[R-sig-Geo] sp/rgdal workflows with PROJ >= 6 and GDAL >= 3

Fri Nov 29 18:30:02 CET 2019

Dear Roger,

    I'd be very interested in participating to the stream talk. Is it
confirmed?

Concerning testing the connection, I'd be happy to do it but I do not know
how much I will be available online in the coming days. You can drop me a
mail/DM on twitter, and if I am available I'll gladly help.

Concerning technology, Zoom usually works quite well (https://zoom.us/
<https://zoom.us/ent?zcid=3172>)

   regards,

Lorenzo

On Sat, 23 Nov 2019 at 13:04, Roger Bivand <Roger.Bivand using nhh.no> wrote:

> A description of the status now with regard to a prototype resolution is
> online at:
>
> https://rsbivand.github.io/ECS530_h19/ECS530_III.html
>
> I'm planning to stream a talk about this at 09:15-11:00 CET on Tuesday 3
> December. I need a volunteer to test the streaming link in advance during
> next week. I'm unsure which technology to use for remote participants to
> provide feedback.
>
> Contributions/comments welcome!
>
> Roger
>
>
> On Fri, 15 Nov 2019, Roger Bivand wrote:
>
> > The development version of rgdal on R-Forge is now at rev 894, and is
> now
> > ready for trying out with PROJ6/GDAL3 workflows, and workflows that may
> > migrate within 6 months to modern CRS representations. The motivating
> RFC is
> > also updated to cover coordinate operations, the use of prepared
> > (pre-searched) coordinate operations, and should be read carefully by
> anyone
> > using rgdal::spTransform(). Note further that rgdal::project() will not
> be
> > adapted for PROJ6, and is effectively deprecated.
> >
> > I'll be running reverse dependency checks, and may be bugging package
> > maintainers. I would really prefer that mainainers of packages using
> > spTransform() checked themselves and joined this thread or the
> associated
> > twitter thread:
> https://twitter.com/RogerBivand/status/1194586193108914177
> >
> > Be ready for modern PROJ and GDAL, they are already being deployed
> across
> > open source geospatial software, like GRASS, QGIS, pyproj, spatialite
> etc.
> >
> > Waiting, hopefully not in vain, for contributions.
> >
> > Roger
> >
> > On Wed, 13 Nov 2019, Roger Bivand wrote:
> >
> >>  And this link explains the CDN proposal for grid distribution:
> >>
> >>  https://www.spatialys.com/en/crowdfunding/
> >>
> >>  Roger
> >>
> >>  On Wed, 13 Nov 2019, Roger Bivand wrote:
> >>
> >>>   Because PROJ >= 6 and GDAL >= 3 change the way that PROJ strings
> >>>   (representations of coordinate reference systems) are handled, steps
> are
> >>>   being taken to find ways to adapt sp/rgdal workflows. A current
> proposal
> >>>   is to store the WKT2_2018 string as a comment to CRS objects as
> defined
> >>>   in
> >>>   the sp package.
> >>>
> >>>   A draft development-in-progress version of rgdal is available at
> >>>   https://r-forge.r-project.org/R/?group_id=884, and for sp at
> >>>   https://github.com/rsbivand/sp (this version of sp requires rgdal >=
> >>>   1.5-1). This adds the WKT comments to CRS objects on reading vector
> and
> >>>   raster data sources, and uses WKT comments if found when writing
> vector
> >>>   and raster objects (or at least does as far as I've checked, possibly
> >>>   fragile).
> >>>
> >>>   An RFC with tersely worked cases for using CRS object comments to
> carry
> >>>   WKT strings but maintaining full backward compatibility is online at
> >>>   http://rgdal.r-forge.r-project.org/articles/PROJ6_GDAL3.html.
> >>>
> >>>   If you have other ideas or concerns about trying to use this
> mechanism
> >>>   for
> >>>   sp CRS objects, please contribute at your earliest convenience.
> >>>
> >>>   http://rgdal.r-forge.r-project.org/reference/list_coordOps.html
> shows
> >>>   the
> >>>   beginning of the next step, to query transformation operations to
> find
> >>>   viable coordinate operation pipelines.
> >>>
> >>>   I'm assuming that the previous behaviour (transform without
> considering
> >>>   accuracy with whatever is to hand) is not viable going forward, and
> that
> >>>   we will need two steps: list coordinate operations between source and
> >>>   target CRS (using the WKT comments as better specifications than the
> >>>   PROJ
> >>>   strings), possibly intervene manually to install missing grids, then
> >>>   undertake the coordinate operation.
> >>>
> >>>   The fallback may be simply to choose the least inaccurate available
> >>>   coordinate operation, but this should be a fallback. This means that
> all
> >>>   uses of spTransform() will require intervention.
> >>>
> >>>   Is this OK (it is tiresome but modernises workflows once), or is it
> not
> >>>   OK
> >>>   (no user intervention is crucial)?
> >>>
> >>>   These behaviours may be set in an option, so that package maintainers
> >>>   and
> >>>   users may delay modernisation, but all are undoubtedly served by
> rapid
> >>>   adaptation (GRASS 7.8.1 released yesterday, libspatialite, pyproj,
> QGIS
> >>>   development versions all state that they list candidate coordinate
> >>>   operations).
> >>>
> >>>   We cannot ship all the grids, they are very bulky, and probably
> nobody
> >>>   needs sub-metre accuracy world-wide. Work in PROJ is starting to
> create
> >>>   a
> >>>   content delivery network for trusted download and mechanisms for
> >>>   registering downloaded grids on user platforms. We would for example
> not
> >>>   want Windows users of rgdal and sf to have to download the same grid
> >>>   twice.
> >>>
> >>>   Comments welcome here and at
> >>>   https://github.com/r-spatial/discuss/issues/28 or
> >>>   https://github.com/r-spatial/sf/issues/1187
> >>>
> >>>   Roger
> >>>
> >>>
> >>
> >>
> >
> >
>
> --
> Roger Bivand
> Department of Economics, Norwegian School of Economics,
> Helleveien 30, N-5045 Bergen, Norway.
> voice: +47 55 95 93 55; e-mail: Roger.Bivand using nhh.no
> https://orcid.org/0000-0003-2392-6140
> https://scholar.google.no/citations?user=AWeghB0AAAAJ&hl=en
>
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