Iceland `places`: multi-part settlements get one label per part #22

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opened 2026-08-01 19:12:55 +00:00 by art-bot · 0 comments

art-bot commented

2026-08-01 19:12:55 +00:00

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mannvirki_flakar multipolygons are ST_Dump-split on import (110 source rows → 126
polygons), so a settlement mapped as several polygons gets one label anchor per part and
the town name can render repeated.

There is also a second, related duplication: a large settlement polygon spanning several
tiles gets one centroid label per tile.

The fix template already exists in this repo — airport_points: a small derived layer
with a pg source, SELECT ST_Centroid(ST_Collect(geom)) … GROUP BY nafnfitju over the
polygon table, used for the label while the polygon layer keeps the fill. Applying the same
shape to places fixes both symptoms at once.

docs/geo-primer.md uses this as its worked example of why ST_Dump-on-import is not free
("it just moves the cost somewhere you can see it"), so update that reference if it is
fixed.

`mannvirki_flakar` multipolygons are `ST_Dump`-split on import (110 source rows → 126 polygons), so a settlement mapped as several polygons gets **one label anchor per part** and the town name can render repeated. There is also a second, related duplication: a large settlement polygon spanning several tiles gets one centroid label *per tile*. **The fix template already exists in this repo** — `airport_points`: a small derived layer with a `pg` source, `SELECT ST_Centroid(ST_Collect(geom)) … GROUP BY nafnfitju` over the polygon table, used for the label while the polygon layer keeps the fill. Applying the same shape to `places` fixes both symptoms at once. `docs/geo-primer.md` uses this as its worked example of why `ST_Dump`-on-import is not free ("it just moves the cost somewhere you can see it"), so update that reference if it is fixed.