Unpopping: Solving the Image-Space Blend Problem for Smooth Discrete LOD Transitions

Markus Giegl, Michael Wimmer
Unpopping: Solving the Image-Space Blend Problem for Smooth Discrete LOD Transitions
Computer Graphics Forum, 26(1):46-49, March 2007. [Preprint]

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Abstract

This paper presents a new, simple and practical algorithm to avoid artifacts when switching between discrete levels of detail (LOD) by smoothly blending LOD representations in image space. We analyze the alternatives of conventional alpha-blending and so-called late-switching (the switching of LODs markusquote{far enough} from the eye-point), widely thought to solve the LOD switching discontinuity problem, and conclude that they either do not work in practice, or defeat the concept of LODs. In contrast we show that our algorithm produces visually pleasing blends for static and animated discrete LODs, for discrete LODs with different types of LOD representations (e.g. billboards and meshes) and even to some extent totally different objects with similar spatial extent, with a very small runtime overhead.

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BibTeX

@article{GIEGL-2007-UNP,
  title =      "Unpopping: Solving the Image-Space Blend Problem for Smooth
               Discrete LOD Transitions",
  author =     "Markus Giegl and Michael Wimmer",
  year =       "2007",
  abstract =   "This paper presents a new, simple and practical algorithm to
               avoid artifacts when switching between discrete levels of
               detail (LOD) by smoothly blending LOD representations in
               image space. We analyze the alternatives of conventional
               alpha-blending and so-called late-switching (the switching
               of LODs markusquote{far enough} from the eye-point), widely
               thought to solve the LOD switching discontinuity problem,
               and conclude that they either do not work in practice, or
               defeat the concept of LODs. In contrast we show that our
               algorithm produces visually pleasing blends for static and
               animated discrete LODs, for discrete LODs with different
               types of LOD representations (e.g. billboards and meshes)
               and even to some extent totally different objects with
               similar spatial extent, with a very small runtime overhead.",
  month =      mar,
  issn =       "0167-7055",
  journal =    "Computer Graphics Forum",
  number =     "1",
  volume =     "26",
  pages =      "46--49",
  keywords =   "popping, LOD switching, levels of detail, real-time
               rendering",
  URL =        "https://www.cg.tuwien.ac.at/research/publications/2007/GIEGL-2007-UNP/",
}