Interactive Dynamic Abstraction

Scott Sona SnibbeInterval Research Corporation

1801-C Page Mill RoadPalo Alto, CA 94107snibbe@interval.com

Golan LevinMIT Media Laboratory

20 Ames Street Room E15-447Cambridge, MA 02139golan@media.mit.edu

ABSTRACT

The history of abstract animation and light performancepoints towards an aesthetic of temporal abstraction whichdigital computer graphics can ideally explore. Computergraphics has leapt forward to embrace three-dimensionaltexture mapped imagery, but stepped over the broadaesthetic terrain of two-dimensional interactive dynamicabstraction. Several experiments in using pure humanmovement as the interface to dynamic abstract systems arepresented with the goal of creating phenomenologicalinterfaces that engage the unconscious mind directly.These applications are visual instruments that allowimmediate understanding of a dynamic system, but pointtowards infinite challenges in their mastery as any goodartistic medium. The lessons from these experiments canbe applied to computer animation, human-computerinterface and the aesthetics of time-varying light.

KEYWORDS

Abstraction, Animation, Art, Computer Graphics,Cognitive Science, Human Factors, PhilosophicalConsiderations, Visual Communication

HISTORICAL BACKGROUND

Those pioneering expression with the time-varying andinteractive aspects of digital media have often seenthemselves to be exploring virgin aesthetic territory. Theintroduction of the first integrated keyboard, bitmappeddisplay and mouse in 1974 with the Xerox Alto is seen bymany as the beginning of the personal computer era [1].For the first time, a graphical user interface allowed accessto the media manipulation capabilities of this new machine.This class of desktop computer then and now has beendescribed in terms of its three main hardware components:input devices, output devices and information processing.However, if we look at the computer instead as amechanism for translating information from one sensephenomenon into another, we can step much further back.

Pythagoras first explored the notion of synesthesia around500 BC [2]. His intuition of the analogy between vibrationsin tone and vibrations in light led him to imagine the Musicof the Spheres as the sounds created by the perfectmovement of heavenly bodies as they proceed along theirinevitable course. These analogies between perceptualmodes caused Pythagoras to imagine that true spiritualtranscendence comes through the re-uniting of the senses,revealing divine geometric harmony and the similarity ofall universal form. This spiritual underpinning ofperceptual aesthetics has been rediscovered or reinventedover the centuries as a means for understanding theconnections between both perceptual phenomena andartistic media.

Wassily Kandinsky embodied the aesthetic and thepsychophysical notions of synesthesia in his work andwriting [3]. It is now understood that one in one hundredthousand individuals have a condition that automaticallytranslates their senses as they perceive reality. The mostwidespread form of clinical synesthesia is the translation ofsounds to colors [4]. We now understand that Kandisky’sadamant labeling of shapes with colors (e.g. triangles areyellow) in Concerning the Spiritual in Art were caused bythis condition. Many viewers at first found abstractpainting impenetrable and imagined it as an acquired tasterequiring education and adaptation. However, recentpsychophysical experiments [5] indicate that the abstractsynesthetic experience is accompanied by a significantlowering of cortical brain activity. The implication of thisresearch for abstract expression is that it is quite possiblethat such abstract perception is part of our lower perceptualmechanisms and that abstract form and color might in factbe akin to pure musical tones – innate notions of beautyshared by all human beings.

Published in the Proceedings of Non-photorealistic Animation and Rendering (NPAR 2000). Annecy, France. © 2000 ACM.

Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. NPAR 2000 Annecy France Copyright ACM 2000 1-58113-277-8/00/6... $5.00

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Kandinsky’s paintings were the first and arguably still thestrongest to explore this connection between form, soundand color in synthetic abstraction – abstract painting whichis entirely nonrepresentational. Three Sounds (Figure 1) inits name and formal structure clearly shows the artistsdeliberate use of musical metaphor and analogy.Kandinsky was part of a spiritual movement thatcrystallized the notions of Pythagoras into a moreformalized belief system called Theosophy. As atheosophist, Kandinsky believed that certain combinationsof color and light could bring on spiritually transcendentexperiences. Theosophist religious books were filled withcolored forms that they believed would bring on suchexperiences. Those sharing Kandinsky’s belief systemincluded many of the prominent artists of his generationand, significantly, one of the great patrons of abstraction,Hilla Rebay, curator of the Guggenheim Foundation fromthe 1920s through the 1950s.

