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Abstract

We present a visibility algorithm that is based on sampling the scene for visible surfaces.  The subset of lines for which the visibility is pre-calculated is defined by a two-plane parameterization.  Each sample represents the portion of geometry that is visible for the lines through that sample's region.  Lumping geometry together in grid cells allows achieving visibility at a coarser level, and improves the solution.  A rendering algorithm that uses this visibility pre-calculation is presented.  Using this method, most hidden geometry is culled and a speedup in rendering time is obtained.

Some problems remain, however, and are discussed here.  Particularly, some cells are left unrendered because they are missed by the discrete sampling procedure, thus potentially creating holes in surfaces.  Techniques to improve the solution are proposed.  In particular, modifying the pre- and post-filtering algorithms used in creating/resampling the field helps remove some of the artifacts.  Nonetheless, the algorithm remains useful for cases where only coarse visibility is needed.

BibTeX entry

@InProceedings{Blais:1998:SV,
  author =       "Martin Blais and Pierre Poulin",
  title =        "Sampling Visibility in Three-Space",
  pages =        "45--52",
  booktitle =    "Proceedings of the 1998 Western Computer Graphics
                  Symposium",
  year =         1998,
  month =        apr,
  conference =   "held in Whistler, B.C.; 23-26 April 1998",
  keywords =     "visibility, occlusion, culling, image-based rendering",
  url =          "http://www.iro.umontreal.ca/labs/infographie/papers/",
  abstract =     "We present a visibility algorithm that is based on
                  sampling the scene for visible surfaces.  The subset of
                  lines for which the visibility is pre-calculated is
                  defined by a two-plane parameterization.  Each sample
                  represents the portion of geometry that is visible for
                  the lines through that sample's region.  Lumping
                  geometry together in grid cells allows achieving
                  visibility at a coarser level, and improves the
                  solution.  A rendering algorithm that uses this
                  visibility pre-calculation is presented.  Using this
                  method, most hidden geometry is culled and a speedup in
                  rendering time is obtained.  Some problems remain,
                  however, and are discussed here.  Particularly, some
                  cells are left unrendered because they are missed by
                  the discrete sampling procedure, thus potentially
                  creating holes in surfaces.  Techniques to improve the
                  solution are proposed.  In particular, modifying the
                  pre- and post-filtering algorithms used in
                  creating/resampling the field helps remove some of the
                  artifacts.  Nonetheless, the algorithm remains useful
                  for cases where only coarse visibility is needed.",
}

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