8 Spatial resolution

library(terra)
library(tidyterra)

Read the Baffin Bay polygon.
Read bathymetry data from the GEBCO 2022 dataset and crop it to the Baffin Bay extent using the win argument.

baffin <- vect("https://github.com/PMassicotte/baffin_bay_polygon/blob/main/data/clean/baffin_bay.gpkg?raw=true")

crop_extent <- ext(project(baffin, "EPSG:4326"))

wm <- rnaturalearth::ne_countries(scale = "medium", returnclass = "sv")

plot(wm, lwd = 0.25)
plot(project(baffin, "EPSG:4326"), add = TRUE, col = "red")

r <- rast(
  "/vsicurl/https://gebco2022.s3.valeria.science/gebco_2022_complete_cog.tif",
  win = crop_extent
) |>
  project(crs(baffin))

plot(r)

Set a new resolution at 50 km
Resample the raster using the bilinear method
Plot the original and resampled rasters
Compare the original and resampled resolution

r2 <- rast(ext(r))
r2

class       : SpatRaster 
dimensions  : 10, 10, 1  (nrow, ncol, nlyr)
resolution  : 163627.1, 186358.9  (x, y)
extent      : 40471768, 42108039, 4602532, 6466121  (xmin, xmax, ymin, ymax)
coord. ref. :

res(r2) <- 50000L

r2 <- resample(r, r2, method = "bilinear")

op <- par(mfrow = c(1L, 2L))
plot(r)
plot(r2)

par(op)

plot(as.polygons(r2))
plot(as.points(r2), cex = 0.2, add = TRUE, col = "red")

plot(r2)
plot(as.lines(r2), add = TRUE)

class       : SpatRaster 
dimensions  : 8067, 7083, 1  (nrow, ncol, nlyr)
resolution  : 231.0138, 231.0138  (x, y)
extent      : 40471768, 42108039, 4602532, 6466121  (xmin, xmax, ymin, ymax)
coord. ref. : GR96 / EPSG Arctic zone 5-41 (EPSG:6059) 
source(s)   : memory
name        : gebco_2022_complete_cog 
min value   :               -2426.086 
max value   :                2273.907

r2

class       : SpatRaster 
dimensions  : 37, 33, 1  (nrow, ncol, nlyr)
resolution  : 50000, 50000  (x, y)
extent      : 40471768, 42121768, 4602532, 6452532  (xmin, xmax, ymin, ymax)
coord. ref. : GR96 / EPSG Arctic zone 5-41 (EPSG:6059) 
source(s)   : memory
name        : gebco_2022_complete_cog 
min value   :               -2348.460 
max value   :                1251.003

r3 <- mask(r2, baffin, touches = FALSE)
plot(r3)
plot(baffin, add = TRUE)