Range camera self-calibration with scattering compensation

Time-of-flight range camera data are prone to the scattering bias caused by multiple internal reflections of light received from a highly reflective object in the camera’s foreground that induce a phase shift in the light received from background targets. The corresponding range bias can have serious implications on the quality of data of captured scenes as well as the geometric self-calibration of range cameras. In order to minimise the impact of the scattering range biases, the calibration must be performed over a planar target field rather than a more desirable 3D target field. This significantly impacts the quality of the rangefinder offset parameter estimation due to its high correlation with the camera perspective centre position. In this contribution a new model to compensate for scattering-induced range errors is proposed that allows range camera self-calibration to be conducted over a 3D target field. Developed from experimental observations of scattering behaviour under specific scene conditions, it comprises four new additional parameters that are estimated in the self-calibrating bundle adjustment. The results of experiments conducted on five range camera datasets demonstrate the model’s efficacy in compensating for the scattering error without compromising model fidelity. It is further demonstrated that it actually reduces the rangefinder offset-perspective centre correlation and its use with a 3D target field is the preferred method for calibrating narrow field-of-view range cameras.