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5 Creating VRML Worlds

5.1 VRML Modellers

The example in section 2 shows that it's quite possible to create a VRML world just using a text editor. However, to build more complex scenes, modelling software will be required. There are currently about a dozen or so different software packages that can create VRML worlds. This number is likely to increase as VRML becomes more popular.

There are basically two types of VRML modellers, object builders and scene assemblers. An object builder enables the user to create arbitrary shapes interactively and then export the geometry in the VRML format. These packages usually support other 3D file formats as well. ClayWorks (Tim Lewis, Lancaster University) and Ez3d (Radiance Software International) are examples of object builders. A scene assembler allows the user to assemble 3D objects into VRML scene, and include hyperlinks, inlines and Level-Of-Detail. WebSpace Author (Silicon Graphics), Fountain (Caligari Corporation) and Virtual Home Space Builder (ParaGraph International) are examples of this type of software.

A hyperlinked list of VRML modellers can be found at the SDSC VRML Repository.

5.2 Geometry Translators

There are a number of different tools available for converting models from other commonly used 3D file formats (such as Autodesk's DXF, 3DStudio and Wavefront) into VRML. This section describes six such tools, four are programs which are freely available via the internet, and the other two are Web sites which provide a public conversion service.

obj2wrl

(John Moreland, SDSC)

Obj2wrl is a PERL (Practical Expression and Report Language) script which reads a Wavefront OBJ file and outputs the geometry in the VRML format.

3DStudio R4 to VRML Converter

(Autodesk, Inc)

Autodesk have produced an IPAS module which converts 3DStudio models into VRML. The module allows the user to attach WWWAnchor links to objects and include WWWInlines. The IPAS routine will only run under 3DStudio Release 4.

ivToVRML

(Silicon Graphics, Inc)

This is a command-line program for the SGI platform which converts Inventor files into VRML. Silicon Graphics also provide translators which convert DXF, stereolithography (SLA), OBJ, Alias, Softimage, IGES and 3DS files into the Open Inventor format. So to convert, let's say, DXF into VRML, one could use DxfToIv and then ivToVRML.

WCVT2POV v2.6

(Keith Rule)

WCVT2POV is a Windows application that converts between many different 3D file formats. VRML is just one of the formats it can export. Formats that it can import include DXF, 3DS, Neutral File Format, OBJ, RAW triangles and TrueType Fonts. It also displays the loaded geometry.

Figure 5-1 WCVT2POV (17K)

Organic Online:

DXF to VRML

Organic Online provide a public DXF to VRML conversion service. It requires uploading the DXF file to ftp.organic.com, waiting two hours, then retrieving the translated file using HTTP.

ORC Inc:

3D formats to VRML

The ORC public translator works in a similar way. But it can translate from Alias, 3DS, IGES, Inventor, SoftImage, SLA and Wavefront, as well as DXF.

The VRML Repository has a complete list of geometry translators.

5.3 Testing the Validity of the VRML

If you intend to put your VRML model on a Web server, it's a good idea to check that it conforms correctly to the VRML specification. A VRML browser may not be able to display the scene correctly if the file contains invalid VRML. There are currently two tools available for checking the validity of VRML documents.

vrmllint

(Silicon Graphics, Inc)

Vrmllint is a program for SGI systems which checks files for invalid VRML. Any problems are reported.

VRML Authenticator

(Daeron Meyer, Geometry Centre)

This Web site contains a VRML authentication script. Enter the URL of the VRML model to be checked in the form, press the submit button, then any errors will be reported.

Figure 5-2 The VRML Authenticator (25K)

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