Real-time range scanning of deformable surfaces by adaptively coded structured light
We present a new active range scanning technique suitable for moving or deformable surfaces. It is a 'one-shot' system, in that 3D data are acquired from a single image. The projection pattern consists of equidistant black and white stripes combined with a limited number of colored, transversal stripes which aid in their identification. Instead of using a generic, static code that is supposed to work under all circumstances, a 'self-adaptive code' is used. Two modes of adaptation are provided. The first mode is off-line, and generates a robust identification code for the current projector-camera configuration. This configuration is supposed to remain fixed during the remainder of the 3D capturing session. The second mode occurs on-line. By introducing a feedback-loop from the reconstruction output to the pattern generation, the pattern can be adapted as to keep its decoding well-conditioned. Within the considered family of patterns, its parameters are optimized on the fly based on the current content of the scene. As a matter of fact, scene content of the current frame influences the pattern projected during the next. This poses a weak temporal continuity constraint. Only a very fast change of scene invalidates this assumption. The higher the throughput of the reconstruction pipeline, the less serious this constraint becomes. Our current pipeline is running at approximately 20 Hz. Our prototype only uses 'off the shelf' hardware.