Smoothing Operation of Normal Directions on Object Surface Produced by Dividing Cubes

There might exist abrupt changes of the normal directions on a voxel object surface generated by Dividing Cubes, which would cause the shading image of the object look coarse and rough. A modified neighborhood weighted average approach was proposed in this paper for smoothing the normal directions on the voxel object surface. To avoid blurring the boundaries among several regions and preserve the details of the shading image of the object surface, the smoothing operation was only applied to those boundary voxels which were relevant, while the boundary voxels which had several isosurfaces were not smoothed. The algorithm of Ray Casting was used to display the object surface to avoid producing missing holes on the screen. The modified approach can eliminate those abrupt changes of the normal directions on the voxel object surface and improve the display quality. A verified example of a medical volume data is presented.