A Suspicious Multi-Object Detection and Recognition Method for Millimeter Wave SAR Security Inspection Images Based on Multi-Path Extraction Network

Minghui Yuan,Yinwei Li,Quansheng Zhang,Yiming Zhu,Yunhao Yan

doi:10.3390/rs13244978

Abstract

There are several major challenges in detecting and recognizing multiple hidden objects from millimeter wave SAR security inspection images: inconsistent clarity of objects, similar objects, and complex background interference. To address these problems, a suspicious multi-object detection and recognition method based on the Multi-Path Extraction Network (MPEN) is proposed. In MPEN, You Only Look Once (YOLO) v3 is used as the base network, and then the Multi-Path Feature Pyramid (MPFP) module and modified residual block distribution are proposed. MPFP is designed to output the deep network feature layers separately. Then, to distinguish similar objects more easily, the residual block distribution is modified to improve the ability of the shallow network to capture details. To verify the effectiveness of the proposed method, the millimeter wave SAR images from the laboratory’s self-developed security inspection system are utilized in conducting research on multi-object detection and recognition. The detection rate (probability of detecting a target) and average false alarm (probability of error detection) rate of our method on the target are 94.6% and 14.6%, respectively. The mean Average Precision (mAP) of recognizing multi-object is 82.39%. Compared with YOLOv3, our method shows a better performance in detecting and recognizing similar targets.

Highlights

With the development of millimeter wave imaging technology, the millimeter wave security scheme is becoming more and more sophisticated [1,2,3]
We adjust the number of repetitions of the residual block, and we focus on using the receptive field of the shallow network
Compared with the You Only Look Once (YOLO) v3 network, the mean Average Precision (mAP) of Multi-Path Extraction Network (MPEN) is increased by 7.57% under the same time-consuming condition

Summary

Introduction

With the development of millimeter wave imaging technology, the millimeter wave security scheme is becoming more and more sophisticated [1,2,3]. The current milli-meter wave imaging systems can be divided into two categories: passive imaging and active imaging. Passive imaging systems use the object’s own radiation for imaging. Because the object’s radiation power is meager, the imaging effect is terrible. Active imaging systems use the reflection characteristics of objects for imaging. Since the power of the emission source is high, the reflected radiation can obtain a clear image of the human body. Different from X-ray, active millimeter-wave security equipment does not cause harm to the human body [10]

Methods

Results

Discussion

Conclusion