Handy

An American sign language recognizer using the Leap Motion controller

Recognizes the American sign language alphabet
Presents a word to be signed to the Leap Motion
Adaptively recognizes similar signs depending on context

Theory

Several sign language letters are unique in number and type of fingers extended, e.g. L is a thumb and index finger while B is all four fingers. By recognizing which fingers are extended we narrow the number of possible signs, continuing until a single sign is reached or there are multiple signs using the same fingers. These signs are differentiated using unique key points on each sign, such as the distance between the tip of the index and middle finger to determine V or R/U, and the angle between the fingers to separate R and U.

Some similar letters, such as T and N are difficult to tell apart. There is a configurable list of similar letters that is used to resolve this ambiguity, allowing letters to be used in place of each other depending on context.