer device is provided, which may be a terminal, and the internal structure of which may be as shown in fig. 6. The computer device includes a processor, a memory, a network interface, a display screen, and an input device connected by a system bus. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The network interface of the computer device is used for communicating with an external terminal through a network connection. The computer program, when executed by the processor, implements a scanless single-channel terahertz radar forward-looking three-dimensional imaging method. The display screen of the computer equipment can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer equipment can be a touch layer covered on the display screen, can also be keys, a track ball or a touch pad arranged on the shell of the computer equipment, and can also be an external keyboard, a touch pad or a mouse and the like.
It will be appreciated by those skilled in the art that the structure shown in FIG. 6 is merely a block diagram of some of the structures associated with the present inventive arrangements and is not limiting of the computer device to which the present inventive arrangements may be applied, and that a particular computer device may include more or fewer components than shown, or may combine some of the components, or have a different arrangement of components.
In an embodiment a computer device is provided comprising a memory storing a computer program and a processor implementing the steps of the method embodiments described above when the computer program is executed.
In one embodiment, a computer readable storage medium is provided, on which a computer program is stored which, when executed by a processor, implements the steps of the method embodiments described above.
Those skilled in the art will appreciate that implementing all or part of the above described methods may be accomplished by way of a computer program stored on a non-transitory computer readable storage medium, which when executed, may comprise the steps of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in embodiments provided herein may include non-volatile and/or volatile memory. The nonvolatile memory can include Read Only Memory (ROM), programmable ROM (PROM), electrically Programmable ROM (EPROM), electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double Data Rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (SYNCHLINK) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), among others.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.