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How to convert STEP (.step,.stp) to U3D (Universal 3D, 3D PDF)?

PolyTrans|CAD+DCC performs mathematically precise CAD, DCC/Animation, GIS and BIM 3D file conversions into all key downstream 3D packages and file formats. Okino software is used and trusted throughout the world by many tens of thousands of 3D professionals in mission & production critical environments, backed by respectable personal support directly from our core development team.



STEP is the defacto 'go-to' MCAD translation file format when you do not have access to the original CAD part and assembly files. It is a long standing 'industry standard' that can be used to move MCAD/CAD file assets into many downstream 3D programs and file formats. Okino's PolyTrans|CAD provides for a defacto 3D STEP file conversion solution used by the world's primary & professional engineering, aerospace, military, corporate, animation/multi-media and VR/AR industries. STEP uses the .stp and .step file extensions.

STEP files are readable ASCII files which encode CAD parts and assembly information. Most respectable MCAD modellers will actively and correctly support the STEP AP203 and AP214 file formats. STEP was originally developed to supercede the IGES file format but has mostly supplemented but not replaced IGES. You would either want to export a "STEP AP214" file or an "IGES BREP solids" file depending on the MCAD modeller.

A much deeper overview plus explanation of STEP, and how it can be best used + understood, is outlined in this Okino WEB page.

Most people initially come to Okino asking for a STEP importer but it should only be used in specific situations as outlined in our "CAD Data Sourcing Suggestons and Rules".



U3D is a semi-obsolete 3D mesh file formats from the 2000-2009 era of the 3D graphics world and whose history is little understood outside the confines of a few 3D graphics companies. Even so, U3D is still a fine 3D file format as a pipeline to get 3D data embedded within 3D PDF files, especially with the full and extensive implementation made by Okino.

For more details on the U3D file format, its core features and limitations, how to embed U3D files within 3D PDF files and the features of the Okino U3D import/export converters, please refer to this WEB page.

Generally speaking, U3D was implemented by a few 3D companies in the mid to late 2000s when it was pushed by Adobe+Intel as part of the line of 'Acrobat-3D' software packages. In very loose terms, U3D is used to convey and embed 3D model data within 3D PDF files, where PDF would be the container for the 3D data.

U3D started off in the 1990s as Intel's "IFX" gaming toolkit which was than thrust upon Macromedia, Alias Research, Softimage and other similar companies around the year 2000 to be accepted as a new "industry standard" 3D file format called "Shockwave-3D". The dotCOM bubble caused SW-3D to die pre-maturely after 2001 only to be rebranded as U3D or the "Universal 3D file Format" in 2004 (ECMA-363). Its specification PDF document described it as "An extensible format for downstream 3D CAD repurposing and visualization". However, U3D was highly profit/sales motivated/biased and not consumer/end-user motivated. As such, partly due to the 2008/2009 recession, those companies and their investments in U3D died away.

Okino is and was critical of U3D back in the day as it was the company which created the main conversion implementation of U3D for both import and export. It understood the limitations of U3D well and of its false promotion as a "universal file format" whose title should really have gone to those such as COLLADA, FBX, VRML2, etc. When implemented well U3D is a fine file format by itself but few companies invested enough time and money to support U3D import and export in a most ideal manner.