Virtual Museum - Technical Information
How We Created The Virtual Museum
Prior to discussing in detail the process of Apple QTVR movie development, a brief statement about the number of people involved, the time spent, and the costs incurred in the production of the Oriental Institute Virtual Museum will be instructive.
When completed, the Virtual Museum will contain 51 separate QTVR panoramic movies, brief descriptions of the museum's history, its overall structure, introductory remarks about our six galleries, and brief text entries from the Museum's registration database describing the approximately 5,000 artifacts on exhibition. Three Institute staff members, Assistant Curator Emily Teeter, Museum photographer Jean Grant, and Head of the Computer Laboratory John Sanders spent eight months, working part time (circa 20% each), planning, photographing, and preparing the text descriptions. Two other University of Chicago personnel from the Visualization and MultiMedia Laboratory, Director Chad Kainz and staff memeber Peter Leonard, spent six months, working part time (Chad at circa 5% and Peter at circa 50%), processing the photographs into QTVR movies.
The Oriental Institute spent an average of $35.00 per panoramic movie to purchase the 35mm Kodak film and have it processed into a Kodak PhotoCD. With 51 movies produced for the Virtual Museum, the Institute spent approximately $1,785.00 on film and film processing. An additional $250.00 was spent purchasing the necessary photographic tripod equipment. The Institute already owned the 35mm camera and wide angle lens used to shoot the photographs, so that equipment did not add to the total project's cost. Overall costs for the project, however, are hard to determine because we were able to utilize existing computer hardware and software in the University of Chicago's Visualization and MultiMedia Laboratory for the post-photography processing required to produce the actual QTVR panoramic movies. Without such a free facility at our disposal, the required Apple computer hardware and software would have added approximately $7,000 at the educational discount price, or $9,500 at full price, to the overall cost of producing the Virtual Museum.
Production of the Oriental Institute Virtual Museum, or any Apple QuickTime VR (QTVR) movie for that matter, can be broken down into three phases:
- The planning, setup, and shooting of the still (film or digital) photographs that will be used to produce the QTVR movie(s).
- The computer processing of the digital photographs described above with Apple's virtual-reality authoring tools software to produce the QTVR panoramic movie files.
- The construction of the HyperText Markup Language (HTML) documents which compose the overall structure of the Virtual Museum, which includes the actual text descriptions of the Museum and artifact exhibitions and links to image files as well as the QTVR panoramic movies.
NOTE: Although the first two steps must be performed in the order indicated, the third step may be worked on before, during, or after the first two, and may be performed by the same or by other individuals.
Apple Computer, Inc. can provide you with full descriptions and recommendations for the entire QTVR production process. I highly recommend you contact your nearest Apple representative and read their documentation if you plan on producing your own QTVR movies.
This phase of the project involved determining how many panoramic movies would be needed to fully document all six galleries of the Oriental Institute Museum, and exactly where in each gallery the camera would be located to shoot the panoramic scenes. Discussions among the Institute Director, Curator, Assistant Curator, Museum photographer, Research Archivist, and Head of the Computer Laboratory went on over a couple of weeks, with many trips through the galleries with camera and tripod in hand, in order to arrive at our final choice of 51 separate locations throughout the Museum and in several other Institute locations which we wanted to include as part of the project. With few exceptions, each alcove of all six galleries was recorded with a single panoramic scene. Some alcoves required two locations because either centrally located cases made viewing the entire alcove from one location impossible, or because the small size of artifacts exhibited in the alcove made a single location impractical.
Once all the locations were chosen, and marked on the floor for future reference, we moved on to the task of assembling all of the necessary photographic equipment. Several choices are possible, each with positives and negatives. Most importantly, (1) it must be determined whether the still photographs that are used to create the QTVR movies will be taken with a digital camera or with a traditional film camera; (2) if the choice is a film camera, will the film be processed to yield digital images on a Kodak PhotoCD or will the film images be enlarged and printed on photographic paper, and then scanned to produce the required digital images.
