Depth from axial differential perspective

Abstract

We introduce an imaging-based passive on-axis technique for measuring the distance of individual objects in complex scenes. Two axially separated pupil positions acquire images (can be realized simultaneously or sequentially). Based on the difference in magnification for objects within the images, the distance to the objects can be inferred. The method avoids some of the disadvantages of passive triangulation sensors (e.g., correspondence, shadowing), is easy to implement and offers high lateral resolution. Due to the principle of operation it is especially suited for applications requiring only low to medium axial resolution. Theoretical findings, as well as follow-up experimental measurements, show obtainable resolutions in the range of few centimeters for distances of up to several meters.

Differential perspective as a nonexpensive distance sensing principle

“…This makes it possible to build a laterally very small sensor and one avoids problems due to occlusion or change of view. The main idea (see 5,6 for a detailed description) is that the axial separation of the two entrance pupils leads to different image sizes of an object being imaged. Based on the ratio of the two image sizes, it is possible to compute the distance to the object (see below).…”