Virtual Reality Systems

Peter Young

Visualisation Research Group
Centre for Software Maintenance

Department of Computer Science
University of Durham

6th February, 1996


Abstract

This is a survey of a number of available VR and VRML software systems which has been compiled from a variety of information sources on the Web. The majority of the VR systems are described on the merit of third party information, whereas a large number of the VRML browsers have been tested first hand and some rough evaluations made. The document is more heavily orientated towards the VRML browsers and provides links to the companies and sources of these browsers.

Unfortunately it will be unlikely that I will have time to update this document so the information given here is only really relevant at the time of writing (6/2/96).

Contents


Introduction

The definitions of Virtual Reality are wide and varied though all imply the same meaning, that of "The illusion of participation in a synthetic environment rather than external observation of such an environment..." [8]. Current technology is far from perfect in creating such an illusion though the present day systems offer a level of interaction and feeling of immersion in such a world that is sufficient for a wide range of applications.

One area of research which has received much attention recently is the use of VR techniques for information visualisation. Initial work in this area was concerned with visualising physical entities such as airflow or particle motion, but recent research has turned to visualising more abstract information such as databases and software structures. These constructs do not have any physical form (other than as information in memory or disk storage) and much work is being performed to give them such a form, or to create an environment from this information which can be easily navigated and interrogated by humans.

Virtual Reality has received a great deal of media attention over recent years and public expectations of it’s capabilities have been inflated out of proportion, viewing the technology as a cure-all for the currently fairly clumsy man-machine interface. This is unfortunately not the case. Virtual Reality may not at present offer the sophistication necessary to create such a fluid interface, but it’s capabilities are still extremely useful in the field of visualisation. VR techniques are receiving widespread use as information visualisation aids, from architects requiring a more realistic rendering of their proposed designs to air craft pilots clocking up hundreds of virtual flying hours in a safe environment. The applications of VR are progressively expanding and we can make a safe assumption that VR technology is here to stay.

This document describes a number of Virtual Reality systems currently available and also explores the rapidly expanding world of VRML which could possibly be the technology to bring VR to casual computer users. In both cases some available systems are listed and described. It was not possible to evaluate the VR systems first hand, hence descriptions are of information gleaned from other sources. It was however possible to evaluate a number of VRML browsers, so more descriptive information has been given.

Virtual Reality

Introduction

There are an extremely large number of Virtual Reality systems available and it would be a very time consuming activity to attempt to evaluate or investigate any large proportion of them. Basically the systems available today are split into two categories, one is the complete virtual world authoring package which allows users to quickly and easily construct worlds then navigate them from within the package or export the files to other formats. The second is the VR API (Application Programmer Interface) which typically provides a large number of facilities or functions which programmers may take advantage of when writing 3D graphics applications. This greatly eases the burden of VR application programming by removing the need to create routines for handling the display, I/O devices, and also for creating the 3D engine itself. These two categories are not mutually exclusive and overlap does exist, for example some APIs provide world editors and some authoring packages provide access to their API.

Available Systems

The following list of VR software is by no means complete and only mentions a small percentage of available systems. For more comprehensive lists please see [1][2][3], which provide information on a much greater number of systems with links to their sources. The descriptions given below have been derived from a number of sources and it is possible that some information may be incorrect as in the majority of cases I have not been able to use the systems myself.

Superscape VRT by Superscape VR plc.

Superscape is a commercially available virtual reality authoring system from Superscape VR plc. based solely on the PC using DOS (a Windows Visualiser is now available). Superscape is principally a single user environment but recent developments offer optional networking capabilities to provide some degree of multi-user participation.

Superscape consists at the lowest level of a Visualiser which is the application used to explore virtual worlds. In order to create new worlds it is required to have Superscape VRT (Virtual Reality Toolkit) which comprises the Visualiser and a number of editors, namely world editor, shape editor, resource editor, sound editor and texture editor. These editors are combined into a single authoring environment allowing seamless movement between them for editing any attribute of the virtual world. All of the editors are based around the same interface which consists of a number of tool icons and a menu system, ensuring that switching between editors is as unobtrusive as possible.

Superscape offers a variety of powerful features, not least of which is the ability to edit or create all aspects of the virtual environment from within one suite of editors, the effects of any changes in an editor are instantly visible from the visualiser or other editors. Also incorporated is a comprehensive selection of object attributes both static and dynamic which allow objects to behave in various ways. Superscape provides it’s own C-like interpreted language, SCL (Superscape Control Language) which allows the user to attach a small script to any object. SCL enables the user to create complex interactions and sophisticated behaviour within worlds, without having to leave the editing environment. Superscape also offers the ability to import and export AutoCAD DXF files and more recently it is possible to export VRML. Superscape SDK development kit is available to enable the addition of further functionality and to allow applications to make use of the Superscape API, though this is not provided with the VRT package.

