Levels Of Detail

• General introductions :
  • Multiresolution Modeling by Michael Garland.
  • Geometry and Illumination Simplification Computer Science Department, Brown University, Rhode Island.
    These a course notes with a list a references to read.
• Level Of Detail for Behaviours, Computer Science Division, UC Berkeley.
• Graphics, Visualization & Usability (GVU) Center, Georgia Institute of Technology :
  • Managing Level of Detail by Degrading Detail in HMD Peripheries.
  • Geometric Simplification for Indirect Illumination Calculations.
• at MIT :
  • Multi-Resolution Simulation, part of the Virtual Worlds Project, Artificial Intelligence Laboratory.
  • Geometry Compression and Simplification at the Graphics Lab.
• Department of Computer Science, University of North Carolina, Chapel Hill:
  The Simplification Group has done work on Polygonal Simplification. One of the technics they have created uses Simplification Envelopes.
• Terrain Simplification, by the Computer Science Department, Carnegie Mellon University, is restricted to generating polygonal approximations of height field.
• Bill Lorensen at General Electric uses Decimation of Triangle Meshes to do Experiments with Smoothing.
• Nick Torkos's work on LODs :
  at the University of Toronto, Canada, he has devellopped a (non-documented) method that builds a compact data structure from which many LODs can be reconstructed very quickly. For instance, he is able to store over 2000 LODs in only four times the amount of data space required for the original model.
• The mesh generation scheme used in the Shastra project at Purdue University.
• Multiresolution models defined by the Geometric Modeling Group, at the University of Genova.
• Surface Simplification work by the Visual Computing Group, CNR-Pisa.
• Unstructured Decimation of Tessellated Domains.

I'm just beginning this section on rendering complexe surfaces and volumes. I've put it here in LODs 'cause the main problem lies in adaptively triangulating a surface or volume representation to get a polygone mesh with the minimum number of polygones given certain display parameters. This is related to the problem of Mesh Generation.

• Interactive Display of Large Scale Trimmed NURBS Models, at UNC's Graphics group.

These are free packages :

• Source code and binaries for [Hoppe et al., 1993].
• UNC's Simplification Envelopes.
• LODESTAR : Level of Detail Generator for VRML 1.0.
• JADE : Multiresolution Decimation based on Global Error.
• M. Garland and P. Heckbert's QSLIB, surface simplification using quadric error metrics.
• Polychop, Fast, Simple, and Effective Polygon Reduction.
• QSlim by Michael Garland.
• qemLOSS2, Lightwave Plugin Object Surface Simplification using Quadric Error Metrics.

These are commercial packages :

• InnovMetric makes IMEdit/IMCompress, a Polygon Editing and Reduction Toolbox, which can produce LODs.
• PolyRed : The Polygon Reduction Tool for VRML.
• Cymage Polygon Reduction Software by CyberWare.
• Polygon Reduction using Alias/WaveFront.

• Polyhedral Simplification used in the IBM 3D Interaction Accelerator.
• Terra/Scape is a software package for generating polygonal approximations of height field, by the Computer Science Department, Carnegie Mellon University.

• Open Inventor, VRML 2 and IRIS Performer have common characteristics for usings LODs. They implement to following nodes:
  • LOD Node: The LOD node, (level of detail), is used to allow browsers to switch between various representations of objects automatically. The level field contains nodes that represent the same object or objects at varying levels of detail, from highest to the lowest level of detail.
  • BillBoard Node: The Billboard node is a grouping node which modifies its coordinate system so that the billboard node's local z-axis turns to point at the camera.
• SGI's WebSpaceAuthor and Cosmo Worlds both have a polygonal simplification tool and a LODs editor.

• The Visualization Toolkit can do decimation.

• Conferences :
• LODs at SIGGRAPH'96
• LODs at EuroGraphics'96.
• Surface Simplification (session 10A) at Visualization'96.
• Algorithmes:
  • Marching Cubes Quadric Patches.
  • Subdivision surfaces, Graphics and Imaging Laboratory, University of Washington.
  • Use of wavelets@.
• A study on Mesh Generation by David Eppstein (and more by Robert Schneiders).
• Fast Rendering of Subdivision Surfaces : slides by Kari Pulli and Mark Segal (presented at 7th Eurographics Rendering Workshop, Porto, Portugal, June '96).
• A cool VRML LOD based visual effect by Carl West.