I heard these suggestions, but my project has a very short life, so I
haven't got the time to experiment really.
On 17/11/17 23:38, Even Rouault wrote:
On vendredi 17 novembre 2017 23:14:19 CET Patrick Dunford wrote:
> I understand (especially with the other comments about the functionality
> and having to wait for images to be retrieved from servers) what you
> guys are trying to achieve with this feature, but in my project the
> rasters I have loaded cover hundreds of square kilometres, and Qgis
> caches all of them, regardless of how far they are from the particular
> point where I am working on a map.
>
If your rasters are in the same projection and same resolution, did
you consider building a virtual .VRT catalog from them ? (or group
them in catalogs per projection and resolution). That could reduce the
number of layers.
> On 17/11/17 21:56, Alessandro Pasotti wrote:
> > Maybe a crazy idea, but if this proves to be an issue, what about a
> > monitoring process that prompts the user to disable this feature when
> > memory goes over a certain threshold?
> >
> > On Fri, Nov 17, 2017 at 8:21 AM, Patrick Dunford
> >
> > <enzedrailm...@gmail.com <mailto:enzedrailm...@gmail.com>> wrote:
> > Most of them are geoJpeg, there are a smaller number of geoTiff
> >
> > On 17/11/17 20:10, Matthias Kuhn wrote:
> >> Thanks, that's an interesting information.
> >>
> >> What datatype are your rasters?
> >>
> >> On 11/17/2017 03:53 AM, Patrick Dunford wrote:
> >>> With the second command
> >>>
> >>> iface.mapCanvas().setPreviewJobsEnabled(False)
> >>>
> >>> when I run that command it drops back to 16 GB
> >>>
> >>> On 16/11/17 23:15, Matthias Kuhn wrote:
> >>>> Hi Patrick,
> >>>>
> >>>> Would be interesting to do this test with previews enabled and
> >>>> disabled. Then we'll see if it's actually the previews or some
> >>>> other mechanism that is causing this.
> >>>>
> >>>> IIRC only a composite image is saved in the preview jobs and
> >>>> not each layer separately, but that's just what I remember and
> >>>> not evidence based.
> >>>>
> >>>> You can enable them in the python console with
> >>>>
> >>>> iface.mapCanvas().setPreviewJobsEnabled(True)
> >>>>
> >>>> and disable with
> >>>>
> >>>> iface.mapCanvas().setPreviewJobsEnabled(False)
> >>>>
> >>>> Thanks for a feedback
> >>>>
> >>>> Matthias
> >>>>
> >>>> On 11/16/2017 08:42 AM, Patrick Dunford wrote:
> >>>>> In my current project using Qgis 2.99, turning off the rasters
> >>>>> uses 16 GB, turning them on uses 52 GB
> >>>>>
> >>>>> I do not believe it is independent from the number of layers
> >>>>> that are being displayed.
> >>>>>
> >>>>> Previous versions of the software did not cache every single
> >>>>> raster (the number of rasters actually being displayed on the
> >>>>> canvas at any one time is a small fraction of the total number
> >>>>> in the project)
> >>>>>
> >>>>> On 16/11/17 20:11, Matthias Kuhn wrote:
> >>>>>> Hi Patrick,
> >>>>>>
> >>>>>> This uses some memory (~ canvas width pixels * canvas height
> >>>>>> pixels * 8 preview images * 32 bit RGBA), so let's assume 50
> >>>>>> MB to 100 MB.
> >>>>>>
> >>>>>> This consumption is independent from the number or type of
> >>>>>> layers.
> >>>>>>
> >>>>>> Matthias
> >>>>>>
> >>>>>> On 11/16/2017 08:02 AM, Patrick Dunford wrote:
> >>>>>>> So to put it another way this is the reason why Qgis wants
> >>>>>>> to use a huge amount of memory (40 GB) when I have a lot of
> >>>>>>> raster images loaded in the background.
> >>>>>>>
> >>>>>>> On 16/11/17 18:56, Tim Sutton wrote:
> >>>>>>>> Hi
> >>>>>>>>
> >>>>>>>>> On 16 Nov 2017, at 04:35, Patrick Dunford
> >>>>>>>>> <enzedrailm...@gmail.com <mailto:enzedrailm...@gmail.com>>
> >>>>>>>>> wrote:
> >>>>>>>>>
> >>>>>>>>> What is this "preview job" function?
> >>>>>>>>
> >>>>>>>> Its application logic to prefetch / pre-render offscreen
> >>>>>>>> content in anticipation of user panning the map.
> >>>>>>>>
> >>>>>>>> Regards
> >>>>>>>>
> >>>>>>>> Tim
> >>>>>>>>
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> >>>>>>>>
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> >>>>>>>>
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