R/spReprojectRaster.R
spReprojectRaster.RdReprojects an Esri shapefile (*.shp) or S4 Spatial object to a new geographic or projected coordinate system, with option to save new object.
spReprojectRaster(
rastfn,
bands = NULL,
crs = NULL,
rast.ref = NULL,
crs.new = NULL,
res.new = NULL,
bbox.new = NULL,
dtype.new = NULL,
NODATA.new = NULL,
resamp.method = "near",
crs.default = "EPSG:5070",
compress = NULL,
BigTIFF = FALSE,
outfolder = NULL,
outfn = NULL,
outext = NULL,
overwrite = FALSE
)String or Raster. File name(s) with extensions, or raster object(s). Note: raster objects must be written to file.
Numeric vector. If rast is a multi-layer raster and only 1 or some layers are desired, specify layer number(s) in a vector format. If NULL, all layers are projected.
Coordinate Reference System (CRS). The CRS of rastfn if not defined. EPSG:code, PROJ.4 declaration, or .prj file containing WKT. For example, PROJ.4: "+proj=moll +lon_0=0 +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m +no_defs". If NULL, and the CRS of rastfn is not defined, uses crs.default.
String or Raster. File name(s) with extensions, or raster object to use as reference raster.
Coordinate Reference System. New CRS for rastfn. EPSG:code, PROJ.4 declaration, or .prj file containing WKT. For example, PROJ.4: "+proj=moll +lon_0=0 +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m +no_defs".
Integer vector. One or two values defining new resolution of raster (in target georeferenced units) (e.g., 30 or c(30,30)).
<xmin ymin xmax ymax> Georeferenced extent or bounding box of new raster.
String. Force a data type of new raster. If NULL, the data type will be same as rastfn (e.g., Byte, Int16, UInt16).
Integer. Set nodata values for new raster. New files will be initialized to this value and if possible the nodata value will be recorded in the output file. Use a value of "None" to ensure that nodata is not defined. If NULL, NODATA and rastfn has a set NODATA value, this value will be used for new raster.
Method for resampling ('near', 'bilinear', 'cubic', 'cubicspline', 'landzos', 'average', 'mode', 'min', 'max', 'med', 'q1', 'q3').
Coordinate Reference System. A default CRS if crs.new=NULL. The default is: EPSG:5070, Conus Albers, PRJ4='+proj=aea +lat_1=29.5 +lat_2=45.5 +lat_0=23 +lon_0=-96, +x_0=0 +y_0=0", "+ellps=GRS80 +towgs84=0,0,0,-0,-0,-0,0 +units=m +no_defs'.
String. An optional compression type ('LZW', "DEFLATE', "PACKBITS').
Logical. If TRUE, compress option for big files (> 4GB).
String. If exportsp=TRUE, name of output folder. If NULL, the working directory is used.
String. Name of output raster. If NULL, default is 'polyrast'.
String. Name of raster extension (fmt). If NULL, uses extension from outfn or rastfn.
Logical. If TRUE, overwrites raster file.
String. Full path name to reprojected raster.
Coordinate Reference Systems (CRS)
An ellipse is an estimated model
describing the basic shape of the Earth and is the basis for all coordinate
systems. There are many ellipsoids designed for local (e.g., NAD27) or
global (e.g., WGS84, GRS80) use. The datum defines the reference position of
the coordinate axes associated with a specific ellipsoid. Specifying the
datum also defines the ellipsoid, whereas specifying the ellipsoid does not
provide information of the datum.
WGS84 vs NAD83 WGS84 and NAD83 datums are often used interchangeably, and use very similar ellipsoids (WGS84 and GRS80, respectively), but have different reference points. Slight tectonic shifts through time have caused increased divergence between the two, with NAD83 datum intended to track movements more consistently.
Common Datums and associated spheroid (ellipsoid):
NAD27 - North American
Datum of 1927 (Clarke 1866 spheroid)
NAD83 - North American Datum of 1983
(GRS 1980 spheroid)
WGS84 - World Geodetic System of 1984 (WGS 1984
spheroid)
From R, use projInfo for list of different projections and datums.
>
projInfo(type="proj")
> projInfo(type="datum")
Common EPSG Geodetic codes in U.S.
EPSG:4326 - Longitude/Latitude (WGS84)
- Common for global displays (used by Google Earth)
EPSG:4269 -
Longitude/Latitude (NAD83) - Common by U.S. Federal Agencies
The sf::st_transform (GDAL) method is used for map projection conversion and datum transformation using PROJ.4 arguments. Datum transformation only occurs if the +datum tag is present in the both the from and to PROJ.4 strings. The +towgs84 tag is used when no datum transformation is needed. PROJ.4 transformations assume NAD83 and WGS84 are identical unless other transformation parameters are specified. Be aware, providing inaccurate or incomplete CRS information may lead to erroneous data shifts when reprojecting. See spTransform help documentation for more details.
# \donttest{
# Get raster layers from FIESTA external data
demfn <- system.file("extdata",
"sp_data/WYbighorn_dem_250m.img",
package = "FIESTA")
# Check original projection
sf::st_crs(terra::rast(demfn))$proj4string
#> [1] "+proj=aea +lat_0=23 +lon_0=-96 +lat_1=29.5 +lat_2=45.5 +x_0=0 +y_0=0 +datum=NAD27 +units=m +no_defs"
# Reproject raster
reprojected <- spReprojectRaster(rastfn = demfn,
crs.new = "EPSG:32613",
outfolder = tempdir())
#> /private/var/folders/kd/4wp69y7d2yd3fxpd1_m64clm0000gn/T/RtmpWUzLtI/temp_libpath10a93f405e55/FIESTA/extdata/sp_data/WYbighorn_dem_250m.img
#> Error: warp raster failed (could not create options struct)
# Check new projection
sf::st_crs(terra::rast(demfn))$proj4string
#> [1] "+proj=aea +lat_0=23 +lon_0=-96 +lat_1=29.5 +lat_2=45.5 +x_0=0 +y_0=0 +datum=NAD27 +units=m +no_defs"
# }