[Qgis-developer] Raster providers

G. Allegri giohappy at gmail.com
Thu Mar 10 17:58:13 EST 2011


Radim, the round() you added in qgsgdalprovider causes problems for me on
VC++ (
http://trac.osgeo.org/qgis/browser/trunk/qgis/src/providers/gdal/qgsgdalprovider.cpp#L664
).

Should we add something like:
#define round(dbl) dbl >= 0.0 ? (int)(dbl + 0.5) : ((dbl - (double)(int)dbl)
<= -0.5 ? (int)dbl : (int)(dbl - 0.5))
?

2011/3/10 Radim Blazek <radim.blazek at gmail.com>

> I fact, I forgot to write a piece of logic, there is a shift.
>
> Radim
>
> On Thu, Mar 10, 2011 at 8:13 PM, Radim Blazek <radim.blazek at gmail.com>
> wrote:
> > I have changed how GDAL provider reads the data, it should be fast again.
> >
> >
> > BUT! I am not absolutely sure that resampling is perfect and the
> > nearest neighbour is alway nearest. I dont think however that anybody
> > could notice that in normal work. I would appreciate however if
> > somebody with fresh brain could check the alignment fiddling.
> >
> http://trac.osgeo.org/qgis/browser/trunk/qgis/src/providers/gdal/qgsgdalprovider.cpp#L529
> >
> > More pointers - more crashes expected!
> >
> > Radim
> >
> >
> > On Wed, Mar 9, 2011 at 8:30 PM, Giovanni Manghi
> > <giovanni.manghi at gmail.com> wrote:
> >> Hi,
> >>
> >> On Tue, 2011-03-08 at 20:17 +0100, Radim Blazek wrote:
> >>> Merged to trunk.
> >>
> >>
> >> I'm testing the new raster capabilities of QGIS and I would like to have
> >> your opinion on a certain matter before eventually filing a ticket.
> >>
> >> I have a bunch of big tiff rasters (> 1gb, sometimes > 2gb), with
> >> internal tiles and/or overviews.
> >>
> >> What I'm seeing is that now those rasters take quite a *lot* (making
> >> qgis not responsive for a while) to be rendered, before the merge it was
> >> all much quicker.
> >>
> >> As exemple:
> >>
> >> on QGIS 1.6 a 1.7gb geotiff with tiles and overviews opens in (more or
> >> less) 1 sec., in trunk now takes (more os less) 1 minute!
> >>
> >>
> >> After the raster show in the canvas, also opening its properties take a
> >> long time. Before the merge was immediate.
> >>
> >> Zooming and panning it is also much slower than before the merge.
> >>
> >> Overall it seems like that tiles and overviews are ignored or not read.,
> >> but to me seems that also opening big tiffs (> 1gb) without internal
> >> tiles and/or overviews takes a *lot* more than before the merge.
> >>
> >>
> >> anyone experiencing the same?
> >>
> >>
> >> cheers
> >>
> >> -- Giovanni --
> >>
> >>
> >
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