On Tue, 8 Dec 2020 at 23:59, Andreas Neumann <[email protected]> wrote: > > Hi Martin, > > Thanks for the explanation. > > I confirm that reducing the maximum error helps to remove the artefacts. WIth > 0.5 mm I could still see them at one particular zoom level, but with 0.4 mm > it was completely gone.
In https://github.com/qgis/QGIS/pull/40504 I've changed the default to 0.3. Thanks for the feedback! Nyall > > Thanks a lot, > Andreas > > > On Tue, 8 Dec 2020 at 13:15, Martin Dobias <[email protected]> wrote: >> >> Hi Andreas >> >> The artifacts you are seeing are caused by the fact how the Entwine tool >> works in the default configuration. When creating the octree index of point >> cloud data, points are organized in a hierarchy of nodes (each containing >> usually tens of thousands of points), with each level of the hierarchy >> having smaller bounding volume and higher density. One optimization that >> Entwine does is that if child nodes contain a small amount of points, they >> get merged into the parent node in the hierarchy - in the hope this will >> lower the number of nodes and therefore also the number of requests that >> need to be done. See Entwine configuration [1] for more details - especially >> the options like minNodeSize, maxNodeSize, overflowDepth, overflowThreshold. >> So the artifacts could be simply fixed by reindexing the dataset with >> modified configuration. >> >> All that said, maybe none of that is necessary: >> 1. I would suggest lowering "Maximum error" in Layer styling to e.g. 0.5 mm >> or even 0.3 mm (assuming the default point size of 1mm) - this should be >> giving you a rendering result with very little holes - it is much nicer to >> look at and the artifacts should be gone at all scales (it will increase >> the rendering time, but I think it is worth it and I think we should lower >> the default maximum error - the higher maximum error was initially used >> mainly as a debugging tool for us to see if the point spacing in the >> rendered map matches the expectations) >> 2. For indexing of point clouds, we will be internally using Untwine [2] - a >> newer approach (also coming from friends at Hobu!) that has different >> configuration and probably won't be showing these artifacts. Peter is >> currently working on the integration [3] >> >> Regards >> Martin >> >> [1] https://entwine.io/configuration.html >> [2] https://github.com/hobu/untwine >> [3] https://github.com/qgis/QGIS/pull/40404 >> >> >> On Tue, Dec 8, 2020 at 10:30 AM Andreas Neumann <[email protected]> wrote: >>> >>> Hi, >>> >>> When testing the 2D point cloud renderer I noticed that in certain scales / >>> zoom levels one can clearly see point cloud tile borders: >>> >>> see screenshot at >>> https://www.carto.net/neumann/temp/point_cloud_artefacts.png >>> >>> There seem to be different densities involved in certain regions here, but >>> clearly they correspond to tile borders. >>> >>> Is this an expected artefact? Can this be avoided? >>> >>> When I zoom in or out, these artefacts seem to disappear. >>> >>> Thanks and greetings, >>> >>> Andreas >>> >>> >>> _______________________________________________ >>> QGIS-Developer mailing list >>> [email protected] >>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer >>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer >> >> _______________________________________________ >> QGIS-Developer mailing list >> [email protected] >> List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer >> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer > > > > -- > > -- > Andreas Neumann > QGIS.ORG board member (treasurer) > _______________________________________________ > QGIS-Developer mailing list > [email protected] > List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer _______________________________________________ QGIS-Developer mailing list [email protected] List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer
