May be this work for rectangular image.
require(rimage)
img<-read.jpeg("file.jpg")
image(rgb2grey(img))
nsamples<-1000
coordinates<-NULL
for (i in 1:nsamples) {
coordinates<-rbind(
coordinates,
cbind(x=as.integer(nrow(img)*runif(1)),
y=as.integer(ncol(img)*runif(1))))
}
But I sugest you give a look at "adehabitat" and "rimage" packages.
Best,
Miltinho
ronggui <[EMAIL PROTECTED]> escreveu:
I have a map of a district (which is JPG format), and I want to do a
sptial sampling based on the map. So is there any function to do
spatial sampling of this type?
Thanks!
--
Ronggui Huang
Department of Sociology
Fudan University, Shanghai, China
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