Vector Clustering of Passive Millimeter Wave Images With Linear Polarization for Concealed Object Detection

Abstract

Passive millimeter (MMW) imaging can penetrate clothing to create interpretable imagery of concealed objects. However, the image quality is often restricted by low signal to noise ratio and temperature contrast as well as low spatial resolution. In this paper, we explore a four-channel passive MMW imaging system operating in the 8 and 3 mm wavelength regimes with linear vertical and horizontal polarization directions. Both registration between different channel images and segmentation of concealed objects are addressed. Multichannel image registration is performed by geometric feature matching and affine transform, and then multi-level segmentation separates the human body region from the background, and concealed objects from the body region, sequentially. In the experiments, several metallic and non-metallic objects concealed under clothing are captured in indoors. It will be shown that our method can separate objects with higher accuracy than the conventional method.

Shape Feature Analysis of Concealed Objects With Passive Millimeter Wave Imaging

“…A person who hides a metallic (gun or hand ax) or a non-metallic (plastic bottle containing liquid) object is captured by the passive MMW imaging system [20]. Figure 4(a) shows the actual size of liquid is not segmented during the global segmentation as shown in Figure 9(a).…”

3-D Printed Antenna Subsystem With Dual-Polarization and its Test in System Level for Radiometer Applications

“…Also the polarimetric observations can be used to retrieve global soil moisture, vegetation water content, and land surface temperature simultaneously [6], [7]. The polarization information can be used to classify materials and to retrieve object surface orientation, and it is also very helpful for object discrimination and identification [8][9][10][11].…”

A technique for detecting concealed objects in terahertz images based on information measure

“…To increase the performance of the concealed objects detection, the authors of work [5] combined images obtained in the terahertz and visible spectral bands. In [6], the objects hidden under clothes are localized using the images obtained in four channels of a system operating in 3-and 8-millimeter wavelengths with vertical and horizontal polarization. A multilevel segmentation algorithm combines the k-means algorithm, the EM algorithm for estimating the parameters of a Gaussian mixture, and the Bayesian classifier.…”