[GRASS-user] Newbie with composite raster import
al1 at ajltech.co.uk
Mon Aug 6 10:30:57 EDT 2007
Please excuse my newbiness. I have been reading documentation left, right
and centre and I may be missing something but I can't find an obvious way
to do this.
I have a set of high resolution digital maps (currently a matrix of about
200x400, each at 1280x1024 resolution). They are saved as GIF files,
though that could be changed, and I know their centre and edge positions
in terms of Lat/Long to a negligible error. These data are stored in a
tab-delimited text file. The map fragments are in a transverse mercator
projection though not UTM. They are plain image files with no geographic
data geocoded into the format.
What I want to do is to import them automatically via shell-scripted
commands to a Grass raster layer(s?) in order to cover the region over
which they spread, so that within grass I can work with it as a contiguous
I have found information about importing scanned maps with graphical
picking of corners but this is both far too time consuming and unnecessary
for what I am attempting (the maps are 'square', not scanned, and I can
provide their edge positions automatically). I have also found some
indications that each raster image has to end up as its own layer... how
does this work with groups, large numbers of map fragments etc? Do I have
to join the raster images within Grass or can they be kept separate?
If someone could point me in the right direction in terms of which
commands I need to use and whether this is possible, I'd be very grateful.
I'm really looking forward to getting this lot into Grass so that I can
start working with it and learning more!
Many many thanks in advance,
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