Alternatively, the edge locations can be derived from the local maximum of the differentiated volumes, or by means of integral edge definitions.  These methods have a significant effect on the precision of the entire system.   These calculation steps can readily be performed for each available volume element at the material borders.  The result is as many measurement points as there are voxels in the transition region.  This captures the entire measured object with the maximum possible point density.  To facilitate further processing of these points, the surface of the object is described by STL format, which means by triangular facets.