[GRASS-dev] new addon: i.variance

GRASS GRASS developer
1

Hi all,

FYI, I uploaded a simple new addon, i.variance [1], which calculates local variance in an image for successively degraded resolution in order to detect whether there are certain scales corresponding to specific, well-represented objects in that image. It is based on [2].

Enjoy !

Moritz

[1] https://grass.osgeo.org/grass72/manuals/addons/i.variance.html
[2] Curtis E. Woodcock, Alan H. Strahler, The factor of scale in remote sensing, Remote Sensing of Environment, Volume 21, Issue 3, April 1987, Pages 311-332, ISSN 0034-4257, http://dx.doi.org/10.1016/0034-4257(87)90015-0.

2

Hi Moritz,

On Tue, Mar 21, 2017 at 1:49 PM, Moritz Lennert
<mlennert@club.worldonline.be> wrote:

Hi all,

FYI, I uploaded a simple new addon, i.variance [1], which calculates local
variance in an image for successively degraded resolution in order to detect
whether there are certain scales corresponding to specific, well-represented
objects in that image. It is based on [2].

Very interesting!

Would you mind to add a note on how to interprete the "peak values of
variance" in the examples?
Say, what to deduce from it in terms of the size of detectable objects?

thanks
Markus

Enjoy !

Moritz

[1] https://grass.osgeo.org/grass72/manuals/addons/i.variance.html
[2] Curtis E. Woodcock, Alan H. Strahler, The factor of scale in remote
sensing, Remote Sensing of Environment, Volume 21, Issue 3, April 1987,
Pages 311-332, ISSN 0034-4257,
http://dx.doi.org/10.1016/0034-4257(87)90015-0.

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Markus Neteler, PhD
http://www.mundialis.de - free data with free software
http://grass.osgeo.org
http://courses.neteler.org/blog

3

Le Thu, 4 May 2017 19:26:12 +0200,
Markus Neteler <neteler@osgeo.org> a écrit :

Hi Moritz,

On Tue, Mar 21, 2017 at 1:49 PM, Moritz Lennert
<mlennert@club.worldonline.be> wrote:
> Hi all,
>
> FYI, I uploaded a simple new addon, i.variance [1], which
> calculates local variance in an image for successively degraded
> resolution in order to detect whether there are certain scales
> corresponding to specific, well-represented objects in that image.
> It is based on [2].

Very interesting!

Would you mind to add a note on how to interprete the "peak values of
variance" in the examples?
Say, what to deduce from it in terms of the size of detectable
objects?

Does r71023 correspond to what you are after ?

Moritz

4

On Fri, May 5, 2017 at 10:37 AM, Moritz Lennert
<mlennert@club.worldonline.be> wrote:

Le Thu, 4 May 2017 19:26:12 +0200, > Markus Neteler <neteler@osgeo.org> a écrit :

...

Would you mind to add a note on how to interprete the "peak values of
variance" in the examples?
Say, what to deduce from it in terms of the size of detectable
objects?

Does r71023 correspond to what you are after ?

Perfetto!

Thanks,
Markus