Dive by SICS

DIVE (Distributed Interactive Virtual Environment) is an experimental VR system which has gained a strong user base particularly in distributed VR research. The system was developed at the Swedish Institute of Computer Science (SICS) and is currently undergoing enhancement from version 2 to version 3 following it’s success in a wide range of research projects. DIVE is currently only UNIX based and as the name suggests it is targeted at multiple users distributed over a network. DIVE is a non-commercial system and can be obtained freely with the source code, thus making it a popular choice with researchers who can tailor the system to their needs. The availability of the source code has also resulted in various home-brew modifications being adopted in future versions of the system. The visualizer or rendering engine used in DIVE is aimed primarily for desktop VR and provides a window-on-world interface. Support for other I/O peripherals such as head-mounted displays (HMD), data gloves and 6 DOF devices is also provided allowing the user to build on the standard interface.

dVS and dVISE by Division Ltd.

dVS [9] is a VR product aimed at simplifying design and development of interactive, multi-user virtual environments. dVS is billed as a VR operating system which provides services such as visual displays, audio output, tracking systems and input devices all at an abstract level. One of the advantages of dVS is that it is platform independent allowing VR developers to readily port their applications between platforms, providing they support dVS. dVS is aimed directly at the programmer level of VR development requiring applications to be written which make use of the dVS features.

dVISE is a VR authoring tool aimed at the non-programmer which allows easy creation of interactive, multi-user virtual worlds without any programming knowledge. dVISE accepts three-dimensional models from various sources, including AutoCAD, 3D Studio, Wavefront, ModelGen, and any system producing standard .DXF files.

OpenGL

OpenGL is a set of C-based software libraries to allow applications to generate interactive 2D and 3D graphics and provide maximum portability. OpenGL is designed to be platform independent and is supported by many vendors on a variety of operating systems, window systems and hardware configurations. An attempt to aid portability requires that all licensed OpenGL implementations must pass a conformance test and come from a single specification document.

RenderWare by Criterion Software

RenderWare is a portable 3D API for a number of platforms, namely DOS, Windows, Macintosh and X-Windows. RenderWare is targeted solely at games development offering high speed texture mapped renderings with good cross-platform support. RenderWare has gained massive support from developers and is established as an excellent 3D graphics engine for all manner of computer games. RenderWare supports a wide variety of hardware, from 3D HMDs to advanced graphics accelerators. RenderWare also provides good performance for sprite manipulation and scrolling. The latest version of RenderWare allows file import from 3D Studio, AutoCAD DXF and even VRML, with a wide range of texture formats.

BRender by Argonaut Software

BRender (Blazing Render) is a Windows / DOS based (primarily DOS) rendering system with an applications interface, graphics libraries and device drivers. BRender is a games orientated platform which is to be expected coming from Argonaut Software. One of the strong points of BRender is that it is easily portable to other games platforms such as the 3D0, Saturn, Jaguar or Playstation. BRender makes a comprise between speed and accuracy of graphic presentation, tending more towards increased rendering speed. BRender comes with tools for creating simple objects etc., but also allows import from file formats such as 3D Studio for more complex models.

3DR by Intel

3DR is a PC based 3D graphics library produced by Intel which allows high speed, real-time 3D graphics applications to be written for MS Windows environments (3.1, NT, 95). 3DR is optimised for the Pentium processor and is available free with no royalty charge. 3DR is also available with an SDK and makes good use of available hardware and advanced graphics cards. Apparently creation of primitive objects is simple using 3DR, but more complex composite objects are quite hard thus making it simpler to import these objects from another system, e.g. 3D-Studio. 3DR is best described as a cross between OpenGL and BRender, offering fairly fast but accurate rendering.

QuickDraw 3D by Apple

QuickDraw 3D is a cross-platform API allowing the creation of high quality real-time 3D graphics. QD3D claims that it "will let users create, manipulate, and incorporate 3D graphics into their documents and presentations as easily as they do with 2D graphics today.". QD3D aims to ease the burden of 3D graphic programming by producing a standard file format, 3D API for developing applications, and a set of interface standards and guidelines to promote consistency between applications. QD3D is also aimed at portability with versions planned for Windows and UNIX environments.

Meme by Immersive Systems, Inc.

Meme is a software package for the development of distributed, multi-participant virtual world applications and providing rich object behaviour. Meme is designed with portability in mind to enable a single virtual world to be inhabited by many geographically distributed users, possibly using different hardware. Meme provides a similar sort of functionality to dVS in that it behaves as a sort of virtual world operating system, providing the programmer with additional system functions specifically for VR. Meme incorporates an interpreted language for definition and control of the virtual environments. Meme makes use of RenderWare by Criterion Software for high performance results.

World Toolkit by Sense8

WorldToolKit (WTK) is a commercial 3D API consisting of a large set (approx 400) of C routines which enable developers to build 3D simulations and VR applications. WTK provides support for a wide range of hardware including many forms of I/O such as HMDs and 6DOF devices. WTK is available on a number of platforms including the PC, though the primary platform is on UNIX based machines using either OpenGL or SGI Performer.

VRCreator by VREAM Inc.

VRCreator is a virtual environment authoring toolkit which is targeted both at programmers and non- programmers. VRCreator allows the user to build powerful VR applications which will run under Windows 3.1, NT and 95. For programmers, VRCreator includes access to it’s API allowing full use of it’s VR capabilities from external applications. VRCreator provides support for sophisticated interaction allowing objects to be given a wide range of dynamic attributes. VRCreator uses Microsoft Reality Lab and allows the creation of multi-participant virtual worlds and applications. Support for importing various file formats such as 3D Studio and AutoCAD DXF is also provided, including the ability to export to VRML.

