KEYWORDS: Detection and tracking algorithms, Reconstruction algorithms, Radar, Stereoscopy, 3D image processing, 3D acquisition, Image restoration, Radar imaging, 3D modeling, Tin
High-resolution near-field three-dimensional (3D) radar imaging techniques with millimeter and terahertz wave have played an increasingly significant role in applications including hidden object detection and nondestructive testing. Currently, imaging methods suffer from low efficiency when imaging defects in stratified media. This is caused by the inadaptability of the fast Fourier transform in the frequency domain due to the alteration of wave numbers in different media. We propose an imaging method based on the nonuniform fast Fourier transform to overcome the problem. Numerical simulations and experiments were carried out to verify our idea. Results show that our proposed method can greatly improve the imaging efficiency while maintaining the imaging quality. This work is of great significance for future development of nondestructive testing technology based on millimeter wave/terahertz imaging.
In recent years, cylindrical millimeter-wave (MMW) holographic imaging technique has attracted a lot of attention for its special advantages, including high resolution, large aperture, and strong penetrability. A modified wavenumber-domain three-dimensional imaging algorithm applied for near-field cylindrical MMW holography is proposed. The core of the proposed algorithm is to generate an accurate and efficient phase compensation factor in wavenumber-domain. Compared with the existing algorithms, the proposed algorithm holds advantages in both imaging speed and imaging quality and is more suitable for security inspection application. Both the simulation results of point targets and the experimental results of the resolution test panel validate the effectiveness of the proposed algorithm.
Attribute scattering centers model (ASCM) can provide important geometric information regarding the illuminated target. However, sliding scattering center (SSC) cannot be well extracted based on the current ASCM. This paper proposes an efficient method to extract SSCs based on density-distance (DD) matching. First, the scattering characteristic of SSC is derived theoretically from the perspective of physical optical (PO). Then, the frequency dependence and estimated position are analyzed by the multi-peak model. The distance and density of each scattering center are constructed and cluster by the proposed DD -based matching algorithm. Finally, the geometrical structure corresponding to each scattering centers can be retrieved. Simulation results validate the feasibility and accuracy of the proposed method.
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