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

458.ConclusionThe algorithm identifies areas of a 3D model that are not of sufficient thickness to be printedproperly. It does this in three steps: First, the model geometry is divided into an octree down tovoxels of a specified depth. Secondly, ray casting is performed in order to determine whichvoxels are interior or exterior to the model. Finally, voxel depth information is flooded outwardfrom the interior, safe-to-print voxels. When the algorithm finishes processing the entire model,it produces an X3D representation of its voxel classifications.This process produces customizable output that gives a representation of the 3-D modeland identifies overly-narrow segments. The algorithm could also be easily adapted to identifyoverly-wide segments as well. There are many cases where it is important for financial reasons tominimize the use of material, and the flooding algorithm could be applied to that purpose,marking voxels as suitable for being hollowed away if they are of sufficient depth.Additionally, its speed coupled with its use of the X3D file format make this algorithmhighly suitable for Web Services applications: one could pass their 3D triangle mesh informationthrough the web, and this algorithm could run and return a visualization highlighting the weakestareas of the model.Furthermore, this algorithm also produces relatively rapid results. Other voxelizationefforts, such as that in the paper “Real-time Voxelization for Complex Polygonal Models”,perform even faster: By utilizing the GPU (graphics processing unit), the authors were able toperform real-time voxelization of polygonal surfaces into 2D textures in video memory. Theirpaper presents a very quick, powerful solution for volumetric representation. However, the paperdoes not present a method to evaluate areas of minimal thickness, as my algorithm does. It doesnot take into account any volume calculations and does not highlight voxels that fail theminimum-thickness threshold. The paper is solely about straight voxelization.In their introduction the authors claim, “As voxelization is basically a 3D scan conversionprocess, it is natural to make use of rasterization graphics hardware in parts of or the wholevoxelization pipeline” [9]. They do so by dividing the volumetric representation into three tasks:rasterization, texelization, and synthesis. During the rasterization step, the triangles of the surfacemesh are rasterized to the discrete voxel space. During the texelization step, volume space isconverted to a 'worksheet' that records all voxelization information. The final stage is thesynthesis stage, during which three directional 'sheet buffers', each representing a part of thediscrete voxel space, are transformed and reformulated to the worksheet representing finalvolume. My algorithm, on the other hand, does not rely on any special GPU hardware and can beused with only common computional resources.Finally, I feel the scalability of my algorithm is a resounding success. Many voxelizationpapers test exclusively on 3D models composed of few triangles, or they test with very lowresolutions, such as 256x256x256 [10]. My algorithm has scaled to resolutions as high as4096x4096x4096 and evaluated models with many hundreds of thousands of triangles.