Therion is

free and open-source Free and open-source software (FOSS) is a term used to refer to groups of software consisting of both free software and open-source software where anyone is freely licensed to use, copy, study, and change the software in any way, and the source ...

cave surveying A cave survey is a map of all or part of a cave system, which may be produced to meet differing standards of accuracy depending on the cave conditions and equipment available underground. Cave surveying and cartography, i.e. the creation of an accu ...

software designed to process survey data, generate maps and 3D models of caves, and archive the data describing the cave and the history of exploration. Therion was developed by the Slovak cavers Martin Budaj and Stacho Mudrak but is available in English. It runs on a wide variety of platforms including Linux, Windows and Mac OS X. Therion is available as part of standard distribution of

Debian Debian (), also known as Debian GNU/Linux, is a Linux distribution composed of free and open-source software, developed by the community-supported Debian Project, which was established by Ian Murdock on August 16, 1993. The first version of D ...

and Ubuntu (operating system) Linux distributions. It is free software, released under the terms of

GNU GPL The GNU General Public License (GNU GPL or simply GPL) is a series of widely used free software licenses that guarantee end users the four freedoms to run, study, share, and modify the software. The license was the first copyleft for general us ...

, with source code available. It does not require any other commercial software to run. The format of all files is human readable plain text (excluding 3D models), which semantically describe the cave, and are compiled by the program into various output forms such as 2D PDF or SVG maps, or 3D models. Other files like map overlays, terrain models and pictures can be incorporated into the output. A graphical editor is provided to help with the drawing process, and a 3D viewer ('loch') for viewing the models.

Survex Survex is free and open-source cave surveying software, licensed under the GNU GPL. It is designed to be portable and can be run on a variety of platforms, including Microsoft Windows, Mac OS X, and Unix-like. Survex is very powerful cave survey ...

is used for the centreline error distribution if installed. The separation of drawing/semantic data entry and output rendering makes the program both complex to learn to use, but also capable of dealing with cave systems still being explored, where new finds and surveys need the drawing to morph to fit. It also allows a survey to be rendered with different national cave-symbol sets. The (UK-based) Cave Surveying Group has been using Therion along with PocketTopo and DistoXs to train cavers and improve the quality of surveying by the use of real time measurement that is available in Paperless surveying. Therion is used in several large projects for the documentation of cave systems. It is listed among 10 of the Best Free Linux Earth Science Software. It was used in a number of scientific projects. Not everyone finds the results satisfying: "Beginning in 2003, the

Mulu Caves Project Mulu may refer to: * Mulu (band), a 1990s British trip hop group * Mulu (company), a social sharing website * Mulu (state constituency), represented in the Sarawak State Legislative Assembly * Mulu, Ethiopia * Mulu, Kermanshah, Iran * Mulu, Maraghe ...

attempted to use Therion on several cave surveys. After many attempts over several years by many different cave surveyors, one of whom was closely affiliated with the software itself, no aesthetically pleasing results were produced." The unmatched feature of Therion software among other software tools for cave surveying is straightforward creating of 3D presentation for

WEB Web most often refers to: * Spider web, a silken structure created by the animal * World Wide Web or the Web, an Internet-based hypertext system Web, WEB, or the Web may also refer to: Computing * WEB, a literate programming system created by ...

pages. One may export

3D model In 3D computer graphics, 3D modeling is the process of developing a mathematical coordinate-based representation of any surface of an object (inanimate or living) in three dimensions via specialized software by manipulating edges, vertices, an ...

from Therion to 3D format .lox, open it in Therion's 3D viewer Loch and export data as

VTK The Visualization Toolkit (VTK) is an open-source software system for 3D computer graphics, image processing and scientific visualization.''Visualization Handbook'', Academic Press, 2005, Chapter 30: the Visualization Toolkit/ref> VTK is distrib ...

. ParaView software is able to open such data and export them in WebGL format. To draw the maps the Speleo-Vulcain group from France is using Visual Topo for simple systems. However, because of the difficulties to build a rigorous synthesis and to update the survey of the complex Jean-Bernard System, they passed to the open source software Therion. Therion was analysed and used in thesis of Eliška Rákocy Two articles in the Annual Report of Cave Administration of the Czech Republic 2010 describe how Therion was used to document the Javoříčko Caves show cave. Described as "State of the Art Cave-Drawing software", Therion was reviewed in ''Compass'', the Cave Surveying Journal of The British Cave Research Association. The review covered installation, use and development of the software.BCRA Cave Surveying Group, Compass Points 33, March 2004, pp 5-12 Since that article, written in 2004, Therion has continued to be developed and is now considered to be the most capable cave drawing software available.

References

External links

Homepage of Therion (software)
* French wiki page about Therion (software)
A review from Linuxlinks.com

Paperless Surveying
Disto X tool and PocketTopo software for in-cave drawing maps. Data could be exported to Therion - check User Guide.
TopoDroid
free software for Android platform for in-cave surveying. Surveying data and maps are in Therion format.
Auriga
free software for Palm OS for in-cave surveying with bidirectional data exchange provided with Compass, Survex, Therion, GH Topo/Toporobot, VisualTopo and Walls.
BCRA Cave Surveying Group, Compass Points 33.

Short review of Therion and other survey software packages (German).
* Joey Bwernard
"Spelunking with Linux"
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Linux Journal ''Linux Journal'' (''LJ'') is an American monthly technology magazine originally published by Specialized System Consultants, Inc. (SSC) in Seattle, Washington since 1994. In December 2006 the publisher changed to Belltown Media, Inc. in Houston ...

'' ({{ISSN, 1075-3583), March 2014, pages23–28. Belltown Media, Inc., Houston, Texas. Cave surveying Geology software Software that uses wxWidgets