STL and OBJ; no these are not text derivatives for cell phone or instant messaging, although if they were maybe they would be Small Taco Lunch and Overheard Bar Joke. No these are file formats. One is used quite often in Rapid Prototyping and CAM manufacturing and the other is used frequently in Visualization software. So let's hit the definitions first. If you already know then you get to skip two paragraphs, time is money.
Definitions:
STL is a file format native to the stereolithography CAD software created by 3D Systems. This file format is supported by many other software packages; it is widely used for rapid prototyping and computer-aided manufacturing. STL files describe only the surface geometry of a three dimensional object without any representation of color, texture or other common CAD model attributes. An STL file describes a raw unstructured triangulated surface by the unit normal and vertices (ordered by the right-hand rule) of the triangles using a three-dimensional Cartesian coordinate system.
OBJ is a geometry definition file format first developed by Wavefront Technologies for its Advanced Visualizer animation package. The file format is open and has been adopted by other 3D graphics application vendors and can be imported/exported from Cheetah3D, Daz3d's Daz Studios, e-Frontier's Poser, Autodesk's Maya, Softimage|XSI, Blender, MeshLab, ZBrush, Misfit Model 3D, 3D Studio Max, and Rhinoceros 3D, Hexagon, Newtek Lightwave, Art of Illusion, GLC Player, Wings3d etc. For the most part it is a universally accepted format. The OBJ file format is a simple data-format that represents 3D geometry alone - namely, the position of each vertex, the texture coordinate associated with a vertex, the normal at each vertex, and the faces that make each polygon.
Granted, the most common out of these two for Inventor users is the STL. Normally the file type is exported through Inventor's Save Copy As function so that rapid prototypes can be created for parts and assemblies. The import process is the rarer occasion as normally this does not have to be worked on after the fact by an Inventor user. There are some occasions that I have been asked for this namely for reference objects or sketch references for recreation of geometry. This would go the same for OBJ file format.
I posted an add-in by a man who is very much more programming intelligent than me a while back involving sheet metal extents. Well Brian was at it again not long ago. He created an add-in for Inventor that would read in STL and OBJ data rather well.
This is accomplished by opening a new Part file and selecting the new icon for importing these types of geometry. Users can select which file type and with the Options choose which units are used.
Once the geometry is in it does not have a lot of modification that can be done on it, but it can be used to section to get references for sketches or just reference data for your assemblies.
There are other importers out there for this kind of data as well if you are avid google searcher, but I rather like how this one is put together. It fits so nicely in the 2010 Ribbon on the add-ins Tab.
You can find the Zip containing the installers (32 and 64) and the Read me here:
Brian Ekins Mod the Machine Posting
Granted this is primarily graphics and not hard features, but it is a start and can be useful in some situations.
Until next time, may your geometries always be created with the right hand rule.
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