And they are making a start on the Internet - a place generally thought of as too fragile to accommodate the large files of visual data needed to create 3D worlds.

One such experiment, based at University College London's Centre for Advanced Spatial Analysis (CASA), is about to open its doors.

In a 30-day trial starting on Tuesday November 30, a virtual environment will be open for anyone to build anything they wish, creating a strange new cyber world. Researcher Andy Smith will be watching and taking notes.

As part of the Online Planning team at the University, Andy has been studying the potential for virtual reality systems on the Web for his PhD in Internet Based Communications.

By using the online virtual web site Active Worlds (www.activeworlds.com), Andy has created an environment called Collaborative Virtual Design Studio (CVDS) where he and some students can design and plan virtual worlds that are more based on reality than your normal architectural drawing or plan.

Rather than glorified architectural space, CVDS allows for a practical response to the real world in a cyber home.

One of Andy's previous projects was a scenario where the user was in a wheelchair, which helped planners to see and understand how their designs would affect wheelchair bound citizens.

People are starting to take notice of the work done at CASA, realising the potential that 3D worlds on the World Wide Web have in terms of town planning and addressing public opinion.

Just using any of the virtual worlds on the Active Worlds web site is an eye opener for anyone who thought that Virtual Reality had gone away or had failed to impact on our lives.

All you need is a special free browser, which you can download from the site. The file is only 1.9 megabytes and downloads quite quickly.

"People will be free to build whatever they wish, with no restrictions", said Andy.

"I'm expecting a lot of really interesting architecture to develop, as well as peoples pictures from Web sites, Web cams etc. Also advertisements and links to other sites.

"And yes I do expect a lot of vandalism, as last week I opened the world up for the students and we had a high level of abuse and vandalism. A sad fact of virtual life, but interesting to study."

So, how will this affect the research done by CASA? "It's set up to explore 'Life in Virtual Worlds' (a chapter of Andy's PhD). All the conversations and building is logged," said Andy.

"A map will be drawn up each day showing expansion and illustrating how virtual worlds grow like real world cities, despite being unplanned."