Convert Other 3D Formats to VRML

There are some terrific models available from repositories, but often they come in some other 3D file format like 3DS, LWO, or DXF. You can still use those models in your VRML worlds if you simply convert them to VRML.

Built-In and Plug-In Exporters

Many VRML modelers import from other file formats. The first thing you should do is fire up the modelers you have on hand, look under "File/Import", and see if they import the format your object is in.

Many 3D modeling and CAD programs already have the capability of exporting VRML 1 and some can even export VRML 2. You may need to select the model you want to export. Choose "File" and "Save As..." or "Export As..." and see if VRML is supported.

Here are other converters, exporters and plugins for popular modeling and CAD programs

• Alias/Wavefront's Maya has a VRML exporter
• AutoCAD's Mechanical Desktop exports VRML.
• Bentley MicroStation has a VRML Publisher
• CAD Studio's VRMLout for AutoCAD
• Kinetix's VRML Exporter is a free plugin for 3D Studio MAX that exports VRML 1 or 2.
• Lightwave Outpost's VRML 97 WorldSaver exports VRML 2 from Lightwave3D.
• MetaCreations' Bryce and Poser export VRML and Poser 4 will export H-ANIM
• Parametric Technologies' Pro/Model.View converts from Pro/E to VRML.
• SolidWorks 97 and 98 built-in VRML export. There are free converters for SolidWorks 96.
• VRMLplot is a function that generates VRML 2.0 from Matlab. Some of the examples are worth seeing, even if you don't have Matlab.

Crossroads 3D

Keith Rule's freeware Win95 program Crossroads 3D converts to VRML 1 or 2 from:

• 3D Studio (3ds)
• Autocad (dxf)
• POVRay V2.2
• RAW triangle
• Caligari TrueSpace (cob)
• Alias/Wavefront (obj)
• WorldToolkit (nff)

and future releases will support 3DMF ASCII and binary, Imagine, Lightwave, and POVRay V3.0.

You can also use Crossroads 3D to convert from VRML 1 to 2, but you should note one feature of this program: it centers objects on the origin. Many times that's exactly what you want. For example, you can convert the famous dolphins (originally 3DS models from the Avalon Repository) one at a time, then combine them into this animated dolphin, turning the second and third dolphin into CoordinateInterpolator keyValues. Sometimes you don't want the object to be centered, for example with CAD drawings of parts that go together into an assembly, and then you may be better off with a regular VRML 1 to 2 converter.

Keith has an older freeware program wcvt2pov which has a few different features, and may be worth getting as well.

3DWinOGL

Thomas Baier's freeware Win95 program 3DWin and 3DWinOGL converts to VRML 1 from:

• Autocad (dxf)
• Imagine (obj, iob)
• LightWave (lwo)
• 3DStudio (3ds, prj)
• RAW ASCII (raw)
• POV-Ray binary (pob)
• Alias (obj)

and exports a bunch of other formats. Even though it only exports VRML 1, its scaling option makes it invaluable for objects that use some other units than meters, and I'm intrigued by (but haven't used yet) its facilities for triangle smoothing and adjacent face joining. The OGL version lets you see a 4-view of the model before exporting. Thomas also has a shareware program 3Dto3D on the same sit that handles even more formats.

Other Converters

Not long ago the best cheap or free modelers you could get were for POVRay, and you had to export or convert to VRML. Illustrating either that VRML has come a long way or that Hopkins people are as crazy as they were when I was there, Paul Thiessen's free vrml2pov converts VRML 97 to POVRay.

Meta Lists

• 3DSite's list of converters - scroll down a bit
• about.com's list of converters
• The Avalon Repository has translators and utilities in their Software section
• Cosmo Software's utilities includes a number of converters
• Aaron Jones's list of converters
• The VRML Repository's list of geometry translators

VRML 1 to 2 Converters

If you've installed Cosmo Player for Windows 95, you already have a program vrml1tovrml2 in your C:\Windows\System folder, or you can get one here (Win95/NT), (Irix 6.2), (Irix 5.3). If you've downloaded Community Place browser, you also have a VRML 1 to 2 converter in your installation directory, or you can get one here. The one I prefer generally varies as each company comes out with a new version.

Build your own

If you can't find a converter in this list, and you know your way around a programming language that supports data structures, writing your own converter is always a possibility. A couple of hints from experience:

• Unless you're planning to publish the converter, you don't have to handle every imaginable file that could appear in that format, just the files you have.
• If you can find free source for a program that reads in the format you're interested in and converts it to something other than VRML, reuse that code; you'd spend more than half your time debugging the section that reads in the file.
• There are only so many ways to represent objects in 3D, and formats frequently borrow from other formats. The good old indexed face set appears in lots of formats, and the big difference is often just in the way it's laid out.

Here's some resources on graphics file formats

• The Avalon Repository has a section on file format specs.
• The Center for Innovative Computer Applications (CICA)'s 3D Object File Formats -- kind of old, but still useful.
• Wotsit's file formats -- 2D, 3D, and lots more.

Hints from Experience

• If the model comes in both DXF and 3DS format, use the 3DS model. Many converters and built-in importers will turn DXF files into one enormous mesh.
• The VRML file you get out of a converter is never ready to use on the Internet. Take the time and use some postproduction tools to check the syntax and reduce the file size.
• You'll also want to look at the VRML file that comes out of your converter in a plain text editor. Some converters and exporters produce normal, normalIndex, color, and colorIndex fields that are a waste of space and often make your file look awful.
• Some otherwise very good converters get the direction of the meshes wrong. If your VRML object looks weird, set ccw FALSE (or TRUE) and see if that fixes it.
• You'll almost always have to fix the colors. The converters that don't simply throw away all the color info will usually get the colors wrong.

Did I leave anything out about converters that you need to know, or did I miss a good converter? Let me know.