Replacing shoretypes layer fails

[wmcclin]

I tried to replace the Shore Types layer in https://seasketch.org/california by dragging / dropping the attached file. It failed and now I cannot even view the Data Source tab in the layer editing dialog box without getting a blank page.

Shore types.geojson.zip

[underbluewaters]

This layer really tests the robustness of the tiling workflow. The source service contains a mix of LineString and MultiLineStrings, and also a number of features that don't contain enough points to form a valid Line. QGIS just drops the invalid features, which is what allows it to display the dataset. Exported outputs from QGIS can be uploaded to SeaSketch because they no longer contain these invalid points.

SeaSketch attempts to convert the dataset to Flatgeobuf before starting tiling. Because some "Lines" are in fact single coordinate Points features, the final output is a file with mixed geometry types. The GeometryType is "Unknown". Tippecanoe fails to tile because unknown geometry type is unsupported.

To solve this issue, the tiler will need to do a few things:

• Identify the primary geometry type of the dataset
• Use the -makevalid and -nlt PROMOTE_TO_MULTI option to promote singlepart features to multi when necessary, and fix or remove invalid features.
• This output may then contain multiple different geometry types. Another ogr2ogr step will need to use the -sql option to drop point (or other) features derived from invalid features and assign a geometry type manually using -nlt LINESTRING|POLYGON|ETC.
• Metadata on the primary geometry type should probably be stored in the geostats info.