Method for converting polygonal surfaces to levelsets

Abstract

A method for use in computer graphics includes receiving data defining an explicit surface representation of three-dimensional (3D) geometry and casting a ray into the explicit surface representation. For each point where the ray intersects the explicit surface, a direction of the ray is compared to a direction of a surface normal of the explicit surface at that point, and then a count is incremented or decremented based on a first rule that uses a result of the comparison at that point. Then, for one or more voxels corresponding to the ray, data is generated for each voxel that indicates the voxel is either inside or outside of the explicit surface based on a second rule that uses a value of the count at that voxel. Another method includes defining a narrow band of voxels near the explicit surface, and then for each voxel in the narrow band, approximating a distance between the voxel and a closest point on the explicit surface by assuming a set of two-dimensional (2D) distances associated with the voxel and a portion of the explicit surface form a triangle. For each voxel outside of the narrow band, a distance to a closest point on the explicit surface is approximated by interpolating the approximated distances in the narrow band.