Paul Klee’s paintings represent a movement towards thedynamic in abstract painting. Although fixed in static formon Canvas, Klee embarked upon a program of discoveringthe dynamic perceptual qualities of color and form. Histhoughts were formalized while teaching at the Bauhaus inthe 1920s, where he wrote the Pedagogical Sketchbook – acomplete course in the dynamics of static form (Figure 2).Like Kandinsky, Klee used musical analogy in describinghis work. A practical answer to this transference ofterminology is that music was the only developed abstractmedium. Furthermore, many of these abstract painterswere musicians before they became visually fluent.However, there is one essential element missing from thesestatic paintings that is intrinsic to music: time.

The first abstract animators used celluloid film to achievetime-varying abstraction. Walter Ruttman has thedistinction of creating the first publicly presented abstractanimated film, Lichtspiel Opus 1 in 1921, which was

created by sequentially photographing turning clay forms,mirrors and hand-painting celluloid. He formed part of asmall group of fervent believers in the power of temporalabstraction. Viking Eggeling began a systematic study ofabstract composition, attempting to discover a “universallanguage of abstract images,” and, borrowing from HansArp, “the rules of plastic counterpoint”. Eggeling’sDiagonal Symphony of 1924 embodies some of theseformal ideas, but his early death prevented him from richerarticulation.

Oskar Fischinger is regarded by many as the master ofabstract animation. Trained as an engineer, Fischinger wasprofoundly affected by this early milieu and dedicated hislifetime to artistic expression. His work, created frame-by-frame, represents the type of control and inspiration that amaster composer wields over musical form. His earlyseries of films, drawn frame-by-frame with charcoal, arenumbered like musical composition, and later films all hadmusical accompaniment (Figure 3). However, these filmsare not visualizations of the music, but provide visualcounterpoint, becoming another parallel expression andinterpretation rather than simply mimicking the temporalstructure of the music. Study No. 7 from 1931 manages tohold its own as a visual accompaniment to Brahms’Hungarian Dance No. 5. For Fischinger, the process formaking such films was much like that of a composer. Heeven worked with visual scores from which he carefullytimed and executed his films. The language of his scores ispersonally idiosyncratic – there is still no universalnotation for any temporal form other than music. EdwardTufte has documented and analyzed a wide range ofexamples in the history of temporal notation outside ofmusic [6].

Len Lye of New Zealand pioneered the first cameralessanimations where the abstract filmmaker creates a film bydirectly painting, drawing or scratching on film. Thequality of such work is frenetic and biomorphic. For thefirst time the hand and the spontaneous mind are visible oncelluloid – like watching the inner thoughts of the artist.

Figure 1. Three Sounds by Wassily Kandinsky, 1926.

Figure 2. Pedagogical Sketchbook, Chapter 1 by PaulKlee, 1920s.

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Free Radicals (Figure 3), made in 1957, is Lye’smasterwork. Produced entirely by scratching onto blackfilm leader, the film portrays three-dimensional linearforms twisting and coming in and out of existence as anhomage to the then exploding understanding ofbiochemistry and the microscopic fights for survival withinliving organisms.

The filmed abstraction of these 20th century pioneers canbe seen as strong analogies to musical composition andrecording. A good overview of their work can be found inCecile Starr’s excellent history of abstract film [7].However, still missing from the filmed medium is the roleof the live performer. Many if not all of these pioneerswere aware of this gap in their expressive potential andmade attempts at creating a color organ – a device forperforming with light.

