2.5 Editing Features
By using our software realistic geo-specific or generic VE can
be generated easily. The user can populate the scene with
thousands of trees, moving people, animals, buildings, bridges,
vehicles etc. With few mouse clicks walls, fences or roads can
be created. The user can browse any object from object library
and place them in 3D environment. It is also possible to select
any object/s in 3D environment and modify it.
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Codie Tog Tonle e Fog oet Dens
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hen : ; s 5
Figure 7. Virtual Environment Editor
3. CONCLUSION AND FUTURE WORK
Our study can be evaluated from two different viewpoints: VE
editor and the rendering performance.
Rendering performance can be evaluated as satisfactory when
we consider the frame rates achieved at scenes where thousands
of static and dynamic entities included. When we consider the
VR scene editor functionality easy interaction with 3D
environment and objects may be the reason behind the rapid
scene development capability. Ability to construct groups from
single objects such as forest from a tree or crowd from a human
helps to populate scenes in a short time. This feature
additionally decreases frustum-culling computations. Rich
content of the object library, skybox library or terrain surface
texture library also meets most of the requirements for realistic
scene generation. Data import ability from existing GIS systems
is also another feature that contributes the editor functionality.
Crowd simulation rather than animation is important future
work. Autonomous agents that act like a real human should
replace the virtual characters in our implementation. Common
algorithms such as boids (Reynolds, 1987) that represent animal
flock behaviors could also be used to model flocks in this study.
Occlusion culling which is believed to contribute achieving
better frame rates is another future work. Audio is
complementary element of any VE. Although we implemented
sound, it should be renewed to meet needs of VEs. 3D sound
feature that works according to position of V-eye is considered
to improve realism and the feeling of immersion.
ACKNOWLEDGEMENT
We would like to express our sincere thanks to Mevliit Ding
who conducted rendering test on various PCs.
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part BS. Istanbul 2004
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