Digital Geography

29. July 2012

unsupervised classification of a raster in R: the layer-stack or part one.

In my last post I was explaining the usage of QGis to do a layerstack of a Landsat-scene. Due to the fact that further research and trying out resulted in frustration I decided to stick with a software I know well: R.
So download the needed layers here and open up your flavoured version of R (in my case RStudio).



What do we need is a package called raster

install.packages("raster")
library("raster")

Now define the working directory where your ETM-bands are stored which is “ETM” in my case:

setwd("~/wd_r/ETM")

Let’s do the last step and create the stack using one line and store this raster object using a second line:

A=stack(c("p134r027_7dt20020722.SR.b01.tif","p134r027_7dt20020722.SR.b02.tif","p134r027_7dt20020722.SR.b03.tif","p134r027_7dt20020722.SR.b04.tif","p134r027_7dt20020722.SR.b05.tif", "p134r027_7dt20020722.SR.b07.tif"))
writeRaster(A, filename="merge.tif")
plotRGB(A, 3, 2, 1, stretch="hist")

That’s it. Easy, wasn’t it?

result of stack and plot of it (click to enlarge)