We present two real-time hidden Markov model-based systems for recognizing
sentence-level continuous American Sign Language (ASL) using a single camer
a to track the user's unadorned hands. The first system observes the user f
rom a desk mounted camera and achieves 92 percent word accuracy. The second
system mounts the camera in a cap worn by the user and achieves 98 percent
accuracy (97 percent with an unrestricted grammar). Both experiments use a
40-word lexicon.