AVRIL by Bernie Roehl

AVRIL (A Virtual Reality Interface Library) is a set of C routines developed by Bernie Roehl (also co- developer of REND386) and designed to be particularly programmer friendly. AVRIL provides a good API for creating and navigating virtual environments and also for interfacing to various VR input / output devices. The advantages boasted by AVRIL are ease of use, portability (the API will soon be available on a number of platforms), good documentation and best of all AVRIL is freely available.

REND386 by B. Roehl and D. Stampe

REND386 is a free virtual reality application designed for simplicity and speed on less powerful computers. REND386 was developed in 1991 by Bernie Roehl (developer of AVRIL) and Dave Stampe and has subsequently become the focus for a number of books, most notably Virtual Reality Creations [4] in which the software accompanied the book. REND386 has continued development under Dave Stampe and has been improved upon and renamed to VR386.

The Minimal Reality (MR) Toolkit, developed by the Computer Graphics Research Group at the University of Alberta, is a software toolkit providing tools and libraries useful in developing 3D graphics and VR systems on UNIX platforms. The toolkit is available free to academic institutions and is also available commercially. MR Toolkit is quite power hungry requiring high end workstations and graphics cards to run effectively but has still managed to acquire a large user base. Multi-user environments and distributed environments are supported, the system is also comes complete with source code so user modifications can be made.

To enable complex behaviours and interactions, MR Toolkit incorporates it’s Object Modelling Language (OML) which is similar in principle to Superscape’s SCL. OML is a procedural run-time interpreted language which defines object geometry and behaviour. A 3D modelling tool is also provided to generate the OML scripts.

VRML - Virtual Reality Modelling Language


Artwork by Kevin Hughes, kevinh@eit.com, Enterprise Integration Technologies.

Introduction

The Virtual Reality Modelling Language (VRML) is a language for specifying 3D virtual worlds networked via the global Internet which can link to or be linked from other sources on the World Wide Web. The aim of VRML is to produce a complete simulation or environment language providing not only static world structure but also the capability for complex interaction and dynamics within these environments to give a truly immersive experience. VRML shares some commonality with the now familiar HTML in that it can provide hyperlinks to other documents such as other worlds, HTML documents, FTP directories or any other valid MIME type. The initial aim was to produce companion applications in which a standard browser such as Netscape would display HTML documents when needed and a VRML browser would display virtual worlds, the two browsers communicating to instruct each other to load particular files. Some of the browsers available today offer features which enable VRML worlds to be embedded within HTML documents just as graphics are at present, this could lead the way to a true multimedia presentation.

The overall desire to create VRML and virtual worlds on the World Wide Web is to move the available data from being machine centred to being human centred. This entails using human skills such as perception by allowing the user to immerse themselves in the Internet universe and navigate the information in a form most natural to themselves. VRML is designed to be a "universal description language for multi-participant simulations".

The VRML Standard

VRML [10] was conceived at the first annual World Wide Web Conference in Geneva, Switzerland in the spring 1994. A meeting was arranged for all interested to discuss Virtual Reality interfaces to the World Wide Web and the attendees agreed on the need for a common language for specifying virtual world descriptions. The term Virtual Reality Mark-up Language was coined, the name later being changed to Virtual Reality Modelling Language, and research began to find a suitable existing format for modification rather than beginning from scratch.

The search for existing technologies settled on the consensus to use the ASCII based Open Inventor format from Silicon Graphics Inc. The Inventor format specifies complete virtual world descriptions with effects such as lighting, textures and ambience. VRML was specified as a subset of the Inventor format with extensions added to perform networking options such as hyperlinking.

VRML is currently in it’s first incarnation, version 1.0, and has been designed to meet the requirements of platform independency, extensibility and performance both during networking and rendering. It was decided at an early stage to ensure that HTML and VRML remained separate formats, this was necessary to ensure that neither was constrained by the progress or features of the other. The decision was also made to ensure that the first version of the specification did not have any motion or interaction features other than simple hyperlinking. This gave the VRML specification a more realisable first goal and also made browser implementation simpler, once the first version was complete these facilities would be planned for incorporation in later versions.

Overview of the Language Structure

This section provides a quick overview of the format and structure of VRML files, a full description of the specification can be found in [10]. VRML is a language for describing the properties and relations of a number of objects, these objects can conceptually be of any form, e.g. 3D objects, images, sound or text. Within VRML these arbitrary objects are termed nodes.

Nodes are arranged hierarchically into constructs called scene graphs which define an ordered collection of nodes. Scene graphs also have a notion of state in that a node at a particular position in the graph can affect all the nodes following it. This is used to give certain nodes a set of attributes or properties by defining these attribute nodes prior to the actual object. For instance, a cube node could be given rotation and texture attributes by defining these nodes in the same scope as, but before the actual cube node. To give a sense of scope to the scene graphs, separator nodes are provided to limit the effect of such properties.

