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A Hierarchical Shadow Volume Algorithm

Aila, Timo and Akenine-Möller, Tomas LU (2004) In Graphics Hardware p.15-23
Abstract
The shadow volume algorithm is a popular technique for real-time shadow generation using graphics hardware.

Its major disadvantage is that it is inherently fillrate-limited, as the performance is inversely proportional to the area of the projected shadow volumes. We present a new algorithm that reduces the shadow volume rasterization

work significantly. With our algorithm, the amount of per-pixel processing becomes proportional to the screenspace

length of the visible shadow boundary instead of the projected area. The first stage of the algorithm finds

8×8 pixel tiles, whose 3D bounding boxes are either completely inside or outside the shadow volume. After that, the second stage performs per-pixel... (More)
The shadow volume algorithm is a popular technique for real-time shadow generation using graphics hardware.

Its major disadvantage is that it is inherently fillrate-limited, as the performance is inversely proportional to the area of the projected shadow volumes. We present a new algorithm that reduces the shadow volume rasterization

work significantly. With our algorithm, the amount of per-pixel processing becomes proportional to the screenspace

length of the visible shadow boundary instead of the projected area. The first stage of the algorithm finds

8×8 pixel tiles, whose 3D bounding boxes are either completely inside or outside the shadow volume. After that, the second stage performs per-pixel computations only for the potential shadow boundary tiles. We outline a twopass implementation, and also describe an efficient single-pass hardware architecture, in which the two stages are separated using a delay stream. The only modification required in applications is a new pair of calls for marking the beginning and end of a shadow volume. In our test scenes, the algorithm processes up to 11.5 times fewer pixels compared to current state-of-the-art methods, while reducing the external video memory bandwidth by a factor of up to 17.1. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
in
Graphics Hardware
pages
15 - 23
publisher
Eurographics Association
external identifiers
  • scopus:29244452672
ISBN
3905673150
language
English
LU publication?
yes
id
cb018985-38ae-49c9-ac33-1b33e52910e1 (old id 746946)
date added to LUP
2008-01-11 09:38:11
date last changed
2017-03-26 04:34:19
@inproceedings{cb018985-38ae-49c9-ac33-1b33e52910e1,
  abstract     = {The shadow volume algorithm is a popular technique for real-time shadow generation using graphics hardware.<br/><br>
Its major disadvantage is that it is inherently fillrate-limited, as the performance is inversely proportional to the area of the projected shadow volumes. We present a new algorithm that reduces the shadow volume rasterization<br/><br>
work significantly. With our algorithm, the amount of per-pixel processing becomes proportional to the screenspace<br/><br>
length of the visible shadow boundary instead of the projected area. The first stage of the algorithm finds<br/><br>
8×8 pixel tiles, whose 3D bounding boxes are either completely inside or outside the shadow volume. After that, the second stage performs per-pixel computations only for the potential shadow boundary tiles. We outline a twopass implementation, and also describe an efficient single-pass hardware architecture, in which the two stages are separated using a delay stream. The only modification required in applications is a new pair of calls for marking the beginning and end of a shadow volume. In our test scenes, the algorithm processes up to 11.5 times fewer pixels compared to current state-of-the-art methods, while reducing the external video memory bandwidth by a factor of up to 17.1.},
  author       = {Aila, Timo and Akenine-Möller, Tomas},
  booktitle    = {Graphics Hardware},
  isbn         = {3905673150},
  language     = {eng},
  pages        = {15--23},
  publisher    = {Eurographics Association},
  title        = {A Hierarchical Shadow Volume Algorithm},
  year         = {2004},
}