The notion of a color organ presents a curious idée fixe inhistory. Adrien Bernhard Klein wrote in 1927, “it is an oddfact that almost everyone who develops a color-organ isunder the misapprehension that he, or she, is the firstmortal to attempt to do so.” The first historical record of acolor organ is Father Loise-Bertrand Castel’s OcularHarpsichord, built in 1734 [8]. A regular harpsichord withcandles placed behind colored glass windows and pulleysfrom the keys of the keyboard created small panes of coloras a musical composition was played. Castel falls squarelyinto the realm of visualizing music rather than acontrapunctal visual music. His work embodied his owntheories of sound/color correspondence in an instrument.

The 20th century brought the technology to make pure lightperformances. Thomas Wilfred created the Clavilux forlarge-scale light performance [9]. These devices consistedof lenses, mirrors, lights, and colored filters for projection.

Starting in 1923, he began a series of public performancesthat he referred to as Lumia. Although sometimesaccompanied by music, these performances were temporalworks of art in light on their own. His Home Clavilux fromthe 1930s is worth noting as an attempt at a personalizedcabinet mounted device for consumers to enjoy abstractlight performances in their home. In these days beforetelevision, the notions of home entertainment were stillavailable for broad speculative exploration. In anunintentional look forward to John Cage, he named each ofthese devices with their loop time, such as the 1936 8hours, 15 minutes, 42 seconds.

Oskar Fischinger also created his own color organs, afterhis health was severely damaged from the under-the-camera oil painting of Motion Painting No. 1. HisLumigraph of 1953 was presented at the groundbreakingshow Art In Cinema at the San Francisco Museum ofModern Art [10]. The Lumigraph consisted of a taut clothsheet that could be pressed into from behind with hands orobjects to intersect thin sheets of light controlled by footpedals (Figure 4). Similar to Wilfred, he hoped that hisdevice could achieve widespread success and he took thetime to patent his invention.

The latter half of the 20th century holds several followersof Wilfred and Fischinger’s pioneering efforts. Althoughthey used similar technology, each of these artistspioneered unique aesthetics of their own. Charles Dockumcreated the Mobile Color Projector in the 1940s forperformance of hard-edged abstraction. Along withWilfred and Fischinger, he also supported the spiritualnotions of Theosophy and found support from Hilla Rebay.Jordan Belson brought light peformance into the

Figure 3. Len Lye’s Free Radicals, 1957 (left) andimages from Oskar Fischinger’s Study No. 7, 1931(right). Figure 4. Patent diagram for Oskar Fischinger’s

Lumigraph.

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psychedelic era with his Vortex Concerts in San Franciscoin the 50s and 60s. His work is the precursor to the lightand rock shows that are still part of large-scale musicalperformance. Beginning in the 50s, John Whitney created aseries of influential abstract films created with custommechanical devices and analog computers.

It is impossible to cover the myriad further aesthetic stepsin abstract film or light performance. However, it isfrustrating to note that this clear line of expression, uniqueto the sensibilities and technologies of the 20th century stillremains without a name or written history. Bill Moritzremains the foremost historian of abstract cinema and lightperformance [11], but his draft of the history remainsunpublished. The association with the spiritual fringe mayalso be responsible for the marginalization of thismovement. Walter Benjamin might suggest that theinability of the art establishment to commodify suchintangible work could account for its continued marginality[12]. Perhaps the next century will witness the widespreadrediscovery of these masterworks.

DYNAMIC ABSTRACTION

The physical color organs face two difficulties in

producing imagery: creating detail or hard-edged imageryrequires specificity – e.g. templates or slides; whilecreating a more general expression of color and lightnecessitates amorphousness – soft, ethereal forms. Freefrom the limitations of physics, mechanics and optics,digital computer graphics promise an unprecedentedpalette of color, light, form and animation. However, themajority of computer graphics tools accurately mirror themathematical processes required for animated production,rather than the aesthetic. Computer animation typicallyrequires several stages. The creation of a two- or three-dimensional model, the manipulation of this model throughsetting mathematical keyframes for the geometricproperties of each model component, and the batchrendering of animations to film or videotape. The processis as time consuming as traditional animation, but theanimator is not using his mechanical dexterity forexpression, but rather his cognitive problem-solving skills.

