Therion – processes survey data and generates maps or 3D models of caves

Therion is a tool for cave surveying. This application archive survey data on computer in a form as close to the original notes and sketches as possible and retrieve them in a flexible and efficient way. This tool also draws up-to-date plan or elevation maps.

Drawings are done over scans and can be distorted to fit the centreline data. Output is in single sheet or atlas style PDF or SVG files. All data is stored in text files and a map editor (xtherion) is provided to aid in the creation of the files.

Therion can also produce realistic 3D models, generated from walls and passage-heights. Output formats supported are Survex .3d files, VRML, DXF, SVG, shapefiles, and the native .loc and older .thm (therion model). Therion is compatible with Survex, and centreline data can be stored in Survex or Therion form. Centreline data and sketches can be imported from PocketTopo.

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).

Therion is a command-line application. It processes input files, which include 2D maps—in text format, and creates files with 2D maps or 3D model as the output.

Features include:

  • Structure of map drawings is fully independent on survey data – draw partial maps as you are exploring and surveying the cave.
  • Complete maps with all the detail. No additional ink stroke is needed.
  • Maps are dynamic, always up-to-date – i.e. they are automatically re-drawn after loop closure, blunder fix, scale or symbol set change.
  • Split the cave into layers and selectively display them.
  • Generate an interactive atlas.
  • Define multiple independent “views” of map structure suitable for different purposes.
  • 3D models are created using 2D maps.
  • Support for LRUD dimensions.
  • Export formats for maps: pdf, svg, xhtml, survex, dxf, esri53, and kml (Google Earth).
  • Export formats for 3D models: loch, .plt (Compass), .3d (Survex), dxf, esri, vrml, 3dmf, and kml.
  • Import formats:  .3d (Survex), .plt (Compass), .xyz (general), PocketTopo Therion.
  • Internationlization support: Czech, German, Greek, English [UK/US], Spanish, French, Italian, Portugese [BR/PT], Russian, Slovak and Albanian.

Support: Documentation, Wiki, GitHub Code Repository
Developer: Stacho Mudrak, Martin Budaj
License: GNU GPL v2


Therion is written in C++ and Tcl. Learn C++ with our recommended free books and free tutorials. Learn Tcl with our recommended free books and free tutorials.

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