convert an object of class 'scan' into a raster of class 'RasterBrick'
scan_to_raster(
scan,
nx = 100,
ny = 100,
xlim,
ylim,
res = NA,
param,
raster = NA,
lat,
lon,
crs = NA,
k = 4/3,
re = 6378,
rp = 6357
)a scan (sweep) of class scan
number of raster pixels in the x (longitude) dimension
number of raster pixels in the y (latitude) dimension
x (longitude) range
y (latitude) range
numeric vector of length 1 or 2 to set the resolution of the raster (see res).
If this argument is used, arguments nx and ny are ignored. Unit is identical to xlim and ylim.
scan parameters to include. If NA include all scan parameters. Reducing the number
of scan parameters speeds up evaluation.
(optional) RasterLayer with a CRS. When specified this raster topology is used for the output, and nx, ny, res arguments are ignored.
Geodetic latitude of the radar in degrees. If missing taken from scan.
Geodetic longitude of the radar in degrees. If missing taken from scan.
character or object of class CRS. PROJ.4 type description of a Coordinate Reference System (map projection). When 'NA' (default), an azimuthal equidistant projection with origin at the radar location is used. To use a WSG84 (lat,lon) projection, use crs="+proj=longlat +datum=WGS84"
Numeric. Standard refraction coefficient.
Numeric. Earth equatorial radius, in km.
Numeric. Earth polar radius, in km.
a RasterBrick
uses scan_to_spatial to georeference the scan's pixels. If multiple scan pixels fall within the same raster pixel, the last added pixel is given (see rasterize for details).
# \donttest{
# default projects full extent on 100x100 pixel raster:
scan_to_raster(example_scan)
#> class : RasterBrick
#> dimensions : 100, 100, 10000, 5 (nrow, ncol, ncell, nlayers)
#> resolution : 4791.787, 4791.787 (x, y)
#> extent : -239589.3, 239589.3, -239589.3, 239589.3 (xmin, xmax, ymin, ymax)
#> crs : +proj=aeqd +lat_0=56.3675003051758 +lon_0=12.8516998291016 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs
#> source : memory
#> names : DBZH, VRADH, RHOHV, ZDR, PHIDP
#> min values : -12.00000, -21.43643, 0.02680, -14.87059, -178.58824
#> max values : 32.000000, 20.684274, 0.999300, 7.905883, 178.588244
#>
# crop the scan and project at a resolution of 0.1 degree:
scan_to_raster(example_scan, ylim = c(55, 57), xlim = c(12, 13), res = .1)
#> class : RasterBrick
#> dimensions : 20, 10, 200, 5 (nrow, ncol, ncell, nlayers)
#> resolution : 0.1, 0.1 (x, y)
#> extent : 12, 13, 55, 57 (xmin, xmax, ymin, ymax)
#> crs : +proj=aeqd +lat_0=56.3675003051758 +lon_0=12.8516998291016 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs
#> source : memory
#> names : DBZH, VRADH, RHOHV, ZDR, PHIDP
#> min values : NA, -0.1880389, 0.9254000, -0.7529409, -103.7647040
#> max values : NA, 0.3760777, 0.9951000, 0.6588239, -27.5294080
#>
# using a template raster
template_raster <- raster::raster(raster::extent(12, 13, 56, 58), crs = sp::CRS("+proj=longlat"))
scan_to_raster(example_scan, raster = template_raster)
#> class : RasterBrick
#> dimensions : 10, 10, 100, 5 (nrow, ncol, ncell, nlayers)
#> resolution : 0.1, 0.2 (x, y)
#> extent : 12, 13, 56, 58 (xmin, xmax, ymin, ymax)
#> crs : +proj=longlat +datum=WGS84 +no_defs
#> source : memory
#> names : DBZH, VRADH, RHOHV, ZDR, PHIDP
#> min values : -8.000000, -20.684274, 0.078400, -9.882353, -161.647058
#> max values : 18.000000, 14.478992, 0.952100, 7.905883, 147.529420
#>
# }