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?
Thanks and regards,
Chethan S.
On Tue, May 17, 2011 at 4:01 PM, Chethan S. <chethanuniversal@gmail.com> 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