On Wed, 19 Oct 2011, Anthony Fischbach wrote:
Thank you for the GRASS suggestion.
It would also be straight forward in ArgGIS, but I seek to run this all in a
scripting environment with the full flexibility of R such that I may
automate the whole process.
I have a feeling that this is stranding on the raster warping difficulty
seen in high latitudes. The projected cells have great difficulty in
"adapting" to longlat, for obvious reasons, as the output cells really
need to differ in shape and form. Would it be possible to "go vector"
instead, and project the vector entities? I have some slides from a course
I gave three years ago but I'm not sure if they are relevant.
Roger
Following on the projectRaster idea, I have tried using the from and to
options, first creating a from raster corresponding to the geographic extent
and resolution of the desired output raster.
ll_lt <- 30.98
ll_ln <- 168.35
ur_lt <- 33.92
ur_ln <- 279.26
rGeo <- raster(nrows=448, ncols=304, xmn=ll_ln, xmx=ur_ln, ymn=ll_lt,
ymx=ur_lt, crs="+proj=longlat +datum=WGS84")
## look at the raster before projecting
rr
class : RasterLayer
dimensions : 448, 304, 136192 (nrow, ncol, ncell)
resolution : 25000, 25000 (x, y)
extent : -3837500, 3762500, -5362500, 5837500 (xmin, xmax, ymin, ymax)
coord. ref. : +proj=stere +lat_0=90 +lat_ts=70 +lon_0=-45 +k=1 +x_0=0 +y_0=0
+a=6378273 +b=6356889.449 +units=m +no_defs
values : ...\SeaIce\NSIDC\NearRealTime\nt_20111011.tif
min value : 0
max value : 1
## Project
rgeo <- projectRaster(from=rr, to=rGeo, method= 'bilinear')
rgeo
class : RasterLayer
dimensions : 448, 304, 136192 (nrow, ncol, ncell)
resolution : 0.3648355, 0.0065625 (x, y)
extent : 168.35, 279.26, 30.98, 33.92 (xmin, xmax, ymin, ymax)
coord. ref. : +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0
values : in memory
min value : 0
max value : 0
It fails to populate with the data.
-----
Tony Fischbach, Wildlife Biologist
Walrus Research Program
Alaska Science Center
U.S. Geological Survey
4210 University Drive
Anchorage, AK 99508-4650
afischb...@usgs.gov
http://alaska.usgs.gov/science/biology/walrus
--
View this message in context:
http://r-sig-geo.2731867.n2.nabble.com/Reading-National-Snow-and-Ice-Data-Center-binary-files-tp6882737p6909785.html
Sent from the R-sig-geo mailing list archive at Nabble.com.
_______________________________________________
R-sig-Geo mailing list
R-sig-Geo@r-project.org
https://stat.ethz.ch/mailman/listinfo/r-sig-geo
--
Roger Bivand
Department of Economics, NHH Norwegian School of Economics,
Helleveien 30, N-5045 Bergen, Norway.
voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: roger.biv...@nhh.no
_______________________________________________
R-sig-Geo mailing list
R-sig-Geo@r-project.org
https://stat.ethz.ch/mailman/listinfo/r-sig-geo
