Good idea! The latest commit provides additional information about
downloads now. Caching is more tricky: we just enable it and Proj then
downloads just small parts of grids relevant to your area and stores
them in its database without letting you know what exactly got
downloaded.

Martin

On Tue, Apr 26, 2022 at 9:43 PM Bruce Mutton <br...@tomo.co.nz> wrote:
>
> Thanks Martin
>
> That helps a lot.  I wonder if therion.log could echo the destination folder 
> for downloaded files?
>
> (I could not find it on my machine)
>
> A suggestion below.
>
>
>
> therion 6.0.6+14fac78 (2022-04-26)
>
>   - 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... done
>
> saved/cached grid file: C:\path\ nz_linz_nzgd2kgrid0005.tif
>
> done
>
>
>
> Bruce
>
>
>
> From: Therion <therion-boun...@speleo.sk> On Behalf Of Martin Budaj
> Sent: Wednesday, 27 April 2022 05:24
> To: List for Therion users <therion@speleo.sk>
> Subject: Re: [Therion] Problem with new default settings and recent proj 
> changes
>
>
>
> On Tue, Apr 26, 2022 at 11:45 AM Bruce Mutton <br...@tomo.co.nz> wrote:
>
> 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 superseded by the proj.ini that is now present in the install folders (as you 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?
>
>
>
> Indeed, thbook needs an update. Now, proj-auto is 'on' by default and 
> proj-missing-grid is 'download'.
>
>
>
> Or maybe I am not looking I the correct place for the ini files that Therion 
> is actually using?
>
>
>
> If the setting is missing in therion.ini, therion just uses the defaults. You 
> can always override them in the therion.ini file.
>
>
>
> Can Therion be run without having internet access (or without first having 
> had internet access for a particular survey dataset at some previous time)?
>
>
>
> Definitely. With the new defaults, it would attempt to download the grid 
> (only if proj can't find it locally) and end with an error message if there 
> is no internet connection.
>
>
>
> You can do either of these:
>
>
>
> * change the proj-missing-grid setting to warn, e.g. (this prints a warning 
> stating which grid you need to download manually, then download it and put 
> somewhere where proj finds it)
>
> * set proj-auto off (this is the old behaviour where proj doesn't look for 
> the optimal transformation)
>
> * get online, run therion once, and the grids would be reused in the 
> subsequent runs without internet connection
>
>
>
>  In the attached file, do the transformations marked [no] and [yes] relate to 
> whether they are used or not?
>
>
>
> All listed transformations are used. AoU: [no] or [yes] indicates, whether 
> proj optimised a transformation for your particular area (defined by the 
> fixed stations in your data set) [yes] or not [no].
>
>
>
> And presumably the accuracies listed are the estimated accuracies?
>
>
>
> Yes, estimated by proj.
>
>
>
> 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?
>
>
>
> Sure, the accuracy when using grids should be in centimeters. It's 
> interesting that in your log file the grid is downloaded (twice!) but not 
> actually used by proj, it would be worth investigating why.
>
>
>
> Anyway, for cases when you think you can do better than proj (including using 
> a grid file), you can use 'cs-trans' to define a custom transformation 
> between two coordinate systems; see an example in thbook. Probably your local 
> GIS community has already defined such transformations; in the case of 
> Slovakia, our cartographic office published such a list for QGIS users, which 
> can be easily adopted for therion.
>
>
>
> Martin
>
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