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snapRoundingNoder on polygons result in MultiLineString #1133
Description
When using the snapRoundingNoder on the attatched dataset with a precision scale of 10, I get a MultiLineString where the number of decimal places are all reduced to 1, but the number of coordinate pairs go from 2818 in the original polygon data to 5419 in the resulting MultiLineString. This makes the data larger in bytes and more complex to work with. Is this the expected behavior?
Also, why is the result a MultiLineString? I don't see an obvious way to convert this back to polygons as there is no info on what were polygon exteriors and what were holes/interiors.
Activity
dr-jts commentedon May 28, 2025
Here's how to use the
SnapRoundingNoderto produce a reduced-precision coverage. The input isTo map this back to the original polygons use point-in-polygon tests (which also finds holes/gaps).
The result smallest polygon has area = 1. The input has 57 polygons of smaller area, which are probably all collapsed. Here's a closeup of an area where the snapped coverage contains fewer polygons, since a narrow polygon has collapsed: