info @ archimuse.com
published: April, 2002
INUIT3D: An Interactive Virtual 3D Web Exhibition
Frank Corcoran, Canadian Museum of Civilization, Jeffrey Demaine, Michel Picard, Louis-Guy Dicaire and John Taylor, National Research Council of Canada
The Canadian Museum of Civilization and the National Research Council of Canada collaborated on the production of Inuit 3D, one of six inaugural Virtual Museum of Canada exhibitions launched in April 2001. Inuit 3D is an interactive exhibition in which visitors navigate through three exhibition halls and interactively examine twelve 3D models of objects from the Museums collection. Introductory videos are presented at the entrance to each room. Pop-up text panels provide information on the objects, as well as on Inuit artists and the Canadian North. To produce Inuit 3D, three technologies developed for Web applications - VRML, 3D Scanning and QuickTime - were used. While these technologies enable museums to produce interactive Web exhibitions, a number of significant technical and Web design issues must be considered. The objective of this paper is to present an overview of Inuit 3D and to discuss technical and Web issues encountered.
Keywords: Web exhibition, virtual museum, 3D digital imaging, cultural heritage, Inuit
In April 2001, the Canadian Heritage Information Network (CHIN) launched the new Virtual Museum of Canada (VMC) (http://www.virtualmuseum.ca/) with six inaugural exhibitions. Inuit 3D was one of the exhibitions and was produced by the Canadian Museum of Civilization (CMC) (http://www.civilization.ca/) in collaboration with the National Research Council of Canada (NRC) (http://www.vit.iit.nrc.ca/). While NRC coordinated the technological aspects, CMC provided the content.
During the planning stages for the VMC, CHIN conducted a survey of focus groups with an interest in museums and culture across Canada (Nadeau, 2000). One of the results noted in the report was:
In each session, a portion of the participants had clear expectations of a three-dimensional tour of one or many museums. Some of these participants clearly explained how the Web site user would be able to control their path through a museum, allowing them to pivot and view any section of the museum and objects in the museum in 3-D.
Inuit 3D is an interactive exhibition which seeks to accomplish this objective. Visitors can navigate through three exhibition rooms - Palaeo-Eskimo, Inuit History and Inuit Art in the virtual museum and interactively examine twelve 3D digital models of objects from the Museums collection (Figure 1). Introductory videos are presented at the entrance to each room. Pop-up text panels provide layers of information on the objects, as well as on Inuit artists and the Canadian North. Also included are historic photographs of the Arctic from the 1913-16 Canadian Arctic Expedition, as well as information and contemporary photographs on prints and the print making process.
Figure 1: (a) View of the Inuit 3D Virtual Exhibition Hall showing the entrance and the three exhibition rooms. Entering on the left, visitors encounter the Palaeo-Eskimos, move to the historic post-contact Inuit History period (center) and conclude with the Inuit today (right). The 3D object models are mounted on pedestals and historic photographs of the Arctic and contemporary prints are mounted on the walls. The entrance/exit hall is shown in (b) including the navigation location indicator in the lower left corner.
To complement traditional exhibitions, interactive 3D Web exhibitions offer museums the opportunity of presenting rich virtual exhibitions which contain accurate or high fidelity three-dimensional digital models of objects together with layers of information and related 2D video and photographic content. Virtual exhibitions also have the potential of reaching much larger audiences and of lasting longer than traditional exhibitions. They can be easily updated and, once the primary exhibition closes, form part of a widely available archival record.
However, an interactive virtual Web exhibition requires a careful selection and integration of 2D, 3D and audio-visual Web application tools and related plug-ins. Constraints such as bandwidth, browser differences, file sizes, plug-in requirements and 3D model compression lurk half-submerged like alligators in a swamp, ready to take a bite out of plans to create virtual exhibitions that are only a few bricks short of looking like the real thing. One must consider trade-offs between image quality and download time, the download tolerance of viewers and whether the goal of the exhibition is to provide entertainment, edutainment or an educational experience.
In addressing these issues, we encountered a number of technological and end-user factors which, in instances, dictated imperfect solutions. Despite these factors, Inuit 3D allows Web visitors to be able to control their path through a museum, allowing them to pivot and view any section of the museum and objects in the museum in 3-D. The purpose of this paper is to present an overview of the production of Inuit 3D and to discuss the technical and Web issues encountered.
