1. A method for modifying an onscreen rendering of three-dimensional data stored in a voxel cell of a voxel grid to produce an altered visual effect for the cell comprising the steps: (a) for each vertex of the voxel cell, determining the data density ratio in neighboring voxel cells, or determining the material type of the voxel cell and/or neighboring voxel cells; (b) for each vertex in the voxel cell, and based on the results of (a), determining to change the spatial position of the vertex; and (c) for each vertex in the voxel cell, and based on the decision in (b), generating vertex location offset coordinates defining a new vertex location.