Regions
The coast, sea, and place commands crop their reference data to a region
box (plus a margin) and, for distance work, project through a Lambert Azimuthal
Equal-Area (LAEA) projection centered on that region. The depth command needs
no region (a grid lookup is global), and nearest computes exact great-circle
distances on the unit sphere, so it needs no region either.
Presets
Pick a region with --region <NAME>:
| Preset | Box (min_lon, max_lon, min_lat, max_lat) |
|---|---|
global (default) | -180, 180, -90, 90 |
baltic | 8, 31, 53, 66 |
norway | -10, 45, 55, 85 |
arctic | -180, 180, 60, 90 |
atlantic | -83, 20, -60, 70 |
europe | -25, 45, 34, 72 |
mediterranean | -6, 37, 30, 46 |
The default is global (the whole globe).
Explicit box and projection center
Any preset value can be overridden with explicit bounds:
geoenrich coast cores.parquet --data ./data/gshhg/... \
--min-lon 8 --max-lon 31 --min-lat 53 --max-lat 66
By default the LAEA projection is centered on the region box center. Override it
with --proj-lon0 / --proj-lat0 if you want the center elsewhere (for example
to reduce distortion over an asymmetric region).
Precedence
For the region box and projection center, later sources win:
preset / built-in default < config file < CLI flag
So a --region preset sets the box, a config file can
override individual bounds, and a CLI --min-lon (etc.) overrides both.
Choosing a region
Cropping keeps the reference data small and the lookups fast, but a point whose
true nearest feature lies outside the region-plus-margin box can be wrong (for
coast, an over-estimate). If in doubt, widen the box or use global; the
unique-location pipeline keeps even a global run affordable.