[Qgis-user] Data volume wms-layer

Wed Mar 20 20:24:21 PDT 2019

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
> –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––
> Hintermann & Weber AG | Ökologische Beratung, Planung und Forschung
> Austrasse 2a | CH-4153 Reinach
> –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––
> Telefon 061 717 88 87 | Fax 061 717 88 89
> hutter at hintermannweber.ch <mailto:hutter at hintermannweber.ch> | 
> www.hintermannweber.ch <http://www.hintermannweber.ch>
> –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––
> Büros in Reinach BL / Bern / Montreux
>
> Anwesenheit im Büro: Mo bis Do
>
>
>
>> Am 19.03.2019 um 15:15 schrieb Patrick Dunford 
>> <enzedrailmaps at gmail.com <mailto:enzedrailmaps at gmail.com>>:
>>
>> 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
>>> hutter at hintermannweber.ch <mailto:hutter at hintermannweber.ch> | 
>>> 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 
>>>> <enzedrailmaps at gmail.com <mailto:enzedrailmaps at gmail.com>>:
>>>>
>>>> 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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