Hi Patrick, Sorry for asking, did you create pyramids (overlays) for your raster "tiles"?
See more information about pyramids on QGIS official documentation: https://docs.qgis.org/3.4/en/docs/user_manual/working_with_raster/raster_properties.html#pyramids-properties To create pyramids on many files, it's probably better to use GDAL directly to process all files in a folder: https://gdal.org/programs/gdaladdo.html My feeling is that the WMS service is doing that for you, and that's the reason why it works well with a service. Alexandre Neto QGIS Support www.qcooperative.net A segunda, 18/11/2019, 09:11, Patrick Dunford <enzedrailm...@gmail.com> escreveu: > Good day to all > > One of the user experiences I have had from using the Qgis software has > been with projects using large numbers of raster tile layers. These layers > are generally tiles that have a size of 4800x7200 pixels in GeoJPEG format > and have either been downloaded directly from tile servers to these locally > stored files, or created from downloaded tiles with other layers overlaid > in Gimp projects. > > There appears to be some architectural limit in Qgis desktop software > relating to either the total number of raster layer [files] in a project or > to the total number of pixels in raster layer [files] in a project. This is > unrelated to the number of layers or pixels currently enabled for display > in the map canvas. In practice, the appearance of this limit is that it is > kicking in long before the host computer's own physical resources are > anywhere near fully engaged. Map digitising and editing is done on systems > with 32 GB of physical memory (RAM) and 200 GB of SSD-based virtual memory > (swap) and these systems are able to edit very large Gimp projects for user > tile creation that often engage all of the system's physical memory and > around 100 GB of the virtual memory without problems. But these types of > numbers are in practice never seen with Qgis projects when the raster layer > limit is being seen. > > The appearance of a raster layer limit is generally experienced in older > versions of the software by layers being displayed on the canvas as > garbage, and in newer versions by the software crashing. It will only start > working again if raster layers are removed from the project. However, when > layers are loaded from WMTS servers, no appearance of limitation is seen. > > The question to be answered, then, is which of any possible range of > resolutions would be appropriate or useful to this predicament. With only > limited understanding of the architectural design of the software, it would > seem the following options exist: > > 1. File a bug report for the software concerning a possible issue with > the design of the product > 2. Amalgamate smaller tiles into larger ones (e.g. 48 tiles at > 4800x7200 can be put into one tile at 57600x28800). This only works if the > software issue is related to the number of file based tile layers and not > to the total number of pixels in those layers. > 3. Post a feature request for sub-project capabilities. This would > allow a project that combines vector and raster layers, to be split into > one project containing the vector layers and a number of projects each of > which contains the vector project as a subproject and a certain subset of > all the raster layers that is smaller than the observable limit. > 4. Set up my own local WMTS server to serve all the raster layers to > my map editing projects. > 5. Explore the possibilities of preconfigured limits in the operating > system that may need to be increased to overcome file based layer limits in > projects (such as the NOFILES limit in Linux, currently set at 10,000 hard > and soft on map editing computers) > > Is anyone who is knowledgeable about the architecture of the Qgis desktop > software able to comment with some detail about possible resolutions. > > > _______________________________________________ > Qgis-user mailing list > qgis-u...@lists.osgeo.org > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
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