Mesh Simplification Based on Shading Characteristic
Zhang H., Shu H.Z., Luo L.M.
Dept. Of Biomedical Engineering,
Mesh Simplification Vision Characteristic Edge Collapse Triangle Decimation
Mesh simplification is a key research area in scientific visualization and virtual reality. The paper presents a new method of polyhedral model simplification based on vision characteristic and edge collapse. This method determines model’s vision characteristic by computing the maximum product of angle between normal of vertex and adjacent triangles with area of these triangles. It can achieve a high decimation rate, while keeping the details of vision. This algorithm can also be extended to triangle decimation criterion easily.
Our algorithm uses the mechanism of vertex merging, and it is described as below: At first compute the normal Nor(Ti) of each triangle, then use some methods to calculate the influence value of each vertex. The two methods we used are to calculate the vision characteristic CA (Vi) or super height SH(Vi), which represent the influence of curvature to result image. Sort these vertexes, according to its influence in vision characteristic; Pick out the first vertex in the queue, as the first candidate point to collapse. Select another one Vj from adjacent vertex set NV (Vi). The policy is to select one which can generate the least characteristic vision value of changed vertex; Finally interpolate the related properties of Vi and Vj, such as vertex position, normal, texture. Then use the new vertex Vk to replace Vi and Vj, delete the regressive triangle. Calculate the value of new point Vk and its adjacent vertex set, and arrange their new position in the vertex queue, repeat last two processed, until reach the required triangle number.
The effect is obvious when vision characteristic value is introduced into edge collapse algorithm. It produces high quality decimation result, while easy to code. This algorithm can also automatically recognize and simplify the nearby co-planar triangle, while keeping the key vertex. Our algorithm can be used to automatic generation of virtual reality and interactive visualization.