Therion is a system for the production of high-quality cave maps. The maps of the cave are generated in PDF format. It is possible to make maps at different scale, and more or less detailed according to the needs.

The advantage of a system like Therion to make and maintain the cave maps are

• the graphical data are digital: this favours the exchange of data, distribution of the drawing task, and team work;
• “vectorization” of the drawing data, therefore without the ambiguities that might arise in printed maps or scanned bitmaps (raster data);
• the possibility to create a database with map infos, where queries can be performed;
• automatic map update as the survey grows, including new cave branches and loops (no need to redraw the map by hand);
• more style uniformity when pieces of the cave map are composed in a single map: the data files contains only commands, while the presentation is specified in the configuration file
• configurability of the output that can be suited to the need at hand: publication, presentation, show, etc.

Therion features are

• Therion is open source, distribuited under GPL licence;
• the format of the input survey data is very close to that of survex 1 , although there are substantial differences;
• it can produce maps in PDF format up to a size of about 5×5 m, or as atlas, collection of tile-pages;
• it can reconstruct the 3D model without the LRUD (left right up down) data, as it uses the information from the drawings;
• it can export data as SQL scripts that can be used to populate a database;
• the individual pieces of the map (called scraps) cannot have overlying passages;
• there is no WYSIWYG (what you see is what you get) program for therion: the graphical interface xtherion is of great help in drawing the scraps, but is far from being WYSIWYG.

Therion is developed by S. Mudrak and M. Budai (with the help of others). The name “therion” comes from ancient greek and means “little animal”. The official web site is http://therion.speleo.sk/. There is already some documentation on therion.

• an introductory guide is on the web site http://www.infonegocio.com/tatel/therion_for_cavers.txt; although unfinished it is nevertheless very useful 2 .
• an article on Compass Point 33 (2004) 3 describes version 0.2.?, but is useful as overview and as introduction;
• there is a wiki for therion (based on dokuwiki), with FAQ, Tips and Tricks, examples, links to other documentation;
• to know all the details of the language there is The Therion Book 4 , always included in the distribution;
• finally, to know and extend therion (and xtherion) there is the source code, and the documentation about cavern, TeX, MetaPost, and pdfTeX, which are the programs used by therion.

There is a discussion list for therion: the mail archives can be found at http://dir.gmane.org/gmane.comp.gis.therion. To subscribe to the list send an empty email to therion-subscribe@speleo.sk.

There are other programs for the drawing of cave maps, or that allow the inclusion of scanned images of the map:

• tunnel http://www.freesteel.co.uk/wiki/index.php/Tunnel
• carto http://www.psc-cavers.org/carto/
• walls http://www.utexas.edu/tmm/sponsored_sites/tss/Walls/index.html
• winkarst http://www.resurgentsotfware.com/WinKarst.html.

Furthermore, general purpose graphics drawing programs can be used to make cave maps. They are however targeted to different customers than cavers, with more sophisticated needs from a graphical point of view, but without the management problems typical of cave maps.

• cave illustrator http://www.caversdigest.com/software.htm
• xara-X http://www.xara.com/products/xarax
• Freehand http://www.adobe.com/products/freehand/
• Canvas X http://www.acdamerica.com/

Other programs could be useful for cavers to integrate they survey in maps.

• Karto http://sourceforge.net/projects/karto/
• KartoMNT http://sourceforge.net/projects/kartoMNT/

Tunnel is open source, is written in Java, and distribuited under GPL licence 5 . It is developed by J. Todd. It's a WYSIWYG program, but, once the individual pieces of the drawing are composed to form the map of the cave, these are no longer of any use. The input format of the centerline data is exactly that of survex. So far it manages only the plan of the cave, and the section (normal and extended) is under development. The documentation is based on a wiki, and although incomplete, is growing. The interface is rather simple and it is possible to check the final outcome while drawing. From this point of view it is a competitor of therion, although it has fewer functionalities.

Carto is open source and distributed under GPL, too. It is developed by R. Hartley 6 , but the development seems stopped at the spring 2005 (version 0.9.8). It is written in Java, uses Compass plot file (extension .plt) and takes in input images in PNG, GIF and JPEG format. It organizes the maps as projects (extension .cto). A project consists of a Compass .plt file, and files of “plan” type (for the plan) each with one or more cave segments. A segment is the scanned image of a survey sketch. The connection between images and centerline is obtained relating points on the images with stations on the centerline. A segment has also a border which defines the portion of the scanned image that belongs to the segment. Segments are included, with suitable deformations, in the map (“plan”) which can be exported as PNG file. Carto documentation is rather good: on the website there is a tutorial and FAQ. The manual is empty, however. It is also possible to browse the source code documentation. Overall, Carto is more a program to put together scanned images rather than a program to make cave map drawings.

