The Making of a Massive Model
(Targeted News Service Via Acquire Media NewsEdge) NEW YORK, April 18 -- The American Museum of Natural History issued the following news release: Fabricating the life-sized model of the sauropod Mamenchisaurus hochuanensis at the center of the new exhibition The World's Largest Dinosaurs (http://www.amnh.org/exhibitions/wld) is a very big job: the model measures 60 feet long and stands 11 feet high at the shoulder; the neck alone is nearly 30 feet long.
But it's all in a day's work for sculptor Hall Train and his colleagues at Hall Train Studios in Mississauga, Ontario, Canada, a team that has made everything from singing Hogwart's frogs for the Harry Potter theme park in Orlando, Florida, to untold numbers of scientifically accurate dinosaur and other animal models for museums across North America.
Essential to the success of designing a huge creature that no human has ever seen is working closely with the exhibition curators, Mark Norell (http://www.amnh.org/exhibitions/wld/about-the-curators.php), chair of the Division of Paleontology at the Museum, and guest co-curator Martin Sander of the University of Bonn, Germany.
"We communicate over the internet a lot," says Norell, showing a typical email in which Train sent him an image of a small sculpture he had made, along with a question about the exact angle of the head. "The internet has made it much easier, sending pictures back and forth." Such refinements go on right down to the final finishes and may even continue afterward if adjustments are needed to accommodate different venues when the exhibition goes on the road.
Along with the constant scientific vetting, creating the model of Mamenchisaurus involved a complex combination of computer imaging, mechanical processing, and skilled, hands-on work.
"While we have created so many highly realistic models of living and extinct animals-even mythical dragons and unicorns-creating an enormous life-sized sauropod to take center stage is a monumental, fascinating undertaking," says David Harvey, senior vice president for Exhibition. "Coordinating talented exhibition designers and preparators with key scientists, engaging specialized fabricators, and keeping an eye on scientific accuracy and educational goals-this one really pulls out all the stops." One of the biggest technical challenges was, naturally enough, size. In traditional modeling--a technique pioneered by the Museum's own Carl Akeley in the early 20th century--a life-sized form is sculpted in clay over a metal or wood skeleton, with as much textural detail on the exterior as possible. Then, plaster is poured over the sculpture, left to harden, and split open to serve as a template for a final, lightweight papier-mache or resin model that can be painted and finished or, in the case of real animals, fitted with actual skins. The original sculpture is generally discarded.
Theoretically, that method could be used for any size model. Train himself has used it for many projects in the past, substituting silicone, polyester resin, and fiberglass for the plaster template and resin and fiberglass for papier-mache. But increasingly sophisticated computer software has made the need for an original true-to-size sculpture unnecessary.
For the Mamenchisaurus, Train did make a real sculpture-but a relatively tiny 5-foot-long one, made of polymer clay that he baked into a hard plastic. He then made an image of it with a special scanner, built by Arius 3D. This 3D computer model was scaled up for size and then "broken down" digitally into manageable sections that formed the basis for Styrofoam templates or molds for the nearly 100 pieces that were eventually fashioned into the final super-sized model. The 3D scan of the sculpture was also used to design an interior armature or "skeleton" for the actual model made, according to those specifications, out of steel and aluminum at Heartland Scenic Studio in Omaha, Nebraska. Train's original sculpture can be seen in an interactive feature designed by the Museum's exhibition media team in which visitors look through a viewer to see the model sport different skin color schemes. Train also created stand-alone 3D models of the sauropod's heart and lungs.
Factored into the final design of the large model were two varying views. One side displays underlying biological features: muscles, ribs, vertebrae. At the center, a smooth white surface serves as a screen for a projected animation--produced by Helene Alonso, head of the Museum's exhibition interactives and media team--which delves deeper into the creature's internal organs to show the heart, lungs, and digestive and other systems at work. The opposite side is simply fleshed out with skin, which presented another challenge for this project because of the texture of Mamenchisaurus skin, the feel of which Train likens to an ostrich's leg.
"Dinosaur skin is like myriad pebbles, each a different size," Train explains.
To achieve such finely detailed texture, a digital artist in Train's Cork, Ireland, studio used a computer sculpting program called ZBrush to create an "infinite digital dinosaur skin" that he could apply all over the 3D computer model for the most realistic effect. "You have to create a graphic version of what the skin looks like," Train explains. "Then you can manipulate it, skew it, compress it, expand it, get it to do all the things a dinosaur's skin should do." In what is literally cutting-edge technology, the completed computer files were used to direct the movements of a mechanical router within a tenth of a millimeter to carve all the sculptural details, including the highly realistic skin texture, onto the surface of the actual Styrofoam molds. The processed molds were shipped to the Museum's Exhibition Department's vast studio on the fifth floor, where they were lined first with color-stained epoxy resin--the flexible, super-strong stuff of fighter planes--and then two layers of epoxy-impregnated fiberglass. Once cured, the lining was released by face-masked staff working in a blizzard of pulverized Styrofoam into perfectly textured pieces of the dinosaur model. To complete the form, metal brackets, wooden buttresses and rare-earth magnets were used to fuse the pieces together. Finally, visible seams were covered and gaps, if any, filled in with resin, and the model was painted and rubbed with diatomaceous earth for a final, natural effect.
"One challenge was that we never saw the Mamenchisaurus as a whole until all the pieces were set up in our gallery during installation," explains Michael Meister, director of exhibition design. "It's only then that we saw the work that had taken place over the year come together." The finished model weighs about 800 pounds, roughly half of that accounted for by the model's interior aluminum armature. In real life, the creature would have weighed 13 tons! Its long neck was lightened by the presence of air sacs within the vertebrae, a key feature that made such extreme anatomy possible. The model lacks this advantage so a barely visible length of aircraft cable helps secure the neck to the ceiling.
Because the model will eventually travel with the exhibition to other venues, a removable section of neck allows for an adjustment in height of the head from 15 feet down to 11 feet above the ground to accommodate lower ceilings. For the same reason, consideration was given to the ease of breaking the model down, shipping it, and reassembling it. This model will disassemble into about 30 discrete sections and arrive at each new location with a detailed instruction guide and helpful photographs for the local crews who will work under the supervision of a Museum staffer.
"All the big work was at the front end," says Train. "It goes together like a big plastic model, like an airplane kit." As for nicks or scratches that happen along the way? The model comes with its own touch-up kit, too.
A version of this story originally appeared in the Spring issue of Rotunda (http://www.amnh.org/join/rotunda/AMNH_RotundaSpring_2011.pdf), the magazine for Museum Members (http://www.amnh.org/join/).
TNS C-NiskSa71- 110419-ns-3346526 71NisakarSahu (c) 2011 Targeted News Service
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