Hi All, I second that: not blaming anybody here. This happens in the real world.
My point was that I think as QGIS we can 'hide' this issue by not using 5.0.0 'yet' in the osgeo4w package. I will happily use/test whatever is available in Debian sid :-) Also tried Kristian's fix. For QGIS users: QGIS does not use the epsg file provided by your proj install, but a srs.db: {QGISINSTALLDIR}/share/qgis/resources/srs.db I edited (using DB browser) and removed the "+nadgrids=@null" clause from the epsg:3857 line. Checked by looking into the srs chooser of QGIS and seeing that it was indeed not visible anymore. But it does not seem a 100% hack with me. While more near the 'real' place, it is still 150m off? Regards and thanks for all the work on Proj: one of the corner stones of QGIS!! Richard Duivenvoorde On 09-03-18 11:38, Even Rouault wrote: > Kristian > > your are certainly not too blame at à personal level. this is the kind > of this that happen inevitably given a certain amount of changes . i'm > surprised that the GDAL autotest suite did not catch this but the cause > is likely that the GDAL c++ class that wraps proj has an optimisation > when transforming from 3857 to 4326. if you transform an array of points > of the same northing they have the same latitude. this is a common case > for gdalwarp internal mechanics. thus you need to do trigonometric > computations just once! so proj is completely short circuited for that > case. > > i'll add a test for the reverse transformation that uses proj (could > receive a similar optimisation but isnt needed when warping unrectified > imagery with RPC to WebMercator) > > Even > --- > Spatialys - Geospatial professional services > http://www.spatialys.com > > > -------- Message d'origine -------- > De : Kristian Evers <kr...@sdfe.dk> > Date :09/03/2018 10:39 (GMT+01:00) > À : qgis-developer@lists.osgeo.org > Cc : > Objet : Re: [QGIS-Developer] proj5 and epsg:3857 ? > > All, > > Just to follow up on this, since I am the one to blame for this error to > show up. > Both by introducing it in the first place and by releasing 5.0.0 with > this as a > known bug. The bug was introduced to fix a range of other potential issues. > Unfortunately the architecture in the old API of PROJ makes it almost > impossible > to both treat other transformations correct while also treating the Web > Mercator > correctly. The problem is that the Web Mercator is, geodetically > speaking, an > abomination of a transformation. It basically defies all logic. This has > been known > for a long time of course. Unfortunately no tests were set up to catch > this specific > transformation. I'll make sure to at least add Jeff's test case. > > Regarding releasing the library with this bug included. The cause of the > problem > was determined very close to the release time (which was announced a month > ahead). We did go through six release candidates. The vote for promotion > of RC6 > to final release was already started so I decided to release anyway > since I did not > want to prolong the process even more. I am sure this bug would have been > discovered earlier if all of you QGIS developers would not have been super > busy with QGIS 3.0 and had had some spare time to test the PROJ release > candidates. I am not blaming anyone, it is just a case of bad timing. > Not much > we can do about that really. Had I been in your shoes I would not have > prioritized > testing other software either, that's for sure! > > The problem has an easy fix. Remove the "+nadgrids=@null" from your epsg > init-file and the transformation should work as expected. A proper fix will > come in 5.0.1 around April 1st. I hope you all will continue to use > PROJ 5.0.0 > in your development builds despite this problem so other bugs can see the > light of day and be fixed in time for 5.0.1. > > I completely agree with not requiring 5.0.0 as a dependency for QGIS. > Hopefully > 5.0.1 is a little better so that can be the recommended PROJ version for > QGIS. > > I would like to encourage you to take a look at the release schedule [0] > for the next > couple of years. We are going to change things in order to keep up with > current > geodetic developments in countries such as Australia, USA and Iceland. > It will > affect QGIS sooner or later. I am of course happy to provide assistance > where > needed. > > /Kristian > > [0] > https://github.com/OSGeo/proj.4/milestones?direction=asc&sort=due_date&state=open > > -----Oprindelig meddelelse----- > Fra: QGIS-Developer [mailto:qgis-developer-boun...@lists.osgeo.org] På > vegne af Jeff McKenna > Sendt: 8. marts 2018 12:50 > Til: qgis-developer@lists.osgeo.org > Emne: Re: [QGIS-Developer] proj5 and epsg:3857 ? > > Hi Richard, > > You can read my report to the PROJ team while I was testing the release > candidates: > http://lists.maptools.org/pipermail/proj/2018-February/008082.html > Sorry, it is a long thread. I was trying to prevent (this here in QGIS, > for example) from happening, before the release. > > -jeff > > > > > > On 2018-03-07 4:13 PM, Richard Duivenvoorde wrote: >> Hi, >> >> Having a geocoder plugins, in 2.18 (still proj4), I can geocode my home >> address, and reproject the epsg:28992 coordinate fine to epsg:3857. >> >> But since last week Debian has proj5, and the same plugin (in QGIS >> master) now is off by 500 meter. >> >> To reproduce: if you have a QGIS 2.18 with proj4, and the >> 'pdokservicesplugin' geocode the zip+number: '2022zj 23' in for example >> the osm xyz layer. >> Now do the same in QGIS master with proj5 and you'll see it is not going >> to the right/same position. >> >> Another observation: IN 2.18 I can 'reproject' the OSM layer to for >> example epsg:4326, and still see (little distorted) map. >> But in QGIS3/proj5 I do not see a map anymore. >> >> Anybody else seeing this? >> >> Regards, >> >> Richard Duivenvoorde > _______________________________________________ > QGIS-Developer mailing list > QGIS-Developer@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@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@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@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer