ls. Fire fighters use remotely operated vehicles to handle some dangerous conditions. Surgeons are using very small instruments on cables to do surgery without cutting a major hole in their patients. The instruments have a small video camera at the business end. Robots equipped with tele-presence systems have already changed the way deep sea and volcanic exploration is done. NASA plans to use tele-robotics for space exploration. There is currently a joint US/Russian project researching tele-presence for space rover exploration. Mixed RealityMerging the Tele-presence and Virtual Reality systems gives the Mixed Reality or Seamless Simulation systems. Here the computer-generated inputs are merged with tele-presence inputs and/or the user view of the real world. A surgeon's view of a brain surgery is overlaid with images from earlier CAT scans and real-time ultrasound. A fighter pilot sees computer generated maps and data displays inside his fancy helmet visor or on cockpit displays. Fish Tank Virtual RealityThe phrase "fish tank virtual reality" was used to describe a Canadian VR system that combines a stereoscopic monitor display using LCD Shutter glasses with a mechanical head tracker. The resulting system is superior to simple stereo-WoW systems due to the motion parallax effects introduced by the head tracker. VR HardwareThere are a number of specialized types of hardware devices that have been developed or used for Virtual Reality applications. Image GeneratorsOne of the most time consuming tasks in a VR system is the generation of the images. Fast computer graphics opens a very large range of applications aside from VR, so there has been a market demand for hardware acceleration for a long while. There are currently a number of vendors selling image generator cards for PC level machines; many of these are based on the Intel i860 processor. These cards range in price from about $2000 up to $6 or $10,000. Silicon Graphics Inc. has made...
