[Qgis-user] Working with irregular magnetometry data points - converting them to an image
Benjamin Ducke
benducke at fastmail.fm
Mon Apr 23 12:30:06 PDT 2018
Hi Calvin,
On 21/04/18 22:37, C Hamilton wrote:
> Ben,
>
> I have been taking a look at this and I am able to get it rasterized,
> but I am not finding the fill in QGIS. All I see under GRASS GIS 7 is
> r.fill.dir and r.fillnulls. Where do I find r.fill.stats? It appears
> that the version of GRASS in QGIS is 7.4
That's strange. I am running QGIS 3.0.1 and GRASS 7.4.0.
I can confirm that r.fill.stats is present in GRASS
7.4.0, but it does not appear in the list of GRASS 7
modules under QGIS' Processing.
I can only guess that the QGIS Processing plug-in
for some reason skips that particular GRASS command.
I guess you could try launching GRASS 7 directly
and using r.fill.stats from within the GRASS shell
or GRASS GUI.
Cheers,
Ben
>
> Thanks,
>
>
>
> On Fri, Apr 20, 2018 at 1:10 PM, Benjamin Ducke <benducke at fastmail.fm
> <mailto:benducke at fastmail.fm>> wrote:
>
> Hi Calvin,
>
> On 20/04/18 18:46, Richard McDonnell wrote:
> > Calvin,
> >
> > Under Processing Toolbox, Type interpolation into the search
bar, the
> > tool you want can be found there.
>
> None of the typical GIS interpolation tools will be
> of much help here, since they have all been optimized
> to work with relatively sparse data. They will be
> too inefficient for high-resolution geomagnetic data.
>
> You data is already dense, with some gaps. So you need
> something that is fast and efficient for small
> interpolation radii, and will not produce too many
> artefacts.
>
> If you can use the GRASS7 plug-in from within QGIS,
> than this is a good processing path:
>
> 1. Rasterize your data points, using a cell size
> small enough so that you don't have too much information
> loss (i.e. not too many occurrences of more than one data
> point per cell). This might take a little trial and error
> to find good settings. You should end up with a raster
> where you have gaps of max. 1-3 empty cells between cells
> with measurement data.
>
> Now you need to fill these relatively small gaps.
>
> 2. Use r.fill.stats from current GRASS 7.4:
>
> https://grass.osgeo.org/grass74/manuals/r.fill.stats.html
> <https://grass.osgeo.org/grass74/manuals/r.fill.stats.html>
>
> ... because that has been designed exactly for the
> purpose. Set the interpolation radius as small as
> possible, so that it just manages to fill the gaps.
> With a small radius, r.fill.stats is very fast and
> memory efficient, even on very large raster datasets.
>
> Note that r.fill.stats is part of GRASS 7 only since
> version 7.4. If your QGIS ships with an earlier
> version, then you might have to update your GRASS 7
> binaries manually.
>
> Best,
>
> Ben
>
> > Regards,
> >
> > Richard.
> >
> > On 20/04/2018 16:42, C Hamilton wrote:
> >> I don't know how many of you have worked with archaeological
> >> magnetormetry data, but I have been asked to help with magnetometry
> >> data of the ancient Mound Builders in North America. I am
looking for
> >> some suggestion on how to best turn the irregular magnetic data
points
> >> into an image.
> >>
> >> I see an Interpolation plugin that perhaps is the solution, but
I also
> >> see that it is not part of QGIS 3. Is this because it has not been
> >> ported yet, or is not going to be porter, or is there a better
solution?
> >>
> >> I don't know if any of the Lidar tools would work for this or not.
> >> LASTools is a commercial product and the locked version only works
> >> with small data sets and adds noise unless you purchase a
license. At
> >> least that is how it was the last time I used it.
> >>
> >> Thanks for any suggestions.
> >>
> >> Calvin
> >>
> >>
> >> _______________________________________________
> >> Qgis-user mailing list
> >> Qgis-user at lists.osgeo.org <mailto:Qgis-user at lists.osgeo.org>
> >> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> <https://lists.osgeo.org/mailman/listinfo/qgis-user>
> >> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> <https://lists.osgeo.org/mailman/listinfo/qgis-user>
> >
> > --
> > *_Richard McDonnell_*
> > *GIS Specialist PgD GIS AssocSCSI*
> > *OPW FRM Data Management*
> > *52 Stephens Green, Dublin 2.*
> > TEL: 01 6476543
> >
> > <http://www.opw.ie/>
> >
> >
> >
> > Email Disclaimer: http://www.opw.ie/en/disclaimer/
> <http://www.opw.ie/en/disclaimer/>
> >
> >
> > _______________________________________________
> > Qgis-user mailing list
> > Qgis-user at lists.osgeo.org <mailto:Qgis-user at lists.osgeo.org>
> > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> <https://lists.osgeo.org/mailman/listinfo/qgis-user>
> > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> <https://lists.osgeo.org/mailman/listinfo/qgis-user>
> >
>
>
>
> --
> Dr. Benjamin Ducke
> Deutsches Archäologisches Institut (DAI)
> Zentrale Berlin, IT-Referat
> * Projekt "Stunde Null" *
> _______________________________________________
> Qgis-user mailing list
> Qgis-user at lists.osgeo.org <mailto:Qgis-user at lists.osgeo.org>
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> <https://lists.osgeo.org/mailman/listinfo/qgis-user>
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> <https://lists.osgeo.org/mailman/listinfo/qgis-user>
>
>
--
Dr. Benjamin Ducke
Deutsches Archäologisches Institut (DAI)
Zentrale Berlin, IT-Referat
* Projekt "Stunde Null" *
On 21/04/18 22:37, C Hamilton wrote:
> Ben,
>
> I have been taking a look at this and I am able to get it rasterized,
> but I am not finding the fill in QGIS. All I see under GRASS GIS 7 is
> r.fill.dir and r.fillnulls. Where do I find r.fill.stats? It appears
> that the version of GRASS in QGIS is 7.4
>
> Thanks,
>
>
>
> On Fri, Apr 20, 2018 at 1:10 PM, Benjamin Ducke <benducke at fastmail.fm
> <mailto:benducke at fastmail.fm>> wrote:
>
> Hi Calvin,
>
> On 20/04/18 18:46, Richard McDonnell wrote:
> > Calvin,
> >
> > Under Processing Toolbox, Type interpolation into the search bar, the
> > tool you want can be found there.
