7.7 Reprojecting raster:
create a new raster object (with different rows/cols)
resampling values of every cell (using different resamploing methods)
Terra’s function project() allow you to do that.
As usual: nearest neighbour method are good for categorical data. You have more option for quantitative data.
cat_raster = rast(system.file("raster/nlcd.tif", package = "spDataLarge"))
crs(cat_raster) |> cat()## PROJCRS["NAD83 / UTM zone 12N",
## BASEGEOGCRS["NAD83",
## DATUM["North American Datum 1983",
## ELLIPSOID["GRS 1980",6378137,298.257222101,
## LENGTHUNIT["metre",1]]],
## PRIMEM["Greenwich",0,
## ANGLEUNIT["degree",0.0174532925199433]],
## ID["EPSG",4269]],
## CONVERSION["UTM zone 12N",
## METHOD["Transverse Mercator",
## ID["EPSG",9807]],
## PARAMETER["Latitude of natural origin",0,
## ANGLEUNIT["degree",0.0174532925199433],
## ID["EPSG",8801]],
## PARAMETER["Longitude of natural origin",-111,
## ANGLEUNIT["degree",0.0174532925199433],
## ID["EPSG",8802]],
## PARAMETER["Scale factor at natural origin",0.9996,
## SCALEUNIT["unity",1],
## ID["EPSG",8805]],
## PARAMETER["False easting",500000,
## LENGTHUNIT["metre",1],
## ID["EPSG",8806]],
## PARAMETER["False northing",0,
## LENGTHUNIT["metre",1],
## ID["EPSG",8807]]],
## CS[Cartesian,2],
## AXIS["(E)",east,
## ORDER[1],
## LENGTHUNIT["metre",1]],
## AXIS["(N)",north,
## ORDER[2],
## LENGTHUNIT["metre",1]],
## USAGE[
## SCOPE["Engineering survey, topographic mapping."],
## AREA["North America - between 114°W and 108°W - onshore and offshore. Canada - Alberta; Northwest Territories; Nunavut; Saskatchewan. United States (USA) - Arizona; Colorado; Idaho; Montana; New Mexico; Utah; Wyoming."],
## BBOX[31.33,-114,84,-108]],
## ID["EPSG",26912]]cat_raster_wgs84 = project(cat_raster, "EPSG:4326", method = "near")
cat_raster_wgs84## class : SpatRaster
## dimensions : 1246, 1244, 1 (nrow, ncol, nlyr)
## resolution : 0.0003150638, 0.0003150638 (x, y)
## extent : -113.2414, -112.8495, 37.12656, 37.51913 (xmin, xmax, ymin, ymax)
## coord. ref. : lon/lat WGS 84 (EPSG:4326)
## source(s) : memory
## color table : 1
## categories : levels
## name : levels
## min value : Water
## max value : Wetlandscat_raster## class : SpatRaster
## dimensions : 1359, 1073, 1 (nrow, ncol, nlyr)
## resolution : 31.5303, 31.52466 (x, y)
## extent : 301903.3, 335735.4, 4111244, 4154086 (xmin, xmax, ymin, ymax)
## coord. ref. : NAD83 / UTM zone 12N (EPSG:26912)
## source : nlcd.tif
## color table : 1
## categories : levels
## name : levels
## min value : Water
## max value : Wetlands