[GRASS-user] r.mfilter produces empty result

[Luí­s Moreira de Sousa]

Thank you Anna, indeed with TYPE P it works correctly.

My first question is why is it in the book with TYPE S? That way it does not seem to be a high-pass filter at all...

I also find the definition of the sequential filter somewhat unclear. Not sure what it does, but certainly can not be used with high-pass or low-pass filters.

Thank you.

--
Luís Moreira de Sousa
Im Grund 6
CH-8600 Dübendorf
Switzerland

Phone: +41 (0)79 812 62 65
Email: luis.de.sousa at protonmail.ch
URL: https://sites.google.com/site/luismoreiradesousa

-------- Original Message --------
Subject: Re: [GRASS-user] r.mfilter produces empty result
Local Time: 11 May 2017 4:41 PM
UTC Time: 11 May 2017 14:41
From: kratochanna at gmail.com
To: Luí­s Moreira de Sousa <luis.de.sousa at protonmail.ch>, GRASS user list <grass-user at lists.osgeo.org>

On Thu, May 11, 2017 at 10:15 AM, Luí­s Moreira de Sousa
<luis.de.sousa at protonmail.ch> wrote:
> Hi Anna, thanks for the help. I can not post the DEM to the list, here is a
> link to Dropbox:

It seems the problem is in the filter specification:

TITLE 3x3 High Pass
MATRIX 3
-1 -1 -1
-1 8 -1
-1 -1 -1
DIVISOR 9
TYPE S

If you change it to TYPE P it will work. S is 'sequential':

Sequential filtering happens in place. As the filter is applied to the
raster map layer, the category values that were changed in neighboring
cells affect the resulting category value of the current cell being
filtered.

So since you have nulls all around it it probably propagates the
nulls. I am not sure if it's a bug. Is the S type required for your
analysis?

Anna

>
> --
> Luís Moreira de Sousa
> Im Grund 6
> CH-8600 Dübendorf
> Switzerland
>
> Phone: +41 (0)79 812 62 65
> Email: luis.de.sousa at protonmail.ch
> URL: https://sites.google.com/site/luismoreiradesousa
>
>
> -------- Original Message --------
> Subject: Re: [GRASS-user] r.mfilter produces empty result
> Local Time: 11 May 2017 3:56 PM
> UTC Time: 11 May 2017 13:56
> From: kratochanna at gmail.com
> To: Martin Landa <landa.martin at gmail.com>
> Luí­s Moreira de Sousa <luis.de.sousa at protonmail.ch>,
> grass-user at lists.osgeo.org <grass-user at lists.osgeo.org>
>
> On Thu, May 11, 2017 at 3:47 AM, Martin Landa <landa.martin at gmail.com>
> wrote:
>> Hi,
>>
>> 2017-05-11 9:36 GMT+02:00 Luí­s Moreira de Sousa
>> <luis.de.sousa at protonmail.ch>:
>>>> r.mfilter input=blenddem output=blenddem.highpass filter=highpass9.txt
>>> 100%
>>> Writing raster map <blenddem.highpass>
>>
>> did you set up correctly computational region?
>>
>> g.region raster=blenddem
>>
>> Ma-
>>
>
> https://gis.stackexchange.com/questions/239556/r-mfilter-produces-empty-result
>
> From the GIS SE question it seems everything is correctly set. In that
> case, could you provide us with your data to test it? You can send a
> link to it, offlist if you need to.
>
> Anna
>
>> --
>> Martin Landa
>> http://geo.fsv.cvut.cz/gwiki/Landa
>> http://gismentors.cz/mentors/landa
>> _______________________________________________
>> grass-user mailing list
>> grass-user at lists.osgeo.org
>> https://lists.osgeo.org/mailman/listinfo/grass-user
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/grass-user/attachments/20170511/2f88f891/attachment-0001.html>