The Wizard of Ethereal Pictures and Virtual Places Timothy Binkley ABSTRACT .. the computeris a 'metaphysical machine' [ 1 J. puter art in addition to being baffled by it. What is the com­ Renaissance artists con­ -Sherry Turkle puter's role in art? Does it have structed pictorial space using algorithms based on Euclidean a legitimate claim to artistic re­ geometry. Computer artists use THE ARTISTIC COMPUTER: spect? Or is it simply a techno­ algorithms based on the analytic logical charlatan, recalcitrant geometry of Descartes to compute A PROTEAN ENIGMA to acculturation and slippery as pictures as well as the subjects in them. An examination of the work­ Computers are protean. Gamboling fromthe churning high Proteus when we try to grasp its ings of these two different types of seas of Postmodern ism, they disturb the cultural waters even essence? algorithm reveals that the com­ funher with their enigmatic and plastic visages. Like the Efforts to navigate these puter offers a radical new approach to making art, which is not yet well Greek god of the sea, they are facile with disparate guises­ troubled waters sometimes liken the computer to a me­ understood. Postmodern a,lgo­ pretending to be now a pencil, then a spreadsheet, a design rithms for picturemaking are more studio, an airplane, a chess partner, a paintbrush, a racon­ dium as a way of explaining its evanescent than their Renaissance teur, and most certainly a sorcerer-all the while remaining role in art [2]. But upon exami­ counterparts because computers process information conceptually nothing other than hyperactive dervishes spinning out my­ nation, I believe we will find the concept of the computer as a instead of storing it physically. The riad illusions by proficiently manipulating numbers. Add to computer is neither a passive this that their sometimes obstreperous mischief makes them medium to be more misleading medium nor a pliant tool, but an seem more demons than deities, and it is no wonder that than useful. Computer art will active creative partner. critics and the artgoing public alike are suspicious of com- be better understood and more readily accepted by a skeptical artworld if we acknowledge Fig. L SamuelEdgerton's rendition (from Ref. [3]) of how how different it is from traditional tools. The computer is Brunelleschi constructedhis first perspective picture. The Bap­ tistryis situated behind the artist. The easel holds a mirror on the an extension of the mind, not of the hand or eye, and, unlike left and a painted panel on the right. Measurements are taken cinema or photography, it does not simply add a new me­ fromthe mirror by caliper and then transferred to the panel. dium to the artist's repertoire, based on a new technology. The role of media in artmaking is fundamentallyaltered by 'thinking machines'. It will help clarify the confusing rubric 'Computer Art', which congregates a multitude of disparate objects and events, by looking at the art-historical context. Let us begin by studying differences between picturing techniques used by Renaissance artists and those employed more recently by computer artists. By comparing the alternative ways perspec­ tive drawings are rendered, we can begin to understand in a familiar context the radical new approach to artmaking in­ troduced by computers. The computer does much more than assist imagemaking, but once we understand its novel approach in familiar territory, we will be better able to chart its wild and woolly antics. So, taking a lesson from the old myth, let us grasp this protean creature relentlessly until it gives us ,some answers. CONSTRUCTIVE ALGORITHMS: THE TRANSPARENT WINDOW Circa 1425 A.O., Filippo di Ser Brunellescho made a revolu­ tionary pilgrimage to the Baptistry of Florence to develop what we now call an 'algorithm' for making pictures. His Timothy Binkley (academic administrator), Institute for Computers in the Ans, School of Visual Arts, 209 East 23rd SL, New York, NY, 10010, U.S.A. <CJ1989 ISAST Pergamon Press pie. Printed in Japan. 0024-094X/89$3.00+0.00 LEONARDO, ComputerArt in Context Supplementallssue. pp. 13-20, 1989 13 Fig. 2. Albrecht Diirer, TheDesi gner of theL ying Woman. In this version of the ConstructiveAlgorithm, the point of view is fixed by a small obelisk marking the place where the artist moves his eye to take readings. The picture plane is the framed grid of strings.A matching grid is drawn on the paper and used to transfer points from the picture plane. Fig. 3. Albrecht Diirer, TheDesi gner of the Can. In this version of the Constructive Algorithm, the artist draws directly on the picture plane, which is transparent. achievement changed the history of embraced by many artists of the Re­ great discoveries, Brunelleschi's art. Perspective had apparently been naissance who used them to create seemed