Hi,
Method 1: Export centerline to kml format in therion:
export model -fmt kml -disable splay-shots -o your_cave_cl.kml
Then you can use a GIS package to extract coordinates, or a simple text editor.
Method 2: Export to database in therion and then convert cartesian coordinates to lat/long with help of GDAL/PROJ4/QGis:
export database -o your_cave.sql
at the bottom of
your_cave.sql file you will have list of commands
insert into STATION values (1, '0', 18, 387675.73, 6056702.67, 180.04);
insert into STATION_FLAG values(1, 'fix');
insert into STATION values (2, '30', 18, 387690.02, 6056686.38, 181.05);
insert into STATION values (3, '11', 18, 387696.58, 6056689.10, 179.76);
...
so those triples are your output coordinate system locations. Usually the coordinate system is some sort of UTM over WGS84 ellipsoid (look at your survey which one),
so you put that triple into txt file, separating values by spaces and run command line tool cs2cs from GDAL/PROJ4/QGis package:
Following example converts cartesian coordinates in the LKS94 coordinate system, which has EPSG (SRID) code 3346 to lat-long over WG84, which has 4326 EPSG code,
with precision up to 8 decimal digits (~1.1 mm accurate).
cs2cs +init=epsg:3346 +to +init=epsg:4326 -f "%.8f" coords_file_lks94 > coords_file_wgs84