Some signs are bigger than others and that they differ in their location around the body. So an obvious thing to think of as a feature is the bounding box of a sign.
This can be seen in figure 5.1. As can be seen, a total
of six features are required to characterise the bounding box:
and 
.
Figure 5.1: The bounding box for the sign same.
In the above, we consider the sign same. The whole sign
fits in the box represented by 
and
.
The calculations for a bounding box are relatively simple. Again,
given a sequence 
, it is clear that the bounding box
is:
