To design a gestural interfaces
Creating a gesture set and defining a gesture-command mapping
Laban feature
Laban Movement Analysis (LMA)
The LMA system provides models for the interpretation of movement, its function and its expression through 4 components: − Body (what) − Effort (how) − Space (where) − Shape (relation with the environment) Effort has 4 Factors thought as a continuum with 2 opposite ends: − Weight : strong, light − Time : quick, substained − Space : flexible, direct − Flow : bound , free
Choosing the device
Structured light
Depth from focus: the further the blurrer Depth from stereo: view different from different angle
Time of Flight (TOF) imaging:
Use phase difference between the radiated and reflected IR wavesis to compute the distance of objects.
Building a recognizer
Rubine algorithm
There is a set of C gesture classes (from 0 to C-1). Each class is specified by example gestures. Given an input gesture g, determine the class to which g belongs.
Statistical gesture recognition is done in 2 steps: first a vector of features f is extracted from the input gesture. Then, f is classified as one of the C possible gestures.
Recognition of 2D single-stroke gestures with a clear start and a clear end
$ Family (Template-based)
$1 one stroke recoginzer
对输入的手势轨迹进行重新采样，将采样轨迹中心点与x轴的连线旋转到0度，将旋转后的手势缩放到标准的正方形大小并进行手势平移。然后，对处理过的手势和搜索匹配模板使用“黄金选择搜索”(GSS)，得到每个模板的最佳匹配得分。得分最高的手势是最终识别的手势
- Resampling the point path (gesture trajectory)
- Rotate once based on the « indicative angle » (parallel to x axis)
- Scale and traslate
- Recognition ( Golden Section Search (GSS))
Limitations: - No way to distinguish a rectangle by a square
- No way to distinguish an ellipse by a circle
- No way to distinguish the orientation of an arrow
DTW (Template-based)
Machine Learning approaches: kNN, SVM…
Providing a teaching method
When
Feedback vs feedforward information: − Feedback: informs about the effects of the actions already performed
− Feedforward: provides information prior to any action, i.e. showing or anticipating the possible future actions.