Inuit 3D Exhibition Theme and Background
The theme for Inuit 3D evolved from a nine-minute 3D Virtualized Reality theatre production on Inuit art CMC presented during the exhibition Iqqaipaa: Celebrating Inuit Art, 1948-1970 in 1999. This program was presented in CMCs 25-seat 3D VR Theatre (MacDonald et al, 1999). It featured high-resolution 3D images of a selection of Inuit sculpture from the Palaeo-Eskimo (700 BC) period up to the 1970s projected in stereo on a 10 x 15 screen. It also included background Arctic visuals and narration on Inuit art and Arctic history.
The VMC exhibition presented the opportunity of re-purposing and adapting the 3D VR Theatre production content to a Web medium, which offered the potential of reaching a much wider audience. In addition, more layers of information on the objects, Inuit history and the Arctic could be included than was possible in the Theatre production.
A requirement for VMC exhibitions is that they are fully functional in Canadas official languages (French and English) using current versions of common browsers such as Netscape and Internet Explorer and that they run on both PC and Mac systems. Plug-ins must be platform independent and supported by the above browsers. Consistent with professional level Web productions, several standard technical requirements including credit and copyright information, Web accessibility requirements for people with disabilities and specifications on multimedia formats are also required (http://www.chin.gc.ca/Vmc/e_update.html).
In selecting the platform, we initially considered using several proprietary software packages. Some provided good pop-up window graphics for interactive object display and examination but did not allow an immersive museum. With others, the opposite was true.
Consequently, for Inuit 3D, we used VRML (Virtual Reality Modeling Language) as the language platform. VRML is an ISO Standard (14772-1:1997) open language and is versatile, fully programmable and widely used for "Web 3D" applications (). It allows users to navigate through a scene or "virtual world," such as a museum, and to interactively examine 3D objects.
After testing several common VRML browsers, Cosmo Player was found to provide the best viewing of the exhibition and is recommended as the VRML plug-in viewer (). QuickTime is required to view the video segments ( ). Instructions for downloading and installing both plug-ins are included on the site.
In order for viewers to experience all the interactive features in the exhibition, for PC users a Pentium with 32 MB of RAM, a 3D hardware-accelerated graphics card with 8 MB of memory and a sound card was recommended as the minimum system. For Mac users, a G3 system running OS8, with 48MB of memory allocated to Netscape (the only browser which supports Cosmo Player on the Mac) was recommended as the minimum system. In addition, it was recommended that the Internet connection should have at least a 56 Kbaud dial-up phone connection. For best viewing, a screen resolution of 1024 x 768 pixels was recommended.
Content Creation and Web Integration
To create the content for Inuit 3D, it was necessary to build a Virtual Exhibition Hall, to reformat the 3D models and audio-visual content from the 3D VR theatre production into VRML models and QuickTime movies suitable for Web presentation, and to fuse them into a seamless exhibition. As discussed above, we had to make trade-offs among the visual quality of rendered models, file size and download times. An important factor, we felt, was the fidelity to the original objects of the 3D models in the exhibition. In this regard, at the expense of longer download times, we chose to use larger file size 3D models. To compensate, we used a smaller model than planned for the Virtual Exhibition Hall. We also tested various QuickTime movie file sizes to determine which file and window size would present appropriate audio/visual fidelity.
Virtual Exhibition Hall
For the exhibition, we wanted to create a virtual space that evoked the feeling of being in a museum or art gallery. That meant high ceilings, neutral walls, lots of circulation space for visitors and a sense that one could contemplate or reflect here. After all, that is what one does in museums - one muses.
During a team discussion on the design of the virtual space for Inuit 3D, where some talked about a virtual museum and others about a virtual gallery space, the idea of a hybrid combination emerged. Generally, in galleries, objects stand largely on their own merits. The labels are minimal, the artworks are exhibited with lots of space between them, and there is minimal use of colour and texture in the architectural surround.
Museums, however, tend to a polar opposite. Artifacts are enveloped in colour, texture and, sometimes, acres of text. Orientation spaces, historical photographs, drawings, models, as well as A/V displays are often included. Our idea was to try to get the best of both worlds, to place the objects in a virtual setting reminiscent of a contemplative gallery situation while, at the same time, providing the wealth of contextualization and information-provision associated with a museum. Thus the idea of the creation of a hybrid museum/gallery Virtual Exhibition Hall emerged.
