Method for converting polygonal surfaces to levelsets

A non-transitory computer readable storage medium storing a computer program executable by a processor based system, the computer program causing the processor based system to execute steps comprising:

• receiving data defining an explicit surface representation of three-dimensional (3D) geometry;
• defining a narrow band of voxels near the explicit surface;
• 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;
• and
• for each voxel outside of the narrow band, approximating a distance to a closest point on the explicit surface by interpolating the approximated distances in the narrow band;
• wherein a first of the two-dimensional (2D) distances associated with the voxel comprises a distance between the voxel and a first point on the explicit surface where a ray corresponding to a first scan line intersects both the voxel and the explicit surface;
• and
• wherein a second of the two-dimensional (2D) distances associated with the voxel comprises a distance between the voxel and a second point on the explicit surface where a ray intersects the explicit surface, wherein the ray corresponds to a scan line that is different than the first scan line;
• wherein the first and second two-dimensional (2D) distances form the legs of a right triangle and wherein the hypotenuse of the right triangle approximates a portion of the explicit surface, the distance from the voxel to the hypotenuse approximating the distance from the voxel to the closest point on the explicit surface.