tl;dr: Why does the mac 3.14 installer use old proj?
I've been using 3.10 on NetBSD (built from pkgsrc, against proj 6.3.2), and on a mac (downloaded from qgis.org). I have imagery data in NAD83(2011), claimed to be registered to 0.1m, and a point feature in ITRF2014 (also about 0.1m), and I am partly trying to check imagery registration, partly just getting used to qgis. With the NetBSD build, everything makes sense. With the Mac build, the alignment of the two is different (and I think wrong). The Mac build is using proj 5.2.0 and probably is using WGS84 as a pivot datum. I bet this is using a null transform from NAD83 to WGS84 and then from WGS84 to ITRF2014, and this is wrong by a meter when transforming modern NAD83 to ITRF2014. (I understand how this came to be, why it's been replaced and why it gets low accuracy answers. Regional ground motion is low enough not to matter at the level of accuracy I am achieving so far.) I then installed 3.14.1 on the Mac, from qgis.org, and still got bad registration, and saw that it's still using proj 5.2.0. I had hoped that moving off of LTR would get me up-to-date proj. It seems obvious to me (said knowing that's very dangerous!) that it's better to use newer proj with qgis to get the more accurate transforms, and that a lot of work has been done in both proj and qgis, so I wonder why the 3.14 official mac build is using old proj, and what the plans are for moving to proj 6.3.2 or 7.x. I'm going to try to build qgis on the mac, using pkgsrc, which will use newer proj, and see how that is, but I expect to get the same behavior (that I think is right/better) because it's building the same sources as I built on NetBSD. Thanks for any insight anyone can provide, Greg _______________________________________________ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
