Visualization of urban environments
Author(s)
Advisor
Güdükbay, UğurDate
2007Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
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Abstract
Modeling and visualization of large geometric environments is a popular research
area in computer graphics. In this dissertation, a framework for modeling and
stereoscopic visualization of large and complex urban environments is presented.
The occlusion culling and view-frustum culling is performed to eliminate most
of the geometry that do not contribute to the user’s final view. For the occlusion
culling process, the shrinking method is employed but performed using a
novel Minkowski-difference-based approach. In order to represent partial visibility,
a novel building representation method, called the slice-wise representation
is developed. This method is able to represent the preprocessed partial visibility
with huge reductions in the storage requirement. The resultant visibility list is
rendered using a graphics-processing-unit-based algorithm, which perfectly fits
into the proposed slice-wise representation. The stereoscopic visualization depends
on the calculated eye positions during walkthrough and the visibility lists
for both eyes are determined using the preprocessed occlusion information. The
view-frustum culling operation is performed once instead of two for both eyes.
The proposed algorithms were implemented on personal computers. Performance
experiments show that, the proposed occlusion culling method and the usage of
the slice-wise representation increase the frame rate performance by 81 %; the
graphics-processing-unit-based display algorithm increases it by an additional
315 % and decrease the storage requirement by 97 % as compared to occlusion
culling using building-level granularity and not using the graphics hardware. We
show that, a smooth and real-time visualization of large and complex urban environments
can be achieved by using the proposed framework.
Keywords
Stereoscopic visualizationslice-wise representation
octree
occlusion culling
occluder shrinking
subdivision
Minkowski difference
fromregion visibility
fromregion visibility
urban visualization
visibility processing