[GRASS-user] Wrangling CityGML with GRASS ?

[Markus Metz]

Hi Peter,

On Tue, Aug 6, 2019 at 12:23 PM "Peter Löwe" <peter.loewe at gmx.de> wrote:
>
> Hi Stefan,
>
> thanks for the link: That's also the latest information we found so far,
except for several OSGeo conference recordings (e.g.
https://doi.org/10.5446/40913 https://doi.org/10.5446/40694).

GML and GMLAS are supported by GDAL 2.2+. However, in order to import GMLAS
properly, some tricks are needed (interleaved reading for non-sequential
layers, see
https://gdal.org/drivers/vector/gmlas.html#performance-issues-with-large-multi-layer-gml-files)
which are built into GRASS 7.6+.

> My colleagues have ingested CityGML datasets into R, which caused issues
with the vector-topology for individual buildings.

That's not related to the data format, but to the content: 3D polygons.
These are not supported in GRASS, when importing you need to convert the
data to 2D with v.in.ogr -2, otherwise you get corrupt topology. Maybe this
is also needed for R.

Markus M

> Also, we have to cope with significant amounts of CityGML datasets, which
would require very large amounts of RAM, if the processing is done in R.
Since GRASS locations are storage-effective AND GRASS handles vector
topologies well, I had hoped that someone already explored this approach
further :-)
>
> If this should be not the case (yet) we'll gladly report at one of next
years FOSS4G events.
>
> Best,
> peter
>
> <peter.loewe at gmx.de>
>
>
> > Gesendet: Dienstag, 06. August 2019 um 11:13 Uhr
> > Von: "Stefan Blumentrath" <Stefan.Blumentrath at nina.no>
> > An: "Peter Löwe" <peter.loewe at gmx.de>, "grass-user at lists.osgeo.org" <
grass-user at lists.osgeo.org>
> > Betreff: RE: [GRASS-user] Wrangling CityGML with GRASS ?
> >
> > Hi Peter,
> >
> > Not personally...
> > I would guess you would import CityGML through GDAL:
> >
https://3d.bk.tudelft.nl/svitalis/citygml/gdal/2017/07/24/messing-around-with-citygml-on-gdal-2.2.html
> > There you can create subsets and the like...
> >
> > What are you planning to do with it, roughly?
> >
> > Cheers
> > Stefan
> >
> >
> > -----Original Message-----
> > From: grass-user <grass-user-bounces at lists.osgeo.org> On Behalf Of
"Peter Löwe"
> > Sent: torsdag 1. august 2019 11:10
> > To: grass-user at lists.osgeo.org
> > Subject: [GRASS-user] Wrangling CityGML with GRASS ?
> >
> > Hi list,
> >
> > I'm looking for information/howtos/etc. about how to deal with large
CityGML data sets using GRASS.
> >
> > Has anybody already explored this ?
> >
> > Best,
> > Peter
> >
> > <peter.loewe at gmx.de>
> >
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