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Virtualizing Reality
Canada’s National Research Council is visualizing the world in 3D
by Marc Rioux

Three-dimensional digitizing and modeling is an emerging field of data imaging techniques used to create 3D copies of physical objects, environments, and even human beings in digital space. At the National Research Council’s Visual Information Technology Group (VIT), we refer to this process as “virtualizing reality”. But why virtualize reality? The answer: because the 3D visualization of real objects and environments can now be used to bring the mountain to Mahomet. From virtual tours of closed historical sites, to the sharing of digitized objects such as fragile fossils or cuneiform tablets between scientists, to digital scanning in space, 3D digitizing is opening up new possibilities for the study of science, culture, and art. This essay will introduce the research activities of the Visual Information Technology Group, and show how new and advanced 3D imaging techniques are allowing us to create digital representations of the real world.

3D Digitizing and Modeling
The 3D digitizing process combines a high resolution polychromatic laser beam scanner, an imaging system, and signal processing to measure and record the shapes of real physical objects as 3D coordinates. Usually about ten overlapping scans are taken all around an object. Then these scans are combined to create a full 3D virtual geometric model. The digitizer also captures colour and texture information, which is used to generate a final colour model that is true to the original.

At this point, the physical object has been recorded as a list of numbers in a computer’s memory. The next step is to visualize that list of numbers — to construct a virtual view of the physical object. This is done using standard computer graphics software. Synthetic illumination is applied to re-create images similar to what you would witness in reality if viewing the object under an equivalent source of light. Threedimensional reconstructions are also available using special stereo vision glasses. Most software today allows real-time rotation of objects in stereo, or real-time navigation around stationary objects positioned in digitized environments.

Visualizing Virtual Time Travel
High-end visualization options, such as virtual reality rooms, are also used to create opportunities to “virtually visit” digitized historical sites — sometimes restored to their past states of glory. At the NRC we call this “cultural heritage recording”, or “virtual time travel”.

For example, in collaboration with the University of Lecce, an entire thousand-year-old Byzantine crypt (Saint Cristina in Carpignano Salentino, southern Italy) has been digitized and modeled. This visualization technique has enabled the digital restoration of faded wall-writings that are almost invisible at the actual physical site today. A complete digital restoration of the site could potentially be made using historical documentation for reference, and by applying techniques such as colour and contrast enhancement to the digitized wall-paintings in order to simulate their original qualities.

Aside from this kind of virtual restoration, the digitization of important historical and archaeological sites can allow people to visit a site even after public access has been closed to reduce the destructive impacts of constant tourism. Other important historic sites visualized by NRC technology in this way have included St. James’ Tomb in Israel, frescoes at the Hippodrome, an Eighth Century Italian abbey, and sites along the Yangtze River which will be inundated by China’s Three Gorges Dam.

In 1998-99, the NRC also collaborated with Stanford University and the University of Washington on the Digital Michelangelo Project. In this initiative, NRC technology was used to create high-resolution 3D models of several of Michelangelo’s sculptures — notably St. Matthew, the four Unfinished Slaves, the seven statues of the Medici Chapel, and the David — in Florence and Rome. These computer visualizations allow art lovers and historians to study the statues from any angle, facilitating the examination of perspectives and features that are sometimes very hard to view in reality. (For example, it is difficult to study subtle details on the face of the David in person, because his head is 23 feet in the air.) Aside from virtual tourism, the high resolution images have also been used to study the microscopic signature of the artist’s chisel marks, and have revealed details such as damaged areas and old graffiti etchings not easily visible to the naked eye. Other microscopic information will be used to measure the effects of deterioration on the sculptures, and to help plan future cleanings and restorations.

More recently, in 2001 the NRC created the online Inuit 3D exhibit with the Canadian Museum of Civilization. This enables people to visit a museum dedicated to Inuit history, and ancient and contemporary Inuit art, using their home computer. Digitized objects are distributed in a virtual museum space as you would find them in a real museum. Navigation tools allow the museum-goer to move about the gallery and view objects on display. Viewers can click on the objects to obtain historical background and detailed 3D models that can be rotated for close examination.

