[Qgis-user] mdal / mesh simple formats

[Peter Petrik]

Hi Matt,

MDAL basically supports a bunch of data formats that are mostly defined by
the suppliers of the results. It comes with the fileformat (e.g. ASCII or
netCDF, ...) + data spec (which arrays are defined/expected with which
properties). So either you need to replicate one of the supported formats
or
alternatively we can write a data reader for your format in MDAL.

Kind Regards,
Peter Petrík
CPO of Mergin Maps
LI <https://www.linkedin.com/in/peter-petrik/>, Mergin Maps
<https://www.merginmaps.com>





On Sat, Aug 27, 2022 at 3:02 AM Matt Boyd via Qgis-user <
qgis-user at lists.osgeo.org> wrote:

> Thanks Richard,
> that looks interesting. I can now get regular grid / square mesh to
> display correctly but I'm working with tri-mesh and anything I try to
> load using that ends up like this..Just a line of squares.
> There's something obvious I'm missing in the format here.
>
> On Fri, Aug 26, 2022 at 4:56 PM Richard Duivenvoorde
> <rdmailings at duif.net> wrote:
> >
> > Hi Matt,
> >
> > I'm not a Mesh expert either, but I use (and create) netcdf using python
> using the
> > https://github.com/Unidata/netcdf4-python module
> >
> > Netcdf is pretty good supported in QGIS in my experience
> >
> > Our data has also a time dimension so we use the CF convention [0] and
> fiddling around with the so called UGRID convention [1] But maybe that is
> both too much for a simple tin...
> >
> > I Googled:
> >
> https://stackoverflow.com/questions/48864357/convert-hdf5-to-netcdf4-in-bash-r-python-or-ncl
> > as being able to convert hdf5 to netcdf... didn't/couldn't try/test
> though..
> >
> > Regards,
> >
> > Richard Duivenvoorde
> >
> > [0]
> https://en.wikipedia.org/wiki/Climate_and_Forecast_Metadata_Conventions
> > [1] http://ugrid-conventions.github.io/ugrid-conventions/#data-variables
> >
> > On 8/26/22 03:32, Matt Boyd via Qgis-user wrote:
> > > Thanks, thats pretty helpful.
> > > I'm running QGIS 3.26.2-Buenos Aires installed from osgeo.
> > > under the xdmf directory there the xmf/hdf files look pretty similar
> > > to what I'm using but they won't load. there's a partial duplicate of
> > > the data in the hdf file in that directory as a 2dm file which does
> > > work.
> > > I'm still not sure if I'm supposed to be able to load the xmf/hdf
> > > files directly using mdal? I can easily drop out my hdf5 data to the
> > > 2dm format is this the proposed way to do it?
> > >
> > > Thanks again
> > > Matt
> > >
> > > On Fri, Aug 26, 2022 at 4:09 AM Delaz J via Qgis-user
> > > <qgis-user at lists.osgeo.org> wrote:
> > >>
> > >> Hi Matt,
> > >>
> > >> The mdal repo has a number of mesh data
> > >> (https://github.com/lutraconsulting/MDAL/tree/master/tests/data) but
> > >> whether these are simple meshes/formats or not is beyond my
> > >> understanding of this data type.
> > >>
> > >> Hope that helps,
> > >>
> > >> Harrissou
> > >>
> > >> Le 25/08/2022 à 09:41, Matt Boyd via Qgis-user a écrit :
> > >>
> > >>> Hi QGIS people,
> > >>> I asked something like this a couple of years ago, managed to find
> > >>> some workarounds and now that I know a little more about what I'm
> > >>> doing I could use a bit of help.
> > >>> I've got some simple tin meshes that I'd like to drop into QGIS, they
> > >>> get generated in a python modelling software I'm using.
> > >>> The data all sits in a single hdf5 file, points with coordinates, the
> > >>> cells which are just the indexes of 3 points, plus attributes for
> each
> > >>> point. About the simplest mesh setup I can imagine.
> > >>> I'm trying to find the simplest format that mdal supports with an
> > >>> example dataset so I can make something similar. (ideally hdf5 so I
> > >>> don't need to work out how to use anything new in python).
> > >>>
> > >>> Any tips?
> > >>> Thanks
> > >>> Matt
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