Design parameters for adjusting the visual field of binocular stereo cameras

Stereoscopic cameras are becoming fundamental sensors for providing perception capabilities for automated vehicles; however, they need to be adequately setup to avoid excessive data processing and unreliable outcomes. Combinations of baselines and lens focal lengths were optimised to adjust the field of view of a stereo camera to provide the two fundamental perceptions required for intelligent vehicles: safeguarding distances around 6 m and look-ahead distances up to 20 m for automatic guidance. The main objective was to develop a systematic procedure to find the parameters that best sense the desired field of view. Quantitative indices to estimate perceptive quality, such as relative errors and efficiencies, were defined and applied to particular cases. Experiments, both in the laboratory and outdoor, led to the conclusion that short ranges under 6 m from the vehicle were best acquired with 8 mm lenses and baselines ranging from 100 mm to 150 mm, whereas 200 mm baselines coupled with 12 mm and 8 mm lenses were more suitable for longer look-ahead distances. These experiments also proved the utility of the methodology proposed.