Well, the problem is that R does not have a real geographical display. While things can be done going back and forth from R to GIS, this procedure soon becomes very inconvenient. It's ok for learning and teaching, but not for real applications. Maybe getting an existing GIS to display spatial R objects is actually easier than developing a geographical display for R. Agus
Dylan Beaudette escribió: > On Thursday 06 March 2008, Thomas Adams wrote: >> Dylan, >> >> I think a solution using GRASS can be found on pages 110-111 of "Open >> Source GIS: A GRASS GIS Approach", 3rd Ed. The same material is covered >> in the 2nd Ed. as well, where you use r.mapcalc to combine two rasters >> and judicious use of MASKs; a conditional statement in r.mapcalc is the >> key. >> >> Regards, >> Tom > > Hi Tom, > > Thanks for the suggestion. This works, but we were hoping to make the plot in > R-- as the PDF output is hard to match with GRASS alone. I suppose I will > just have to try using two rasters with spplot() and see what happens. > > Cheers, > > Dylan > >> Dylan Beaudette wrote: >>> 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 > > > -- Dr. Agustin Lobo Institut de Ciencies de la Terra "Jaume Almera" (CSIC) LLuis Sole Sabaris s/n 08028 Barcelona Spain Tel. 34 934095410 Fax. 34 934110012 email: [EMAIL PROTECTED] http://www.ija.csic.es/gt/obster _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo