The Decompose to Convex Parts operator splits area objects into smaller areas automatically. Each smaller area created will be a convex hull for the locations it encloses. This operator is often used to split area objects into smaller areas to allow computations or to create centroids that fall within areas.
Given an area at left the Decompose to Convex Parts transform will split it into smaller areas as seen at right. Each smaller area is a convex hull for locations it contains. There are many possible decompositions of a larger area into smaller areas in this way. The algorithm generates one such decomposition.
Note that since each smaller area is a convex hull for the locations it contains, the centroid of each of the smaller areas is guaranteed to be located within the area.
With some areas, as seen above, the centroid lies outside of the area. If centroids are created to allow transfer of areas to points via the Spatial Overlay dialog (that is, using "point in polygon" operations) for analytic or other purposes, the centroid point might not fall within the desired area. One approach to solving this problem is to split each area into smaller areas and to then use centroids for those smaller areas.
We can use Decompose to Convex Parts to split the area into smaller areas.
The centroids for each will fall within the area. We can now transfer data using spatial overlays knowing that the fields for each area will transfer to a centroid point within that area.
Notes
· Use the Centroids (Weight) operator to create centroids that are more centered on each smaller area.
· The transfer of data fields to the new areas will be governed by the Transfer Rules for the fields.