Importing from CAD

The most difficult aspect of creating good Synthetic Environments is acquiring or creating suitable 3D models. Most 3D modelling packages are designed for high detail output to cinema, TV and game graphics. These models often have far too many polygons for real-time display. The process (below) involves acquisition (or creation), conversion, polygon reduction and then export to VRML. Remember: fewer polygons = better performance!

	Model archives on the Internet will usually provide a description of the model, its file format and sometimes a thumbnail image.
	When using 3D models acquired from the Internet it is often necessary to unzip (decompress) them before use.
	Due to the variety of different 3D file formats available you may need to convert the format using a popular 3D modelling package like 3D Studio Max or a program like InterChange.
	High detail models are next to useless for real-time virtual reality. You can reduce the detail with programs such as Rational Reducer or the free Lodestar DOS utility. 3D Studio Max also has a modifier called Optimise which performs a similar task.
	Both 3D Studio Max and Rational Reducer can export to VRML format. Many other 3D programs have similar capability - try it!
	Once in VRML format the model can be imported into a VRML authoring package such as Cosmo Worlds. Some VRML tools allow the direct importation of other popular 3D formats - thus conversion isn't required.

Common 3D File Formats

3DS	3D Studio mesh file
MAX	3D Studio Max scene file
DXF	AutoCAD file
OBJ	Alias/Wavefront file
WRL	VRML1 or VRML2 world file
WRZ	VRML world file compressed with gzip
IV	Open Inventor (precursor to VRML) - can be imported by Cosmo Worlds