Hand animation models for surgeons
Researchers at the University of British Columbia (UBC), Canada, have developed new computer animated models of the hand which show how the muscles and tendons function while moving. This new software uses 'anatomical data from medical images to model the 17 bones and 54 tendons and muscles of the hand and forearm.' With the help of this graphics software, surgeons will soon be able to reconstruct damaged hands more effectively. This work has been presented at the SIGGRAPH 2008 conference in Los Angeles on August 15, 2008. But read more...
You can see above a screenshot of the UBC hand simulator. "Fixed constraints are shown in cyan, sliding constraints in green, and surface constraints in maroon. Surface constraints allow the strands to move axially as well as laterally. The input animation target is shown in wireframe." (Credit:UBC)
This research work has been done at UBC's Sensorimotor Systems Laboratory. The team was composed of Shinjiro Sueda and Andrew Kaufman, under the supervision of Professor Dinesh K. Pai.
For the graphical interface, the research team has chosen to implement a plug-in for Maya (developed by Autodesk, Inc., San Rafael, CA). You can see above this Maya interface with their custom shelf. "Strands are shown in blue, and constraints are shown in green." (Credit:UBC)
Here is how Sueda describes the team's approach to New Scientist. "'Motion capture is data driven -- you just capture the data and play it back,' says Sueda. 'Our approach is a simulation in which the starting point is the physics of muscle and tendon movement.' Sueda's team also clothed their virtual muscles and tendons in a layer of skin. Just like real skin its shape depends on the anatomy beneath it. 'The parameters to control the deformation of the skin aren't biomechanical – it's just cosmetic,' says Sueda. But because the underlying controlled muscles and tendons are accurately placed, the result is a hand animation that is highly realistic."
For more information, here is a link to the project home page. You'll see that the results of this work are included in the Proceedings of SIGGRAPH 2008 under the name "Musculotendon Simulation for Hand Animation." Here is the abstract. "We describe an automatic technique for generating the motion of tendons and muscles under the skin of a traditionally animated character. This is achieved by integrating the traditional animation pipeline with a novel biomechanical simulator capable of dynamic simulation with complex routing constraints on muscles and tendons. We also describe an algorithm for computing the activation levels of muscles required to track the input animation. We demonstrate the results with several animations of the human hand."
From the project page, you'll have access to a 10 MB movie and to the full paper (PDF format, 8 pages, 1.53 MB) presented at SIGGRAPH 2008. The illustrations in this post have been extracted from this document.
Here are the conclusions of the paper. "We have developed a method for efficient biomechanical simulation of subcutaneous tendons and muscles. The simulation is incorporated into a traditional animation pipeline and can automatically generate secondary motion of the skin. We are able to produce dynamic simulations with complex routing constraints that were previously not tackled in either the graphics or the biomechanics communities. We have also developed a novel controller that automatically computes the muscle activation levels, given some target movement of the skeleton. We demonstrated the effectiveness of our approach by simulating the musculotendons of the human hand."
The researchers also plan to use their new method to other parts of the human body. "Other than the hands, our method should work well with areas where muscles and tendons are near the surface with little subcutaneous fat, such as the feet, neck, forearms, and hamstrings. However, more work needs to be done before it can be applied to areas of the body with volumetric muscles, such as the shoulder or the spine."
Sources: Colin Barras, New Scientist, August 14, 2008; and various websites
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