Specifying Gestures by Example

SPECIFYING GESTURES BY EXAMPLES

Dean Rubine

Information Technology Center

Carnegie Mellon University

Pittsburgh, PA

Dean.Rubine@cs.cmu.edu

Hola! I'm going to give a short summary of the above mentioned paper. At the end, I'll express my view and opinion. 

The author, Dean Rubine, talks about GRANDMA, a toolkit that allows users to define gestures on direct manipulation surfaces and associate them with certain actions. The motivation for the project came from the fact that most of the systems using gesture recognition required users to hand- code the gesture- recognizer and this was a difficult and a complicated task. The author also talks about GDP, a gesture- based drawing program built using GRANDMA.

GDP

An example usage of GDP is as follows:

Figure 1

In the above example, the user draws a rectangle by making a 'L' gesture. An ellipse can be created by starting at the center of the ellipse and then making a circle. Part (d) shows how to "pack" multiple views together which enables the user to treat them as one object. Part (e) shows how to make copies of a drawing. Part (f) demonstrates the rotation scaling features. As it can be seen, it is very convenient to work with gestures using this system. Note that all the gestures are single- stroke.

Figure 2

Figure 2 shows how the class hierarchy of GDP system. The author explains the above diagram in detail in the paper. Then he proceeds to explain how sketch- recognition is done in the GRANDMA system.

When the gesture is made, all the points are recorded along with a time- stamp, that is, the time at which the points were drawn. 

Figure 3

Now, a set of features is constructed for the gesture. There are 13 such features as follows:

Figure 4

The above mentioned features are calculated for a gesture and then they are used to match the gesture with other predefined gestures already stored. The author explains how this statistical comparison is done. The evaluations show that this algorithm is very effective. It can be extended to support Eager Recognition and Multi- finger recognition. 

In my opinion, this can be a very useful tool for people who do not have a lot of experience in gesture programming. It is very easy to build a UI that supports gesture recognition using GRANDMA. I believe that  extending this framework to support more complicated gesture- recognition can prove to be very useful.

I used the following sources for this blog post:

[1] Proceeding SIGGRAPH '91 Proceedings of the 18th annual conference on Computer graphics and interactive techniques. Pages 329-337. ACM New York, NY, USA ©1991

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