[QGIS-Developer] Point cloud renderer: tile borders visible?

[Andreas Neumann]

Thank you!

On Wed, 9 Dec 2020 at 02:37, Nyall Dawson <nyall.dawson at gmail.com> wrote:

> On Tue, 8 Dec 2020 at 23:59, Andreas Neumann <andreas at qgis.org> 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 <wonder.sk at gmail.com> 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 <a.neumann at carto.net>
> 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
> >>> QGIS-Developer at lists.osgeo.org
> >>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer
> >>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer
> >>
> >> _______________________________________________
> >> QGIS-Developer mailing list
> >> QGIS-Developer at lists.osgeo.org
> >> 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
> > QGIS-Developer at lists.osgeo.org
> > 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)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/qgis-developer/attachments/20201209/278ece2b/attachment-0001.html>