Thanks Martin
14fac78 solved both the proj download related crash and the ~100 m positional error for lat-long and NZTM fixed points. I have attached a cut down version of the therion.log file that was produced.
I am a little confused, as Therion automatically downloaded the grid and yet my therion.ini does not have any of the proj-auto or proj-missing-grid settings mentioned in the 14fac78 Therion Book pg 86-87, which raises for me many questions. I assume the functionality of those ini statements is now superseded by the proj.ini that is now present in the install folders (as you described as "use the best transformation and download the grids if needed") and that the Therion Book is yet to be updated?
Or maybe I am not looking I the correct place for the ini files that Therion is actually using?
Can Therion be run without having internet access (or without first having had internet access for a particular survey dataset at some previous time)?
In the attached file, do the transformations marked [no] and [yes] relate to whether they are used or not?
And presumably the accuracies listed are the estimated accuracies?
Can I use proj-missing-grid to improve the accuracy of my example further or is 4m accuracy the best I am likely to get for this particular dataset?
Regards
Bruce
From: Therion <therion-bounces@speleo.sk> On Behalf Of Bruce Mutton
Sent: Monday, 25 April 2022 21:12
To: 'List for Therion users' <therion@speleo.sk>
Subject: [Therion] Problem with new default settings and recent proj changes
Martin
Something bad happened between 6.0.0 and 6.0.5 that we only just noticed today (because for day to day work we only compile small sections of the cave).
Therion 6.05 has moved some of our fixed stations about 100 m north (those specified with cs lat-long and cs EPSG:2193 NZTM) and others (specified with cs EPSG:27200 NZMG) stayed in their correct locations, severely distorting our cave. No errors reported, just outputs with large loop errors and distorted cave.
Interestingly, it is the old archaic format NZMG that performs correctly and the modern and lat-long are relocated.
The image below is located with NZMG, as is the cave entrance in the centre. The cave entrances left and right are located with either lat-long or NZTM.
Before reporting this I thought I'd better at least try 6.0.6+3bc6556
I get a crash right away as the therion.log transcript below indicates.
therion 6.0.6+3bc6556 (2022-04-21)
- using Proj 9.0.0, compiled against 9.0.0
initialization file: C:\Program Files (x86)\Therion/therion.ini
reading ... done
configuration file: thconfig-GLMESM_System5000Map.thc
reading ... done
reading source files ... downloading the grid https://cdn.proj.org/nz_linz_nzgd2kgrid0005.tif...
C:\Program Files (x86)\Therion\therion.exe: error -- couldn't download the grid
writing xtherion file ... done
Should I be using one of the new cs-trans or proj-* commands or is there something else?
Regards
Bruce
-----Original Message-----
From: Therion <therion-bounces@speleo.sk> On Behalf Of Martin Budaj
Sent: Friday, 22 April 2022 07:32
To: List for Therion users <therion@speleo.sk>
Subject: [Therion] new default settings
Hi all,
Therion has been supporting the advanced features of the Proj library for some time now. (Proj's purpose is to do transformations between coordinate systems.) This functionality was disabled by default and you could enable it using 'proj-auto' and 'proj-missing-grid' options in the initialization file.
'proj-auto' lets Proj choose the best transformation and you can set 'proj-missing-grid' to download a grid file (see
https://proj.org/usage/transformation.html#grid-based-datum-adjustments)
if the transformation needs it; see the therion book for details. The log file lists all the transformations chosen and used at the end.
The latest commit (3bc6556) enables this "use the best transformation and download the grids if needed" functionality. We know that automatic downloads are a sensitive issue, but in this case we can trust the Proj library not to do any harm
( https://proj.org/usage/network.html ) and the user experience is much better.
Could you check if this version works well with your data sets? The windows installer is available here:
https://github.com/therion/therion/actions/runs/2203811478 (use the
msys2 version which uses up-to-date Proj library; you need to be logged in to github to download it).
M.
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