Faced with these tools when I began exploring abstractcomputer animation in 1989, I realized that the mediumneeded an important step backward – computer graphicsmoved too rapidly to stereoscopic three-dimensionaltexture mapped polygons of virtual reality. What wasexpressible with two-dimensional graphics and directexpression through your body?

MOTION SKETCH AND MOTION PHONE

The first tool I developed was Motion Sketch, a digitalanimation loop which runs continuously while humanmovements made through a mouse or tablet are recordedinto the loop (Figure 5). On a desktop computer, you maynotice that the most interesting object on the screen is thecursor, moving with personality and non-mechanicalsophistication. Motion Sketch simply allows thismovement to take center stage, transformed into abstractdynamic form. Although the loop is short (about a second),the compositions created have a great deal ofsophistication, since as the loop re-cycles, more marks areadded to the screen. Thus, it is possible to create

Figure 5. Time lapse from Motion Sketch (1991) and stills from the Motion Phone (1995). With both programs, humanmovement is directly translated into abstract dynamic form and color. The motion phone allows abstract visualcommunication through a network connection. The two images at right are stills from two-person collaborative animations.

Figure 6. Motion Phone installed at Ars Electronica 96.

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sophisticated rhythms of form, color and light – a temporalpainting.

The process of animation, rather than painting, informs thetools of Motion Sketch. By taking the numerical derivativeof successive screen positions, the shapes are made toorient in the direction of movement. Squash-and-stretch –the cartoon notion of motion blur, is accomplished byskewing the shapes in the direction of motion, proportionalto velocity. Finally, the entire system is non-modal. Thisnon-modality is at the heart of the program’s construction– simply enable the animator to draw while playing andyou have created Motion Sketch. Similarly, the othercontrols over size, color, shape, etc. are all non-modal – theprogram functions like an instrument (in the sense of amusical instrument) rather than a machine or desktopcomputer application. A further advantage of non-modalityis the ability to chord changes – for example size and colorcan change simultaneously while performing youranimation.

In 1995 I developed a networked version of Motion Sketchcalled the Motion Phone (Figure 6). With this software,multiple machines, networked via the Internet, cancommunicate together, working at once in the samedynamic canvas. This represents an interesting step awayfrom the virtuosic one-man shows of the master lightperformances. A duet, trio or even orchestra ofsimultaneous expression is possible.

As an experiment in abstract visual communication, theMotion Phone presents a few social rules. Instead of afixed size canvas, the Motion Phone provides an infinitelyzoomable plane, much like Ken Perlin’s Pad system [13].Multiple “conversations” or compositions can take place atany position or scale within this virtual world. However,this results in a perceptual problem – each performercannot be certain what the other is looking at. Similarly,performers have independent control of frame rate. If oneperson sets their frame rate low, they can seem to runcircles around the other – creating at miraculous speed andwith incredible temporal precision. Each player can onlyerase their own work, and one can also choose to notdisplay anyone else’s work if privacy is desired. However,the background color is set to the last person’s choice sothat there is at least one aesthetic decision to fight over.Changes to background color are instantaneous andstartling.

Most attempts at distance communication concernthemselves with reducing latency. Even in the bestvideoconferencing or phone systems, the speed of lightremains a bounding factor. By working from a sharedtemporal model, the Motion Phone avoids the issue oflatency. The steadily running loop on each end of aconversation assures that the canvas is always alive. Assoon as new material arrives, it is added to the dynamiccanvas. The act of communicating is like a set ofcommentaries – as long as material arrives within a few

seconds the process remains lively. It is worthwhile toimagine extending this metaphor to video, audio and othercommunications realms – how might we expand ournotions of communication to allow asynchronousconnection through a shared temporal model whichmaintains the feeling of simultaneity?

