Repeating/duplicate state label points

[PetersonGIS]

No description provided.

[PetersonGIS]

Currently: state_label_points from ne_10m_admin_1_label_points; zoom 4-10, filter scalerank == 2

Fix: use ne_10m_admin_1_label_points_details instead. It contains just one point per state.

[PetersonGIS]

The url for the dataset mentioned above 404s.
http://naciscdn.org/naturalearth/10m/cultural/ne_10m_admin_1_label_points_details.zip
Even though it is available in the natural earth geopackage.

[PetersonGIS]

Selecting for adm0_sr = 1 from ne_10m_admin_1_points is the solution. Requires adding adm0_sr to tegola.toml sql as this field isn't currently used.

[PetersonGIS]

This shows the difference between the two state label point layers. The only immediately visible problems are the Vermont and Indiana placements. But this seems better than the current state of labeling in the tegola-osm repo.

[PetersonGIS]

See more on the above issue at
nvkelso/natural-earth-vector#145

[PetersonGIS]

clhenrick's solution in above mentioned thread works beautifully in tegola:

Using the following in the config.toml

[[providers.layers]]
name = "ne_110m_admin_1_states_provinces"
geometry_fieldname = "geometry"
id_fieldname = "ogc_fid"
sql = "SELECT DISTINCT ON (name) name, admin, scalerank, ST_AsBinary(ST_PointOnSurface(wkb_geometry)) AS geometry, ogc_fid, name, admin, scalerank, min_label, max_label FROM ne_110m_admin_1_states_provinces WHERE wkb_geometry && !BBOX!"

[PetersonGIS]

And, using the 10m table to add in all the states worldwide and the tegola zoom token, the optimal sql seems to be:

sql = "SELECT DISTINCT ON (name) name, admin, scalerank, ST_AsBinary(ST_PointOnSurface(wkb_geometry)) AS geometry, ogc_fid, name, admin, scalerank, min_label, max_label FROM ne_10m_admin_1_states_provinces WHERE (min_label - 1) <= !ZOOM! AND wkb_geometry && !BBOX!"

[PetersonGIS]

In summary, we're deleting the old state labels, which had a lot of duplicates showing up at the same time and were based on the table containing admin 1 labels and instead using a custom sql query on a new table that we'll add to the database containing admin 1 polys converted via sql to distinct points. We're keeping the same final name for the output layer ("state_label_points") so that the styles that use that layer won't break, though they may need to be tweaked once the change goes through since they are based on scalerank=2, which will probably no longer be a needed constraint.