3DCT HELIXX is the power behind
the entire 3DCT product family. It’s our proprietary
compression and content engine for 3D meshes with best-in-class
compression and functionality.
Lossless compression rates are typically
95% or 1:20. Combine this with lossy compression (polygon
reduction) and compression rates are higher, for example
98% or 1:50. 3DCT HELIXX supplies the
technology so you can tailor the compression to your
3D Data Compression at 3DCT
The next wave in multimedia content
is interactive 3D data. Advances in graphics hardware
have made it possible to display sophisticated, interactive
3D content. Unfortunately, advances in bandwidth have
lagged, thus making it difficult to share this content.
Commercial applications such as gaming and e-commerce
are awaiting a method to make this content available
over thin pipes. Business-to-business and research
applications such as CAD, medical, and scientific
research, which have access to fat pipes and deal
with very large 3D files, are waiting for a technology
to make the sharing this content feasible.
3D Compression Technologies (3DCT)
has developed compression and optimization algorithms
for 3D content which meets the needs of those dealing
with thin or fat pipes.
3D Data Compression
Standard compression techniques such
as Huffman encoding, Lemel-Zif, JPEG, or MPEG rely
on recognizing the repeating patterns of bytes to
compress data. These are very effective in text as
well as 2D image compression. However, these technologies
are unable to capitalize on the additional compression
possible for 3D objects or meshes.
Due to the needs of graphics hardware, 3D content
is primary formatted as 3D triangular meshes. These
meshes consist of geometry -- data points defined
as (x,y,z) locations in 3D space, and connectivity
-- a data structure indicating how the points are
connected to form a triangular mesh.
Beginning in the mid-'90s, several compression
methods have been developed to take advantage of this
mesh structure. Some pointers to literature include
M. Deering, Geometry compression,
In SIGGRAPH'95 Conference Proceedings, pp. 13-20,
G. Taubin and J. Rossignac, Geometry
compression through topological surgery, ACM Transactions
on Graphics, pp. 84-118, July 1998.
Jarek Rossignac Edgebreaker: Connectivity
compression for triangle meshes IEEE Transactions
on Visualization and Computer Graphics, 5(1), pp.
47-61 (January - March 1999).
3D Compression Technologies
has improved these foundational results by
incorporating our teams expertise in geometric algorithms.
3DCT analyzes the mesh for inherent 3D knowledge,
and uses this to smartly encode the connectivity of
objects and compute the precision required to represent
the geometry, while preserving key attributes or features
in an object. In addition, 3DCT also compresses normal,
color, and texture information with a similar approach.
The methods in the literature above, and the approach
taken by 3DCT are called lossless compression. Within
a given floating point precision, this type of compression
does not degrade the data: After decompression every
triangle and point is restored.
Optimization: Polygon Reduction
Compression Technologies further capitalizes
on 3D knowledge with a polygon reduction tool. Laser
digitizers frequently over sample, thus calling for
elimination of redundant polygon data. 3DCT provides
a sliding-scale control of the amount of reduction,
which allows each user to customize their data for
their particular application. We strive to reduce
file size while maintaining important shape characteristics.
This type of compression is called lossy compression.
Bringing It All Together
Compression Technologies supports
lossless and lossy compression. This combination allows
3DCT's mesh-based compression technology to be adapted
into a progressive mesh compression tool. If levels
of detail (LOD) are desired, several lossy versions
of the mesh may be delivered to the client before
the lossless version.