For the Virtual Exhibition Hall a simple or light 500 KB 3D model was created. As an architectural space, it consists of three thematically linked exhibition rooms (Figure 1) arranged in a circular chronological layout that has the look and feel of gallery space. Neutral walls, high ceilings, overhead lighting, floor texture, minimal signage, display plinths are suggestive visual cues to facilitate navigation. The doors were made larger in scale than normal doors to present a wider-angle view of what lies ahead in the next room
The model consists of only a few dozen primitive shapes and a few small textures which are repeated to create the floor, walls, display cases, doors and ceiling. In addition, images of photographs and prints were included to decorate the walls (Figure 2). To assist navigation, invisible bumpers were added around doors, corners and display cases to help point users in the right direction. The model was created directly in a text editor using the easily programmable and well-documented VRML language.
Figure 2: (a) View of the Palaeo-Eskimo hall. The model was kept simple using a few primitive shapes and small textures to create. Bilboard images of the small objects were placed in individual display cases and images of arctic photographs and prints were added to the walls. Clicking on an object in a display case (b) opens two new pop-up windows (c). The left pop-up window contains the 3D VRML model of the object, which can be interactively examined. The right pop-up window contains information on the object as well as links to related information on other sites.
Visitors can use one of three methods to navigate through the exhibition. For complete interactive navigation, a mouse or the directional arrow signs on their keyboard can be used. In addition, a dropdown viewpoint list can be used to guide visitors to a series of fixed viewpoints. A navigation location indicator is always visible in the lower left corner to remind visitors of their location.
One design feature, which led to considerable discussion, concerned the small size of the objects. The Palaeo-Eskimo objects, such as the 2 x 3.5 cm Tayara Maskette, are quite small and, in relation to the size of the Hall, were difficult to see from a distance.
Although it was technically feasible to graphically enlarge them, we felt it essential to present them in their true scale. To address this, similar to a traditional museum exhibition, display case pedestals were used to showcase the objects and draw the visitors attention to them. Two-dimensional VRML format billboard images of the objects are mounted on the pedestals. These images rotate about their vertical axis to face the viewer and ensure they are always visible.
The object images contain a hypertext link to the 3D model file. Clicking on an image downloads two pop-up windows; one contains the interactive 3D VRML image while the other contains a 2D image and information on the object (Figure 2b and 2c). Similarly, clicking on the images of Arctic historic photographs and contemporary prints mounted on the walls opens pop-up windows which contain information on the images. This linkage of actions occurring in the three-dimensional space with effects in the encapsulating browser serves to integrate the two technologies, exploiting the advantages of each in support of specific tasks. (The total file size of the Virtual Exhibition Hall complete with wall images is 500 KB).
3D Model Creation
Within the constraints of a Web exhibition, one primary objective was to display 3D models of the objects which represented the shape, subtle color variations, material characteristics (ivory, bone, stone, metal) and features such as tool mark details as closely as possible to the actual object. In short, the fidelity of the 3D models to the actual objects was a priority.
The 12 Palaeo-Eskimo and Inuit objects in the exhibition had previously been scanned along with a lager suite of objects at CMC in 1997 using a High Resolution Color Laser Scanner (Figure 3) developed by NRC and manufactured by Hymarc Ltd.
Figure 3: The NRC High Resolution Color Laser scanner. This system scans a low power white laser light spot (shown as a line in this photo due to time exposure effect) on an object and records the xyz shape coordinates as well as the rgb color values in high resolution and in perfect registration. This technology is currently licensed to Airus3D (www.arius3d.com).
A unique feature of this technology is that the scanner digitizes the color and shape details of objects in high-resolution and in perfect registration (Baribeau et al, 1996). This enables the rendering of very accurate high fidelity 3D models for interactive display on high-end information kiosks or in 3D VR Theatres within a museum or at a remote site connected with high-speed communications systems (Livingstone et al, 1997).
The software (PolyWorks TM www.innovmetric.com) can be used to prepare lower resolution models, which retain excellent object-model fidelity for Web display. In compressing the high-resolution models, the software computes a texture mapped compressed triangular mesh. The algorithm for the automatic generation of the texture map is coupled to the mesh vertex removal compression. When the tessellated texture map is applied to the compressed model, it generates a 3D appearance that approximates the appearance of the full resolution colored model (Figure 3).