The Motion Phone has been shown at a series of artinstallations from 1995 through 1998 [14]. In publiclyinstalling the piece, my perception of the work moved fromthat of an intuitive animation tool to providing insights intohuman-computer interface. My first surprise in public usewas that a significant minority of people stayed on with thesystem for long periods of time. Some individuals used thesystem for hours and came back every day over the courseof 3-day to 3-week installation times. What about theprocess made the experience worthy of long-termattention? After some thought, my hypothesis is that theMotion Phone short-circuits the normal cognitive loop ofcomputer interfaces. The process of interacting is also theproduct of interaction – namely the movement of yourhand. By short-circuiting this cognitive loop, a person isbrought into a flow experience – one moment leadingdirectly into the next. This is most commonly found invideo games, with the constant goals of the particular gamepulling you forward. Similarly, the work of creative artistsin all media from painting to film can induce similar states.However, the Motion Phone manages to induce a flowstate without a concrete goal and without the expertiserequired of an aesthetic practitioner.

The second observation of users’ behavior is that as peoplebecome comfortable with the tool, unique styles emergereflecting their personalities. Instead of the shortdemonstration that I imagined the piece to be, the worksuggests that this is in fact an expressive medium allowingthe personality of the creator to come through. Users arecapable of becoming successively better and more fluent inthe system’s expressive potential.

DYNAMIC LINE

Observations of the Motion Phone experience prompted aseries of new explorations specifically targeted atachieving a balance between the seemingly contradictorydesign goals of instant knowability and infinitemasterability. Most software systems are either easy tolearn with limited expressive potential, or extremelypowerful with an interface which is difficult to learn andmaster. However, in the physical world there exist manysuch instantly knowable, infinitely expressible instruments,such as the piano and the pencil. Although almost any four-year-old can quickly discover their basic principles ofoperation, it is common for an adult to spend many yearspracticing these tools, and still feel that more mastery ispossible or that more compositions remain to be expressed.Such systems, moreover, have the property that anindividual may eventually reveal a unique and personal

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voice in that medium. We all have our own spatio-temporalsignatures, our own unique ways of moving through space;successful instruments bring the character of these tracesinto relief and reflect them back to us. In the work thatfollows I sought to design visual instruments that couldpossess these qualities of simplicity, intuitiveness andpossibility. To support this I deliberately restricted myselfto the design of continuous interactions with purelysynthetic 2D graphics, situated in a "cinematic" screen-space free of distracting sliders, menus, and buttons.

The first set of experiments was done with the aestheticcollaboration of Golan Levin in 1997. Inspired by PaulKlee’s Pedagogical Sketchbook, we embarked upon anexploration of the line’s potential for dynamic expression.Klee’s instructional drawings strongly suggest how a linemight be brought to life. Among his first words in this bookare, “A line is a walk for walk’s sake.” Our work wouldemphasize the process of creation over the product.Finally, instead of statically recording movement, wewould create dynamic interaction with a computationalmodel, using human movement as the driving impulse(Figure 7).

Streamer represents our first collaboration. A curved lineemerges from the movement of the pen as long as thebutton is down. This curved line is rapidly exaggerated andamplified, similar to smoke from a cigarette, although ouralgorithm is linear rather than chaotic. Each line segmentbetween successive mouse movements serves as the vectoralong with the endpoint is pushed from frame-to-frame,proportional to the segment’s length. The positive feedbackof this process results in rapid exaggeration of gesture,with curved trails overlapping and quickly flying in alldirections away from the cursor. As soon as the button isreleased, the line dissolves into blackness – the temporalmodel is an ephemeral one, like ripples in watermomentarily disturbed. The curved line itself isconstructed by connecting a Catmull-Rom spline throughthe successive pen points.

A second piece, Escargogolator, represents a differenttemporal model. In this piece, a process is set up on screenwhich can then be observed without further interaction (if

one so desires). The movements between pen down andpen up are sampled and a set of parallel lines are drawnbetween samples with length proportional to the speed ofdrawing and perpendicular to the direction of movement.From frame-to-frame, the line is evolved based this time onits curvature. Thus this work is handed – a counterclockwise movement results in an inward collapse andinversion, while a counterclockwise movement results inexpansion. The quality of motion, suggested by the name,is like that of a twisting snail. There is much expressivepotential in this application – an interesting exercise is towrite in cursive and watch the letters evolve into ameaningless scribble.

