Sweden landcover: fold in Topo 10 `sankmark` for `inland_marsh` / `peat_bog` #14

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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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Topo 10's mark GeoPackage carries a sankmark layer — 1.31M "Sankmark, fast" plus 140k
"Sankmark, våt" — that would give Sweden the CORINE inland_marsh and peat_bog classes it
currently has no way to express. The data is already on disk in the Geotorget order we have,
so there is no new download and no new credential.

It is not a config change, and it needs design before implementation. sankmark is an
overlay, not part of the mark coverage: a mire can sit inside forest or inside open land.
Folding it in naively breaks the thing ST_CoverageSimplify depends on. Doing it properly
means a nationwide ST_Difference/ST_Intersection against 3.5M polygons — expensive, and
the validity of the result has to be checked, not assumed.

Worth doing because Sweden's natural_grassland (2640 "Öppen mark") is 1.9M polygons of the
source's own catch-all, and wetland is a real part of what is hiding in there.

Poland's half of this item is done — all twelve BDOT10k PT classes are now fetched and
mapped. Background: docs/country-sweden.md, docs/country-poland.md.

Topo 10's `mark` GeoPackage carries a `sankmark` layer — 1.31M "Sankmark, fast" plus 140k "Sankmark, våt" — that would give Sweden the CORINE `inland_marsh` and `peat_bog` classes it currently has no way to express. The data is already on disk in the Geotorget order we have, so there is no new download and no new credential. **It is not a config change, and it needs design before implementation.** `sankmark` is an *overlay*, not part of the `mark` coverage: a mire can sit inside forest or inside open land. Folding it in naively breaks the thing `ST_CoverageSimplify` depends on. Doing it properly means a nationwide `ST_Difference`/`ST_Intersection` against 3.5M polygons — expensive, and the validity of the result has to be checked, not assumed. Worth doing because Sweden's `natural_grassland` (2640 "Öppen mark") is 1.9M polygons of the source's own catch-all, and wetland is a real part of what is hiding in there. Poland's half of this item is **done** — all twelve BDOT10k PT classes are now fetched and mapped. Background: `docs/country-sweden.md`, `docs/country-poland.md`.