Validation methodology

Validation uses labelled sites including Hodlekve and Kvamskogen.

Source	Role	Caveat
Forhåndsmelding points	Primary positives and construction windows	Curated but incomplete.
FKB-Bygning census	Negative/precision backbone	Dates can be mapping dates with lag.
Footprint appearances	Supplementary positives	Re-survey campaigns can look like appearances.
FKB-Tiltak	Direction/permit context	Schema/date availability varies by year.

Metrics include recall, date error, precision proxy, and false-alarm checks on stable-building/open-terrain controls where available. No source gives a perfect construction-step date.