Basically, a node has the following properties associated with it:

The node type
This defines what a node actually represents, i.e. a rotation attribute, texture attribute or a 3D object such as a cube or cone.
The fields of the node
A node can contain fields which allow parametrisation of a particular type of node. For instance, a cube node could have dimensions or a sphere node could have a radius, etc.
The node name
Nodes can optionally be assigned names which will prove a very useful feature in later versions of the specification when, hopefully, scripting capabilities will be provided. Nodes having names will enable them to be referenced directly from within these scripts.
Child nodes
As previously mentioned nodes are arranged in a hierarchy, thus a node must define itself and all of it’s children. A node which can have children is termed a group node.

Available Browsers

This section attempts to review or mention a number of available VRML browsers to hopefully give an indication of the current state of the software. The descriptions given here are fairly vague as with such a large number of browsers available it is not feasible to investigate each one in any great detail. The descriptions given are often a mixture of the browser’s own publicity, other peoples opinions and my own personal opinions hence they may not be particularly accurate. Approximately ten of the browsers below have been tested by myself using an Intel Pentium P75 PC running Microsoft Windows 95 with 8Mb of physical memory and a standard SVGA graphics card (running in 1024 * 800 mode, though most browsers were run in smaller windows). No networking capability of the browsers was tested with all files used being loaded locally. It must be noted that hardware and OS performance will have a very large affect on the quality and speed of browsers, thus any reference to performance of the browsers described here is purely based on my machine spec given above.

The variety of browsers available is great [5][6], with a very wide quality range though it should be noted that quality and performance could vary greatly on different systems. The majority of the browsers were used as stand-alone applications which are either called by a standard HTML browser or call a standard HTML browser when needed. Some of the browsers, namely WebFX and WIRL, are provided as Netscape Navigator plug-in applications which fit seamlessly to provide an additional range of features. There are also quite a large number of VRML authoring tools available, though the only one used here was Caligari WorldSpace, others are not mentioned. The availability of the various browsers for different platforms is often mentioned in the descriptions below, but a summary is also provided in Table 1 below.

Please note that not all of the following browsers have been tested due to either problems with availability or incorrect hardware. All browsers listed down to VRealm, inclusive, have been tested and all those following it have not.

Fountain (Caligari WorldSpace) by Caligari Corporation

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Current version : 0.9

Fountain (also known as Caligari Worldspace) is a complete MS Windows based (3.1 and 95) VRML authoring tool and is basically a cut-down version of Caligari Truespace with added VRML capability. Fountain offers fast rendering and motion through fairly complex worlds, but as always performance is heavily dependent on hardware and Fountain claims to be optimised to take advantage of any 3D acceleration cards. Fountain is based on Intel’s 3DR graphics libraries and so any hardware geared to high performance 3DR operations would be an obvious advantage. Fountain has also been licensed by Microsoft for inclusion in "Blackbird".

Fountain offers a wide range of features to the VRML author and allows for quick and easy world construction. The world editor allows rapid modelling, real-time manipulation of texture mapped objects and interactive lighting. Some of the object tools boasted by Fountain are 3D primitives, 2D polygons, facet editing, lathing, sweeping, extrusion and tips as well as being able to extrude TrueType fonts. It is also possible to texture-map whole objects or single facets and even paint vertices with a wide range of user-defined colours / textures. A variety of light sources are provided which can be user defined by altering colour, intensity and beam type. Support is also provided for importing existing 3D worlds or objects from established file formats such as TrueSpace, AutoCAD DXF, 3D Studio, Wavefront OBJ, LightWave and Imagine. 2D image support is also given for PostScript, Windows BMP and JPEG.

Both the world builder and world navigator within Fountain are operated via a very aesthetically pleasing iconic interface. The appropriate tool is selected from the icons then the operation performed using the mouse. When within the world navigator all movement is provided solely via the mouse using the standard click and drag interface for velocity control, left button for forward, reverse and turning and right button for horizontal and vertical translation. The standard walk, fly and look-at views are available. During movement through the scene Fountain uses a wireframe rendering and then returns to a full textured rendering for static scenes. Although primarily a VRML authoring tool, Fountain does provide on-line access and can be used to download and explore VRML worlds. HTML links can be handled by configuring Fountain for use with any standard web browser.

Personal experience using the tool found that Fountain was an excellent authoring package and it was quite easy to construct simple worlds using it, though no attempt at more complex constructions was made. One awkward point in constructing the worlds was that positioning, orientation and scaling of the objects was provided through a mouse interface. This made it very easy to see the result of the operations, but quite hard to get any accurate position data. One other point of note was that Fountain did not perform too well at loading other VRML scenes, though due to the wide differences in VRML styles this is not too surprising.

Fountain is available only on Windows 95 and 3.1 platforms at present.

WebFX by Paper Software Inc.

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Current version : Bleeding Edge Beta

WebFX is a plug-in application for the Netscape Navigator (2.0) browser and provides embedded VRML worlds and 3D special effects which can be incorporated seamlessly with standard 2D web pages. Other browsers such as Spyglass and Mosaic are supported but Netscape Navigator provides the most functionality. WebFX is probably one of the fastest and most impressive MS Windows based VRML browsers available at present and offers exceptional quality and flexibility. In addition to viewing VRML files on their own, WebFX allows multiple VRML worlds to be embedded within web pages just as images are in current pages. Also provided are collaborative virtual worlds, 3D special effects and 3D IRC chatting using VRML avatars within virtual ‘chat rooms’.

