In the second stage of their Greenspace collaborative virtual reality project, the University of Washington’s Human Interface Technology Laboratories and Fujitsu Ltd are set to increase the number of people that can meet in a virtual environment by limiting their vision of each other. The Greenspace projects are intended to grow local and regional virtual spaces in which people can meet and work in cyberspace. Greenspace II will bring around 100 people together in a shared virtual environment where participants will have their own character, each with an aura – a radius of virtual space outside of which the person cannot be seen. The aura technique, which has also been used in virtual collaborative projects involving the UK universities of Nottingham and Lancaster, detects when a person’s virtual character is near before showing them to whoever else they are close. The developers of the Greenspace project said this was vital as sending an image of every person to every other person would immediately exhaust the bandwidth and immobilise the network. Describing the project to this year’s Virtual Reality 95 conference in San Jose, Paul Danset, who heads the technical department of University of Washington’s lab, said he hoped to have a system this year capable of running under Unix, Posix, Posix.4 and Windows NT. It will use OpenGL rendering and the new Virtual Reality Modeling Language, VRML, which is a lot more than a three-dimensional graphics language. It should do what HyperText Mark-up Language did to Hypertext, he said. Greenspace runs over the growing Multicast Backbone, MBone, which duplicates packets to individuals as demanded rather than forcing the sender to issue a separate packet for each recipient. Danset said the current network is very fragile at 300Kbps – a novice turning on an application could easily flood the MBone – but maintained that acceptance of the MBone was happening so fast that in two to three years, hooking up to the Internet will mean hooking up to the MBone. Greenspace I, held in November last year, was largely a p ublic relations exercise to create awareness of the project and invite funding. Danset said it had been successful but the sponsors of the second stage of the project have not yet been disclosed. More people will be added to Greenspace II: only six were present in the original, and audio and video quality will be improved. The latter was so poor in the demonstration it had to be switched off.
Aura technique
The universities of Nottingham and Lancaster demonstrated the aura technique last year by playing the popular drinking game, Bunnies, between 10 people at five sites in Germany, Sweden and the UK. People were represented by virtual cubes with an ear on each side and a face on the front. When one person was pointed at, he had to raise both ears, the person on each side having to raise the ear closer to the person chosen. Nottingham University said it was an excellent way to test the network’s ability to respond to immediate instructions, not to mention the researchers. – Morgan Holt
