Hi Jan,
In response to your ps. I think using rgdal is the best way to go. If
your data is for example in a GeoTIFF file, reading it is as simple as:
GRID = readGDAL("your_file.tif")
Saves you some hassel and a number of lines of code.
cheers and hth,
Paul
[EMAIL PROTECTED] wrote:
Dear all,
I'm working with satellite images in R and plotting them via the code
below.
I was wondering whether coordinates (spatial["x"], spatial["y"]) are
used as centre coordinates of the pixels in the GRID? In this script;
spatial["x"] & spatial["y"] are the centre coordinates of the satellite
image pixels. I'm asking this because some software packages use the
upper left corner of a pixel as a reference.
require(sp)
# --> Create GRID and image in R
S <- SpatialPoints(cbind(spatial["x"], spatial["y"]), proj4string =
proj)
SP <- SpatialPixels(S, proj4string = proj, tolerance = 5e-07)
GRID <- SpatialPixelsDataFrame(points = SP , tolerance = 5e-07, data
= spatial[columnname])
proj4string(GRID) <- proj
gridded(GRID)
nr <- 30
zaxis <- c(0.7, 1)
plot(as(GRID, "Spatial"), axes=T)
title(main = paste(" Day ",dy[i,1], " Year ",dy[i,2], sep=""))
image(GRID, zlim=zaxis, col=rainbow(nr,start=0, end=2/6),add=T)
Thanks for your help,
Regards,
Jan
Ps. Is this good approach to plot satellite images as spatial grids in
R? is rgdal an better approach?
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--
Drs. Paul Hiemstra
Department of Physical Geography
Faculty of Geosciences
University of Utrecht
Heidelberglaan 2
P.O. Box 80.115
3508 TC Utrecht
Phone: +31302535773
Fax: +31302531145
http://intamap.geo.uu.nl/~paul
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