Cave surveying - 2D and 3D drawing software
Therion aids the process of drawing up cave surveys (maps). Drawings are done
over scans and can be distorted to fit the centreline data. Output is in single
plan or atlas style in PDF files. All data is stored in text files and a Tcl/Tk
map editor (xtherion) is provided to aid in the creation of the files. It is
compatible with Survex and uses it for the centreline processing. TeX and
metapost are used to generate the images. libtk-img is needed to use scans in
formats other than GIF and PNM (such as PNG and JPEG).