[QGIS-Developer] QGIS 3D: Fails with large DTM image

C Hamilton adenaculture at gmail.com
Mon Dec 18 06:41:23 PST 2017


Martin,

Thanks. That is the issue. I'm sure the 3D support is going to continuously
evolve and get better and hopefully sometime in the near future it will
handle no-data values. In the meantime I will use your suggestion of
remapping the no-data values.

Happy holidays,

Calvin

On Sat, Dec 16, 2017 at 12:03 PM, Martin Dobias <wonder.sk at gmail.com> wrote:

> Hi Calvin
>
> I have tested with your layer and the problem is with the no-data
> values - right now the terrain generator does not have a concept of
> no-data values so they are interpreted as valid values, which in this
> case is a very high number (around 1e38) and that breaks the 3D view.
> Best to keep an eye on https://issues.qgis.org/issues/17558 as that is
> essentially the same problem. As a temporary workaround, you could try
> to change your layer's no-data values closer to the valid range (e.g.
> zero or 500).
>
> Cheers
> Martin
>
>
> On Fri, Dec 15, 2017 at 10:51 PM, C Hamilton <adenaculture at gmail.com>
> wrote:
> > The current DEM that I am working with is located here:
> >
> > http://gis3.oit.ohio.gov/ZIPARCHIVES/ELEVATION/
> GRIDMOSAICS/GRE_DEM_MOS.zip
> >
> > I'm surprised that resizing did not help so I am not sure what is wrong.
> I
> > created a small 560x460 image that I have attached. It does not work for
> me.
> >
> > Thanks,
> > Calvin
> >
> > On Fri, Dec 15, 2017 at 4:22 PM, Martin Dobias <wonder.sk at gmail.com>
> wrote:
> >>
> >> Hi Calvin
> >>
> >> Could you please point me to such a DEM to try it out myself? Or even
> >> better, file a ticket on issues.qgis.org so that we do not forget
> >> about it. Not sure from the top of my head what could go wrong there -
> >> the raster size should not be the reason really as the raster data
> >> access is using the same code paths as 2D rendering would. Maybe there
> >> is something in the data that causes the problem. If you resize the
> >> large DEM to e.g. 5000x5000 pixels, does that help?
> >>
> >> Regards
> >> Martin
> >>
> >>
> >> On Fri, Dec 15, 2017 at 8:38 PM, C Hamilton <adenaculture at gmail.com>
> >> wrote:
> >> > QGIS 3D has a lot of potential and works well with small DEM data
> sets,
> >> > but
> >> > when ever I try it with a large DTM image I just get a white screen. I
> >> > tend
> >> > to work with large DEMs (50000 x 50000 pixels and larger) and I would
> >> > love
> >> > for this to work with it properly.
> >> >
> >> > Do you have any ideas why this is the case? I have tried this with an
> >> > AIG/Arc/Info Binary Grid image as well as a GeoTIFF with overviews.
> >> >
> >> > OS: Windows 7; QGIS 3 Version: 2.99.0-238
> >> >
> >> > Thanks,
> >> >
> >> > Calvin
> >> >
> >> > _______________________________________________
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> >
>
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