Improved CNN-Based Marker Labeling for Optical Hand Tracking.

Hand tracking is essential in many applications reaching from the creation of CGI movies to medical applications and even real-time, natural, physically-based grasping in VR. Optical marker-based tracking is often the method of choice because of its high accuracy, the support for large workspaces, good performance, and there is no wiring of the user required. However, the tracking algorithms may fail in case of hand poses where some of the markers are occluded. These cases require a subsequent reassignment of labels to reappearing markers. Currently, convolutional neural networks (CNN) show promising results for this re-labeling because they are relatively stable and real-time capable. In this paper, we present several methods to improve the accuracy of label predictions using CNNs. The main idea is to improve the input to the CNNs, which is derived from the output of the optical tracking system. To do so, we propose a method based on principal component analysis, a projection method that is perpendicular to the palm, and a multi-image approach. Our results show that our methods provide better label predictions than current state-of-the-art algorithms, and they can be even extended to other tracking applications.