Researching the relationship between PDF/E, U3D, PRC and 3D PDF in general is not that easy, without diving into complex standards specifications, but if you are a developer and would like to understand what each of these brings to the world of the 3D PDF, this article clarifies the whys and whats of each.
Today most 3D PDF files found “in the wild” are ordinary 3D PDF files not marked as conforming to PDF/E specifically. PDF/E – short for the PDF standard for Engineering documents – is essentially an international PDF standard that specifically concerns the exchange and archive of engineering documents– in particular, 3D engineering model data and workflows. You can read more about it here: About PDF/E
U3D, which is referenced in the PDF/E standard, is a general 3D graphics format and was the original file format used in 3D PDF before the more recent PRC was introduced. U3D enables attributes, such as meshes, lines, points, textures and colours, to be attached to 3D objects within the PDF. You can learn more about U3D here: About U3D
PRC is the next generation of 3D graphics format used for embedding 3D data into a PDF file. Significantly more feature rich than U3D, PRC allows highly compressed geometric and visual representations to be added to 3D models and allows detailed structure, geometry and product manufacturing information (PMI) to be included. More detail on PRC can be found here: About PRC
Naturally, U3D is the better-known format which you’ll discover if you do your own research and this is purely as a result of its longevity, however PRC should be the format you investigate further as it is gaining ground within engineering, manufacturing, aerospace, geophysics, mining and medical industries as the preferred encoding method for PDF/E documents.
We hope that sheds some light on the terminology used within 3D PDF engineering. For further reference, you can view example 3D PDFs in our gallery, which use both PRC and U3D.