On Tue, May 17, 2011 at 4:01 PM, Chethan S. <[email protected]> wrote: > Hi all! > > I am confused about the utility of r.patch and i.group w.r.t. image > classification. > > In ERDAS for supervised classification layer stacking can be done followed > by classification. > > A way to layer stack in GRASS would be r.patch (since layers are more than > 3, I can't use r.composite). But for classifying in GRASS since i.group has > to be used, can I use i.group to do layer stacking instead of using r.patch > and then classify?
If you want to mosaik (compose spatially *adjacent* maps), then use r.patch. If you want to vertically merge images in order to close holes, use r.patch. If you want to vertically merge images in order to make a RGB composite or HIS composite, use r.composite etc If you want to *logically* combine a stack of maps in a group (that's only targeting the metadata essentially), use i.group. Most i.* commands expect a group to be defined in order to easily tell them which images to be analysed. That's all that i.group does. Hope this helps Markus _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