The high-resolution model contains 443,628 polygons of shape information (lower right) in an 11.8 MB file. This model is the archival quality model used for research applications and for preparing lower resolution models for other applications. The compressed model contains 1000 polygons of shape detail (lower right) in a 1.2 K file. When the 512 x 512 texture map is applied to the compressed model, it generates a 3D appearance that approximates the appearance of the full resolution colored model (top left). Thus a close approximation to the fidelity of the high-resolution model is retained in the 3D model used for Web applications.
To select the appropriate models in terms of fidelity and size for use in Inuit 3D, a range of model sizes were prepared for evaluation. The models ranged in size from 3500 to 1000 polygons of shape information with texture maps of 512x512 pixels to 256x256 pixels. Significantly, it was decided to use a 1000 polygon model with a 512x512 texture map, instead of the smaller 256x256 texture map to represent the models. Although the higher resolution texture map meant a longer download time for each model, it clearly enabled the display of higher fidelity models in the exhibition.
Consequently, to prepare the models, each of the original 12 high-resolution files which typically contained 500,000 700,000 polygons of shape information in a 12 - 15 MB file was compressed to a 1000 polygon 512x512 texture map model and was saved as 1.2K zipped VRML (WRL) file. In total, the file size of all 12 models is 1.65 MB.
As noted above, the object images in the Exhibition Hall have an embedded hypertext link to their respective VRML 3D model files. Clicking on the object images downloads the VRML 3D object file, which appears in a smaller secondary pop-up window on the top left of the users' screen. Users can interactively rotate the object to view it from all angles similar to the walk around display case experience one has in a real setting.
In addition to the window containing the VRML model, a second pop-up window appears on the upper right of the users' screen. This window contains textual information regarding the object's discovery or creation, and further explanatory material including links to additional information on the CMC site.
Another important factor to note is that due to the archival quality of the original high-resolution files, as faster Internet connections become available in the future, Inuit 3D can be readily upgraded. Higher resolution models, which have even greater fidelity to the object, can quickly be substituted for the 1000 polygon models used in the launch.
Consistent with museum tradition, there is an orientation video at the entrance to each room to provide information on Palaeo-Eskimo and Inuit history as well as on the Arctic.
After a review of the various Internet audio/visual players available, we selected QuickTime Player for the videos. QuickTime versions are readily available and easily installed on all Windows and Macintosh operating systems particularly the older versions that are still widely used. QuickTime Player also enables streaming video presentations (i.e. the users are able to listen and view the video content while the video is being downloaded) from a 56 KBaud or higher dial-up phone connection. In addition, QuickTime editing tools are readily available, easy to use, and allow access to many compression techniques.
To prepare the videos, three 45-second segments were extracted from the original nine-minute 3D VR Theatre presentation. As these files were approximately 150 MB in size in uncompressed AVI format, for QuickTime streaming it was necessary to convert them to MOV (QuickTime) format and compress them. To determine an appropriate file size for compression, a series of smaller files were prepared using Sorenson video compression. After performing tests using modem lines and video stream files and windows of different sizes, we found that a 0.8 MB file size in a 320x240 pixel window offered a satisfactory video in terms of image quality and download time. Similar to the 3D models, while a smaller file size could have been used with a smaller window to enable a faster download time the image quality was not considered satisfactory. The original audio was compressed using a compression scheme known as QDesign Music 2.
To view the videos, visitors click on the movie projector symbol at the entrance to each exhibition room. This causes the video to download and open in a pop-up window in the upper right of the screen.
Photographs and Prints
In addition to 3D object models and QuickTime videos, imagery (JPG) evocative of the time period is aesthetically hung on the virtual walls. In the earliest time period we see images of geological formations, snowscapes and archaeological remains. The post-contact period is represented through historic photographs taken during the 1913-16 Canadian Arctic Expedition while the modern era features a quartet of splendid Inuit prints. Clicking on these images downloads and opens pop-up windows that provide information on the image as well as additional background information on Inuit artists, the print making process and the Canadian North. A bibliography including information on Inuit terminology is also included.
Navigation and Plug-in Instructions
To assist viewers in installing the required plug-ins and in navigating through the exhibition, detailed instructions on each, including instructional photographs, printable instructions and links to external help files were provided. These instructions also included information on download times based on a 56 Kbaud modem.
