[GRASS-user] multi-date image segmentation in grass

Markus Neteler neteler at osgeo.org
Tue Sep 28 16:28:21 EDT 2010

On Tue, Sep 28, 2010 at 1:12 PM, maning sambale
<emmanuel.sambale at gmail.com> wrote:
> Hi,
> I have several Landsat (4-7) images from 1990-2002  which will be used
> for change analysis of land cover.  FAO's FRA-RSS [1] developed a
> standard methodology for integrating multi-temporal Landsat into a
> consistent sample tiles. The article [2] outlined the general method
> as:
>  - Image subsetting
>  - Radiometric normalization
>  - Contrast enhancement
>  - Multi-date image segmentation
> Most of the processing procedures I was able to do in GRASS GIS,
> except for the last step.  The process combined the multi-date imagery
> where an automated image segmentation was implemented to derive
> preliminary polygons to identify changes.  I believe they used
> ecognition for the segmentation.

We can (start to) recommend r.seg from Addons for this (I will ask
the author to accept inclusion in GRASS 7 as i.segmentation). We
could greatly improve the performance of i.smap by preprocessing
data with r.seg.

>  I've used i.smap for preliminary
> segmentation on separate dates but not for a combined multi-date
> imagery.  Anyone tried this with GRASS? Can i.pca do this or another
> tool?

I didn't try but it sounds interesting also for us (just lack of time). If could
provide me with a small spatial excerpt of all the channels as location,
I would try a few ideas and report.


> Any idea
> [1] http://www.fao.org/forestry/fra/remotesensingsurvey/en/
> [2] http://www.informaworld.com/smpp/content~content=a923063789~db=all~jumptype=rss
> --
> cheers,
> maning
> ------------------------------------------------------
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