How to survey a cave?
Exploring caves is hard enough. To survey them and draw maps is reserved for experts only, you might think. But in fact it is pretty easy to survey a cave or any other three dimensional cavity like the way from the entrance of your house across the TV in the living room to the water-tap in the bathroom.
After reading this page you'll be fit for it. All you need is a measuring tape, a compass and a clinometer. Or, if you own an Android Smartphone sinply download cavemeter Application for Android.
For calculating and drawing the map afterwards, an ordinary computer is all you need. The software you need is available on this homepage for free. And it works with Windows, Linux and MacOSX. So let's get started
We bundle up the measuring tape, compass and clinometer and head for the entrance of our test cave, the door of the house. And here we face a problem. Where to start? Usually you select a point that makes sense and is reproducable. If there is a bolt for roping down, it would be a good idea to use it as measuring point number 1. As we stand in front of the entrance door I would suggest something like the upper left corner.
We can not see the TV from this point. So we need a point in between that we can draw a straight line to. The umbrella stand? Too easy to dislocate. Let's use the painting of the belling stag. Choose a corner and ... call your friend. Someone must hold the other end of the measuring tape. 3 meters and 47 cm.
At the compass you don't struggle with east and west. It is usual to take north as 0 degrees and go round clockwise for 360 degrees. So east would be 90 degrees. From the door to the picture you measure 223 degrees, which is about south west.
Unfortunately there are two different ways to read the clinometer. Some (e.g. Sunto) define horizontal as 0 degrees. Upwards they count positive till plus 90, downwards they use negative numbers. The others are afraid of getting confused with writing plus and minus and define horizontal as 90 degrees. Upwards they increase the numbers till 180, downwards they decrease. So a vertical pit is not -90 but 0 degrees. You measure -12 degrees. Later on, in the computer list, you add "Kommando: messung sunto", to make the program know which system you used
So the second point in three dimensional space is defined exactly. You continue your survey over the sideboard to the TV, up to the wall clock and finally to the water-tap. So you get a chain of lines called traverse, that represents the way through the cave. To be able to draw the sizes of the corridors, pits and halls later on you will need additional notes and drafts. For the drawing it is also important to note where the measuring points were located.
Your traverse might look like this:
|1||2||3.47||-12||223||to the belling stag|
|2||3||2.17||-4||308||sideboards drawer knob|
|4||5||4.12||+18||286||wall clock upstairs|
|5||6||2.98||-53||45||water-tap and current end of exploration|
Back home you start the program copycave and click on (Survey) "New". After inserting the survey points you save the file and press the button "3D". You can already let the traverse rotate and get a 3D impression.
Now you click "Show/Draw Map" and draw the countours and other parts of the cave. For printing you can create a PDF of the map. That's it.