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Issue: Volume 33 Issue 6: (June 2010)

Viewpoint


Gergely Vass

Early Motion-capture Techniques

To master the skill of creating imaginary characters or natural scenes—regardless of artistic style—painters, sculptors, and graphic artists spend a great deal of time replicating reality by working from models, landscapes, or other references. It is not any different for animators: One has to understand and completely embrace human or animal motion to be able to create expressive, stylistic, or realistic-looking animations.

To study the mechanics of a talking face, only a mirror is needed; a galloping horse or a running cheetah, however, is a more complicated subject. Stepping through video sequences or 3D motion-captured data could be essential for learning such complex motion—without good references, the subtle nuances of the movement are impossible to identify. But where should we look for quality references? There are some fine albums published more than 100 years ago that you should check out first!

The demand to capture animal and human motion emerged way before computers or even animation and motion pictures were born. Artists, doctors, and scientists were desperate to find out how different animals move, how birds and insects fly, or how cats manage to always land on their feet. One problem of particular interest was the locomotion of four-legged animals. As later research has proved, all four-legged animals have the same walking pattern for maximum stability. However, a lot of old paintings showed running horses with all four legs stretched out, a pose that never occurs during any type of gait. Interestingly, horses and dogs in the shape of toys, sculptures, book illustrations, and stuffed animals are often depicted incorrectly.

 
The famous photographic sequence by Eadweard Muybridge, “The Horse in Motion” (1878).

In 1872, Leland Stanford, governor of California, businessman, and race-horse owner, set off to find the answer for the popularly-debated question of the time: Did all four hooves of a horse leave the ground at the same time during a gallop? Supporters of one side believed that one leg has to provide support at any moment during the gait, but Stanford (and others) claimed the contrary, and wanted scientific evidence to back his belief. He commissioned the English photographer Eadweard Muybridge to develop some technique to capture the moment. Since motion-picture cameras did not exist at that time, Muybridge assembled a device with a special electrical trigger mechanism and custom chemical formulas for processing, and managed to photograph Occident, Stanford’s race horse, completely airborne in 1877. (This can be seen in the famous 1878 photographic sequence by Eadweard Muybridge called “The Horse in Motion.”)


Bottom: An incorrect depiction of horse gaits on the painting “Le derby d’Epsom” by Théodore
Géricault (1821).

Expanding the experiment—still funded by Stanford—Muybridge devised a new (and, arguably, the very first) motion-photography, or chronophotography, scheme involving 24 high-speed cameras positioned side by side and covering 20 feet of a long shed. Using innovative ideas to release the shutters as the horse (or other subjects) passed in front of the cameras, or alternatively by a clockwork mechanism, he created photographic sequences of a wide variety of animals and athletes in motion. The images were not of particularly good quality, but the wood engravings based on them were successfully published in scientific and photographic journals. Muybridge ultimately produced more than 100,000 sequence photographs, of which approximately 20,000 were reproduced as collotype prints, and the reader is likely to find multiple albums containing these on the shelves of nearby bookstores—invaluable references for all animators. 

 

Another significant figure of early motion capture, and a friend and competitor of Muybridge, was Étienne-Jules Marey, a French scientist and chronophotographer. He was obsessed with human and animal motion, and developed new, innovative techniques to aid his studies. His revolutionary idea was to record several phases of movement on the same photographic plate. In order to achieve this, he needed a fundamentally new kind of instrument, and built his high-speed “chronophotographic gun” in 1882 that was capable of shooting 12 consecutive frames a second.

Using his device—which he later improved significantly—he studied horses, birds, dogs, donkeys, sheep, elephants, fish, and more. He was the first to capture how birds and insects fly—a significant accomplishment employed by aviation engineers not much after. Marey also conducted a study about cats always landing on their feet, and found that without any external force, they are indeed capable of twisting their body in air. Chickens, rabbits, and puppies were subjected to the same test, but only the rabbits came out on top....

Being a man of medicine, Marey became fascinated by the internal movements of the body and studied blood circulation, respiration, heart beats, and skeletal movements. For the latter, he used a similar technique to current optical motion capture: He attached reflective markers to the joints of actors wearing a black suit so he could capture the skeletal movement during walking and running cycles. While Muybridge was primarily a photographer with great engineering and scientific skills, Marey was an educated scientist executing innovative measurements. Both these men and their colleagues had a great influence on photography, medicine, aviation, engineering, and other sciences, as well as art—including animation and motion pictures. They produced countless photographs of human and animal motion, perfect references for computer animators.

 

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