0029 Cueva Subterránea
1975 jpg rotated 5.7deg left to bring compass rose up the page

Scale Bar    Blue: 0000ff (Scalebar color)
North Arrow Green: 00ff00 (Orient color)
Centreline    Red: ff0000 (Export color)

0) Follow Patrick Warren's Workflow advice. (ReadMe.md in https://github.com/patrickbwarren/inkscape-survex-export/releases/tag/v2.0)
1) Recreate centreline in inkscape trying to place 'survey stations' at any change in height / passage floor. The 'stations' can be highlighted using start, centre and end 'markers'.
2) Take a screen shot for reference.
3) Extensions / Export / Export drawing to .svx file ... See Colours above. 
4) Most stations are 1m (waist height) above the floor. 
5) The legs / stations have been left in the generated, 2 batch svx file with the generated names.
6) Change *data normal tape compass clino to *data cylpolar tape compass depthchange
7) Replace the '0' as necessary to show the depth change between stations.
8) Process the .svx to produce the 3d file
9) Edit the .svx file to show some widths (if deemed necessary!). Widths were measured with a wooden ruler, off the screen.

The chamber was measured across as well as front-to-back. Not unreasonable, I think.

Juan Corrin