Performing Visual Surveys of Non-planar Benthic Terrain

A key issue facing any ROV or AUV-based benthic visual survey is how to point the camera normal to the terrain during the survey. Though planar terrain surveys can be executed using a constant camera orientation, non-planar terrain surveys require that the commanded camera orientation change during vehicle movement.. This paper proposes a method that generates a smooth camera orientation command by first spatially filtering local terrain orientation measurements through the construction of a spline-based model of the terrain. The method then calculates an orientation command from the spline model using the spline point projection algorithm. A real-time version of this algorithm has been fielded on a Monterey Bay Aquarium Research Institute ROV, allowing the ROV to maintain camera perpendicularity autonomously over non-planar benthic sites and enabling small-scale visual surveys of these sites.