Freeform Shadow Boundary Editing

Oliver Mattausch, Takeo Igarashi, Michael Wimmer
Freeform Shadow Boundary Editing
Computer Graphics Forum (Proceeding of EUROGRAPHICS 2013), 32(2):175-184, May 2013. [draft]

Information

Abstract

We present an algorithm for artistically modifying physically based shadows. With our tool, an artist can directly edit the shadow boundaries in the scene in an intuitive fashion similar to freeform curve editing. Our algorithm then makes these shadow edits consistent with respect to varying light directions and scene configurations, by creating a shadow mesh from the new silhouettes. The shadow mesh helps a modified shadow volume algorithm cast shadows that conform to the artistic shadow boundary edits, while providing plausible interaction with dynamic environments, including animation of both characters and light sources. Our algorithm provides significantly more fine-grained local and direct control than previous artistic light editing methods, which makes it simple to adjust the shadows in a scene to reach a particular effect, or to create interesting shadow shapes and shadow animations. All cases are handled with a single intuitive interface, be it soft shadows, or (self-)shadows on arbitrary receivers.

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BibTeX

@article{MATTAUSCH-2013-FSBE,
  title =      "Freeform Shadow Boundary Editing",
  author =     "Oliver Mattausch and Takeo Igarashi and Michael Wimmer",
  year =       "2013",
  abstract =   "We present an algorithm for artistically modifying
               physically based shadows. With our tool, an artist can
               directly edit the shadow boundaries in the scene in an
               intuitive fashion similar to freeform curve editing. Our
               algorithm then makes these shadow edits consistent with
               respect to varying light directions and scene
               configurations, by creating a shadow mesh from the new
               silhouettes. The shadow mesh helps a modified shadow volume
               algorithm cast shadows that conform to the artistic shadow
               boundary edits, while providing plausible interaction with
               dynamic environments, including animation of both characters
               and light sources. Our algorithm provides significantly more
               fine-grained local and direct control than previous artistic
               light editing methods, which makes it simple to adjust the
               shadows in a scene to reach a particular effect, or to
               create interesting shadow shapes and shadow animations. All
               cases are handled with a single intuitive interface, be it
               soft shadows, or (self-)shadows on arbitrary receivers.",
  month =      may,
  issn =       "0167-7055",
  journal =    "Computer Graphics Forum (Proceeding of EUROGRAPHICS 2013)",
  number =     "2",
  volume =     "32",
  pages =      "175--184",
  keywords =   "shadows, real-time rendering",
  URL =        "https://www.cg.tuwien.ac.at/research/publications/2013/MATTAUSCH-2013-FSBE/",
}