A more practical example

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A more practical example

Consider the sign language domain discussed earlier. Figure 4.5 shows the gloss for building. It is clear that the y value (the vertical up and down movement) for this sign is important for classification.

**Figure 4.5:** The gloss for the sign `building`, from [Joh89].
$\begin{figure}\begin{center} \leavevmode \epsfxsize =4in \epsfbox{building-gloss.eps}\par\centering\centering\end{center}\end{figure}$

A plot of the y value for an instance of the sign building, recorded from a native signer, is shown in Figure 4.6.

**Figure 4.6:** An example of the variation in the y value of the sign `building`.
$\begin{figure}\begin{center} \leavevmode \epsfxsize =5in \epsfbox{building-y.eps}\par\centering\centering\end{center}\end{figure}$

One type of event of interest is intervals when the signal is increasing. Hence we might consider developing an Increasing metafeature that would allow us to extract all of the cases where the signal is increasing. We would hope that it would pick up the three periods during which the signal is clearly increasing; from around time 7 to time 11, from time 18 to time 26 and from time 32 to time 40. However, there are some practical issues that arise when doing so.

Next: Representation Up: Practical metafeatures Previous: Practical metafeatures Contents

Mohammed Waleed Kadous 2002-12-10