I haven't been able to find out much about the render caching feature. I
am now running all my computer with the render caching turned off, so
that less memory and swap resources are consumed in the computer. It
might be intended with this feature to reduce the time delay for
downloading tiles from a remote server for people that are using server
based resources but would also have the (in your case) less desirable
consequence of consuming significant amounts of data.
On 20/03/19 8:22 PM, Pascale Hutter wrote:
Hi Patrick
Thanks for you reply! It already helps me a lot, as it confirm my
impression of the new GIS caching far more data in the memory. I was
unsure whether this was really the case, as I found nothing on the
Internet about it. However, if you made the same experience this means
that there is something different in the way it handles raster data.
I will check, if I can change something in the settings for
rendering, to solve the problem. If I do find something, I will let
you know. Would be really great if the data volume could be decreased
this way. Otherwise I can see no way how I can use QGIS 3.x for small
environmental projects, which would be a pity.
Thank you for your help!
Pascale
M. Sc. Biologie
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Am 19.03.2019 um 15:15 schrieb Patrick Dunford
<[email protected] <mailto:[email protected]>>:
I left this question for a few days because I hoped someone with more
technical knowledge than me of how Qgis works with this type of data
would be able to answer your question. As a user I don't have the
same technical insight as one of the developers who may be reading
this question and more familiar with data processing in the software.
I currently work with projects that use large numbers of data layers
of raster type, however in my case they are all in files that I have
downloaded to my computer and loading locally, rather than any type
of data that could be accessed from an online server.
I have found in experience with working with raster layers that Qgis
3 is handling them quite differently from previous versions (I have
been using Qgis since 1.8). It was not until version 2.14 that I
started working with the projects using these large numbers of raster
images, and have been using them through 2.14, 2.16 and 2.18 and now
in releases of version 3.
The map projects I am working on cover a part of New Zealand
specifically a corridor around 6000 kilometres long and about 20
metres wide which is covered by geojpeg rasters varying from 0.4 to
0.1 metre per pixel resolution and the size of each raster is
generally 4800x7200 pixels.
The experience I had is that Qgis 3.x appears to be caching a lot
more raster data in memory than I saw with 2.x and it seems to be
caching every raster in my project, not just the ones that I am
displaying at the moment. It uses up the resources in my system a lot
faster than 2.x ever did. And if I use larger size raster files, I
have seen it run out of resources on the system more than once.
So in terms of the way it consumes resources for rasters, my
experience is more related to the way I see it using up the physical
resources on my computer like the physical or virtual memory. I ended
up adding more RAM to my system and more swap disk space to help deal
with the extra drain on resources that has happened since upgrading
to version 3.
There is a section in the settings dialog that specifically relates
to rendering. I'm not completely confident this is the type of
situation that would be relevant to your scenario. It may affect my
situation more if I spent some time playing with these settings
(render caching for example) but it might not be so relevant to you,
unless the render caching is causing the software to download a lot
of raster data from your WMS server. You could try experimenting with
some of those settings.
On 20/03/19 2:08 AM, Pascale Hutter wrote:
Hi Patrick
Thanks for your interest! Its raster data of aerial images
(https://shop.swisstopo.admin.ch/de/products/geoservice/swisstopo_geoservices/swisstopoWMS).
I often use this for small environmental projects of mine, where I
have no budget to buy any additional data. So far the 5’000
Megapixel were enough to work during the whole year. Now it was
finished up within a month, although I did much less work.
I did read, that the whole wms-layer part was newly written for the
QGIS version 3.x, so maybe this has something to do with it?
Thank you for any kind of help!
Pascale
M. Sc. Biologie
–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––
Hintermann & Weber AG | Ökologische Beratung, Planung und Forschung
Austrasse 2a | CH-4153 Reinach
–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––
Telefon 061 717 88 87 | Fax 061 717 88 89
[email protected] <mailto:[email protected]> |
www.hintermannweber.ch <http://www.hintermannweber.ch/>
–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––
Büros in Reinach BL / Bern / Montreux
Anwesenheit im Büro: Mo bis Do
Am 19.03.2019 um 13:33 schrieb Patrick Dunford
<[email protected] <mailto:[email protected]>>:
What is the type of data which is within your wms layer. Is this
vector or raster type of data?
On 19/03/19 12:59 AM, Pascale Hutter wrote:
Hi there,
I’m quite new to QGIS version 3, and was before working with QGIS
2.18. I often use wms-layer, where I purchase a certain
data-volume (p. ex. 5’000 pixel) to work with. However, with the
new QGIS 3.0 this data volume is used up far more quickly. In QGIS
2.18 it lasted a lot longer. I was wondering if any of you mades
some similar experiences? Do you have any idea, if there is a way
to change the settings so the data volume would last longer again?
Thank you very much for any suggestions!
Pascale
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