Developing Quality Metadata

39

Calculate Centroid of Area

There are some complex formulae and the engineering approaches that are well suited to handling regular shapes that can be simplified.

For a postal region, the irregular shape can be divided into a low-resolution grid and the average worked out in X and Y using a numerical method. We can grid this as shown in Figure 39.

Figure 39 Gridded polygon

First we can consider the horizontal. The top row has cells 5, 6, and 7 filled. The total is 18 and the average is 6. We add all the horizontal coordinates together and divide ...