Vision Based Hand Gesture Interfaces for Wearable Computing and ...

Chapter 2. Literature Review
dynamical model (of the object velocity), which we could add to our method as
well. Depth information combined with color as in Grange et al. [52] also yields
a robust hand tracker, yet stereo cameras are more expensive and cumbersome
than the single imaging device required for our monocular approach.
Object segmentation based on optical flow (for example, normalized graph
cuts as proposed by Shi and Malik [157]) can produce good results for tracking
objects that exhibit a limited amount of deformations during global motions and
thus have a fairly uniform flow [137]. The Flock of Features method relaxes this
constraint and can track despite concurrent articulation and location changes.
2.3.3 Recognition
Recognizing or distinguishing different hand configurations is a very difficult
and largely unsolved problem in its generality. First attempts have recently been
made by Ong and Bowden [124] with fairly good results. However, to achieve the
more stringent requirements of user interface quality, robustness and a low false
positive rate are more important than recognition of the complete hand configu-
ration space from the entire view sphere. The posture recognition task becomes
more tractable for a few select postures from fixed views. Segen and Kumar’s
Shadow Gestures [153] demonstrated how heavy constraints on the scenery make
computer vision a viable user interface implementation modality: they require a
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