Multi-Flash Camera for Shape Boundary Detection
We describe a new type of multi-flash camera that can capture and convey shape features of real-world scenes. We compute the depth discontinuities in a scene with a shadow based technique. We take a very different approach to capturing geometric features of a scene than traditional approaches that require reconstructing a 3D model. This results in a method that is both surprisingly simple and computationally efficient. The entire hardware/software setup can conceivably be packaged into a self-contained device no larger than existing digital cameras.
Background & Objective: Depth discontinuities corresponding to silhouettes and shape boundaries play an important role in scene understanding in Computer Vision. Unfortunately, majority of the techniques based on stereo cameras or range finders fail at depth discontinuities due to partial occlusion from one of the views. Time of flight based range scanners cannot detect small depth differences. We use an active illumination approach and exploit shadows as a robust cue for depth discontinuity.
Technical Discussion: We use a camera with multiple flashes that are strategically positioned to cast shadows along depth discontinuities in the scene. The projective-geometric relationship of the camera-flash setup is then exploited to detect depth discontinuities and distinguish them from intensity edges due to material discontinuities. We can highlight the detected features, suppress unnecessary details or combine features from multiple images. The resulting images more clearly convey the 3D structure of the imaged scenes. We can also use the depth edges to improve stereo reconstruction, detection change in scenes (for surveillance) or object recognition.
Publications:
Technology Area: Off the Desktop Interaction and Display
Modification Date: July 7, 2008