الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 163 |  |  |
| | | from | 163 | | |
Abstract
Terrain rendering has many important applications in the fields of modeling,
geographic information systems, videos games, space modeling,
flight simulation, synthetic vision systems (SVSs) and others. Due to
this, it has been an active area of research for decades. Terrain rendering
methods have been devised to handle the rendering of massive
terrain datasets in real-time. These methods are designed to deal with
large datasets at interactive frame rates to render terrains covering large
areas in real-time.
In this research, several approaches to this problem are investigated
and based on this investigation, a quad-tree level-of-detail (LOD) multiactivity
based method for real-time terrain rendering is presented. The
method uses two concurrent activities running in parallel. The errors
activity decides what to be rendered and the rendering activity do the
actual rendering. The two activities communicate with each other via a
LOD hierarchy that is constructed by the errors activity and stored in
main storage and each one of them is assigned a CPU thread and a GPU
context. The rendering activity then renders the whole terrain as small
blocks with different sizes using reusable vertex and index buffers with
different scaling and translation parameters based on blurred versions of
the height-field texture that are calculated on-the-fly on a vertex shader.
Discontinuities are handled using incremental constant vertex and index
buffers that cover all possible cases of LOD differences ensuring a tight
mesh of terrain geometry where each LOD difference adds a number of
1
Contents
indices from the same index buffer used to handle all cracks.
A hybrid fuzzy texturing method that combines real and artificial
details is also presented. It is based on an automatic fuzzy system for
blending different detail textures with the terrain base texture to give
varying artificial details based on terrain geometry. The original base
color that comes from the real terrain texture is still preserved though
by using a weighting scheme that favors the base color.
The results of the conducted case study show that although the
proposed Hierarchical Error Map method achieves expected interactive
frame rates at guaranteed very small screen-space errors of 1, 2, and 3
pixels, the CPU usage is been kept minimum due to the proposed notion
of errors texture that is calculated entirely on the GPU.