Environment Shape and Layout from Active Shadows
M. Langer, G. Dudek, S. W. Zucker
We are looking at the problem of estimating 3-d space occupancy using shadow
information from video
imagery in the context of mobile robotics. A stationary robot
observes a cluttered scene from a single viewpoint, and a second robot
illuminates the scene from a sequence of directions thus producing a
sequence of grey-level images. Differences of successive images are
used to compute a sequence of shadowimages. The problem is to compute
free space and occupied space from these shadowimages. Solutions to
this problem are known for the special case of terrain scenes. We
generalize these solutions to non-terrain scenes by making two key
observations. First, there is a subset constraint on the shadowimages
of a non-terrain scene, which allows the visible surfaces of a
non-terrain scene to be recovered by a terrain-based technique.
Second, the remaining regions of the shadowimages provide a
conservative estimate of the occupied space hidden by these visible
surfaces.
Recent papers on our shadow work (postscript files):
