Test data contain invalid geometries
See original GitHub issuecountries.geo.json
contains self-intersecting Multipolygons, which is illegal. GeoJSON obviously doesn’t care about that, but JTS doesn’t accept them, and neither would e.g. PostGIS.
I would suspect that the tool which was used to simplify the geometry didn’t care about topology.

This is a bit mean because it prevents me from experimenting with standard geometric algorithms. ,-)
Issue Analytics
- State:
- Created 6 years ago
- Reactions:1
- Comments:20 (20 by maintainers)
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Fixed by #2188
https://www.jasondavies.com/simplify/koch/