The followingpaper was published in the IEEE Proceedings for Information Visualization1999; presented at IV '99 on July 15, 1999 at the Univeristyof London
ISBN: 0-7695-0210-5
IEEE Computer Society Order Number PR00210



Collaborative Visualization: New Advances in Documenting VirtualReality with IGrams


Ellen Sandor, Janine Fron,Kristine Greiber, Fernando Orellana and Stephan Meyers, (art)ⁿLaboratory, and Dana Plepys, Margaret Dolinsky, and MohammedDastagir Ali, Electronic Visualization Laboratory, Universityof Illinois at Chicago.

Abstract

(art)ⁿLaboratoryand the Electronic Visualization Laboratory (EVL) at the Universityof Illinois at Chicago have collaborated on the development ofthe first real-time, stereoscopic hardcopy output of virtualreality applications - the ImmersaGram (IGram). The results ofthis new technology directly address a broad range of informationvisualization issues along a wide spectrum of disciplines fromart, architecture, and science, to medicine, engineering andeducation.

Keywords:Virtual Reality, Art, Science, lenticular, PHSCologram,autostereography

1. Introduction
How can virtual reality applications be documented and sharedoutside the virtual environment without the use of expensivecomputer hardware, access to limited resources, simulators, etc.?What medium is available for artists/scientists to record theirwork in-progress to contemplate, assess and evolve without directaccess to the virtual reality system? Is there a way to extendone's artistic expression beyond the virtual application itself?An underlying answer to these and many other questions is theIGram - a virtual reality snapshot.

Among the more principal andcritical concerns has been the ability to capture a fleetingmoment or state within a virtual reality experience. Video andphotographic documentation of virtual reality participants andenvironments has yielded only marginal results; the interactivenature of the experience can be documented, though image qualityis significantly compromised due to resolution loss, monoscopicdisplay and difficult lighting circumstances. High-resolutiondigital slides or photo-graphs can be created, but do not recordthe stereoscopic nature of the event, and cannot be generatedin real-time. IGrams address these problems by providing a lowcost, real-time method for printing three-dimensional virtualimagery to an 8"x10" or 11"x14" stereo transparency.Larger format 20"x24", and 20"x40" mediumpriced IGrams are viable with a Hewlett Packard Design Jet 2500CP.Other printing variations are optional and currently being explored.

2. Aesthetic background
IGrams are a direct outgrowth of (art)ⁿLaboratory'scomputer interleaving process, known as PHSColograms. The resultsof computer interleaving provide an archival three-dimensionalphotograph from computer rendered content. PHSCologram is anacronym for photography, holography, sculpture and computer graphics.In search of new artistic paradigms, the PHSCologram foundingartists synthesized the arts of sculpture, photography and computervisualization. PHSColograms are made from a series of 10-65 (ormore) snapshots of a virtual environment that are photographedinside of the computer. This series of frames is then combinedinside of the computer, output to film and viewed with a barrierscreen or lenticular lens [1]. PHSCologram artistry traversesfrontiers of science and medicine, as well as educational andhistorical documentation while remaining true to the fundamentalsof fine aesthetics and new technology.

(art)ⁿ 's body ofwork in PHSColograms created a unique dialogue between photographyand sculpture in computer graphics and virtual reality [2]. ThePHSCologram process draws on earlier advances in photography,including daguerreotypes, photogravures and gelatin silver prints.Rodin was among the first sculptors to use photogravures to publishhis "Monument to Balzac" in the famous Camera Workquarterly [3]. Brancusi and David Smith are also known for usingphotography to document their works. Brancusi's photographs showhis vision of the artist in the studio; Smith's photographs revealthe artist in the landscape [4]. The documentation produced bythese artists are strong works in their own right. It is (art)ⁿ 'svision for IGrams to inspire a new aesthetic consciousness invirtual environments that encourages artists to explore photographyand sculpture in their own work.

3. The IGram system
IGram development has addressed the desire to better documentvirtual reality environments created for EVL's CAVE(tm) virtualreality system [5]. The CAVE is a fully immersive 10'x10'x10'cubic room, where stereo images are projected onto three wallsand the floor. A participant wears LCD shutter glasses, equippedwith a tracking device to create the stereo effect and definethe user's location within the environment. A three-dimensional'wand' is used to navigate and interact with virtual objectswithin the space. IGrams are created within the CAVE system -virtually - while exploring and manipulating the three-dimensionalspace.

