Two virtual reality companies are touting US-developed products around the UK market. Virtual Presence Ltd of London is selling its WorldToolKit development tool for Windows, and Ambitron Ltd of Wokingham, Berkshire is looking for third parties to sell the CrystalEyes virtual reality head set, which weighs 5 oz. The WorldToolKit software is a Windows-based virtual reality applications development package, which was meant to be sold under the name Mercury by New York firm Sens8 Inc, (CI No 2,183), although it was vapourware until now. The package, which is also available on Sparc and Silicon Graphics Inc workstations, is a C library but includes several applications that can be compiled and used. Users can define their own worlds to be displayed on a computer screen by defining three-dimensional objects using other modelling packages and linking them together in hierarchical structures. Different lighting can be set, and models can be linked to sensors. They can also be placed to follow predefined paths. The product should be available now for UKP575 in beta form, and users will be upgraded free to the full release product when it ships in January. The company also offering the Metafile C compiler with the product for an extra UKP600 – this isn’t necessary to use the toolkit unless you want to develop applications with it. Other features include the ability to link the toolkit into spreadsheets to create virtual reality graphs. The CrystalEyes headset is made by StereoGraphics Corp of San Raphael, California. UK distributor Ambitron, which also deals in computer rental, is aiming the product at any three-dimensional or computer-aided design visualisation applications, and is working on making it compatible with AutoCAD, Animator Pro and 3D Studio. The glasses contain fast liquid crystal diode lenses that switch alternately at 120 times per second to produce full colour three-dimensional images which are updated 60 times a second. The headset is not immersive, so users can only look at images on the monitor; it is compatible with stereo-ready software on Sparc, Silicon Graphics Inc, Digital Equipment Corp Alpha, IBM Corp RS/6000, iAPX-86 personal computer and Apple Computer Inc Macintosh machines. The headset gives users six degrees of freedom – vertically, horizontally, backwards and forwards – in which to alter their view by moving around. The position of the headset is sampled 50 times per second using a phase-shifting sound array that is set up by three speakers and picked up by three microphones in the headgear. The headset costs UKP1,400 while the related virtual reality software will set you back UKP2,500. CrystalEyes and versions of VirtualToolKit have been bundled in the US, although there is no such deal expected in the UK.