Virtually there: computers allow viewers to immerse themselves in Charlotte Davies' Osmose. Credit: C. DAVIES

Computer-generated virtual reality is a new form of art only in terms of its medium, according to art historian Oliver Grau of the Humboldt University in Berlin, Germany. In his highly original book Virtual Art: From Illusion to Immersion (MIT Press, $45), Grau argues that artists have been using a variety of techniques to immerse observers within their works for millennia.

The earliest trick simply involved physically surrounding the viewer with images. The frescos covering all four walls in a room in the Villa dei Misteri at Pompei, Italy, created in about 60 bc, draw observers into a 360° depiction of the preparations for a cult ritual. Those adorning a room in Livia's Villa at Prima Porta, dating from about 20 bc, create a 360° illusion of a garden. Post-antiquity, the frescos in the Chambre du Cerf (Chamber of the Stag) at Pope Clement VI's palace in Avignon, France, from 1343, place the observer at the centre of a hunting scene.

Mathematical perspective was the visual trick of the Renaissance. It is epitomized by the sixteenth-century Salle delle prospettive (Chamber of Perspectives) at the Villa Farnesina in Rome, the walls of which depict a columned hall. Between the pillars of the portico appears a view looking out onto the city and to the hills beyond.

Peepshow boxes — the forerunners of the stereoscope and the head-mounted display — first appeared in the eighteenth century, and in 1787 Robert Barker patented his hugely successful process for producing panoramic views on circular canvasses in correct perspective for observers standing at the centre. The techniques of cinematography and computing simply extended the opportunities for artists to immerse observers in an illusory world, according to Grau.

In the 1990s, the developers of virtual reality began to hire artists to assist them. Among these was Charlotte Davies, whose Osmose, shown here, is a total immersion in the fabric of the living Earth — rocks, roots, trees and leaves. It is is a product of her relationship with the Canadian software company Softimage.

But digital artworks are vulnerable to extinction as the operating systems on which they are based become redundant. Grau is cooperating on an international, interdisciplinary level with art academies and research laboratories to document two decades of computer-based art, much of which already cannot be shown. He has, for example, built a database of virtual art, a cataloguing project that is part technological and part art-historical, and is intended to support preservation efforts. Osmose is one of hundreds of works that will become publicly accessible through this database in the coming months.