High resolution acquisition of detailed surfaces with lens-shifted structured light
We present a novel 3D geometry acquisition technique at high resolution based on structured light reconstruction with a low-cost projector-camera system. Using a 1D mechanical lens-shifter extension in the projector light path, the projected pattern is shifted in fine steps at sub-pixel scale with a granularity of down to 2048 steps per projected pixel, which opens up novel possibilities in depth accuracy and smoothness for the acquired geometry. Combining the mechanical lens-shifter extension with a multiple phase shifting technique yields a measuring range of 120x80 mm while at the same time providing a high depth resolution of better than 100 micron. Reaching far beyond depth resolutions achieved by conventional structured light scanning approaches with projector-camera systems, depth layering effects inherent to conventional techniques are fully avoided. Relying on low-cost consumer products only, we reach an area resolution of down to 55 micron (limited by the camera). We see two fields of benefit. Firstly, our acquisition setup can reconstruct finest details of small Cultural Heritage objects such as antique coins and thus digitally preserve them in appropriate precision. Secondly, our accurate height fields can be viable input to physically based rendering in combination with measured material BRDFs to reproduce compelling spatially varying, material-specific effects.