WebFX is the first plug-in VRML browser available (and the first 3rd-party plug-in application for Netscape Navigator) and as such it makes good use of the available Netscape functions such as the hotlist, history, caching and security features. This in turn expands Netscape’s capabilities greatly and offers true 2D / 3D unison with high quality results. Also available (though not at time of writing) is the WebFX Explorer which is a stand-alone browser claiming to take full advantage of the Windows 95 interface providing web management facilities similar to the Windows Explorer file handler. This will provide object oriented drag and drop operations, shortcut creation, folders, sorting and user customisation. The claim is that this will make it possible to explore the Web in a similar manner to exploring a disk file system. WebFX Explorer will also be available for Windows 3.1 and NT operating systems and should offer the same functionality.

WebFX is probably one of the more VRML 1.0 compliant browsers available and gives good, fast renderings of most VRML files loaded even at full screen (1024*800), though this is again hardware dependent. WebFX also supports 3D acceleration hardware such as Creative Labs’ 3D Blaster. Extensions to the VRML standard have been provided such as animated textures, sound and collision detection, in addition to texture file support for GIF, BMP, RAS, RGB and JPEG formats. Navigation within WebFX worlds is extremely simple and intuitive using only the mouse with key combinations. Physics based navigation is provided with the standard walk, fly and point movement types with optional collision detection. Preset viewpoints can be easily accessed via a shortcut menu with orthogonal views available as standard. The control system also features an optional HUD (Head Up Display) with a description of the currently selected control method.

Overall, my opinion is that WebFX is an extremely good and simple to use VRML browser. The added features enabling VRML embedding within HTML documents should make WebFX a resounding success in the future. Current work at Paper Software is to include Java support within WebFX, enabling Java applets to be linked to VRML worlds, again this should prove extremely popular within the VRML market. WebFX is currently available on Windows 95, 3.1 and NT, and will soon be available for the Macintosh.

WIRL by VREAM

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Current version : Alpha

Similar to WebFX, WIRL is a plug-in application for the Netscape Navigator browser and offers much of the same functionality but with a number of extensions of it’s own. WIRL features in-line extensions allowing fully interactive virtual reality at an early stage of the VRML standard. In addition to standard features, WIRL allows complex object behaviour, interaction and logic functions. As with WebFX, WIRL offers the ability to include VRML worlds embedded within HTML documents. The quality of the rendering and fluidity of movement is excellent, even full screen, and the supplied example worlds do justice to the added functionality. Object manipulation such as rotating, translating and zooming are extremely fluid even when faced with a number of detailed textures.

Bearing in mind that the VRML standard does not at present support any form of interaction or object dynamics, WIRL has took a large step forward and offered these additional features with high quality results. Examples of some of the demonstration worlds are:

Unfortunately, screen shots and descriptions of the possibilities do not do justice to actually interacting with the world personally.

The control system used in WIRL is extremely simple and gives a high degree of freedom. The two basic modes of Walk and Inspect are given allowing the user to walk through the scene or to inspect an object. Control is provided through either the standard click and drag mouse interface using Shift and CTRL keys for different movements, or through an icon interface which is exceptionally comfortable to use. The icons are grouped into three sets and on selecting they enlarge into a working area allowing the mouse to control the direction and velocity. The icons are grouped into the following control sets: Forward, reverse and yaw; horizontal and vertical translation; and pitch and roll.

WIRL uses it’s own file format (extension .VRW) but will readily import standard VRML files. Unfortunately it was not possible to load any standard VRML files into WIRL due to machine set-up (WebFX was also plugged into Netscape causing a conflict), so compatibility could not be tested. Overall, WIRL appears to me as another highly successful VRML browser which offers a high degree of functionality at a very early stage. Providing WIRL adheres to forthcoming VRML standards it should no doubt become a very successful package. WIRL is now available for Windows 95 and windows NT using Netscape Navigator and is currently at Beta 1, though only the alpha version was tested in this review. The beta 1 version of WIRL provides Java support and also allows the use of a Head Mounted Display (HMD). Also included with beta 1 are a number of additional VRML demos which demonstrate the interactive capabilities.

NAVFlyer by MicronGreen Inc.

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Current version : 2.2b

NAVFlyer is a freely distributable VRML browser available on DOS, Windows 3.1, NT and 95 operating systems. NAVFlyer comes in two basic flavours, the freeware version which allows only keyboard control and the commercial version currently retailing at $199 which offers full mouse control and support for advanced control and display devices. As the name suggests, the only movement mode currently available in NAVFlyer is flying or vehicle control. NAVFlyer supports a fairly wide range of file formats, namely AutoCAD DXF, 3D Studio (3DS), VRML and it’s own NAV format.

It must be said that the keyboard control severely hampers free movement through world in addition to the browser being extremely slow even within a small window. NAVFlyer does offer a good selection of detail levels for both static and dynamic states, though these did not improve the speed enough on the testing hardware. Overall opinion of NAVFlyer was poor, though it is quite possible that performance would be acceptable on a more 3D graphics enhanced machine. Without mouse control NAVFlyer is pretty awkward but I could not advocate paying such a large amount of money when far better browsers are available either free or for lesser amounts.

