[R-sig-Geo] Reading National Snow and Ice Data Center binary files

[Anthony Fischbach]

In my previous post I happily handled the binary National Snow and Ice Data
Center sea ice imagery and cast it into a GeoTiff.
My next challenge is to wrap the GeoTiff into a kml overlay.
Continuing the code from the previous post, I pick it up just after writing
the raster object to the geoTiff.

...
 rr <- writeRaster(rr, geoTiffFile)

>From there I sought to use the maptools package functions 
GE_SpatialGrid and kmlOverlay to create the kml, 
but first I needed to cast my raster into a spatial points dataframe 
and project to geographic coordinates.

spdf <- rasterToPoints(rr, fun=NULL, spatial=TRUE) ## cast as a spatial
points data frame
xyWGS84 <- project(coordinates(spdf), inv=TRUE, proj=prj) ## Project to
WGS84 geographic

But this generates an error: 

Traceback:
 1: .C("project_inv", as.integer(nc), as.double(xy[, 1]), as.double(xy[,    
2]), x = double(nc), y = double(nc), proj, NAOK = TRUE, PACKAGE = "rgdal")
 2: project(coordinates(spdf), inv = TRUE, proj = prj)
Error in project(coordinates(spdf), inv = TRUE, proj = prj) : 
  caught access violation - continue with care

Apparently rgdal's project function is failing to invert the projection from
the NSIDC projection, 
here referenced as 
prj <- CRS('+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')

Any suggestions?

-----
Tony Fischbach, Wildlife Biologist
Walrus Research Program
Alaska Science Center
U.S. Geological Survey
4210 University Drive
Anchorage, AK 99508-4650

AFischbach at usgs.gov
http://alaska.usgs.gov/science/biology/walrus
--
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