QUANTIFYING THE DISTORTION OF DISTANCE OBSERVATIONS CAUSED BY SCATTERING IN TIME-OF-FLIGHT RANGE CAMERAS

Time-of-flight range cameras simultaneously gather object distances for all pixels of a focal plane array by evaluating the round-trip time of an emitted signal. In contrast to competing techniques, cameras combining continuously emitted, amplitude modulated signals and Photonic Mixer Devices (PMD, lock-in pixels) to derive signal phase shifts and hence object distances, have reached mass production and are available at low costs. While ranging precisions typically amount to some centimetres, accuracies may be worse by an order of magnitude. Systematic distortion factors of the ranging system can be grouped into local and non-local errors. While local distortions affect the pixels individually, non-local ones contaminate larger areas of the sensor. 'Scattering' denotes one of these non-local errors, meaning the spreading of portions of the incident light over the sensor due to multiple reflections between the sensor, lens, and optical filter. The present contribution analyses this phenomenon with respect to various capture parameters, with the objective of a better understanding and a validation of assumptions.