A popular (but often expensive) way to animate 3D characters is by using motion capture hardware. Motion capture dates back to 1915, when it was invented by Max Fleischer, involving only the use of cameras and drawings. In its early stages it was the study and capture of human and animal locomotion, known as rotoscoping. This information was used to help artists animate cartoons, such as “Koko the Clown” and “Snow White.” The pioneer in turning this work into entertainment was Walt Disney, who was undoubtedly the most successful and well-known 2D animator.
It is now used to digitally capture human movements using specialized hardware, often in the form of a motion capture suit worn by the individual. These suits vary in complexity and cost, with the most advanced suits often requiring less post-processing, such as data cleansing. There are four types of motion capture systems. The first is inertia motion capture systems, which use an array of small sensors to track the movement of joints and limbs. This data is then sent wirelessly to the host computer, which requires no external tracking hardware such as cameras etc. These suits are in the £25,000 range (Wiki 2008).
Mechanic Motion capture systems come in the form of a set of semi-rigid plastic rods containing a series of potentiometers that measure joint movement and angle. The suit is worn like an exoskeleton, with the control box located on the wearer’s waist or back. The advantages of this system are that it is free to occlude and low cost from £12,500 (Wiki 2008), making it a popular choice for small studios and educational institutes.
Magnetic The systems use a series of coils throughout the suit that measure changes in voltage and current to determine the position and orientation of parts of the suit. The advantage of this is similar to mechanical systems, in that they are not subject to occlusion or interference from reflective surfaces. However, they are vulnerable to EM and electrical interference.
The most modern and advanced motion tracking system is Organic Motions Markerless Motion Capture (MMC) System, which was introduced at the 2008 Consumer Electronics Show. Subjects are not required to wear a suit or any type of marker system. Instead, the system uses complex algorithms to identify and make sense of human movement, detecting which part of the body is which. However, it has trouble detecting subtle movements of certain areas, such as fingers and facial expressions, as reported by Wiki (2008) “These systems work well with large movements, but tend to have difficulty with fingers, face, wrist rotations and small movements. .”. As the technology of the external tracking system improves, you will certainly be able to capture every movement and expression efficiently.
Similar to traditional 2D animation, 3D animation can be created by hand. This is the cheapest and slowest way to animate a character in 3D. Also, to create realistic animation, the artist must have a good understanding of human/animal movement. It is about incorporating physics and emotion into these movements, such as the weight and personality of the characters. Both will affect the way the character moves, even in a basic walk. A crucial part of making this happen is creating good joints.
This is done by making sure the weight gradient between the bones is a smooth curve, for example a 33%/50%/66% skew for bone A. This is as opposed to a straight gradient like 25/50% /75%. which creates a hard warp, while a curved gradient results in a much softer warp. The most important thing is to add a ring of vertices that are affected by both bones. By allowing these bones to warp the furthest parts of the mesh, your creature or person will animate much better. This method should be applied to any joint. The crimping that occurs due to the nature of 3D junctions can be corrected using the Skin Morph modifier (in 3D Max). Much steeper curves can be achieved using a gradient bias of 12.375%/33%/50%/66%/87.6% for one bone. As more gradient values are added, it takes longer to set up the skin morph. This method of gradient drop can be applied to any character manipulation tool within the myriad of 3D applications available.
In my next article, I’ll walk you through the process of creating a very simple joint in 3D Max.