On the way towards Escargogolator, we introduced an off-by-one error in the computation of the line, along with abug in the queuing of points. The resulting piece we savedin intermediate form as a work in its own right calledSchizosticks. Schizosticks presents rapidly evaporating thinlines. As soon as a segment is ended, it is frozen in time. Inthe foreground, new segments may be drawn. If a singleclick is made, however, it suddenly springs the frozen linesto life in a shattering explosion. We unintentionallyrecreated one of Oskar Fischinger’s masterful motifs. Inmany of his early works a choreographed set of lines willmove with one motif of music. When that motif switches,the lines will not disappear, as sound must, but rather hangwaiting in the background, then come back to life when themotif reappears. The recognition of “mistakes” is animportant part of computational creation, often dismissedin other engineering disciplines. However, the discipline ofthe arts sees this as a different type of thought – thinkingthrough the process, the interaction of the artist with hismedium. Computer code is no less such a medium thanpaint or stone and invites the give-and-take familiar tothose fluent in other media.

Several other experiments in dynamic line were donetogether, along with independent work of Levin ofincreasingly refined sophistication after he began his studywith John Maeda at the MIT Media Lab [15]. While doingthis work, we arrived at a set of criteria for evaluating oursuccess and rejecting near misses:

Figure 7. Stills from Streamer, Escargogolator and Scizosticks.

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• Can you use the instrument with no instructions?

• How long can you use the instrument?

• Does your personality come through?

• Can you get better at using the tool?

Additionally, we came to develop an antagonisticrelationship to the Cartesian grid. The commonplacedecision to map x- or y- input coordinates to visualcontrols is one that relies on an abstract and artificialconvention, rather than on geometric intuitions that aremore analogous to the natural world. Although Cartesiancoordinates are convenient for input and output, thereactions and processes of nature obey an organic logicwhich is often poorly described by relationships to theCartesian grid. We therefore adopted the more perceptuallyoriented primitives of pre-Cartesian geometry as thebuilding blocks of our graphic environments: direction,velocity, orientation, and curvature.

COMPUTATIONAL AND ALGORITHMIC INSPIRATION

Following on from this work, I began exploring some ofthe tools and techniques that I had learned while a graduatestudent in Computer Science. Quite often, the intermediateresults of algorithms seemed intrinsically more compellingthan the problems they were solving. In particular,computational geometry offered a set of richly complicatedstructures constructed for the solution of planar and spatialgeometric puzzles. The Voronoi diagram [16] holdsparticularly strong appeal for its relationships acrossnatural and human disciplines. These diagrams areconstructed about a set of points such that a polygonencloses all of the area around each point that is closer tothat point than to any other point on the plane. Thisdiagram can then be used to solve, for example, theNearest Neighbor problem, which seeks the closest point toa given point on the plane. This diagram mimics thestructure of bubbles, the patterns of animal and communitydominance, the patterns of cells and honeycomb, fishesscale patterns, the drying of desert sand and, in the firstknow drawing of a Voronoi diagram, Descarte’s analysis ofthe gravitational influence of stars in 1644. Even in theworld of marketing, these diagrams find use in analyzing

the distance of consumers to the nearest fast foodrestaurant.

The Bubble Harp is an instrument that uses Voronoidiagrams as aesthetic territory. As long as the pen button ispressed, the exact temporal and spatial movement of thatpoint is recorded. When the button is let up, the pointrepeats this motion endlessly. As successive points areadded, a Voronoi diagram is dynamically constructedaround these points. Since each point’s playback durationdiffers, the repeat period of this system is very large. Thisis analogous to Brian Eno’s tape loop experiments [17] thatused multiple cycling audio tapes with their own varyingdurations to create complex and unanticipated temporalinterrelationships. With a second button on the pen ormouse, the creator can draw out a string of points emergingat short intervals from their movement. The compositionalprocess of this system is not strictly additive or subtractiveas the media of painting or light. As points are added, theysuccessively add lines, but, depending on their placement,they may subtract space, creating openness instead of morecomplexity.