WorldView by Intervista Inc.

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Current version : 0.9g pre-beta (0.9f reviewed)

Worldview is another stand alone VRML browser available for Windows 3.1, NT and 95, with future versions available for the Macintosh. WorldView is a fairly straight forward browser which offers minimal options but easy navigation through either mouse based movement or icons. Two viewing modes are supported, flying (walking) and inspect modes - the former allowing a scene to be explored and the latter allowing a single object to be rotated and viewed. WorldView performed well with the supplied demonstration worlds but did not perform as well with other files though the fact that the program is still a Beta version could account for this. The display and movement of fairly simple worlds and objects is very fast and smooth but tends to drop drastically with complex scenes. The present version does not support different detail levels while moving, but the overall detail level (moving and stationary) can be selected. Other reviews of WorldView claimed high performance though any differences in hardware could account for this.

Overall impression of WorldView was that it is simple to use and offers fast and accurate rendering for average complexity models. The official release could prove to be quite a successful browser, though a number of competitors also perform equally well if not better.

VR Scout by Chaco Communications Inc.

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Current version : 1.1

VR Scout is a VRML compliant browser available for Windows 3.1, NT and 95 as either a stand- alone browser or a Netscape Navigator plug-in. VR Scout is based on either the Intel 3DR or Microsoft Reality Lab 3D graphics libraries and produces good renderings and movement through average complexity worlds. VR Scout supports only the VRML file format and does not load any other forms of 3D file.

Movement in VR Scout is provided through standard click and drag mouse operations with the detail level apparently dropping slightly during movement. VR Scout provides only minimal options which unfortunately do not include variable detail levels or viewpoint controls. Standard movement modes of examine, walk and fly are provided. VR Scout also was found to be quite fragile to VRML input files, some producing good renderings whereas others were not rendered correctly, often without colours or textures.

Overall opinion is that VR Scout is a not a particularly good browser and provides very few options for the user.

VRweb by IICM, NCSA, and the University of Minnesota

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Current version : 1.0 Beta 4

VRweb is implemented on a very large range of platforms using either OpenGL or the similar Mesa library. Unfortunately the current version tested has been superseded by a faster version and so maximum speed could not be gauged. The version tested moved fairly quickly for average complexity models but was crippled by more complex worlds.

Motion in VRweb is provided by the standard set of motion controls (go to, walk, fly, etc.) either selected from the window menu or from the available HUD. The HUD is probably the most intuitive control method consisting of four icons representing different movement types. Clicking and dragging the mouse from one of these icons results in that form of movement being used - speed is controlled by the mouse’s position from the point of the click.

VRweb offers a good range of detail options for increasing performance and when used this does increase usability for more complex models. Overall opinion of VRweb is that it is a fairly good browser with reasonable performance, I am sure that newer releases will advance the performance and should make VRweb a popular browser.

WebSpace by TGS and SGI

Webspace fly mode Webspace inspect mode

Current version : 1.0 Beta 2

WebSpace is a stand alone VRML viewer available on a number of platforms. The initial version of WebSpace was developed by SGI and aimed specifically at their workstations, TGS have subsequently developed WebSpace on a number of other systems, currently Windows 95, NT, SUN Solaris and IBM AIX with several others to follow. WebSpace is also considered as a defacto standard among VRML browsers, though it does typically require high-performance hardware to run effectively. The Windows 95 version tested performed reasonably well, producing good quality renderings but unfortunately performed a bit sluggishly on more complex worlds.

WebSpace navigation comes in two modes, walk and inspect, each having a different interface. The interface is provided as a virtual dashboard containing a number of controls depending on the movement mode. The use of these controls is incredibly intuitive and works very well to provide one of the simplest interfaces. The walk dashboard consists of the following controls. A ‘point’ icon allows the user to point to a place in the world and the viewpoint will move automatically to that point. The joystick provides forward, backward and yaw movement with an additional ‘thumbwheel’ providing pitch control. Finally, a thumb-pad like controller offers horizontal and vertical translation. The inspect mode offers the following controllers. The ‘point’ icon moves the selected object to the centre of the view. A rotating sphere or ‘trackball’ is provided to spin the object, and a zoom slider provided to move the object closer or further from the view. Finally the same thumb-pad allows horizontal and vertical translation.

In addition to loading VRML worlds WebSpace will also load Open Inventor files, though these were not tested. WebSpace was fairly reliable at loading most VRML files given, though it did fail on a number of complex worlds. WebSpace provides only minimal detail options allowing the user to select from ‘Full’, ‘No Textures’ and ‘Low’ detail levels with an optional ‘Degrade on Moves’ feature. Overall impressions of WebSpace are of a high quality product which has already established itself well on powerful graphics platforms. No doubt it will also succeed on more common hardware.

GLView by Holger Grahn

GLView GLView rendering of BT VRML portal

Current version : 2.05

The first point to note about GLView is the fact that it has been designed and implemented by a single individual and uses the Windows OpenGL graphics libraries. The second point to note is the fact that it is an excellent VRML and general 3D Browser, with some authoring capabilities. The quality of GLView puts it easily near the top of the browsers reviewed here.

