Robust Automatic Surface Reconstruction with Structured Light

For the measurement of surfaces of close range objects, which do not show sufficient surface texture, an automatic system based on the projection of structured light has been developed. An off-the-shelf slide projector projects chromium slides with a regular dot pattern of 800 ... 8000 dots and perfectly binary transparency characteristics onto a surface. For robust point determination the object is imaged by three or four CCD cameras, which allows to reduce the number of ambiguities in the establishment of correspondences drastically by the method of intersection of epipolar lines. The advantage of the method is the fact that it does not require any approximate values nor an initial match given by a human operator and does though offer the advantages of a photogrammetric system like redundancy, accuracy and compatibility with triangulation methods. The paper will give an overview of the hardware of the system and the chain of data processing, discuss reliability, accuracy and applicability and give a comparison with competitive methods. Results will be shown from the measurement of a model car surface and from a carbon panel put under load in a deformation analysis.