[R-sig-Geo] Adding Scale bar in the Image

[Roger Bivand]

On Thu, 1 May 2008, PUJAN RAJ REGMI wrote:

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but the thread is probably broken.

In fact, this thread was broken by you intially, because you simply took 
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> Thanks for prompt reply. Anyway to be a absolutely certain here I am 
> giving overview of my data type. My data has a four column of which 1 
> and 2 are coordinates in meters. Where as 3rd to 6th are reflectances in 
> 4 bands. Here I am using 3rd to 5th bands to plot the (RGB) image of my 
> study area. So here I want to add scale bar and if possible bar plot 
> also with color range as displayed in the image. I would be thankful if 
> you suggest me wayout.
> Thanking you
> Pujan
>
> My programme code:

No, you said:

library(rimage)

first, but that wasn't obvious, was it?

> A<- matrix (scan("test.txt",n=29613*6,sep="",skip=8),29605,6,byrow=TRUE)

What about:

A <- read.table("test.txt", skip=8, header=FALSE)
names(A) <- c("x", "y", "greenchannel", "redchannel",
   "nearinfraredchannel", "midinfraredchannel")
library(sp)
coordinates(A) <- c("x", "y")
gridded(A) <- TRUE

> greenchannel<-matrix(A[,3],nrow=155,ncol=191,byrow=TRUE)
> redchannel<-matrix(A[,4],nrow=155,ncol=191,byrow=TRUE)
> nearinfraredchannel<-matrix(A[,5],nrow=155,ncol=191,byrow=TRUE)
> midinfraredchannel<-matrix(A[,6],nrow=155,ncol=191,byrow=TRUE)
> mat <- array(0,c(155,191,3))
> mat[,,1] <- nearinfraredchannel/1000
> mat[,,2] <-redchannel/1000
> mat[,,3] <-greenchannel/1000

then

A$red <- A$nearinfraredchannel/1000
A$green <- A$redchannel/1000
A$blue <- A$greenchannel/1000

image(A, red="red", green="green", blue="blue")
axis(1, col.axis="blue", font.axis=4)
axis(2, col.axis="blue", font.axis=4)

using the image() method for SpatialPixelsDataFrame objects, then the base 
graphics approach as before - use locator() to find the offset. This is 
untried, because you did not either show a publically available data set, 
or provide a (subsetted) copy of your own.

For your bar plot, see layout() or ?par - see the mfrow= argument to add 
another plot to the graphics device.

Roger

> plot(imagematrix(mat))# To plot image in Color.
> axis(1,col.axis=?blue?,font.axis=4)
> axis(2,col.axis=?blue?,font.axis=4)
> title(main = list(" COLOR IMAGE", font = 4,col=?Blue?), xlab=list(?E-W Direction (Unit in Meters)?,font=3,col=?blue?),ylab= list(?N-S Direction (Unit in Meters)?, font=3,col=?blue?))
>
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-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no