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Green Image
Issue No. 06 - June (1989 vol. 11)
ISSN: 0162-8828
pp: 650-655
<p>Two simple methods are given for obtaining the surface shape using a projected grid. After the camera is calibrated to the 3-D workspace, the only input date needed for the computation of surface normals are grid intersect points in a single 2-D image. The first method performs nonlinear computations based on the distortion of the lengths of the grid edges and does not require a full calibration matrix. The second method requires that a full parallel projection model of the imaging is available, which enables it to compute 3-D normals using simple linear computations. The linear method performed better overall in the experiments, but both methods produced normals within 4-8 degrees of known 3-D directions. These methods appear to be superior to methods based on shape-from-shading because the results are comparable, yet the equipment setup is simpler and the processing is not very sensitive to object reflectance.</p>
2D images; surface orientation; computer vision; pattern recognition; projected grid; surface shape; surface normals; nonlinear computations; distortion; calibration matrix; parallel projection model; computer vision; computerised pattern recognition; matrix algebra

N. Shrikhande and G. Stockman, "Surface Orientation from a Projected Grid," in IEEE Transactions on Pattern Analysis & Machine Intelligence, vol. 11, no. , pp. 650-655, 1989.
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