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Animating signs of a sign language requires on
demand bone movement of a signing avatar based on single
posture, multi posture signs for the words with a known sign,
and fingerprinting signs for representing unknown words
character by character. Ordering and sequencing of different
types of signs corresponding to words/phrases of a typical
spoken/written language are the most essential features of a 3D
signing avatar. Typical techniques of signing avatar animation
are video sequencing of signs of corresponding words of a
sentence, or replaying movements of signs with motion-captured
animation sequences. This paper presents a multi-facet 3D
avatar and an animation framework that supports the definition
and animation of sign gestures without motion capture
hardware. The system is developed to accommodate any sign
language, but a prototype has been built for the Sinhala sign
language (SSL). The avatar system is initially built with 10
bones per arm. It is then extended to 29 bones per arm to
improve flexibility in palm and fingers. The avatar animation
framework is capable of signing 200 plus gestures of both single
and multi posture SSL signs and 40 fingerprinting SSL signs.
Speed and uniformity of the sign gesture animation is achieved
by the automatic calculation of intermediate sequences of arm
movements of signs within a given number of frames, or with a
user defined increment value per bone. Animation system also
supports the definition of fingerprinting signs, with a user
defined tag set corresponding to the alphabet of any given sign
language.
