Measurement errors in polarization-based 3D vision systems

Multiple reflections can degrade significantly depth data acquired by laser rangefinders. However, analysis of the polarization state of the reflected light can provide additional clues to distinguish the first and subsequent reflections. Such estimates depend critically on the ratio between absolute differences of intensity measured by a camera with different settings of some polarizing optical components. Errors introduced by weak signals, the nonlinear response of the sensors, noise and quantization in the video channel can be very significant. When a laser is used as the illumination source, fluctuation of the source intensity can introduce additional errors if comparisons are made between images acquired at different times. We presents a discussion of the type and effects of these errors, guidelines on systems settings and an upper-bound analysis of the error on the estimates of the orientation of the completely polarized component of light, a fundamental quantity used in several polarization vision systems for diverse applications. ©2005 Copyright SPIE - The International Society for Optical Engineering.