A survey of Real-Time Soft Shadows Algorithms
Recent advances in GPU technology have produced a shift in focus for
real-time rendering applications, whereby improvements in image quality
are sought in addition to raw polygon display performance. Rendering
effects such as antialiasing, motion blur and shadow casting are
becoming commonplace and will likely be considered indispensable in the
near future. The last complete and famous survey on shadow algorithms
-Woo, 1990- has to be updated in particular in view of recent
improvements in graphics hardware, which make new algorithms possible.
This STAR covers all current methods for real-time shadow rendering,
without venturing into slower, high quality techniques based on ray
casting or radiosity. Shadows are useful for a variety of reasons:
first, they help understand relative object placement in a 3D scene by
providing visual cues. Second, they dramatically improve image realism
and allow the creation of complex lighting ambiances. Depending on the
application, the emphasis is placed on a guaranteed framerate, or on
the visual quality of the shadows including penumbra effects or ``soft
shadows''. Obviously no single method can render physically correct
soft shadows in real-time for any dynamic scene! However our survey
aims at providing an exhaustive study allowing a programmer to choose
the best compromise for his/her needs. In particular we discuss the
advantages, limitations, rendering quality and cost of each algorithm.
Recommendations are included based on simple characteristics of the
application such as static/moving lights, single or multiple light
sources, static/dynamic geometry, geometric complexity, directed or
omnidirectional lights, etc. Finally we indicate which methods can
efficiently exploit the most recent graphics hardware facilities.
Images and movies
See also
BibTex references
@Article\{HLHS03a, author = "Hasenfratz, Jean-Marc and Lapierre, Marc and Holzschuch, Nicolas and Sillion, Fran\c{c}ois", title = "A survey of Real-Time Soft Shadows Algorithms", journal = "Computer Graphics Forum", number = "4", volume = "22", pages = "753--774", month = "dec", year = "2003", keywords = "soft, shadows, survey, star, r", url = "http://artis.inrialpes.fr/Publications/2003/HLHS03a" }