Evidential Sensor Fusion of Long-Wavelength Infrared Stereo Vision and 3D-LIDAR for Rangefinding in Fire Environments

A method of sensor fusion was developed to combine long-wavelength infrared (LWIR) stereo vision and a spinning LIDAR for improved rangefinding in smoke-obscured environments. This method allows rangefinding in clear and smoke conditions, relying on LIDAR’s high accuracy in clear conditions and the perception ability of LWIR cameras in smoke. Sensor data were combined using evidential (Dempster–Shafer) theory in a 3D multi-resolution voxel domain for occupied and free space states. A heuristic method was produced for separating significantly attenuated and low-attenuation LIDAR returns using return intensity and distance. A sensor model was developed to apply free space state information from LIDAR high-attenuation returns. Sensor models were developed for applying occupied and free space state information from LIDAR low-attenuation returns and from LWIR stereo vision points. The fusion method was evaluated in two fire environments: a room-hallway scenario with a range of clear to dense-smoke conditions and a shipboard fire scenario. Room-hallway tests were evaluated by assessing performance against baseline rangefinding. For the occupied state, the fusion method and LIDAR are within typically 5% to 10% for clear conditions, and the fusion method is more accurate than the LIDAR by typically 5% to 10% for smoke conditions, with LIDAR providing no data in the densest smoke. For the free space state, the fusion method outperformed the LIDAR in smoke conditions by as much as 40% and was typically within 5% of the LIDAR in clear conditions.