Photographs and text by Marc Levoy
March, 2004
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This replica was made by Gentle Giant Studios of Los Angeles using a 1.25-million polygon computer model generated by the Stanford Digital Michelangelo Project. Their pipeline consisted of a thermojet wax printer to make a master (shown above under construction), followed by a latex molding and casting procedure. The final replica, which stands 15 inches tall, is made of plastic resin, although other materials could have been used. The finish is a light matte gray (the photographs above are a bit too yellow). As sculptors know, off-white usually looks better than white because it reduces interreflections in concavities, in this case improving the visibility of David's musculature.
During construction of the master, Gentle Giant performed a few "touchups" in wax. They say that the facial features were not involved in this step. Their most extreme touchup was reportedly to the hair on top of his head, which they sharpened a bit to compensate for 400 years of rain-induced erosion of the original statue. Franca Falletti, director of the Galleria dell'Accademia in Florence, has stated a slight preference for not touching up the master. After all, she says, this is part of the history of the statue. Thus, if we have an opportunity to begin again from the polygon model, we might avoid performing any touchups.
Interestingly, when we began the Digital Michelangelo Project in 1998, a carver in Pietrasanta (a famous center of marble quarrying) warned us that, when you make a reduced-scale replica of a statue, you must soften its features; otherwise, it appears precious and cartoony. Well, our replica of David does look a bit too angular when viewed in person, especially around his face. However, the photographs above look fine, because they don't give away their scale. I've also measured the replica with a micrometer, and it's faithful to our computer model, which although not perfect is certainly accurate enough for a replica of this size. So I guess the carvers were right!
For comparison to our scan-based replica, the photographs below show replicas one can buy in Florence. The example at left, which stands 3 feet tall, was made by Professor Gianelli of Egregia Studios, Volterra, and was found in The David Shop on Florence's Via Ricasoli. Except for slight errors in the angle of the head and the shapes of the lips and brow, it looks pretty good. The example at right, 16 inches tall, was bought from a vendor in the Florence street market. Like many inexpensive replicas of the David, his belly looks sucked in. Click here to read my conjecture on how Michelangelo avoided this unsightly effect.
Our replica is not yet for sale to the public, although it eventually will be. (In fact, we're currently looking for a distributor.) Meanwhile, you can study our polygon model by downloading ScanView, our client-server software system that permits the public to fly around our computer models - no license required. The particular model of the David that is embedded in Scanview is the same one used to generate the replica shown above. Well, except for some "special modifications" we made to each model, effectively watermarking them so that we can identify illegal copies of either our physical replica or our ScanView model. We discuss this issue in our SIGGRAPH 2004 paper on protection of 3D content. A shortened version of this paper appears in the June 2005 issue of CACM, with the third image above reproduced on the front cover.
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| A good hand-made replica | Not so good |