Missing polygons

[Plantain]

Hi,
I have a GeoJSON file that renders on tools such as Mapshaper.org as follows:

Run through tippecanoe, half the content seems to be lost, as shown by mbview.

Same behaviour with -zg or with manually specified levels.

Attached mbtiles file, and GeoJSON data.
mbtiles+json.zip

[e-n-f]

Thanks. I'll download it and take a look.

[e-n-f]

What you get by directly uploading the GeoJSON to Mapbox looks a lot like the Tippecanoe output, so Tippecanoe and Mapnik must be interpreting it similarly.

Still trying to figure out what Mapshaper is doing differently.

[e-n-f]

The discrepancy is introduced by the use of Wagyu to clean the polygon geometry. With polygon cleaning turned off, the geometries are strange, but there are a lot more of them.

[e-n-f]

The fundamental problem is that many of the outer polygon rings are marked in the GeoJSON as being interior rings.

   o  For Polygons with more than one of these rings, the first MUST be
      the exterior ring, and any others MUST be interior rings.  The
      exterior ring bounds the surface, and the interior rings (if
      present) bound holes within the surface.

Ignoring the GeoJSON spec and detecting inner/outer rings by winding rather than by ring order within the geometry gives the intended result:

So the big question is: should I treat this as an error in the source data, or should I add --use-original-winding and --reverse-original-winding flags to detect inner and outer rings by winding rather than by ring order?

[Plantain]

I have seen this behaviour from files generated with a number of different tools, so I think there might be some merit in adding the flags you mention. This particular file was generated by geojsoncontour, I will open an issue and investigate with them too.

[e-n-f]

#581 adds the --use-source-polygon-winding and --reverse-source-polygon-winding flags.