3D Visual Detection of Correct NGT Sign Production

A 3D visual hand gesture recognition method is proposed that detects correctly performed signs from stereo camera input. Hand tracking is based on skin detection with an adaptive chrominance model to get high accuracy. Informative high level motion properties are extracted to simplify the classification task. Each example is mapped onto a fixed reference sign by Dynamic Time Warping, to get precise time correspondences. The classification is done by combining weak classifiers based on robust statistics. Each base classifier assumes a uniform distribution of a single feature, determined by winsorization on the noisy training set. The operating point of the classifier is determined by stretching the uniform distributions of the base classifiers instead of changing the threshold on the total posterior likelihood. In a cross validation with 120 signs performed by 70 different persons, 95% of the test signs were correctly detected at a false positive rate of 5%.