Most of the vision approaches have filters with equal
sizes, but cars might have different sizes or been seen from
different distances.. Therefore, we decided to have variable
size filter as shown in Figure 3. The filters are defined on
three levels and the size of the largest one is 5 x 15. The
smaller ones have portion of the whole filter. The side view
image of a car can be taken from both sides, therefore, it is
needed to have filters for both views. The left and right side
of Figure 3 deal with this issue.