Victorian Speleological Association Inc.

Peter Freeman · Posted: Tue Jun 01, 2010 12:11 pm Post subject: Cave Surveying Discussion

I use Fountainware's 'Cave Compass' software for data reduction and plotting of my cave surveys. Compass can interpret LRUD data as relating to the TO station or the FROM station of a survey shot. Of course you must tell the software (in 'settings') which way to use the data. I think the default is FROM.

I tend to measure my LRUDs at the TO station. This means that in dead-ends I don't have to create a dummy (zero-length) shot in order to get LRUDs at the passage-end. The downside is that I have no LRUDs at the start of a survey leg, especially, for example, at an entrance. If necessary, I create a dummy shot there.

My reasoning is that a typical cave has many more dead-ends than entrances (or other survey start point), and so I use the TO-station method.

Any thoughts? I'd like to hear the views of experienced surveyors.

Peter Freeman · Posted: Wed Jun 02, 2010 4:19 pm Post subject: Super-distometer

For in-cave surveying I use a Leica Disto D3 to measure distance and inclination, and a Sunto KB14 compass for azimuth. There have been, for some time now, certain 'home-brew' options to measure all three required dimensions using just one instrument: The Shetland Attack Pony (SAP) from UK is one, and it also automates the transfer of data to a Palm Pilot PDA so there is no need to take a notebook into the cave except for sketching; The 'Disto X' is a third-party add-in daughter board for a certain Leica Disto model (A5 I think), which does much the same. Being 'home-brew' solutions, these devices suffer from the usual problems of dodgy firmware, lack of technical support, unreliability, etc. Also, I understand that calibration is a pain, and required rather too often.

There are commercial units that seem to fit our requirements, though they are expensive. My reservation, apart from the expense, is whether they are rugged enough for the cave environment.

The TruPulse unit is here:

http://www.precisionlasers.com.au/images/uploads/trupulse360.pdf

The Laser Ace unit is here:

http://www.mdl.co.uk/resources/LaserAce--Survey_Rev_01_09_06_06.pdf

The Laser Ace is perhaps the right choice for us: better accuracy at our usual shot lengths.

If you have 2.5 to 3.0 k$ to spare, I think these would be really good gadgets to try out.

Comments sought!

(Thanks to Neil for first sending me the TruPulse links)

Peter Freeman · Posted: Thu Jun 03, 2010 7:48 pm Post subject:

I asked Bob Kershaw for his view on the LRUDs issue. Bob is very experienced in this area as he manages the survey data and mapping for the Bullita system, Australia's longest cave. Here is his reply:

"Hi Peter. The short answer is what ever suits you. Providing your survey party knows what you are doing and, if you have someone else input the data, [that they know what you are doing]. At Bullita the LRUDs are made at the FROM station: a historical protocol and one which I think most people do in Australia. I appreciate the dead end bit comment – worthwhile to think about. Cheers, Bob"