In yet another collaborative project (with the Carleton University Department of Earth Sciences), the NRC recently demonstrated its 3D digitizing technology in the field of palaeontology. 3D models were made of fossilized dinosaur bones using the same polychromatic scanning technique described above. One of the benefits of this application is that 3D digitized models have the potential to eventually replace actual physical specimens in some fossil research. Palaeontologists often share unique specimens with one another across large distances for the purposes of study and classification. But with 3D modeling at their disposal,scientists will now have the option of sending high-resolution 3D images instead, avoiding the need to expose fossils or costly replicas to the physical dangers of excessive handling and transport. The same preservation strategy has also been applied to cuneiform tablets and other fragile cultural artefacts.

Virtualizing the Body: Cleopatra and Caesar
3D digitizing technology can also be used to capture the images of human beings, a feat recently accomplished by the CAESAR (Civilian American and European Surface Anthropometry Resource) project, an international collaboration between corporations and governments which scanned and collected the 3D data of more than 5000 human subjects in North America and Europe. Such statistics, once compiled into databases, have uses in both industry (eg., the design of workstations, automobiles, cockpits and clothing to accommodate a range of body types) as well as security.

NRC labs participated in the project by developing and supplying Cleopatra, a 3D database management tool designed to allow users to visualize and navigate a database of human subjects. Cleopatra organizes scanned human images according to 3D geometrical features of the human form (eg., the length of a right arm) and other demographic data, and groups individuals according to similar physical attributes.

In a standard search of the database, the user can click on a shape (eg., the image of a whole full-body scan of a particular person) and then enter it in a “search box” (similar to that of a text search engine like Google). Clicking “Search” starts a similarity classification. The results bring up the database entry with the closest physical body shape first, then the second best match, and so on until you reach the end of the database.

Virtualizing the Body: Cleopatra and Caesar
3D digitizing technology can also be used to capture the images of human beings, a feat recently accomplished by the CAESAR (Civilian American and European Surface Anthropometry Resource) project, an international collaboration between corporations and governments which scanned and collected the 3D data of more than 5000 human subjects in North America and Europe. Such statistics, once compiled into databases, have uses in both industry (eg., the design of workstations, automobiles, cockpits and clothing to accommodate a range of body types) as well as security.

NRC labs participated in the project by developing and supplying Cleopatra, a 3D database management tool designed to allow users to visualize and navigate a database of human subjects. Cleopatra organizes scanned human images according to 3D geometrical features of the human form (eg., the length of a right arm) and other demographic data, and groups individuals according to similar physical attributes.

In a standard search of the database, the user can click on a shape (eg., the image of a whole full-body scan of a particular person) and then enter it in a “search box” (similar to that of a text search engine like Google). Clicking “Search” starts a similarity classification. The results bring up the database entry with the closest physical body shape first, then the second best match, and so on until you reach the end of the database.

Seeing in Space
The NRC has also built many 3D digitizing prototypes for application in fields like mechanical engineering, robotic welding, industrial inspection, and also space applications. The latter project began in 1987 in collaboration with NASA, the Canadian Space Agency, and Neptec. The resultant scanner technology was flown aboard the Space Shuttle in August 2001. It successfully demonstrated its laser tracking and imaging capabilities under difficult light conditions — for example, the presence of the Sun in the background. The long-term goal of this project is to provide the Canadarm with a laser scanner “eye” for use in robotic tasks such as space station assembly and the repair and inspection of satellites.

Scanning the Horizon: Future Search Trends
The same 3D laser tracker system developed for space is now being used in the NRC’s lab to research potential applications in medicine.For example, we are collaborating with the Ottawa Cancer Institute to demonstrate the application of our scanner during radiation treatments.

The scanner would be used in combination with body-penetrating imaging techniques (such as MRI) to provide real-time data about the 3D location of tumours underneath the surface of a patient’s skin. This would allow constant repositioning of the patient during radiation therapy, in order to maintain radiation exposure to the tumour and the tumour only.

Other future NRC projects will see the development of 3D digitizing techniques for capturing the shape and colour of translucent materials, transparent and reflective surfaces, and even objects with fluorescent properties. The VIT group is also exploring new software tools for creating virtual reality displays that will have applications in fields such as visual communication, e-commerce and remote monitoring.

A physicist trained at Laval University, Marc Rioux is Principal Research Officer of the National Research Council of Canada’s Visual Information Technology Group. He has been developing 3D digitizing and modeling techniques for a wide range of applications since joining the NRC in 1978.

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