31 May 2010

Depends on how you look at it

Tom Malzbender's presentation to the Smithsonian Associates on the Antikythera Mechanism focused on Polynomial Texture Mapping. PTM has its roots in computer graphics techniques for rendering artificial surfaces (in game applications, for instance), but in this case it's used to enhance surface detail of physical artifacts.

The process starts with high-resolution image acquisition from multiple POVs: the object to be imaged is mounted in a domed frame fitted with dozens of digital cameras. (The contraption looks something like the Trinity device, to me.)

Once the images are captured, software apps can manipulate the apparent direction of the light source (to realize the artist's "raking light"), and more astonishingly, the apparent surface characteristics (e.g., reflectivity) of the artifact.

The application of this technology to recovering lost surface detail on chunks of bronze that have been sitting in saltwater for two millennia is a natural. Mazlbender and John Seiradakis report that the metal plates that comprise the Antikythera Mechanism's "user's manual" have revealed an additional 2,200 characters, thanks to PTM techniques.

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