[GRASS-user] Re: Import question
micha at arava.co.il
Mon Sep 20 13:42:28 EDT 2010
On 09/20/2010 06:35 PM, Hermann Peifer wrote:
> On 20/09/2010 18:09, Adam Dershowitz, Ph.D., P.E. wrote:
>> I have a large ortho image, that is in MrSID format (A full county
>> at high res). The file is ~3.5 gig. It covers a much larger area
>> then I need. So I set my region to the size that I do need, and then
>> imported. The import took something like 10 hrs. And, I now see
>> that in my PERMANENT folder I have 3 files that are each 15 gig (one
>> red, one blue, one green),
>> The map was imported, but if I zoom to the size of the current map,
>> it seems that the whole map was imported, not just the area inside
>> the current region.
>> I thought that imports are cropped to the current region? Am I
>> mistaken about this? Is there some setting to cause this to happen?
>> I did the import with r.in.gdal. I am using the binary release of
>> 6.4 on a Mac.
>> The reasons that I care are 1) This map, for a small area of
>> interest, it taking up 45 gig on my hard drive. 2) Because the map
>> is so large, it takes a while for the display to update when I make
>> any changes.
>> Any guidance?
If you used r.in.gdal, then I guess your gdal has MrSID support. So you
should be able to use the gdal_translate utility with the -projwin flag
to clip out the area you need, and create a new tif. Something like:
gdal_translate -projwin ulX ulY lrX lrY original.sid clipped.tif
> > Raster import and export
> > The module r.in.gdal offers a common interface for...
> > The full map is always imported.
> see http://grass.osgeo.org/grass64/manuals/html64_user/rasterintro.html
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