[Therion] Creating GeoTIFF files

[Bill Gee]

Thanks Xavier and Andrew!

I do not know enough about GIS systems to understand why my friend 
wanted a GeoTIFF file.  I set up Therion to create ESRI output, and he 
seems happy with that.  He has imported those files into ArcGIS and says 
they are useful.  He is taking surface topography data from LIDAR scans 
and overlaying the cave maps.

QGIS is available for Linux.  I do not have it installed, mostly because 
I know so little about what it can do and how to use it.

So far we are experimenting with a couple of very small caves.  One is 
less than 30 meters, the other is about 150 meters.  They are only 50 
meters apart, and there are numerous sinkholes nearby.  The larger cave 
has a debris pile in the back that blows air and might be possible to 
dig through.  We want to see if there are corresponding surface features.

===============
Bill Gee

On 7/7/23 02:25, Xavier Robert wrote:
> Hi Bill,
> 
> I do not really understand why to export survey stations as a geotiff 
> file (raster, image). Survey stations are points (vectors) and are more 
> easier to manage through GIS softwares as shapefiles (vector format). 
> This is the Therion ESRI output.
> 
> In the ESRI output folder, you have several shapefiles in 2D (exported 
> as map) and in 3D (exported as model): outline, areas, lines, areas, 
> points, shots3d, stations3d (several files for each shapefile).
> 
> Stations3d contains all the stations of the survey…
> The points shapefile should also contain the points station. See the 
> attribut table associated to this file and use that to select the points 
> you want to plot.
> 
> 
> For one of my main project, I wanted to produce a clean georeferenced 
> map with :
> 
>   * the survey with a rendering depending on the zoom used,
>   * at important zoom, the stations with their altitude,
>   * and overlays as OSM, Geology, hillshade, altitude contours,…
> 
> 
> We used that in a QGIS project that we coupled with the Merging Maps 
> app. This is still in development, but that permits to do field 
> prospection with all the cave database and GPS positioning on your phone.
> 
> 
> 
> Unfortunately, the direct ESRI Therion output is not clean enough to 
> produce such GIS maps. I needed to write Python scripts to :
> 
>   * add the stations and entrances altitude as a new column in the
>     attribute table,
>   * cut the lines and areas shapefiles to keep only what is inside the
>     outline (expect for the option clip off); Before running this
>     script, I often need to test the validity of the polygons shapefiles
>     to make sure that they are valid… 
> 
> We also make some svg symbols corresponding to symbols used by Therion, 
> but this is not yet complete. (If someone has already a svg symbols 
> library for therion shp, I am interested !)
> 
> For those interested, this is now partially included in the Samoëns cave 
> repository : https://github.com/robertxa/Topographies-Samoens_Folly 
> <https://github.com/robertxa/Topographies-Samoens_Folly> (written mostly 
> in French)
> To make the GIS files, I run the « SamoensGIS.thconfig ». After 
> compiling Therion files, it calls Python scripts (edit the .thconfig to 
> check if the lines are not commented) that are in Samoens-GIS/Scripts 
> (https://github.com/robertxa/Topographies-Samoens_Folly/tree/master/Samoens-GIS/Scripts <https://github.com/robertxa/Topographies-Samoens_Folly/tree/master/Samoens-GIS/Scripts>). The whole QGIS project is not uploaded on GitHub as some files are to big for Github. But I can share it on demand.
> 
> For now, this is still a bit dirty (and still dedicated to this project, 
> you will need numerous changes to apply it to an other project), I am 
> still working on this. If you try it, if you miss a specific file, if 
> you have any questions or suggestions/improvements, etc. do not hesitate 
> to contact me !
> 
> Cheers,
> 
> Xavier
> 
> 
>> Le 7 juil. 2023 à 02:01, Bill Gee <bgee at campercaver.net 
>> <mailto:bgee at campercaver.net>> a écrit :
>>
>> A question has come up from one of my caver friends who is very new to 
>> cave survey but an old hand at ArcGIS and various other ESRI tools. 
>>  He earns a living as a GIS expert.
>>
>> He would like to get a georeferenced TIFF (GeoTIFF) which includes GPS 
>> coordinates of survey stations.  I looked at the KML file produced by 
>> Therion and find no references to survey stations.  A KML file is 
>> really just a long (very long!) list of GPS coordinates, so it 
>> probably could include survey stations.
>>
>> So my question for the group:  Is there a way to produce a GeoTIFF 
>> file which includes survey stations?
>>
>> Related question:  Do the ESRI outputs from Therion include survey 
>> stations?
>>
>> Thanks!
>> -- 
>> ===============
>> Bill Gee
> 
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