GPU Iso-surface Renderer

Iso-surfaces are ubiquitous in computer graphics, especially in applications where geometry undergoes significant topological changes over time. Level sets are a special type of iso-surface where the volumetric data is a Euclidean distance field. Fluid simulations often use level sets to track the fluid surfaces over time, using the distance zero-crossing to represent interfaces. This real-time renderer was written for Naiad Studio and uses a volume rendering approach based on camera-aligned proxy geometry and shaders. This method is well explained in GPU Gems. Volume data is stored as a 3D texture on the GPU and the fragments generated from the proxy geometry are used as sampling locations into this texture. This approach has several advantages over methods that extract explicit geometry from volumetric data (e.g. Marching Cubes). The distance field is shown “as is”, avoiding artefacts caused by super-imposed structures. Per-pixel shading is inherently provided and it becomes trivial to render any iso-value without additional setup.

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