Particle systems represent an almost endless technique forexploring the interactions of matter large and small. Arecent Hubble image of galaxies colliding exemplifies thetemporal and spatial complexity of such systems (Figure9). Gravilux attempts to address the notion of what itwould be like to draw with stars. A field of individualmasses is simulated, such that gravitational attraction iscomputed between the cursor position and all of theindividual stars’ positions. Although the system isphysically based, it is not physically realistic. Mutualattraction between all points is not computed, as in a truegravitational system. Further, the addition of viscousdamping causes the points to come to a halt when not beingmanipulated. The space itself is two-dimensional ratherthan three-dimensional, though the simulated movementssuggest three-dimensional forms. The space wraps on thetop and sides, creating a toroidal topology that alwayscontains the full set of about 10,000 points. Finally, anti-gravity may be applied with a second button, rippingthrough the space. As one becomes fluent with the tool,one starts to tease out lines by leading on the system at itsdensest points. Further possibilities include particle-

Figure 8. Bubble Harp, Gravilux and Myrmegraph.

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accelerator like phenomena that can be achieved byclicking directly on a dense section. Numerical instabilitynear zero creates this explosion, which was deliberately leftin as a pleasing aesthetic effect.

Myrmegraph is the only representational piece of theseries. Drawing from the emergent group behavior of ants,this piece uses a combination of lattice and particle system.As the performer draws, he lays down both pheromone andants. These ants are particles that obey a simple set of rules– they follow pheromone gradients stored invisibly in theimage and have limits on their speed and turning to givethem lifelike movement. From moment to moment, theycan change their heading to better pursue the trail ofpheromone. The chaos of the natural world is tamed intoan expressive medium. Unlike the real world, however, youcannot kill the ants. By pressing with the second button,you can erase the pheromone and release the ants fromtheir trail, but you cannot destroy them.

The final screen-based piece, Lasso draws from the realmof signal processing. Digital filters are used to modifysignals for the practical purposes of cleaning or extractinguseful information. Kernel-based filtering passes a smallconvolution filter along a set of samples to achievedifferent effects based on the filter weights. For example,the blur and sharpen filters in Photoshop are both kernel

filters with different weights. By passing a simple 3-element kernel filter over a line while you are drawing it, itis possible to add character to the line, while admittedlydistorting the artist’s form (Figure 10). The purpose of thetool is the process of interacting with this filter, rather thanthe final drawing. A center-weighted filter results in asmoothed line – no matter how crooked or idiosyncraticyour line, it dissolves into a 1950s style pleasing softabstraction. With a filter weighted toward the end, the linebecomes lazy. Instead of the instant snapping to attentionof computer drawing programs, this line has some inertia.This is more than simply amusing – imagine addingphysical qualities to drawing programs so that you reactagainst a system, rather than exerting exact, instantaneouscontrol over the form.

IMPLEMENTATION

The platforms under which these tools were developedstrongly influenced their aesthetic and expressive range.The original Motion Sketch was written for a SunSparcstation c. 1989 which allowed direct access to theframebuffer and mouse without a windowing system. Suchan environment provided a great place to build up graphicsfrom scratch – something becoming increasingly difficultwith the layers of windowing software now mandatoryunder most operating systems. The Motion Phone wasimplemented on an SGI Indy with OpenGL and Motif fordeployment on any number of Indys. The rest of theapplications described here were written on a PC with astandard graphics card using the DirectDraw API.Although the number of graphical primitives is limited, thisconstrained space serves a useful function of honing onesideas to their essential components.

Java ports and some downloadable versions of theseprograms are available for online exploration athttp://www.snibbe.com/scott.