We chose to use a 35mm film camera, with Kodak KodaColor Royal Gold Plus (100 ASA) film, set to a 4 second exposure @ F16 with a FLD florescent filter, and process the film onto a Kodak PhotoCD for the following reasons:
- We already owned a Canon F1 35mm Single Lens Reflex (SLR) film camera and a Vivitar Series I 28-105mm zoom lens which would be adequate according to Apple's recommendations, saving us the cost of purchasing a digital camera (circa $250.00 to as much as $15,000.00).
- In our opinion, digital cameras at the less expensive end of the price scale did not have the quality of glass in their lenses nor an adequate choice of focal lengths for their lenses as did our Canon 35mm camera.
- Post-photography processing of the 35mm film onto a Kodak PhotoCD would produce digital images of our photographs at five different resolutions (192x128dpi, 384x256dpi, 768x512dpi, 1536x1024dpi, and 3072x2048dpi), and the best Kodak PhotoCD images are at a higher dot-per-inch (dpi) resolution then those produced by the less expensive digital cameras on the market today.
Choice of the camera tripod equipment was next, and as with the camera choice above, the Institute already owned a basic, heavy-duty tripod. The need for very accurate leveling of the tripod and the need to turn the tripod a specific number of degrees as each still photograph is shot as part of the panoramic scene, however, requires a special mounting bracket between the camera and the basic tripod base. Two alternatives exist for obtaining this intermediate mounting: (1) purchase the complete assembly in a single unit designed specifically for shooting QTVR panoramic movies, such as the one sold by Kaidan, Inc., at a cost of $250.00-$400.00; or (2) purchase the individual components, as described in the Apple documentation mentioned above, from a camera supply company of your choice. We chose to purchase separate components and build the mounting bracket ourselves, so that some of the components could be used by the Institute photographer for other purposes after the Virtual Museum project was completed. With hindsight, for ease of use and peace of mind I suggest purchasing the all-in-one mounting bracket specially designed for shooting QTVR panoramic movies.
The last major decision was the choice of the focal length for the camera lens, which determines the number of photographs, and, therefore, the number of degrees the camera is turned between each photograph, to compose each panoramic scene. As detailed in the Apple documentation, the best results are obtained using either a 15mm, 24mm, or 28mm lens, and adequate results obtained with a 35mm lens. Of these choices, use of the Institute's Vivatar 28-105mm zoom lens at the 28mm setting meant that we needed to shoot 18 photographs at each location to produce a panoramic movie, turning the camera exactly 20 degrees between each photograph. For comparison purposes, use of a 15mm lens, for example, would result in the need for 16 photographs at each location, turning the camera 22.5 degrees between each photograph.
I cannot over emphasize the following two issues (see the Apple documentation for further details):
- Whichever mounting bracket you use, extreme care must be taken to insure accurate leveling of the camera throughout the entire 360 degree turning required to complete a panoramic scene.
- Whichever mounting bracket you use, extreme care must be taken to insure that the exact number of degrees to be turned between each photograph be correct and precisely the same for each turn. Accuracy in the post-photography processing by the Apple virtual-reality authoring software used to produce the QTVR movie files is dependent upon proper overlap of each photograph with its left and right corresponding photographs.
After the gallery photography was completed, the rolls of film were processed by a commercial laboratory in Chicago and the images placed onto a Kodak PhotoCD. We can make several recommendations here, based on our experiences:
- Because of varying lighting conditions within our galleries, and between galleries, and also because commercial laboratory change their development chemicals routinely, process all rolls of film from a single gallery (or area with similar lighting conditions) in a single batch, at the same time. This will help to reduce color variations from one panoramic movie to another.
- Do a test shooting in each area with differing lighting conditions, changing exposure settings and time of exposure within a set of photographs for a single scene in order to evaluate these two variables to determine the optimum settings. The extra cost of a few more rolls of film and their processing is minimal compared to the cost and aggravation of having to shoot several locations again because of changed lighting conditions that you thought were the same as other areas.
