Depth estimation method using depth-of-field imaging with a retroreflector.

We propose a method for depth estimation using a tilted retroreflective structure, which consists of a beam splitter and a micro-corner cube array. Existing depth estimation methods commonly use an active light source to detect the depth of an object. However, sunlight interferes with their depth measurements and decreases their accuracy outdoors. The proposed method does not need any active light source because depth information is obtained in the image domain, not in the object domain. The depth of field imaging by a retroreflector indicates the depth position of the object image, immediately. We believe that the proposed method can be applied to depth measurement systems such as LIDAR and time of flight cameras. An experiment is performed, whose results are compared with theoretical calculations, which confirms the feasibility of the proposed method.