[GRASS-user] Re: Import question

[Micha Silver]

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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-- 
Micha Silver
Arava Development Co. +972-52-3665918
http://www.surfaces.co.il