GLView offers very fast and detailed rendering with smooth movement control even for complex objects / worlds at high detail levels. If the motion is impaired by the detail, GLView also offers one of the most extensive detail configurations of all the browsers reviewed. Both static and dynamic detail levels can be selected from a list of : vertices; vertices with spheres; normals; wireframe; bounding- box; solid; flat; and gouraud, also including textured / lighted / antialised options. The inevitable range of extensions have also been added to GLView to give some interesting added functionality such as animations, morphing, extruded TrueType fonts and a variety of file formats.

GLView uses it’s own file format (3DV) for storage of the enhanced features but is capable of importing Wavefront OBJ, AutoCAD DXF, RAW and GEO files. GLView is also capable of exporting to RAW, GEO, STL, POV and VRML files but is limited to single objects only. The other thing to note is that GLView is probably the most resilient browser out of all tested and produced good, accurate renderings of all VRML files which I loaded. GLView was also the only browser I tested which was able to load and navigate the BT VRML portal and site model. The uncompressed file size of one of these worlds was in excess of 1.2Mb and none of the other browsers would load them to any extent, needless to say the movement was far from smooth but still smoother than some other browsers on far simpler models. This fact may be attributable to machine configuration, having a less than ideal amount of physical memory may have hampered other browsers but if so this would be a good testimony to the efficiency of GLView.

Overall opinion of GLView is that it is an excellent browser with a wide variety of configuration options and special effects. The resilience to input files and quality of the rendering and speed make it my first choice as stand-alone browser. GLView is a shareware application available only on Windows 95 and NT platforms and requires OpenGL libraries (freely available).

Virtus Voyager by Virtus Corporation

Select for full size image

Current version : Alpha a145

The current version of Virtus Voyager is a good example of an Alpha release. The version reviewed had no HTTP access yet and absolutely no options whatsoever (unless they were very well hidden). The quality of the renderings was poor and it did not appear to have texture support yet. The control system was fairly standard allowing either mouse-drag control or more primitive iconic control which if anything made the browser feel not particularly user friendly. General opinion of Voyager was of a very primitive browser with very little functionality though hopefully this is due to it being an Alpha version. Voyager is currently available for Windows 95 and Macintosh.

VRealm by Integrated Data Systems, Inc. and Portable Graphics, Inc.

Select for full size image

Current version : Alpha

Again, another alpha release that requires a lot more work, though VRealm is in a far better state than Voyager. The main thing you notice when running VRealm is the excessively large dashboard at the bottom of the window with instruments such as artificial horizon, compass, navigation pad, throttle control and mode select icons. Movement within VRealm can be controlled by mouse dragging which is extremely tricky and requires modification if it is to be at all user friendly, or by vehicle control. The quality of VRealm is really very good considering that it is an alpha release, but as with a lot of browsers it begins to slow down quite a bit on more complex scenes.

VRealm does offer a very good range of detail options both for static and dynamic modes and also provides a very good viewpoint manager. Overall it looks as though VRealm could be quite a successful product providing improvements are made before the full release. VRealm is currently supported on Windows 95 and NT, with a variety of platforms to follow.

CyberPassage by Sony Corporation, Inc.

Current version : n/a

CyberPassage is a VRML browser and is part of a suite of three VRML packages produced by Sony for viewing, authoring and sharing VRML worlds. CyberPassage enables you to navigate the world using a selection of modes and is also equipped with enhanced features for manipulating moving images, movies and sound. CyberPassage is claimed to be fully VRML 1.0 compliant in addition to supporting several new extension which Sony is hoping to incorporate in forthcoming standards. The movement modes available in CyberPassage are walk through, jumping eye and scouter mode.

The following features are mentioned:

WebView by San Diego Supercomputer Center

Current version : Alpha

SDSC WebView is a publicly available VRML browser for SGI/UNIX systems and is released with full source code. The aim of WebView is to provide a freely available platform for developing and testing experimental additions to the VRML specification.

Terraform by Brilliance Labs, Inc.

Current version : Beta version 1

The TerraForm VRML browser is based on Intel’s 3DR graphics engine and provides interaction features in addition to the VRML standard, allowing direct manipulation of individual objects within the virtual world. Terraform supports the full VRML standard and aims to include support for ActiveVRML. Multithreaded graphics and networking.

WebOOGL by The Geometry Center

Current version : 2.0 beta

WebOOGL is a public domain 3D Web browser which does not fully support the VRML standard. Most of the specification is in place, but a number of nodes are ignored, in particular texture mapping. The browser is built onto Geomview which is the Centre’s 3D graphics viewer.

NeTpower Vizia 3D by NeTpower Inc.

Current version : 1.0

Very little information is known about Vizia 3D, only that it is a VRML viewer designed to work in co-operation with a standard HTML Web browser.

VRML Equinox by North Plains Systems Inc.

