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Home > Supported File Formats > Parasolid to Universal Scene Description


How to convert Parasolid (.x_t,.x_b) to Universal Scene Description (.usd,.usda, .usdc.usdz)?


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.

     

Parasolid

Parasolid is a 3D geometric modelling toolkit developed by Siemens PLM's components group in Cambridge, U.K. This toolkit provides hundreds of complex mathematical algorithms and functions which allow software developers to create 3D modelling software based on "BREP solids" modelling techniques (among others). The toolkit uses a "transmit" file format to move data to and from the Parasolid toolkit in native format. The ASCII form uses the .x_t file extension and the binary form uses the .x_b file extension.

Since the late 1990s Parasolid has been used as the core modelling kernel by well known MCAD programs such as Unigraphics NX, SOLIDWORKS, Solid Edge, MicroStation, ANSYS, Delcam and others. Newer versions of the JT file format also include Parasolid functionality by way of the "XT BREP" geometry primitive.

Okino's PolyTrans|CAD provides for a defacto 3D Parasolid file conversion solution used by the world's primary & professional engineering, aerospace, military, corporate, animation/multi-media and VR/AR industries. However, we generally prefer that our core customers utilize either the original native CAD files (such as native SolidWorks files), a STEP AP214 file or an 'IGES BREP solids' file as outlined on our "CAD Data Sourcing Suggestons and Rules" page.

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

     

Universal Scene Description

The USD format (“Universal Scene Description”) is an open 3D model and scene format designed for efficient storage and streaming of 3D asset data. It is a high-performance extensible framework and ecosystem for describing, composing, simulating, and collaboratively navigating and constructing 3D scenes. An extensive overview of USD is provided in the Okino USD documentation.

Pixar Animation Studios originally created the USD platform (as its fourth generation variation after its Marionette & Preso systems) to improve studio-wide collaborative workflows. USD provides a concept of "scene composition", building a unified scene from potentially thousands of loosely-coupled source assets. For example, the mesh, rigging, materials, and animation for a single model might all come from different "layers" (files), each created and maintained by a different artist or department. Layers can store multiple "variants" of any given data, helping to solve problems of versioning/approval. The coupling between layers is very dynamic and loose, allowing for greater flexibility during the production process. The entire USD system is designed to facilitate a large studio making feature films, with all of the scale that that implies.

USD should be considered more of a code framework (“OpenUSD”) for use in group collaboration, to help with the aggregation of various 3D data sources into a unified scene through a process referred to as scene composition. A subset of that code framework provides for reading and writing USD disk-based files as well as rendering USD scenes (Hydra). The system is rather complex to implement (for software developers) and to use (from first principles) as a 3D graphics artist. The USD file format itself is not for faint of heart and is best read/written using the OpenUSD SDK + various programming APIs. More commonly used ASCII 3D file formats such as COLLADA, VRML2 and Wavefront OBJ are much easier to manipulate/understand/use on a human level basis.

File extensions used by the standard include:

  • .usd, Either ASCII or binary-encoded
  • .usda, ASCII encoded
  • .usdc, Binary encoded
  • .usdz, Zero-compression, unencrypted zip file