RE: Transform - Overlay in v9 removes duplicates

espinello — Thu, 15 May 2025 16:01:20 GMT

I am doing a fairly straight-forward Topology Overlay in Manifold 9, with a point layer of 1,288 records, being overlayed by a polygon layer, so that the polygon fields are assigned to the points within them. The operation is doing exactly what it should with respect to the field assignments. However, the resulting table is reduced down to 1,252 records. Doing a quick review of the ones missing, it appears that rows having the same addresses (and presumably geocoded to the same coordinates) seem to be treated as duplicates, with only one unique record being returned for each location in the new table.

The 4 options for an overlay are: identity, intersect, union, and update. According to the manual, the only option that specifically indicates that duplicates will be discarded is the "union". I have tried all four but still get the same result in every case.

Is there a way to generate an overlay without losing "duplicate" location records?

RE: Transform - Overlay in v9 removes duplicates

espinello — Thu, 15 May 2025 16:20:44 GMT

Well, I just realized that I should have been using a spatial join instead of an overlay, so my problem is solved, but I am curious why the overlay removes duplicates.

RE: Transform - Overlay in v9 removes duplicates

volker — Fri, 16 May 2025 10:45:46 GMT

yes spatial join in this case teh right function.

With Topology overlay MFD automatically does a NORMALIZE TOPOLOGY that's the cause.

Manifold Community Site: Transform - Overlay in v9 removes duplicates

RE: Transform - Overlay in v9 removes duplicates

RE: Transform - Overlay in v9 removes duplicates

RE: Transform - Overlay in v9 removes duplicates