1 Using Voxelization and Ray-Tracing to Identify Wall Thinness of ...

Figures 21 and 22 demonstrate the limitations of highlighting distance-1 unsafe voxels.Any time a relatively narrow curve is introduced, the likelihood of a fully 'safe' voxel decreases.Since they only border safe-by-proxy voxels, the voxels in the red columns are flagged asdistance-1 unsafe voxels, and the user is presented with a confusing set of unsafe voxels.Floating Point ProblemsAnother problematic issue occurs during ray-casting. What if the ray should intersect atriangle, but misses? An instance of this is shown in Figure 23.35Figure 23: Mysterious column of distance-1 unsafe voxelsWhen the voxels are analyzed, it is apparent that this column of unsafe voxels borders asafe column. Specifically, there is a safe of solid material which in the image is to the upper rightof the red column. Since the voxels in the red column border this safe area, the column shouldactually be categorized as Safe-by-proxy rather than distance-1 unsafe. What is going on here? Alook at the mesh geometry instead of the shaded geometry provides a clue.Figure 24 is an image of the unshaded mesh geometry, in which the triangles of thepolygonal object are visible. To help the viewer make sense of the image, Figure 25 adds anoverlay of the voxelization on top.