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How to convert IFC (Industry Foundation Classes) to OBJ (Wavefront .obj,.mtl)?

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.

IFC

The Industry Foundation Classes (IFC) is a CAD data exchange object-based file format with a data model developed by buildingSMART to facilitate interoperability in the architecture, engineering and construction (AEC) industry, and is a commonly used collaboration format in Building information modeling (BIM) based projects.

IFC files can be written out by such industry standard programs as: ArchiCAD, Allplan, Autodesk's AutoCAD and Revit, Microstation, Tekla Structures, SmartPlant3D and Vectorworks.

Please note: you would always want to use the DWF-3D file format and the Okino DWF-3D file importer to import 3D model data from Autodesk's AutoCAD, Navisworks and Revit, as well as AVEVA's PDMS software.

It is may be safe to say that few 3D graphics users properly understand IFC or why/how it should be used, when it should be used or how it is to be used. In simplistic terms, IFC is NOT a universal data interchange file format like COLLADA, FBX, 3ds, OBJ, DXF, DWG, etc. Rather, IFC is more of an "abstraction" for an architectural model so that BIM companies can exchange IFC files for design iterations without any loss in overall geometric quality. Hence, the basis of IFC is to make an abstract building with stories, floors, doors, columns, windows, etc. From these hang "abstractions" such as 2D plan views and 3D renderable geometric data.

While IFC can be considered a standardized file format by BuildingSmart, not all 3D programs or 3D viewers will "interpret" an IFC file in the same manner due to the abstract nature of the file format and also by the generally loose manner in which a model can be defined and with different contexts and representations.

OBJ

Wavefront OBJ is a little understood but highly used and prevalent 3D "polygonal mesh" file format used throughout the 3D graphics world. Okino, Alias Research and McNeel made it popular in the early to mid 1990s as a general purpose, simple-to-read, storage and transmission 3D file format, especially for the then-new companies who began to sell 3D mesh models via the Internet.

Relatively speaking, OBJ is a rather simple file format but a bit better than STL although similar to the more modern 3MF format.The OBJ format allows for 1 or more unique polygonal mesh objects to be defined, each with optional UV texture coordinates and vertex colors. Material definitions can be linked to the mesh geometry as defined in the separate 'MTL' file. The material definitions are rather simple (ie. no PBR material support) but acceptable, and with varied levels of texture mapping support. OBJ format does not provide support for object hierarchy, local transformations, meta data, lights, cameras, skinning or animation. Most notably, OBJ does not allow for 'object instancing' and hence 1000 copies of a screw would be saved to OBJ as 1000 explicit copies, rather than 1000 references to one master object.

A short history: In the 1980s there was a program called Wavefront Visualizer which ran on UNIX and ran its early rendering pipeline as a series of tee'd command line 'applets'. The data flowed from one applet to another via various ASCII based files - OBJ for geometry, MTL for materials and other ASCII files for animation, skinning, deformation, etc.

Okino knows of the Wavefront OBJ file very well as it provides the one and only full implementation of the OBJ file format and with the ability to consume exceedingly large OBJ files quickly and efficiently. This includes the only known implementation of OBJ-centric 'NURBS geometry' (surfaces and curves) within the OBJ file format (which is little or not used) other than that from the McNeel Rhino-3D software.

IFC import converter's overview

OBJ export converter's overview