Detecting and Classifying Umblic Points from Polynomial Fitting Point Cloud

The topology of a tensor field is partially defined by its degenerate points, called umbilical points. We proposed a new approach for distinguishing them as trisector and wedge points on polynomial fitting surface of point-sampled models. Firstly, the polynomial fitting surface over neighborhoods of each point is obtained, and then the degenerate points are preliminary detected by building a Hessian matrix of the polynomial fitting. Computing the neighbor principal directions of the detected degenerate points, trisector and wedge points are finally classified according to the behavior of the nearby vector field.