August 3, 2012
Software Converts 3D Surface Models Into Action Figures For 3D Printing
|With funding from Pixar, graphics experts led by computer scientists at Harvard have created an add-on software tool that translates video game characters — or any other three-dimensional animations — into fully articulated action figures, with the help of a 3D printer.|
The project is described in detail in the Association for Computing Machinery (ACM) Transactions on Graphics and will be presented at the ACM SIGGRAPH conference this month.
Returning a virtual character to the physical world therefore turns the traditional animation process on its head, in a sort of reverse rendering, as the image that's on the screen must be adapted to accommodate real-world constraints.
Bächer and his coauthors demonstrated their new method using characters from Spore, an evolution-simulation video game. Spore allows players to create a vast range of creatures with numerous limbs, eyes, and body segments in almost any configuration, using a technique called procedural animation to quickly and automatically animate whatever body plan it receives.
As with most types of computer animation, the characters themselves are just "skins"—meshes of polygons—that are manipulated like marionettes by an invisible skeleton.
"As an animator, you can move the skeletons and create weight relationships with the surface points," says Bächer, "but the skeletons inside are non-physical with zero-dimensional joints; they're not useful to our fabrication process at all. In fact, the skeleton frequently protrudes outside the body entirely."
Bächer tackled the fabrication problem with his Ph.D. adviser, Hanspeter Pfister, Gordon McKay Professor of Computer Science at SEAS. They were joined by Bernd Bickel and Doug James at the Technische Universität Berlin and Cornell University, respectively.
This team of computer graphics experts developed a software tool that achieves two things: it identifies the ideal locations for the action figure's joints, based on the character's virtual articulation behavior, and then it optimizes the size and location of those joints for the physical world. For instance, a spindly arm might be too thin to hold a robust joint, and the joints in a curving spine might collide with each other if they are too close.
Then the 3D printer sets to work, and out comes a fully assembled, robust, articulated action figure, bringing the virtual world to life.
|Before and after. - Image Source: Moritz Bächer.|
Bächer's model does not allow deformations beyond the joints, so squishy, stretchable bodies are not yet captured in this process. But that type of printed character might be possible by incorporating other existing techniques.
For instance, in 2010, Pfister, Bächer, and Bickel were part of a group of researchers who replicated an entire flip-flop sandal using a multi-material 3D printer. The printed sandal mimicked the elasticity of the original foam rubber and cloth. With some more development, a later iteration of the "3D-print button" could include this capability.
|Image Souce: Moritz Bacher|
"Perhaps in the future someone will invent a 3D printer that prints the body and the electronics in one piece," Bächer muses. "Then you could create the complete animated character at the push of a button and have it run around on your desk."
Harvard’s Office of Technology Development has filed a patent application and is working with the Pfister Lab to commercialize the new technology by licensing it to an existing company or by forming a start-up. Their near-term areas of interest include cloud-based services for creating highly customized, user-generated products, such as toys, and enhancing existing animation and 3D printer software with these capabilities.
SOURCE Harvard School of Engineering and Applied Science
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Tags: 3D, 3d printing, action figures, computer graphics, concept design, Harvard, Moritz Bacher, patent, pixar, spore, toys
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