Defines which res-res hexagons tile the ocean and their area_km2 — it
does not interpolate any values (see the module INTERPOLATION PRINCIPLE).
A res-7 hex (~5.16 km^2) is smaller than a 0.05 degree pixel (~23 km^2), so
each ocean pixel (non-NA in mask_layer) is polyfilled into the hexes whose
centre falls inside it (h3_polygon_wkt_to_cells, center-containment → a
gap-free, overlap-free tiling). Values are attached afterwards with
hex_interp_idw() from the source centroids.
Usage
hex_ocean(r, con, res = HEX_RES, mask_layer = names(r)[1], out_tbl = "hex")Arguments
- r
a terra::SpatRaster in EPSG:4326
- con
a DuckDB connection
- res
H3 resolution (default HEX_RES)
- mask_layer
layer whose non-NA pixels define ocean coverage (default
names(r)[1])- out_tbl
DuckDB table to (over)write with columns
hex_id(BIGINT) andarea_km2(default"hex")