Therion and DistoX Training Course Guide

A guide to the content of the cave surveying course run by the Cave Surveying Group in Yorkshire, November 2011

 This guide is based on survey data recorded during a course run at Bull Pot Farm in Yorkshire using a DistoX and PocketTopo running on a PDA. The survey was done by course members in ‘Bull Pot of the Witches’ and covers the chamber at the bottom of the entrance shaft plus a bit of passage coming up into the chamber from underneath the floor of the main chamber. This provides an example of overlapping passages requiring two scraps in Therion to draw the plan view of the survey. These notes were written by Footleg based on a course structure designed by Andrew Atkinson. This guide goes into more detail than could be covered on the course and extends the course beyond what is usually covered in a weekend. (The eventual plan is to include elevations, but that part is not written at this stage).


The raw data file saved on the PDA is in a file named ‘bpw.top’ and contains all the data that is required to follow this guide.You can download the data file and examples for each lesson in this course guide here:

Therion Training Data

You will also need a copy of the following applications:

  • PocketTopo (v1.3 or later can be run on a Windows computer or Windows Mobile v6 PDA)
  • Survex (Cave data processing application and viewer)
  • Therion (Cave survey drawing and cave data management application with viewer)

To create the landscape overlay for the survey you will also require:

This course guide was written using the following software versions:

Don’t be put off by the Therion version being listed as the ‘unstable’ version. It just means it contains the latest features which have not had all that much testing yet. But it works fine and contains some features that we want for this course.