Terrain LOD: Pre-computed TIN Approaches

Creating a TIN from a heightfield grid is itself a form of "lower LOD", albeit a less flexible one.  If the terrain area is small, largely piecewise flat, or won't require significant distance culling, then it can be much faster and simpler to create and render a TIN than to do continuous LOD.

Creating pre-computed TINs

• TinLib: Free Triangulated Irregular Network library
• many other libraries
• countless academic papers

Limited LOD with pre-computed TINs

• Garland and Heckbert's Terra / Scape project
  • source paper: Fast Polygonal Approximation of Terrain and Height Fields (PDF)
  • Michael Garland's Terrain Simplification page
  • Heckbert contributed in 1995, but since then appears to be working on general multi-res meshes
  • this approach appear less suited for realtime than the others on this page
• Terrex SmartMesh™
  • similar to MultiGen pre-computed TIN LODs, but improves on them by avoiding the edge-matching artifacts
  • doesn't require a custom runtime, uses plain OpenFlight files
  • however, their approach is patented to Terrex and therefore not meant for widespread usage
• MultiGen
  • also capable of generating static TINs, but not as sophisticated as Terrex
• Prof. Leila De Floriani of the University of Genova and
  Enrico Puppo of IMA-CNR of Genova
  • extremely prolific in the field of TIN terrain LOD (and multiresolution volume data as well)
  • De Floriani L, Marzano P, Puppo E. (1994) Line-of-sight communication on terrain models. International Journal of Geographical Information Systems 8, 329-342
  • L. De Floriani, P. Marzano, E. Puppo, Multiresolution Models for Topographic Surface Description
  • L. De Floriani, P. Marzano, E. Puppo, Multiresolution Modeling in Geographical Information Systems, INNOVATIONS IN GIS 3
  • L. De Floriani, P. Marzano, E. Puppo, Hierarchical terrain models: survey and formalization, Proceedings ACM Symposium on Applied Computing (SAC), March 1994
  • M. Bertolotto, L. De Floriani, P. Marzano, An Efficient Representation for Pyramidal Terrain Models, Proceedings 2nd ACM International Workshop on Advances in Geographic Information Systems, December 1994.
  • L. De Floriani, P. Magillo, E. Puppo, VARIANT - Processing and visualizing terrains at variable resolution, Proceedings 5th ACM Workshop on Advances in GIS, November 1997
  • P. Magillo, E. Puppo, Algorithms for Parallel Terrain Modelling and Visualization, Parallel Processing Algorithms for GIS, Chapter 16 (1998)
  • L. De Floriani, P. Magillo, 1997, Visibility computations on hierarchical triangulated terrain models, Geoinformatica, Vol.1, No.3, pp. 219-250, Kluwer Academic Publishers, Norwell, MA, USA, 1997