Based on the size camera lens described above, the eighteen digital photographs required to construct a 360 degree QTVR panoramic movie are read off the Kodak PhotoCD. Using Apple QTVR authoring software on a Macintosh computer, described in detail below, these photographs are combined by a proprietary Apple algorithim into one large, 9 MB file, based on our choice of the mid-range, 768x512dpi resolution images on the Kodak PhotoCD (use of higher resolution images would yield larger composite files). This process is know as "stiching" the eighteen images together, using the "overlap area" which each photograph contains with respect to its adjacent photographs. This overlap area is present in each photograph because the 20 degree turning radius is less than the number of degrees captured in each photograph using a 28mm camera lens. Briefly stated, the algorithim looks for matching edges in the overlap areas of adjacent photographs in order to join them as it moves through the series of eighteen images.
The large stitched image is then "diced" into areas of equal size . This division enables the Apple authoring software to map these equal area images into "virtual space" in the next phase of the process. The diced image is then processed into an Apple QuickTime VR movie file, reducing the 9 MB composite file to about 800 KB in size.
- Power Macintosh 8500/132
- 132 MHz PowerPC 604 processor
- 48 MB RAM (40 MB allocated to MPW)
- 2 GB hard disk array (RAID)
- 17" Color Monitor
- Apple QuickTime VR Development Kit
- Apple Macintosh Programmer's Workshop (MPW)
- Adobe Photoshop 3.0.1 (PPC-enhanced)
- Equilibrium Debabelizer Toolbox (PPC-enhanced)
- Processing Time
- Estimated processing time for standard movies: 7 minutes per movie file
- Estimated processing time for "difficult" movies: 2 hours per movie file
The QuickTime VR movie file, when viewed with appropriate viewing software, such as the Apple QTVR Player program, is distorted in real-time on the user's computer to correspond with the user's "viewing angle." As you pan right, for example, pieces of the movie file that move away from you to the left are shrunken, according to how the eye perceives change in perspective view in the real world. The fact that this distortion process happens in real-time on the user's computer is the reason that the speed and smoothness of the panning process differs depending upon the user's computer processor speed. A faster processor can perform this operation more quickly, resulting in a smoother, less jerky, sequence of movement.
The initial impetus for developing the Virtual Museum on the World-Wide Web (WWW) was the imminent closing of the Oriental Institute Museum during its renovation and construction project. Although the re-installation plans are still being developed, the curatorial staff have said from the outset that the re-installed galleries will not follow the Museum's previous exhibition arrangement. So recording the Museum with Apple QTVR panoramic movies prior to the start of the renovation project and once again after the galleries are re-installed will be of great historical value for the Institute. It will also provide future visitors a chance to see how the Museum was originally concieved, and to evaluate our new gallery exhibitions in light of this previous design.
With this basic statement of purpose, several principles guided our construction of the Virtual Museum's file structure and overall presentation:
- QTVR panoramic movie coverage should be complete enough to document all gallery alcoves, exhibits, and display cases with a "reasonable" level of photographic detail. Capturing every artifact on display was not necessary, but, at the other end of the scale, recording certain cases with only a vague, distant photographic image was deemed unsatisfactory.
- Because visitors to the Virtual Museum may not be familiar with the Museum's floor plan, we could not rely on a "floor-plan-only" orientation for the Virtual Museum. In fact, an informative and rewarding visit to the Virtual Museum should not be at all dependent upon knowledge of the Museum itself. Such knowledge should only add to the visitors experience of the Virtual Museum. Accordingly, several methods for navigating through the Virtual Museum were developed, each offering a different approach:
- A text-based, Regional and Topical structure.
- A graphics-based, Museum Floor Plan structure.
- A graphics-based, gallery/alcove "thumbnail" image structure
- To the extent possible with the underlying Apple QTVR technology, as much information as would be included on Museum label copy should be provided in the Virtual Museum, and, where practical, we should use the technology to provide even more information about the artifacts on exhibition, and in ways that would not be possible in a traditional Museum setting.
- Because important related material about the archaeological excavations which produced many of the artifacts on exhibit in the Virtual Museum is already included in other parts of the Oriental Institute WWW database, direct links between Virtual Museum components and these WWW documents should be part of the Virtual Museum in order to further enhance the visitors knowledge and experience.
Revised: February 19, 2007