A new technique for computing intrinsic surface properties is developed in this research. Intrinsic surface properties refer to those properties of a surface which are not affected by the choice of the coordinate system, the position of the viewer relative to the surface, and the particular parametric representation used to describe the imaged surface. Since intrinsic properties are characteristics of a surface, they are ideal for the purposes of representation and recognition. The intrinsic properties which we are interested in are the principal curvatures, the intrinsic distance, and the lines of curvature. We propose to adopt a structured lighting sensing configuration where a grid pattern is projected to encode the object surfaces for analysis. At each stripe junction, the curvature of the projected stripe on the object surface is computed and related to that of the normal section which shares the same tangential direction as the projected curve. The principal curvatures and their directions at the stripe junction under consideration are then recovered using Euler's theorem. Application of this technique to represent and discriminate several simple surface types is also addressed.
Y. F. Wang, Y. F. Wang,
"On The Computation Of Intrinsic Surface Properties With Structured Lighting", Proc. SPIE 1095, Applications of Artificial Intelligence VII, (21 March 1989); doi: 10.1117/12.969282; https://doi.org/10.1117/12.969282