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This is now replaced by the much simpler 2025 process which does not go back and forth between survex format and GPX format.
This text is not deleted because we a re not sure whether some of it may yet be useful (July 2025).
In :loser:/gpx/ This: regenerates the surface tracks as survex files from GPS .gpx files. Also requires the gpx2survex program.
We used to use the OCAML program gpx2survex but we now also have a python equivalent gpx2survex.py which is used by make_svx2.sh This is part of the make_essentials generation process.
gpx2survex simplifies a track so that it is less voluminous.
For the reverse process we don't need a script. For svx-to-gps we can use survexport: Olly says [2022]: "you shouldn't need to mess around with undocumented scripts - since 2018, you can just do: survexport --entrances all.3d essentials.gpx"
But that does rather rely on all.3d being properly generated, which troggle does not currently do reliably and automatically.
Documented, by man survexport, survexport --help, and in the Survex manual on survexport.
ogr2ogr -f GPX -nlt MULTILINESTRING -t_srs EPSG:4326 -s_srs EPSG:32633 boundaries.gpx 4_Teilgruppen_UTM_33_N_2021_01.shp -dsco GPX_USE_EXTENSIONS=YES
Obsolete. We do not need this as we use ogr2ogr on the command line to generate the boundaries as a GPX file from the shapefile (.shp) format. This only needs to be done once.
Unusually, this is in the :loser: repository, in :loser:/fixedpoints/scripts/convert_shx/
We think this turns a shapefile which holds the coordinates of the 1623, 1624 boundaries into GPX. But we have mislaid the shapefile containing this vital data. We now have the shapefile again.
It runs ogr2ogr -f csv -lco GEOMETRY=AS_WKT outputfile inputfile and then extensively post-processes the shapefile output. It is written in OCAML. Therefore it must be Mark Shinwell's responsibility.
ogr2ogr is a file conversion utility. It seems to be being run to convert CSV files into something else. The "shx" part of the name implies a shapefile index format.
We suspect this was part of the production process for originally making essentials.gpx, but we don't need it as we now have the boundary data in other formats.
This needs re-writing because the process is highly confusing: see the "documentation" in the diagram on the right. ALSO the 2024 process created a GPX track which was unusable in OSMand (our preferred GPS app) because it put every point into a separate trkseg.
In :loser:/gpx/ [2024 text]
Makes essentials.gpx - see GPS on expo. This used to require the gpx2survex program (written in OCAML) but now doesn't (since 2023). Get the OCAML file from GitHub https://github.com/mshinwell/gps2survex;
Read the README file in :loser:/gpx/y.
Someone needs to document this and and make_svx.sh properly.