[R-sig-Geo] NA color composite

[Robert J. Hijmans]

Carsten,

Thanks for reporting this. I fixed the NA handling in plotRGB in
raster 1.3-1, which should be available from R-Forge later today, and
from CRAN later this week.

In stead of first reading the data with rgdal, a more direct way to
get at what you want with 'raster' is:

d1 <- stack('Hasenheide')
# or d1 <- brick('Hasenheide')
plotRGB(d1, r=14, g=7, b=1, scale=1)


With the current version, you could perhaps use a work-around like:

d1<-readGDAL('Hasenheide')
d1 at data[is.na(d1 at data)] <- 0
fn<-stack(raster(d1,14),raster(d1,7),raster(d1,1))
plotRGB(fn,1,2,3, scale=1)


Robert


On Tue, Jul 20, 2010 at 6:27 AM,  <carstennh at aol.com> wrote:
> Dear list members,
>
> I'm having trouble creating a rgb color composite based one a multiple grid object. Both the SGDF2PCT function from rgdal package and the  plotRGB function from raster package can not handle NA's. For my  work it is necessary to include No Data values for masking the study area.
>
>
> Is there any way to combine rgdal or raster objects in a rgb color mixture  with No Data values??? My two approaches are given below.
>
> Very Great Thanks for any help!!!
>
> Carsten
>
> 1. Approach
>
> library(rgdal)
>
> vismaps = readGDAL("Hasenheide")
> vismaps$red = vismaps$band14
> vismaps$green = vismaps$band7
> vismaps$blue = vismaps$band1
>
> ###Display as a RGB image###
> RGBimg = SGDF2PCT(vismaps[c("red", "green", "blue")], ncolors=256,
> adjust.bands=TRUE)
>
> ##########Error in if (bmax == bmin) bmax <- bmin + ncolors :
>  missing value where TRUE/FALSE needed################
>
> col<-rgb(d1 at data[[4]],d1 at data[[7]],d1 at data[[1]])
>
> vismaps$idx <- RGBimg$idx
> image(vismaps, "idx", col=RGBimg$ct)
>
>
>
>
> 2. Approach
>
> library(raster)
>
> d1<-readGDAL('Hasenheide')
> fn<-stack(raster(d1,14),raster(d1,7),raster(d1,1))
>
> ###Display as a RGB image###
> plotRGB(fn,scale=1,1,2,3)
>
> ################Error in rgb(getValues(r), getValues(g), getValues(b), max = scale) :
>  color intensity nan, not in [0,1]#############################################
>
>
>
>
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