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

Collaborative Visualization: New Advances in Documenting Virtual Reality with IGrams
Ellen Sandor, Janine Fron, Kristine Greiber, Fernando Orellana and Stephan Meyers, (art)ⁿ Laboratory, and Dana Plepys, Margaret Dolinsky, and Mohammed Dastagir Ali, Electronic Visualization Laboratory, University of Illinois at Chicago.

Abstract

(art)ⁿ Laboratory and the Electronic Visualization Laboratory (EVL) at the University of Illinois at Chicago have collaborated on the development of the first real-time, stereoscopic hardcopy output of virtual reality applications - the ImmersaGram (IGram). The results of this new technology directly address a broad range of information visualization issues along a wide spectrum of disciplines from art, architecture, and science, to medicine, engineering and education.

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

1. Introduction
How can virtual reality applications be documented and shared outside the virtual environment without the use of expensive computer hardware, access to limited resources, simulators, etc.? What medium is available for artists/scientists to record their work in-progress to contemplate, assess and evolve without direct access to the virtual reality system? Is there a way to extend one's artistic expression beyond the virtual application itself? An underlying answer to these and many other questions is the IGram - a virtual reality snapshot.

Among the more principal and critical concerns has been the ability to capture a fleeting moment or state within a virtual reality experience. Video and photographic documentation of virtual reality participants and environments has yielded only marginal results; the interactive nature of the experience can be documented, though image quality is significantly compromised due to resolution loss, monoscopic display and difficult lighting circumstances. High-resolution digital slides or photo-graphs can be created, but do not record the stereoscopic nature of the event, and cannot be generated in real-time. IGrams address these problems by providing a low cost, real-time method for printing three-dimensional virtual imagery to an 8"x10" or 11"x14" stereo transparency. Larger format 20"x24", and 20"x40" medium priced 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)ⁿ Laboratory's computer interleaving process, known as PHSColograms. The results of computer interleaving provide an archival three-dimensional photograph from computer rendered content. PHSCologram is an acronym for photography, holography, sculpture and computer graphics. In search of new artistic paradigms, the PHSCologram founding artists synthesized the arts of sculpture, photography and computer visualization. PHSColograms are made from a series of 10-65 (or more) snapshots of a virtual environment that are photographed inside of the computer. This series of frames is then combined inside of the computer, output to film and viewed with a barrier screen or lenticular lens [1]. PHSCologram artistry traverses frontiers of science and medicine, as well as educational and historical documentation while remaining true to the fundamentals of fine aesthetics and new technology.

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

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

Any 'Performer-based' CAVE application can be used to capture IGrams. The three-dimensional scene is ported to the IGram utility and displayed in the CAVE, where the user manipulates (translates, rotates and scales) the scene within a virtual three-dimensional frame representative of the IGram (hardcopy) output area. The 'depth-of-field' is controlled by changing interleaving values/distances with the 'wand', which affects the stereo perspective projection. In this process, the CAVE itself is akin to a virtual camera, the virtual frame in 3-space - the camera's view-finder, and the wand - the lens/aperture controls.

Interleaving is the digital simulation of the photographic combing procedure. (art)n's autostereo-graphic process is a result of interleaved computer graphics based on the concept of binocular disparity. Following the virtual 'positioning' of a digital setting, individual images are captured at slightly different angles across the scene in a straight line from left to right. Each of the images is broken up into rows and columns of pixels. (art)n Laboratory's proprietary software combines these rows and columns of pixels, and arranges them into a single image. The image is output onto a piece of film or paper. The result is a blurred image on transparency film. A barrier screen is placed over this image to complete the 3-D effect. In the case 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 technical and aesthetic evaluation before committing to final hardcopy output. When cropping and framing results are satisfactory, interleaved IGram images are sent to the Epson Photo EX color inkjet printer to 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 application beyond the walls of the CAVE environment was an obvious choice. A creative and aesthetically pleasing scene was selected for development, in order to assess whether or not the IGram could capture the essence of the virtual experience, preserve the sense of immersion, and act as an extension of the original artwork into the domain of virtual hardcopy.

Results of early experiments were somewhat enlightening. Of concern was how to capture a vast space within a limited frame. Since virtual space can be infinite, objects within the scene can be located at great distances from each other. The ability to quickly move from place to place in virtual reality minimizes this distance, yet in trying to document the scene in time, does not necessarily yield visually appealing results. To address the spatial considerations, it became obvious additional control over the environment position and scale was required. These features are inherent to the IGram program, and are used to compose or select the most representative portion of the virtual scene for archival. A sequence or series of IGram 'snapshots', as in any 'photographic' medium, most readily documents states in time, as well as vast space not easily captured in a single image.

An unexpected discovery was that the artist could use an IGram as a creative development tool. Having an accessible hardcopy to analyze the interrelationship of objects and composition within a specific area of the scene is incredibly beneficial. Access to the virtual display environment can be limited to application review. Scenes are developed in a simulator on the workstation, then checked in the virtual display environment. Going back and forth between writing code to displaying the results can be somewhat disconcerting and indirect for the creative process. The artist's ability to 'study' the scene with some consistency and accessibility can be vastly improved by using the IGram as a working 'sketch' from which to develop and enhance the artwork when not at a workstation or in the virtual system.

5. Conclusion
The primary goal in developing the IGram hardcopy was to archive the virtual environment, while creating a derivative art form or document that can stand on its own merit, tell a story or evoke an emotion. Clearly, it was not developed strictly to document artistic and creative virtual reality applications, but the wide range of virtual reality application areas. In the case of scientific, engineering or medical applications, the IGram can reveal an important feature or aspect of a data set. For architecture/design applications, the IGram can be used for design review, client presentations, as well as recording 'stages' in the production cycle. As virtual reality applications evolve, the IGram will continue to play an important role in preserving and enhancing the exchange of information and recording of technology across a diverse and expanding audience base.

[1] S. Meyers, E. Sandor and J. Fron, PHSColograms and Rotated PHSColograms. Computers & Graphics 19.4 (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 Virtual Environment, Communications of the ACM 35. 6 (June 1992): 65-72.
[6] M. Dolinsky, Creating art through virtual environments, Computer Graphics 31.4 (November 1997): 34-5