If you work with 3D visualisation and 3D modeling, you’ll be interested to know that, after 7 years, the PRC format for 3D data has now finally been approved as an ISO standard as of December 2014 under ISO 14739-1:2014.
This ISO announcement marks the release of a 284 page document titled, ‘Document management – 3D use of Product Representation Compact (PRC) format‘ which is the result of many years of internal committee refinement, international voting and approval, and the ISO publication process.
We have been at the forefront of the PRC standards, having campaigned for its use and standardization for many years, and have participated directly in the ISO standards committee for the PRC format specification and PDF/E for engineering applications, since 2010.
Having spearheaded this recognition of PRC standardisation, we were keen to read ‘Document management – 3D use of Product Representation Compact (PRC) format’.
Our Review of the Document: ISBN 978 0 580 68764 8
As far as ISO standards documents go, we were impressed to see all the key areas have been included with 3D entities and colour illustrations, which is rare for ISO. Some code snippets and hints towards implementations are present for a few key areas too. Some areas also dive into low-level bit and byte structures, including Huffman coding and various compression methods.
However, the document does not contain an introduction to the topic of PRC data structures, and does not give much hint to applications, usage cases or examples. As a technical document, it does assume the reader is familiar with transformation matrices, coordinate systems, connectivity and high-order curved surfaces. There is little explanation on the complex 3D geometric file format. This is intentional, as it’s a specification not a text book.
Saying that, this information was not easy to find in the public domain before the publication was released. It’s very likely that this document will now enable new and diverse PRC based applications to emerge.
As a large technical specification document, it’s best to treat it as reference material. It will be a useful guide for those implementing new PRC software systems, particularly as it largely documents the version of PRC as currently implemented in the Adobe Acrobat and Reader software for 3D PDF.
What is PRC?
As the document doesn’t give much introduction to the subject of PRC, here’s a brief overview.
Essentially, PRC (Product Representation Compact) describes the file format and data structures for 3D content model data. It can be used for generating, viewing, and sharing 3D data and is designed to be used as the 3D visualization and exchange method used in 3D PDF documents, as well as being optimized to store, load and display various kinds of 3D data, typically similar to CAD systems.
It enables users to view high quality, detailed 3D images without having access to the original software used to create it. It also allows software applications to calculate accurate 3D objects from various data.
PRC is meant serve multiple purposes, depending on the original information, and the intended use. The PRC internal storage definition provides two ways to store models in exact geometry and in approximate tessellation. With the primary context being the storage used in 3D PDF, and referenced by other PDF standards, PRC is not intended as a data format for CAD interoperability as a stand-alone file interchange format. It is however intended to complement native or open standard CAD and PLM formats as a compact, concise binary form for visualization and documentation.
You can read more about PRC here in our article titled: ‘What is a PRC file?’
Who uses PRC?
PRC is widely used in CAD PLM Manufacturing, Engineering, CAE, Scientific Data Visualization, Geospatial 3D Mapping, Survey, Medical, Dental, BIM, Architecture, Energy, and the Mineral Exploration industries for those very reasons.
Because the PRC format describes hierarchical assemblies and parts, trees of 3D entities (coordinate systems, wireframes, surfaces, and solids), exact geometry representation (BREP) and tessellated (triangulated) representation, most industries using, sharing and reporting in 3D PDF benefit from and prefer PRC encoding (to U3D ), due to its rich coverage of 3D entities, and efficient compact representation. The PRC tessellation scheme also has very high compression characteristics, ideal for large polygonal meshes typical of many scientific and engineering applications.
The result of many years refinement
Adobe first submitted the PRC format specification to ISO in 2008 with the intention it should become an independent international standard. Since then many have helped along the way, including Visual Technology Services, and so the result truly is an international team effort and a big win for all involved.
Interested in using PRC?
Visual Technology Services continues to apply PRC in commercial solutions, integration and software applications.
To benefit from PRC when creating 3D PDF documents, PDF3D’s ReportGen and SDK products feature the technology as the default encoding for the generation of 3D PDF document files. Read more at PDF3D.com and let us know what you think.
Appreciation
We’d like to thank and acknowledge the great efforts of:
- Betsy Fanning, AIIM, Secretariat of ISO Technical Committee 171 SC2,
- Stuart Galt, Boeing,
- Leonard Rosenthol, Adobe,
- Phil Spreier,
- Alan Shipman, BSI
Ordering
The ISO standard PRC format specification document may be obtained directly from ISO at:
http://www.iso.org/iso/catalogue_detail.htm?csnumber=54948
or in the United Kingdom from BSI (British Standards Institution) at:
http://shop.bsigroup.com/ProductDetail/?pid=000000000030208201