obvious once articulated, and used in ancient times, but there ex­ spectacular works of art with hereto­ the rules of the algorithm are simple isted no records of any formulae that fore unseen depth and startling points to follow. Its purpose is to correlate might be applied systematically to con­ ofview [ 4]. The illusionary panoramas points on the image with points in the struct a perspective picture. By using a these algorithms produce have be­ represented setting. This is done by re­ mirror to ascertain picture elements, come so much a pan of our culture peatedly connecting the point of view Brunelleschi essentially delineated a that we no longer feel the aston­ to points in the scene (using light rays process that can be described with a ishment they provoked in fifteenth­ in Figs 1 and 2 and a taut string in Fig. set of step-by-step instructions for century Florentines. 3). Lines so constructed will intersect transferring the appearance of the Brunelleschi's algorithm, like its the picture plane at a point that repre­ everyday three-dimensional world to a progeny, is based on the constructive sents the corresponding point in the convincing two-dimensional image on geometry of Euclid. Its essentjal pa­ world. With this sort of algorithm, the a panel [3]. According to Samuel rameters are fixed in the pictured set­ perspective picture is actually con­ Edgerton's hypothesis (Fig. 1), the art­ ting: a point-the point of view-from structedfollowing Euclid's classic prin­ ist placed a mirror on an easel next to where the scene is seen, and a plane-­ ciples of geometric construction with the panel to be painted. With his back the picture plane-determining straightedge and compass. The con­ toward the Baptistry and his own re­ where the image will be cast onto a sur­ viction of the apparition so fabricated flection partially obscuring the view, face [5]. These elements are more ap­ is grounded in Euclid's Twenty-First Brunelleschi transferred magnitudes parent as well as easier to use in one of Proposition (Fig. 4), which guarantees of reflections in the mirror onto the Albrecht Dure r's renditions (Fig. 2), by similar triangles that proportions in panel by means ofa caliper. His algo­ where the point is determined by a the picture will preserve those in its rithm spawned others that were codi­ small obelisk and the plane by a subject as perceived from the view­ fied by Alberti 10 years later and were framed grid of strings. Like many point. 14 Binkley,The Wizard of Ethereal Pictures and Virtual Places Once his algorithm became known, tion of what was outside. Brunelleschi at how the two types of picturing algo­ industrious artists foundmany ways of and his peers broke through the bar­ rithms differ. implementing and modifying Brunel­ rier of the wall and instituted a com­ The underlying frameworks are leschi's insight. Durer made a number pletely systematic method of project­ similar: beginning with an object, a of woodcuts depicting different meth­ ing three dimensions into two to plane, and a point, we create a repre­ ods. In yet another of his constructive reveal a pictured world so clear and re­ sentation of the object in the plane by algorithms (see Fig. 3), the artist again fined that it appears as if viewed scrutinizing lines connecting the ob­ fixed the pointof view with a screw eye through an open window. Easel paint­ ject and the point. Perspective projec­ mounted on a wall, but the picture ing was born on moveable framed tions using the two algorithms may plane was a transparent sheet and the panels. sometimes have similar app.earances, lines of sight were intersected with the but they are quite different and can picture plane by aiming them through yield rather different-looking results. a viewing tube attached to a string tied COMPUTATIONAL In order to highlight their differences, to the screw eye. All of these algo­ ALGORITHMS: THE let us step up to the easel beside Bru­ rithms involved geometrical construc­ nelleschi and compare 'manual' exe­ tions that are accomplished with man­ LUMINOUS SCREEN cutions of both. ual tools such as pens, strings, rulers Two hundred years after Brunel­ As Brunelleschi deftly gleans the and calipers and were carried out in leschi's discovery, Descartes built the outlines of his picture by casting the actual presence of the depicted foundation for a rather different kind glances at his mirror, we laboriously setting. Related techniques were de­ of picturing algorithm based on ana­ begin setting up a coordinate system veloped by Alberti and subsequently lytic geometry. Although such algo­ by arbitrarily (but we hope conven­ by others for designing perspective rithms were not widely used until the iently) locating an origin and three images of simple geometrical shapes advent of computers, they can be de­ perpendicular axes.