Abstract: The region growing method is applied in the research of segmentation of random data and extraction of quadric surfaces geometric features. Firstly, seed regions are located automatically, then these regions are grown by recurrent processes composed by iteration and surface fitting. To enhance the reliability of this presented method, a direct quadric surface fitting algorithm based on normal vectors of random data points are proposed particularly by using linear least square technique to calculate geometric parameters of various quadric surfaces based on their characteristics. Above algorithm avoid the low efficiency and stability brought by inaccurate setting of initial geometric parameters, and the effect of it is proved by an example.

Key words: Feature extracting, Reverse engineering, Quadric surface, Surface fitting