[Qgis-user] Canvas larger than viewport is rendered/drawn for vector layers, but not for raster layers

[Thomas Larsen Wessel]

I have tried out version 3.34 with the rendering profiler.  However, I
misunderstood your response and thought that it was a feature that would
let me set a rendering profille, ie let me choose to have some raster
layers prerendered outside the visible extent.

Anyway, the profiler feature is quite cool feature, and interesting
to watch :)

Lets say I have a some locally stored raster data, e.g. xyz tiles or
geopackage. What would it take if I wanted those to be prerendered outside
the visible extent? I think my PC should be able to handle that. Would I
need to dig into the C++ code and make my own build with my own preferences?

Are there any articles out there that I should have a look at? I suspect I
am not the first one who is looking to have raster layers prerendered :)

Sincerely





On Sat, Dec 16, 2023 at 2:49 PM Thomas Larsen Wessel <mrvelle at gmail.com>
wrote:

> Thanks :) I am looking forward to testing that new feature out :)
>
> On Mon, Dec 11, 2023 at 10:47 AM Nyall Dawson <nyall.dawson at gmail.com>
> wrote:
>
>>
>>
>> On Thu, 16 Nov 2023, 2:40 am Thomas Larsen Wessel via QGIS-User, <
>> qgis-user at lists.osgeo.org> wrote:
>>
>>> This screen capture demonstrates much better than words:
>>> https://imgur.com/5LSEsiY.
>>>
>>> Is there any way I can make it prerender the raster data as well?
>>>
>>> What I have already tried:
>>> * setting almost infinite cache size
>>> * all the relevant QGIS options/settings I could find
>>> * both local (gpkg) and remote WMS raster data
>>> * both Windows and Linux
>>> * QGIS 3.22 and 3.30
>>> * different CRS for layer
>>>
>>> Some of my tests did make the rendering speed up, but no matter what it
>>> always renders the raster data only for the canvas inside the view port,
>>> and does not render anything outside of the view port, whereas vector data
>>> is always rendered for an area that extends outside the view port.
>>>
>>
>> There's a few parts to the logic defining whether a layer will be
>> included in the outside-visible-extent preview:
>>
>> - WMS layers are **never** included. This is by design, to reduce
>> unnecessary server load
>> - when a layer is drawn the time taken to render it is recorded. If this
>> time exceeds a certain threshold, then the layer is marked as too expensive
>> to render in these optional out-of-canvas areas.
>>
>> (You can check the new renderer profile option available in the F12
>> debugging tools panel in 3.34 for more detailed information about layer
>> render times)
>>
>> Nyall
>>
>>
>>
>>> Sincerely, Thomas
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>>
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