Simplifying Isosurfaces (Part 2)

Very interesting article on techniques for simplifying 3d surfaces, including an interactive WebGL demo comparing the various techniques. Simplifying 3d surfaces is important for maintaining frame rate in interactive applications when objects are far away; it is a way of managing level of detail in an automated fashion.

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To briefly recap, our goal is to render large volumetric environments.  For the sake of both efficiency and image quality, we want to introduce some form of level of detail simplification for distant geometry.  Last time, we discussed two general approaches to level of detail — surface and volumetric — focusing primarily on the former.  Though volumetric terrain is not exactly the same as height-map based terrain, we can draw an imperfect analogy between these two problems and the two most popular techniques for 2D terrain rendering: ROAM and geometry clipmaps.

ROAM vs. Clip Maps

ROAM, or Realtime Optimally Adapting Meshes, is in many ways the height-field equivalent of surface based simplification.  In fact, ROAM is secretly just the simplification envelopes algorithm applied to large regular grids!  For any viewing configuration and triangle budget, ROAM computes an optimally simplified mesh in this sense.  This…

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