Walls is not free software and is available only for Windows. It is written by D. Mckenzie of the Texas Speleological Society. The work is organized as projects (files with extension “.prj”) and the output is in SVG format, which needs a SVG viewer to be seen (e.g. Adobe SVG viewer). A project is hierarchically organized under a root, and can contain survey data file and graphics SVG files. Walls is not a drawing editor: the map drawings must be made with a SVG editing program (e.g. Adobe Illustrator) using the SVG file of the centerline data, exported by Walls. There is practically no documentation, but Walls includes an introductory example and a more complex one which should help to learn how to use the program.

WinKarst was born in 1995, from karst, a program for the processing of centerline data under DOS, created in 1987 7 8 9 . It has reached version 12.3 and is essentially a software for the processing of the centerline data, but it manages overlaying of DEM (digital elevation model) and SDTS (Spatial Data Transfer Standard, the USGS data format) files. It can import drawings and allows to register the imported image on the centerline, by fixing two points (which define the orientation and the scale). It can export bitmaps or DXF file.

Cave Illustrator is a plugin for Adobe Illustrator version 9 http://www.adobe.com/products/illustrator/ and is available only for Windows. It uses the Compass “.dat” files. It draws the shots as Illustrator artwork objects, that can then be edited by Illustrator. The station names are drawn as text objects. It is possible to select and manage graphically the stations and the shots. Plan and extended section can be drawn both on the same page, or on different pages. The plan can be rotated, i.e. the north can be oriented in a direction other than the vertical. I do not have direct experience of Cave Illustrator for two reasons: it is for Windows, and Illustrator is not freeware. However it seems to be an addon for Illustrator, to specifically handle the survey data, leaving to Illustrator the drawing.

Xara X is a program for graphical drawings 10 . It is very similar to Illustrator, and has a rich set of graphics functionalities. However it is a generic program, not specifically designed for the drawing and the management of cave maps. A large amount of documentation about xarax is on the website http://www.xaraxone.com.

Canvas X is a technical drawing software.

Macromedia Freehand MX is an Adobe product to make graphics.

Karto is open source and distributed under GPL, too. It is developed by G. Fernandes but the development seems stopped since 2006 (version 0.8.2). You can enter in the project and follow the developments. It is written in Java. The software is a cartographic program used by cavers (and other users) to point a great number of caves on maps or aerial photography. After a calibration a the map (you give at least the coordinates of 3 different points) you can import big files of coordinates witch are immediately positioned on the map. You can build your own maps. Data is saved in text files. Useful to check if you cave database coordinates is OK. Work with all maps scanned and some aerial photography. Doc in English. Coordinates in meters, miles, km, … You can also report the cave plan on the map.Karto

KartoMNT is open source and distributed under GPL, too. It is developed by French students drived by G. Fernandes but the development seems stopped since 2004 (version 2.1). You can enter in the project and follow the developments. It is written in Java. The goal of the software is to generate your own Digital Elevation Model data using scan maps. The software use scan maps, detect the level lines, and calculate the DEM of the maps. You cans export the DEM to import it on you own SIG. Project needs someone to follow it (bugs, new features). KartoMNT

If we consider the trend of suite of programs, initiated as simple aids to the processing of the centerline data, we may notice that they have evolved with more and more additional functionalities:

• 2D and 3D display of cave data, with some sort of management of surface maps, digital terrain model (DTM), and integration of geogaphical data (GPS);
• organization of the data, through custom databases, for the management of large cave system projects;

The possibility to include scanned images of the cave drawings, and automatically stretch them to fit the centerline is a first step towards the inclusion of cave drawing functionalities in the suite. From this point of view, therion complements the survex suite. Hades is expected to have scanned sketch inclusion and drawing features 11 .

These pages were written while I was learning Therion. They are based on Therion versions 0.3.9 and 0.3.10. They are distributed in the hope that they may be useful to other people approaching Therion.

They may contain inaccuracies and mistakes. If you find any, please report it to me so that I may fix them. They are distributed in the hope that they may be useful to other people approaching Therion.

Most of the references are to “The Therion Book” [thbook] and the wiki [thwiki]. I also used citations from the Therion users mail group. If I missed the author of any, please report that to me, and I will put that in.

marco corvi