Encoded puppets for 3D animation modeling

The Interactive Geometry Lab at ETH Zurich designs a new way to move and post virtual characters.

By Jon Peddie

Trying to ma­nipulate and move a model, or an idea, that’s in 3D while dealing with a 2D screen has never been easy. Various at­tempts have been made to give design­ers a 3D control or feel that could be translated into a computer-based 3D model like Maya or SketchUp. Buttons have been added to mice, and boxes with nine knobs on them were popu­lar in the past. Today the 3Dconnexion oine of 3D controllers are prob­ably the most popular, and there are high hopes for gesture-based devices like Leap Motion.

The Space Navigator, the most popular model of 3D mouse from 3DConnexion. (Source: 3DConnexion)
The Space Navigator, the most popular model of 3D mouse from 3DConnexion. (Source: 3DConnexion)

Back in school, some of you may have played with molecule models made from sticks and balls that could be assembled to visualize and study complex molecules.

Artists use puppet-like models to visualize a per­son or animal and then try to draw it on paper or on a screen because skeletal shape deformation is one of the most popular techniques for bringing 3D characters to life.

Artists use puppet-like models to visualize characters.
Artists use puppet-like models to visualize characters.

Something similar has taken shape (pun intended) in the Interactive Geom­etry Lab at ETH Zurich.

Professor Olga Sorkine-Hornung and her students have come up with a clever way to manipulate virtual shapes, like animated characters on a computer screen. They have developed a joystick-like system to move and pose virtu­al characters made up—similar to the molecule models—of modular building blocks. An artist can assemble these blocks into an approximate represen­tation of any virtual character, be it a human, a dog or an elephant, or even just single body parts like arms or a hand.

This is a full-tech system. It uses 3D printed animated joints that have three axes of measurement using Hall sen­sors and small magnets embedded in the joints. They are realizing angular accuracy of about 1 degree, and angu­lar precision of less than 0.1 degree; the sensors are read at 250 Hz.

The 3D joystick to manipulate virtual puppets is created from 3D printed parts. (Source: ETH Zurich)
The 3D joystick to manipulate virtual puppets is created from 3D printed parts. (Source: ETH Zurich)

The researchers have made the blue­prints for their device’s building blocks available as Open Hardware, hoping to foster further research. “Anyone can 3D-print the separate units and with the help of an engineer integrate the elec­tronics,” said Sorkine-Hornung.

Also, a set of 25 ready-made building blocks might be made available com­mercially at some point. Sorkine-Hor­nung says they are going to present the device at Siggraph.

An artist can assemble a character from a library of body parts. (Source: ETH Zurich)
An artist can assemble a character from a library of body parts. (Source: ETH Zurich)

What do we think?

This is one more tool in the animator’s kit that will find many adherents, and probably become very popular in schools. Ani­mation is such a tricky job, no one tool can satisfy all the needs any more than can one program.