Extracting smaller raster images from big ones

[Philip Verhagen]

> Help! I don't know if this is an obvious question, but I have been 
> searching the Grass manual and can't find an answer - I have large raster 
> images and want to extract smaller ones from them for the purpose of 
> supervised classification. How do I do this? I have the coords of the 
> smaller images I want. Defining smaller regions doesn't help, since 
> i.class doesn't take a region name, it simply loads the entire image !
> Please help.... I don't want to export to IDRISI, then extract, and then 
> reimport, as that would take rtoo much time.
> Thanks a lot
> Harini
> 
> ------------------------------------------------------------------------
> | Harini Nagendra               E-MAIL : harini at ces.iisc.ernet.in      |
> | Center for Ecological         PHONE  : 91 80 309 2639 (Hostel: LR-94)|
> | Sciences                             : 91 80 309 2506 (Department)   |
> | Indian Institute of Science   FAX    : 91 80 334 1683                |
> | Bangalore 560 012 India       TELEX  : 845 8349 IISc IN              |
> ------------------------------------------------------------------------
> 

The trick is to save the zoomed image as a new raster file. So, first specify
your new region, then use r.resample to obtain a new image. Good luck!

Philip Verhagen

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