level of detail

Screen Space Meshes. Mueller, et al. SCA ’07

Mueller, Schirm and Duthaler present a method for constructing a polygonal mesh in screen space from depth information resulting from fluid simulation. By applying a variant of Marching Squares (which is itself a 2D variant of Marching Cubes), they extract the polygonal surface of visible fluid surfaces. By smoothing the depth values before extraction, they produce a smoother fluid surface. Additionally, they discuss “smoothing” the silhouette boundary by iteratively averaging vertex positions along the silhouette. Silhouette locations are typically where SPH methods reveal their nature because of a reduced number of neighboring spheres to smooth. This method reduces the blobby edge effect. I’d be curious to see a video with this silhouette shrinking in action. I would think you would get some flickering or popping effects when spherical elements of the underlying simulation break free of the silhouette.

Overall, I don’t see a clear reason why this method is preferable over a meshless method (besides the silhouette shrinking). Refraction, occlusion and reflection could all be done without a mesh. It is likely possible to shrink the silhouette as described using image processing methods.

Unsmoothed

Smoothed

While the gaming world waits patiently for the release of Valve’s Team Fortress 2, Jason Mitchell et al. have been releasing a deluge of material on the rendering style of the game. While there is nothing especially novel about the techniques, I think the paper is an interesting exercise in authoring a lighting model to achieve a desired look. It helps that the trailer videos are fun to watch.

Illustrative Rendering in Team Fortress 2, Mitchell et al. NPAR 2007.

Rendering techniques featurette with commentary