Download Time Information
During the preparation of the exhibition, we undertook download tests using different systems connected to T1 lines as well as cable network modems and standard to 56 and 28.8 Kbaud modems connected to telephone lines. From these tests, using a 28.8 K baud line, it typically required 15 minutes to download Cosmo Player and approximately 20 minutes for QuickTime (if QuickTime was not previously installed). For the exhibition itself, it took approximately 2 minutes to download the complete Virtual Exhibition Hall, 2-3 minutes per 3D VRML model and up to 4 minutes to download a QuickTime movie.
In contrast, home testers with a cable connection reported a download time of less than 25 seconds for the Virtual Exhibition Hall and around 10 seconds each for the 3D VRML models and QuickTime videos. Those fortunate enough to have a T1 connection found that it took about 7 seconds to download the Exhibition Hall, 3 seconds for the 3D VRML models and 4 seconds for the QuickTime videos. These times are comparable to the time required to download other Internet tools such as a new browser version, games or music files.
As the exhibit seeks to deliver both textual and graphical information to the user, the design of the Inuit3D Web site as a whole takes into consideration the relative strengths of the technologies available for delivering such information. While 3D graphics are appropriate for displaying sculptures, the available screen "real estate" can be used most efficiently if the standard Web browser is used to display text and other 2D material.
Significantly, the linkage of actions occurring in the three-dimensional space with effects in the encapsulating Web browser (and vice-versa) serves to integrate the two technologies into a seamless user experience: The 2D map of Canada's Arctic changes to indicate where the selected 3D artifact was discovered or created. The "language" button below the virtual museum itself enables users to select whether actions in the 3D museum will cause information to be displayed in English or French.
The location of these secondary display and control features is a logical extension of their function. As they pertain to the virtual museum, but are not part of the exhibit itself, their placement outside of the virtual space enables the exhibit to remain visually uncluttered.
The site contains a Feedback link which enables viewers to send comments back to the VMC. CHIN provided the following summary:
Classy, impressive, excellent and really cool represent some of the comments received frequently from visitors to Inuit 3D. Although some comments pertained to the exhibits advanced technological requirements, links and instructions to access all the required components are provided. The majority of visitors appreciated both the content and the sites superior quality and professionalism, and many who provided feedback also commented on the value of the resources provided by Inuit 3D.
As noted in the Introduction, during the VMC planning consultations it was noted that a portion of the participants had clear expectations of a three-dimensional tour of one or many museums and that some of these participants clearly explained how the Web site users would be able to control their path through a museum, allowing them to pivot and view any section of the museum and objects in the museum in 3-D. In creating, Inuit 3D, we attempted to do just that.
Despite early predictions, 3D technology has, for a variety of reasons, remained on the fringes of the Web. One of the reasons for this is a lack of compelling content. We hope that museum exhibitions such as Inuit 3D will help address this issue. Another reason relates to the need to install plug-ins and to download times. Web researchers are currently working on new platform-independent Java-based 3D viewers which promise to cancel the need to install plug-ins. At the same time, faster Internet connection systems are rapidly and widely becoming available. When these become available, 3D virtual museum exhibitions such as this will become much more viable.
As noted above, virtual exhibitions offer museums a great way to complement a real exhibition, increasing its scope and impact. With a supplementary virtual exhibition, reserve collections can be accessed (most major museums, CMC included, have the exhibition space to display only 3-5% of their collections). It allows an enriched presentation style such as scaling up the design on a cylinder seal so that it can be truly seen and appreciated and adding layers of information. Moreover, when the traditional exhibition closes and the objects go back in storage, the virtual exhibition remains as an archival record which is widely available and readily updated.
In the future, virtual exhibitions may also offer museums advantages over those of a real exhibition. For example, a curator can develop a dream exhibition, which one could never hope to pull together in the real world. Objects scattered around the globe, some too fragile to travel, some too expensive to borrow, some committed to other exhibitions or loans for research, can be drawn together into a virtual exhibition. There is no need to pay for an accompanying curator, exhibition preparators or insurance premiums. And if you dont like the exhibition flow, the layout of the galleries, the size or colour of the labels or even the lighting, alternatives lie just a mouse click or two away. It is this ability to create a virtual exhibition, to juxtapose on the screen objects from both sides of the Atlantic, that would make applications such as this of enduring interest to curators.
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