My purpose is to make a graphical  representation using the command "persp"
of a digital terrain model. I have to start form these points:
-a digital terrain model (computed on 25 meters)
-the same digital terrain model, this time computed on 5 meters

These data are easily available as .txt files on the website. Once I get
these files, i turned them into matrices (using the following script:
data25<-read.csv('Cortina25.txt')
z<-data
z<-as.matrix(z)

data5<-read.csv('Cortina5.txt')
k<-data
k<-as.matrix(k)


Now the thing I have to do this step:
-I need to extract a submatrix from k in such a way that at the end I
should get the graph of the dtm 25  with the small portion of the dtm5
superposed on it that corresponds to the submatrix of k.

I hope I've been clear.
Thank you for your help

-- 
Chiara Odorisio

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