Any 'Performer-based' CAVE applicationcan be used to capture IGrams. The three-dimensional scene isported to the IGram utility and displayed in the CAVE, wherethe user manipulates (translates, rotates and scales) the scenewithin a virtual three-dimensional frame representative of theIGram (hardcopy) output area. The 'depth-of-field' is controlledby changing interleaving values/distances with the 'wand', whichaffects the stereo perspective projection. In this process, theCAVE itself is akin to a virtual camera, the virtual frame in3-space - the camera's view-finder, and the wand - the lens/aperturecontrols.

Interleaving is the digitalsimulation of the photographic combing procedure. (art)n's autostereo-graphicprocess is a result of interleaved computer graphics based onthe concept of binocular disparity. Following the virtual 'positioning'of a digital setting, individual images are captured at slightlydifferent angles across the scene in a straight line from leftto right. Each of the images is broken up into rows and columnsof pixels. (art)n Laboratory's proprietary software combinesthese rows and columns of pixels, and arranges them into a singleimage. The image is output onto a piece of film or paper. Theresult is a blurred image on transparency film. A barrier screenis placed over this image to complete the 3-D effect. In thecase of IGram production, once virtual "positioning"of the scene is complete, ten individual images are captured,interleaved and displayed full scale in the CAVE for technicaland aesthetic evaluation before committing to final hardcopyoutput. When cropping and framing results are satisfactory, interleavedIGram images are sent to the Epson Photo EX color inkjet printerto transparency material and final processing.

4. Experiences
Early on in the development cycle of the IGram CAVE utility,virtual 'art' environments were selected as the initial focus[6]. Capturing the virtual art experience and extending the applicationbeyond the walls of the CAVE environment was an obvious choice.A creative and aesthetically pleasing scene was selected fordevelopment, in order to assess whether or not the IGram couldcapture the essence of the virtual experience, preserve the senseof immersion, and act as an extension of the original artworkinto the domain of virtual hardcopy.

Results of early experimentswere somewhat enlightening. Of concern was how to capture a vastspace within a limited frame. Since virtual space can be infinite,objects within the scene can be located at great distances fromeach other. The ability to quickly move from place to place invirtual reality minimizes this distance, yet in trying to documentthe scene in time, does not necessarily yield visually appealingresults. To address the spatial considerations, it became obviousadditional control over the environment position and scale wasrequired. These features are inherent to the IGram program, andare used to compose or select the most representative portionof the virtual scene for archival. A sequence or series of IGram'snapshots', as in any 'photographic' medium, most readily documentsstates in time, as well as vast space not easily captured ina single image.

An unexpected discovery wasthat the artist could use an IGram as a creative developmenttool. Having an accessible hardcopy to analyze the interrelationshipof objects and composition within a specific area of the sceneis incredibly beneficial. Access to the virtual display environmentcan be limited to application review. Scenes are developed ina simulator on the workstation, then checked in the virtual displayenvironment. Going back and forth between writing code to displayingthe results can be somewhat disconcerting and indirect for thecreative process. The artist's ability to 'study' the scene withsome consistency and accessibility can be vastly improved byusing the IGram as a working 'sketch' from which to develop andenhance the artwork when not at a workstation or in the virtualsystem.

5. Conclusion
The primary goal in developing the IGram hardcopy was to archivethe virtual environment, while creating a derivative art formor document that can stand on its own merit, tell a story orevoke an emotion. Clearly, it was not developed strictly to documentartistic and creative virtual reality applications, but the widerange of virtual reality application areas. In the case of scientific,engineering or medical applications, the IGram can reveal animportant feature or aspect of a data set. For architecture/designapplications, the IGram can be used for design review, clientpresentations, as well as recording 'stages' in the productioncycle. As virtual reality applications evolve, the IGram willcontinue to play an important role in preserving and enhancingthe exchange of information and recording of technology acrossa diverse and expanding audience base.

[1] S. Meyers, E. Sandor and J. Fron,PHSColograms and Rotated PHSColograms. Computers & Graphics19.4 (July/August 1995): 513-522
[2] M. Neal, More then Science, More than Art. Computer Graphics\& Applications. 8.6 (November 1988): 3-5
[3] E. Steichen, Camera Work 34/35 (April/July 1922):7-11
[4] Pachner, J. David Smith Photographs 1931-1965. San Francisco:Fraenkel Gallery, New York: Matthew Marks Gallery & San Francisco:Fraenkel Gallery, 1998
[5] C. Cruz-Neira, D. J. Sandin, T. A.DeFanti, R. V. Kenyon,and J. C. Hart, The CAVE: Audio Visual Experience Automatic VirtualEnvironment, Communications of the ACM 35. 6 (June 1992): 65-72.
[6] M. Dolinsky, Creating art through virtual environments, ComputerGraphics 31.4 (November 1997): 34-5