Geometric and Photometric Consistency in a Mixed Video and Galvanoscopic Scanning Laser Projection Mapping System.

We present a geometric calibration method to accurately register a galvanoscopic scanning laser projection system (GLP) based on 2D vector input data onto an arbitrarily complex 3D-shaped projection surface. This method allows for accurate merging of 3D vertex data displayed on the laser projector with geometrically calibrated standard rasterization-based video projectors that are registered to the same geometry. Because laser projectors send out a laser light beam via galvanoscopic mirrors, a standard pinhole model calibration procedure that is normally used for pixel raster displays projecting structured light patterns, such as Gray codes, cannot be carried out directly with sufficient accuracy as the rays do not converge into a single point. To overcome the complications of accurately registering the GLP while still enabling a treatment equivalent to a standard pinhole device, an adapted version is applied to enable straightforward content generation. Besides the geometrical calibration, we also present a photometric calibration to unify the color appearance of GLPs and standard video projectors maximizing the advantages of the large color gamut of the GLP and optimizing its color appearance to smoothly fade into the significantly smaller gamut of the video projector. The proposed algorithms were evaluated on a prototypical mixed video projector and GLP projection mapping setup.