Graphics Reference
In-Depth Information
2
Scene Building in Virtual Interactive Presentation
Nowadays virtual scene modeling in interactive presentation design is mostly carried
out by software like 3DS MAX, AUTO CAD, MAYA, etc. The advantage by using
this method is that geometric shapes can be controlled by the designer to produce
high-quality models with low complexity. However, all the processes totally rely on
manual operations, which requires a long modeling period and present a poor sense of
reality. Image-based 3D reconstruction [4] can make up these weaknesses well by
acquiring three-dimensional structure from the real world directly so as to obtain high
geometric accuracy, photo-realism of the results and the modeling of the complete
details in a short time with a more portable and flexible approach.
According to various complexities, immovable cultural heritage and artifacts in-
volved in this paper can be divided into three categories:
Architectural objects with simple shape and flat surfaces. Such as houses, grounds,
stone steps, horizontal inscribed boards. In this category, modeling can be achieved
by simple geometric transformation while the shape always presents repeatability
in some certain directions. Especially in Chinese traditional architecture, com-
pound structures in one building group present to be largely identical with minor
differences. Houses in one group are all with similar symmetry and façade. As a
result, models in one virtual scene can be adopted with little changes in their tex-
ture maps.
Sculpture objects with a complex shape and concave-convex surfaces. Such as the
stone lions, carved drum-like stones and other stone carvings with vivid, flexible,
varying shapes. Different from modern factories' mass production, ancient stone
sculptures always manufactured by craftsman only one at a time containing their
inspiration and cultural emotion. Too much time and energy will be cost in recon-
structing this kind of artifacts by traditional geometric modeling and the final effect
is often limited by modeler's capacity which can easily reduce the realistic feeling
of the whole virtual scene. Therefore, approach of image-based feature points
matching [5] should be adopted.
Artifacts carved in relief with a simple integral shape and complex detail expres-
sion. For example, brick and wood carvings are both main forms of traditional re-
lief sculpture technics. Brick carving refers to carving some patterns describing
human figures, landscape, flowers and other traditional literary quotations on blue
bricks used in building ridges, screen walls, arches over gateway and so forth.
These objects often replaced by some ordinary geometric structure with their fron-
tal photograph as mapping texture in traditional geometric modeling, which builds
a realistic view for users who are roaming in the scene at a long distance from the
model. But when users get very close to these geometric models, flat surfaces
without depth information cannot provide stereoscopic impression. So a patch-
based multi-view stereo approach will be used in this article to reconstruct a screen
wall in Qiao's Grand Courtyard automatically outperforming than traditional
method in many ways.
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