Research on key technologies of real-time non-line-of-sight imaging based on array time-of-flight camera

In order to solve the problems of slow imaging speed, small imaging range, complex and expensive imaging system in existing non-line-of-sight (NLOS) imaging technologies, a real-time NLOS field imaging method based on the array time-of-flight (ToF) was proposed, and a theoretical model of NLOS imaging of array ToF was established to study the effects of imaging distance and light source illumination angle on system reconstruction results and system performance. The evaluation index of ToF NLOS imaging was constructed. This system uses 850 nm modulated laser as illumination light source, and the CMOS array as sensor to receive the scattered light. The true depth map of the hidden target can be extracted by peak bandpass filtering from the raw depth data. The experimental results show that the system can achieve real-time NLOS scene reconstruction of small targets such as the 15 cm×19 cm×30 cm plaster statue when both of the intermediate plane and the hidden object are near Lambertian bodies within the imaging distance of 3.5 m. The illumination angle of the light source can be adjusted within the range of 60° to 90°, and the real-time imaging speed of NLOS area is 2.0565 frames per second. The pixel size is 320×240, the maximum pixel size of the target corresponding area is 150×100, and the minimum distance of horizontal multiple target images without aliasing is 3.5 cm. The key technology of real-time NLOS field imaging based on array ToF camera is demonstrated in this paper. The system we proposed can achieve NLOS imaging with large imaging range, fast imaging speed, high imaging resolution and strong anti-interference ability.