Current version : Alpha

VRML Equinox is based solely on the Macintosh Power PC and makes use of Apples QuickDraw 3D to ‘present realistic rendered environments’. VRML Equinox is designed to cooperate with Netscape Navigator using it to fetch VRML (or any other files) for it by supplying it with the appropriate URL. Future plans for VRML Equinox include the support of object behaviours and scripts.

AmberGL by DIVE Laboratories, Inc.

Current version : Alpha v1.0

AmberGL is a VRML browser built using DIVE laboratories OpenGL based virtual environment development kit. The alpha release supports features such as multiple lights and varying detail levels but does not currently support a number of core VRML features such as cylinders, spheres, point sets and textures.

DIVE by Olof Hagsand (SICS)

DIVE (Distributed Interactive Virtual Environment) is distributed multi-user VR system allowing population and interaction with shared virtual worlds. Users of the worlds are aware of the presence and action of other users and can communicate with them. DIVE also has a VRML interface which allows worlds or objects to be imported into the environment allowing interaction with these worlds. The VRML support is standard so no DIVE enhanced features may be imported from it, though these can be defined once the file has been imported.

Microsoft VRML Add-In by Microsoft Inc.

Current version : Beta 1.1

Microsoft VRML Add-In is a fully integrated VRML application which adds virtual world browsing capabilities to Microsoft Internet Explorer 2.0. The only supported platform is Windows 95.

Whurlwind by Bill Enright and John Louch

Whurlwind is a VRML browser based on Macintosh Power PCs using QuickDraw3D and allows users to view and explore both VRML and 3DMF models. The current release only allows users to select from a number of camera positions and to select hyperlinks, future versions will enable free navigation.

Summary of VRML browser availability

BrowserProducerCurrent VersionCurrently Available Platforms
Fountain (Caligari WorldSpace)Caligari Corporation0.9Windows 3.x, 95 and NT
WebFXPaper Software Inc.Bleeding Edge BetaWindows 3.x, 95 and NT
WIRLVREAMBeta 1Windows 95 and NT
NAVFlyerMicronGreen Inc.2.2bWindows 3.x, 95 and NT
WorldViewIntervista0.9g pre-betaWindows 3.x, 95 and NT
VR ScoutChaco Communications Ltd.1.1Windows 3.x, 95 and NT
VRWebIICM, NCSA, and the University of Minnesota1.0 Beta 4Windows 3.x, 95 and NT, Linux, SGI, DEC, HP, SUN, AIX
WebSpaceSGI and TGS1.0 beta 2Windows 95, NT, SUN and AIX (TGS)
SGI (SGI)
GLViewHolger Grahn2.05Windows 95 and NT
VoyagerVirtus CorporationAlpha a145Windows 95, MAC and Power PC
VRealmIntegrated Data Systems, Inc. and Portable Graphics, Inc.AlphaWindows 95 and NT
CyberPassageSony Corporation Inc.n/aWindows 95
WebViewSan Diego Supercomputer CenterAlphaSGI / UNIX
TerraformBrilliance Labs, Inc.1.0 BetaWindows 95 and NT
WebOOGLThe Geometry Centre2.0 BetaSGI and Sun
NetPower ViziaNetPower Inc.1.0Windows NT
VRML EquinoxNorth Plains System Inc.AlphaPower PC
AmberGLDIVE Laboratories Inc.1.0 AlphaWindows NT
DIVEOlof Hagsand (SICS)n/aSGI, Sun and HP/UX
Microsoft VRML Add-InMicrosoft Inc.1.1 BetaWindows 95
WhurlwindBill Enright and John Louchn/aPower PC

Table 1 - VRML Browsers

References

[1] UK VR-SIG 3D Object Archive
http://www.dcs.ed.ac.uk/home/mxr/objects.html

[2] On The Net: Internet Resources in Virtual Reality
Maintained by Toni Emerson, Human Interface Technology Laboratory, Washington University
http://www.hitl.washington.edu/projects/knowledge_base/onthenet.html

[3] 3D Real-Time Graphics Engines list
Karsten Isakovic, Technical University of Berlin
http://www.cs.tu-berlin.de/~ki/engines.html

[4] Virtual Reality Creations
D. Stampe, B. Roehl and J. Eagan
Waite Group press, 1993, ISBN: 1-878739-39-5

[5] The VRML Repository, San Diego Supercomputer Center, Inc.
http://www.sdsc.edu/vrml/

[6] VR and VRML Links at 3DSite
http://www.lightside.com/~dani/cgi/VRML-index.html

[7] Virtual Reality Systems
R.A. Earnshaw, M.A. Gigante and H. Jones, Academic Press Ltd. - Harcourt Brace & Company, 1993

[8] Virtual Reality : Definitions, History and Applications
M.A. Gigante, printed in [7]

[9] dVS - A distributed VR systems infrastructure
Steve Ghee, Division Ltd., 1995
http://www.division.co.uk/users/steve/sigpaper/sig95www.html

[10] The Virtual Reality Modeling Language - Version 1.0 Specification (Draft)
G. Bell, A. Parisi and M. Pesce.
http://vrml.wired.com/vrml.tech/vrml10-3.html


This page is maintained by Peter Young, please send any comments, jokes, insults or general abuse to (peter.young@durham.ac.uk).
Last updated: Wednesday 7 February, 1996.


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