>
> None of the typical GIS interpolation tools will be
> of much help here, since they have all been optimized
> to work with relatively sparse data. They will be
> too inefficient for high-resolution geomagnetic data.
>
> You data is already dense, with some gaps. So you need
> something that is fast and efficient for small
> interpolation radii, and will not produce too many
> artefacts.
>
> If you can use the GRASS7 plug-in from within QGIS,
> than this is a good processing path:
>
> 1. Rasterize your data points, using a cell size
> small enough so that you don't have too much information
> loss (i.e. not too many occurrences of more than one data
> point per cell). This might take a little trial and error
> to find good settings. You should end up with a raster
> where you have gaps of max. 1-3 empty cells between cells
> with measurement data.
>
> Now you need to fill these relatively small gaps.
>
> 2. Use r.fill.stats from current GRASS 7.4:
>
> https://grass.osgeo.org/grass74/manuals/r.fill.stats.html
> <https://grass.osgeo.org/grass74/manuals/r.fill.stats.html>
>
> ... because that has been designed exactly for the
> purpose. Set the interpolation radius as small as
> possible, so that it just manages to fill the gaps.
> With a small radius, r.fill.stats is very fast and
> memory efficient, even on very large raster datasets.
>
> Note that r.fill.stats is part of GRASS 7 only since
> version 7.4. If your QGIS ships with an earlier
> version, then you might have to update your GRASS 7
> binaries manually.
>
> Best,
>
> Ben
>
> > Regards,
> >
> > Richard.
> >
> > On 20/04/2018 16:42, C Hamilton wrote:
> >> I don't know how many of you have worked with archaeological
> >> magnetormetry data, but I have been asked to help with magnetometry
> >> data of the ancient Mound Builders in North America. I am looking for
> >> some suggestion on how to best turn the irregular magnetic data points
> >> into an image.
> >>
> >> I see an Interpolation plugin that perhaps is the solution, but I also
> >> see that it is not part of QGIS 3. Is this because it has not been
> >> ported yet, or is not going to be porter, or is there a better solution?
> >>
> >> I don't know if any of the Lidar tools would work for this or not.
> >> LASTools is a commercial product and the locked version only works
> >> with small data sets and adds noise unless you purchase a license. At
> >> least that is how it was the last time I used it.
> >>
> >> Thanks for any suggestions.
> >>
> >> Calvin
> >>
> >>
> >> _______________________________________________
> >> Qgis-user mailing list
> >> Qgis-user at lists.osgeo.org <mailto:Qgis-user at lists.osgeo.org>
> >> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> <https://lists.osgeo.org/mailman/listinfo/qgis-user>
> >> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> <https://lists.osgeo.org/mailman/listinfo/qgis-user>
> >
> > --
> > *_Richard McDonnell_*
> > *GIS Specialist PgD GIS AssocSCSI*
> > *OPW FRM Data Management*
> > *52 Stephens Green, Dublin 2.*
> > TEL: 01 6476543
> >
> > <http://www.opw.ie/>
> >
> >
> >
> > Email Disclaimer: http://www.opw.ie/en/disclaimer/
> <http://www.opw.ie/en/disclaimer/>
> >
> >
> > _______________________________________________
> > Qgis-user mailing list
> > Qgis-user at lists.osgeo.org <mailto:Qgis-user at lists.osgeo.org>
> > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> <https://lists.osgeo.org/mailman/listinfo/qgis-user>
> > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> <https://lists.osgeo.org/mailman/listinfo/qgis-user>
> >
>
>
>
> --
> Dr. Benjamin Ducke
> Deutsches Archäologisches Institut (DAI)
> Zentrale Berlin, IT-Referat
> * Projekt "Stunde Null" *
> _______________________________________________
> Qgis-user mailing list
> Qgis-user at lists.osgeo.org <mailto:Qgis-user at lists.osgeo.org>
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> <https://lists.osgeo.org/mailman/listinfo/qgis-user>
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> <https://lists.osgeo.org/mailman/listinfo/qgis-user>
>
>
--
Dr. Benjamin Ducke
Deutsches Archäologisches Institut (DAI)
Zentrale Berlin, IT-Referat
* Projekt "Stunde Null" *
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