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Smooth Levels of Detail
Incremental Encoding of Polygonal Models
Project duration:
1996-1997
Contact:
Dieter Schmalstieg,
Gernot Schaufler
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Description
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A new representation for geometric objects allows incremental refinement
of the visual fidelity as data is sent over a network, and also yields
significant compression.
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Application
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Every application that needs to send geometry data over a network benefits
from the approach, such as distributed virtual environments, concurrent
engeneering, and collaborative visualization.
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Problems
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Geometric representations of objects must usually be available completely
before the data is usable, so users always have to wait for downloads to
complete.
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Approach
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"Smooth LODs" are a method to generate a stream of data which continuously
refines a polygonal model from the coarsest representation to the original
high-fidelity model. Unlike conventional level of detail algorithms that use
only a small number of discrete approximations for each object, our method
allows a smooth, continuous refinement of the object over time while the
stream is transmitted.
The approach is based on a hierarchical clustering
algorithm which produces the model representation of steadily increasing
detail and has several advantages over conventional models with few, discrete
levels of detail: The model can be transmitted and decoded incrementally,
yielding a valid approximation at any stage of the process. The incremental
encoding is extremely compact, so models are smaller than in their original form. Any desired level of detail can be selected during rendering at interactive speed. It is also possible to have variable detail resolution within a single model, which is useful for rendering models with large extent.
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Publication
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Smooth Levels of Detail
:
D. Schmalstieg, G. Schaufler
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