[Qgis-user] Mac 3.14 dmg, proj

[William Kyngesburye]

My [official] alternate build (separate framework base and python install) uses proj 6.3.

-----
William Kyngesburye
<kyngchaos at kyngchaos.com>
<http://www.kyngchaos.com>

Don't Panic

> On Jul 25, 2020, at 7:45 AM, Greg Troxel <gdt at lexort.com> wrote:
> 
> 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
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