fix: re-georeference flood zones and make them clearly visible

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The previous affine fit slid along the mostly north-south river (an
ill-conditioned direction) leaving the zones ~1 km south-west of their
true position. New approach: extract the scanned river band by color,
match it to the OSM Ping mainstem centerline by arc length (which pins
the along-river position), then correct residual translation using
known district locations cross-checked against the river residual
(533 m -> ~300 m median; Chang Khlan zone centroid now within 200 m).
Mountain-area artifacts are clipped away via the municipality hull.

Zones were also nearly invisible at fillOpacity 0.16 - base opacity is
now 0.38, rising with the live 24 h exceedance probability, and 0.72
with a solid red border once the river is at or above a zone's level.

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grabowski

2026-08-10 16:38:09 +07:00

parent f05289e628

commit c4e0fb6bae

2 changed files with 3 additions and 3 deletions

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src/static/flood-zones-p1.geojson

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