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 needs.

3D Data Compression at 3DCT

Introduction

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 the following.

M. Deering, Geometry compression, In SIGGRAPH'95 Conference Proceedings, pp. 13-20, August 1995.

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

3D 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

3D 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.