[R-sig-Geo] spplot with two rasters

[Dylan Beaudette]

On Tuesday 04 March 2008, Edzer Pebesma wrote:
> I find it hard to imagine how you want to plot two raster files on top
> of each other. Do you want some form of transparency? If it is just one
> overlaying the other, you could use overlay to find out which cells in
> raster 1 to replace with those in raster 2 before plotting.
> --
> Edzer

Hi Edzer,

I generally agree that plotting one raster file "over" another raster file 
would be of little use. In this case, one of the raster files (the 
interesting one) has been masked with nodata, such that it only really covers 
about 30% of the region of interest. The other raster is just contextual 
data, and thus would be useful to plot "behind" the first raster.

Ideas?

Dylan 

> Dylan Beaudette wrote:
> > Hi,
> >
> > Is it possible to plot two raster images using spplot() in a manner
> > similar to:
> >
> > pts <- list("sp.points", points_file, pch = 4, col = "black", cex=0.5)
> > spplot(raster_file, zcol="elev.pred", sp.layout=list(pts))
> >
> > Note that one of the raster images is an aerial photo, used only for
> > context, while the second one is one with interesting z-values. The
> > second raster is masked and thus does not cover the entire region.
> >
> > Thanks,
> >
> > Dylan



-- 
Dylan Beaudette
Soil Resource Laboratory
http://casoilresource.lawr.ucdavis.edu/
University of California at Davis
530.754.7341