A PHENOMENOLOGICAL PERSPECTIVE

These aesthetic experiments point towards a larger set ofprinciples that may be more broadly applied to animation,drawing tools and computer interfaces. Within thephilosophical world there has been much exploration of therealm of perception that is immediately apprehensible to

Figure 9. Colliding Galaxies NGC 4038 and NGC 4039.October 21, 1997. B. Whitmore and NASA.

Figure 10. Lasso time series. Kernel-based filtering of a dynamic line.

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the body, rather than the rational mind. Phenomenology isthe study of how perception presents the world directly toconsciousness. The dynamic abstract work presented heredemonstrates a set of successful experiments in creatingphenomenological user interfaces that directly engage thebody.

Edmund Husserl [18] invented and mapped out theterritory of Phenomenology – the first substantialphilosophy centered on an individual’s unique perceptualapparatus and his knowing of himself. Husserl brokeperception into the unreflective life-world which is thestereotypical accepted reality of the world and irreality, thesubjective nature of experience. It is this subjectiveexperience that this work in dynamic abstraction attemptsto explore in non-representational form. By acknowledgingthese fundamental principles of perception, we can open uppossibilities already present in screen-based dynamicmedia. Progress in animation and graphical interface neednot be a straight arrow of technology pointing into thefuture, but should also include an inward pointing arrowwhose starting point was given to us early in this centuryby both these philosophers and the abstract animators andartists of pure light.

ACKNOWLEDGEMENTS

Golan Levin, my co-author, provided many hours offruitful discussion and aesthetic collaboration whileworking on the dynamic line pieces with me in 1997 atInterval Research. Adobe Systems and Silicon Graphicssupported the Motion Phone while I worked at Adobe as amember of the After Effects team from 1994 through 1996.Andy van Dam and many members of the BrownUniversity Computer Graphics Group helped me becomeeducated in the language of computer graphics while anundergraduate and graduate student. Larry Cuba, ElfriedeFischinger and Bill Moritz are all wise mentors who havecritiqued my work and broadened my knowledge ofabstract light performance and animation history. BillVerplank has been a constant mentor, source of inspirationand dedicated user of these tools. Perry Hobermanintroduced me to the world of interactive art installations,where I learned from watching people use these tools. ItsuoSakane, Machiko Kusahara and Michael Naimark arecolleagues from the world of interactive art who havesupported me and pushed me to refine and addsophistication to my naïve early experiments.

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[9] Thomas Wilfred: A Retrospective. Concoran GalleryExhibition Catalog. Washington, 1972.

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[17] Brian Eno. Discreet Music. Editions E.G. Records, 1975.[18] Edmund Husserl: Philosopher of Infinite Means.

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[11] William Moritz, “The Dream of Color Music,” in TheSpiritual in Art : Abstract Painting 1890-1985. Los AngelesCounty Museum of Art. Abbeville Press, 1986.

[12] Rochlitz, R. (translator). The Disenchantment of Art:The Philosophy of Walter Benjamin. Guilford Press, 1996.

[13] Perlin, K. “Pad: An Alternative Approach to theComputer Interface.” Proceedings of SIGGRAPH '93.

[14] Schöpf, Christine (ed.). Prix Ars Electronica 96.Springer-Verlag, New York, 1996.

[15] Levin, Golan. Interface Metaphors for AudiovisualPerformance Systems. M.S. Thesis, MIT Media Laboratory,June 2000.

[16] Okabe, A. and Boots, B. Spatial Tessellations :Concepts and Applications of Voronoi Diagrams,. JohnWiley and Sons, 1992.

[17] Brian Eno. Discreet Music. Editions E.G. Records,1975.

[18] Maurice Natanson. Edmund Husserl; Philosopher ofInfinite Task. Northwestern University Press, 1973.

[1] Chuck Thacker, Edward McCreight, Butler Lampson,Robert Sproull and David Boggs. Alto: A PersonalComputer. Xerox PARC Technical Report. August 1979.

[2] Iamblichus, Life of Pythagoras (translated into Englishby T. Taylor). Los Angeles. Theosophical PublicationHouse, 1905.

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