Harald Piringer
Occlusion Culling Using Hardware-Based Occlusion Queries
[
thesis]
Information
- Publication Type: Master Thesis
- Workgroup(s)/Project(s):
- Date: July 2003
- First Supervisor: Michael Wimmer
- Keywords: real-time rendering, occlusion queries, occlusion culling
Abstract
Today, a major challenge of computer graphics is the generation of realistic images at rates that arouse the impression of fluid motion in the viewer. Of central importance in this context is the application of specialized hardware, which has experienced an impressive evolution in recent years, increasing both speed and functionality in a significant fashion. However, displaying complex scenes like whole cities requires dealing with such an amount of data, that dedicated acceleration algorithms are still necessary in order to cope with the tight temporal constraints. In doing so, methods for detecting invisible parts of the scenery play a key role. A particular challenge is classifying those objects in an efficient way which are invisible due to being entirely occluded by other objects in front of them. Although this visibility problem belongs to the classical tasks of computer graphics, just recently introduced extensions to the graphics hardware permit the design of new algorithms with fascinating opportunities, but also requirements that have been of no concern to previous approaches.This master thesis deals with the task of developing an efficient algorithm for solving the visibility problem for arbitrary scenes, which is tailored towards the NV_occlusion_query OpenGL extension, in different ways:
One method approximates the potential occlusion within a given scenery from a certain viewpoint by constructing a directed acyclic graph, which is in turn used to be able to issue as many occlusion queries as possible in a concurrent fashion. Several extensions amend and improve the core algorithm by employing a more equal load balancing and exploiting both temporal and spatial coherence. Finally, this approach is extended by incorporating an appropriate spatial hierarchy.
Although this technique is by and large significantly superior to rendering without occlusion culling, the obtained results are not satisfactory in every respect. Therefore, a second approach is proposed that does not rely on any graph. This hierarchical algorithm depends entirely on the visibility classification of previous frames and stresses thus the aspect of temporal coherence. Even though it is considerably simpler than the first approach, it yields superior and generally convincing results.
Both approaches are conservative (which means that they do not affect the correctness of the resulting image), but can easily be modified in a way that permits to trade off quality for speed by tolerating precisely definable mistakes.
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No further information available.BibTeX
@mastersthesis{PIRINGER-2003-HBOQ,
title = "Occlusion Culling Using Hardware-Based Occlusion Queries",
author = "Harald Piringer",
year = "2003",
abstract = "Today, a major challenge of computer graphics is the
generation of realistic images at rates that arouse the
impression of fluid motion in the viewer. Of central
importance in this context is the application of specialized
hardware, which has experienced an impressive evolution in
recent years, increasing both speed and functionality in a
significant fashion. However, displaying complex scenes like
whole cities requires dealing with such an amount of data,
that dedicated acceleration algorithms are still necessary
in order to cope with the tight temporal constraints. In
doing so, methods for detecting invisible parts of the
scenery play a key role. A particular challenge is
classifying those objects in an efficient way which are
invisible due to being entirely occluded by other objects in
front of them. Although this visibility problem belongs to
the classical tasks of computer graphics, just recently
introduced extensions to the graphics hardware permit the
design of new algorithms with fascinating opportunities, but
also requirements that have been of no concern to previous
approaches. This master thesis deals with the task of
developing an efficient algorithm for solving the visibility
problem for arbitrary scenes, which is tailored towards the
NV_occlusion_query OpenGL extension, in different ways: One
method approximates the potential occlusion within a given
scenery from a certain viewpoint by constructing a directed
acyclic graph, which is in turn used to be able to issue as
many occlusion queries as possible in a concurrent fashion.
Several extensions amend and improve the core algorithm by
employing a more equal load balancing and exploiting both
temporal and spatial coherence. Finally, this approach is
extended by incorporating an appropriate spatial hierarchy.
Although this technique is by and large significantly
superior to rendering without occlusion culling, the
obtained results are not satisfactory in every respect.
Therefore, a second approach is proposed that does not rely
on any graph. This hierarchical algorithm depends entirely
on the visibility classification of previous frames and
stresses thus the aspect of temporal coherence. Even though
it is considerably simpler than the first approach, it
yields superior and generally convincing results. Both
approaches are conservative (which means that they do not
affect the correctness of the resulting image), but can
easily be modified in a way that permits to trade off
quality for speed by tolerating precisely definable
mistakes.",
month = jul,
address = "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria",
school = "Institute of Computer Graphics and Algorithms, Vienna
University of Technology ",
keywords = "real-time rendering, occlusion queries, occlusion culling",
URL = "https://www.cg.tuwien.ac.at/research/publications/2003/PIRINGER-2003-HBOQ/",
}