The interface to a virtual environment is a Virtual Body, not a keyboard and mouse. For the world to feel right, the virtual body needs to be exactly calibrated to the physical body, and the virtual world needs to be scaled to an appropriate size. In our first virtual worlds, one step travelled hundreds of yards -- sure you felt like a giant, but it did not help when picking up a chair. The concept is that of presence, how much do you feel as though you belong where you are.

These pieces contributed to the initial design of Mercury, the VEOS virtual body interface, a project initiated and lead by Andy MacDonald. The last one is a report to the NSF Committee on Virtual Reality.