Calculate the centroids of polygons found in a PolySet.
calcCentroid (polys, rollup = 3)
PolySet to use.
level of detail in the results;
1, the results contain a centroid for
PID only. When it equals
2, they contain
entries for outer contours only. Finally, setting it to
prevents roll-up, and they contain a centroid for each unique
PolyData with columns
SID (may be missing),
1 2 3 4 5 6 7