The iso-heightfield is built on a grid with 60 degree-axes that produce an equilateral tessellation, which is the closest packed regular tessellation. We design a grid- to world-space mapping that is convenient for triangle strips and provides square tiles for level of detail and texture management. This makes the iso-heightfield an efficient drop-in replacement for the orthogonal heightfields commonly used today. We introduce several new support algorithms including fast vertex normals and self-shadowing. The iso-heightfield requires resampling when data was previously captured from an orthogonal grid or irregular samples. This is a lossless process if the original sampling filter is known and the Nyquist rate was observed.

@techreport{ mcgsib05heightfield,
  author = "Morgan McGuire and Peter Sibley",
  title = "A Heightfield on an Isometric Grid",
  month = {Oct},
  year = {2005},
  number = {CS-05-14},
  institution = {Department of Computer Science at Brown University},
  URL = {ftp://ftp.cs.brown.edu/pub/techreports/05/cs05-14.pdf}
}

@article{ mcguire04heightfield,
  author = "Morgan McGuire and Peter Sibley",
  title = "A Heightfield on an Isometric Grid",
  month = {Aug},
  year = {2004},
  journal = {SIGGRAPH 2004 Sketch},
  URL = {http://graphics.cs.williams.edu/papers/IsoSIGGRAPH04/}
}

Hari Khalsa implemented the gradient descent and error measurement code used on this project. The Wake Island data set was created by and is used with permission of Digital Illusions. The Mars data set is from NASA and is used in collaboration with James Head III of the Brown University Planetary Geology Department. Max McGuire at Iron Lore Entertainment first suggested exploring hexagonal tessellation to us. The curvature measurement code is based on code by Tomer Moscovich.