Depth Measurement Based on Bifocus Imaging

This paper presents a novel approach for depth recovery based on bifocus imaging. The imaging system with bifocus lenses may focus at different focal lengths of the same scene to produce bifocus images. Depth information can be extracted from the disparities between the image pair. This paper has given the detailed analysis of the system parameters and their appropriate values in long range detection. According to the influences on depth resolution by system parameters, matching precision of image points plays an important role in depth measurement. An efficient method is proposed to calculate the locations of image points accurately. And a rotating imaging device is applied to improve depth resolution in the center region of field of view. Experimental results of sub-pixel registration, close and long range detection have demonstrated the depth measurement proposed of high precision. The relative error of recovered depth can be less than 0.4% when the photography distance is less than 800 m and rotating angle is about 40deg.