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TOPIC: Brief Report on the Survey weekend

Brief Report on the Survey weekend 7 years 9 months ago #11812

  • LesW
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Brief Report on the Survey weekend 7 years 9 months ago #11813

By way of reply to both Les and New S.

I am most impressed by the form of surveying used on the Nottingham Cave Program. See....

nottinghamcavessurvey.org.uk/

This is an extensive system of caves and also an extensive web site. The equipment used here was expensive, but I guess they got some funding to help. It may well be that we can get the equipment for short periods to try it out at least.

I feel that an equally versatile method could be achieved using a sequence of well taken still photographs, operated by a program similar to Google Street View. This would allow you to move forwards and backwards through a cave system, and also make route choices. See...

ogof.net

Beware, this gets addictive!

Also this...


much cruder and less interactive.

This next link shows a simpler laser scan system that runs as a continuous video but the raw data could be displayed in other ways.



I think this was done by a single laser beam (like in the distoX) that revolves as it progresses along the mine tunnel, and this provides a string of data distances calibrated with the distance travelled and the angle of rotation. This is a simple data set as two of the three vectors are relatively constant. The form of scanner used in the Nottingham Cave Survey produces a vast amount of data.

I also like this method...



Looks simple, and may be very suitable for caves.

In researching this subject I have found many more links on You Tube and on different forums dealing with surveying buildings and working with lasers.

I do feel that the next immediate step for us is to get Tims kit working and collect some good data for an easy cave system such as Poachers main passage, or Belgrave top level. We then need to put into practice all that we were taught on the survey weekend. I suggest we make a set of four posts with round headded screws on to be used as a jig for calibrating the DistoX as this is a very long task and has to be done each time the Disto is turned off. Then on a weekend in the Spring next year, when all the players are available, we should tryout the laser machine.
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Brief Report on the Survey weekend 7 years 9 months ago #11817

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JohnNicholson wrote:
This next link shows a simpler laser scan system that runs as a continuous video but the raw data could be displayed in other ways.



I think this was done by a single laser beam (like in the distoX) that revolves as it progresses along the mine tunnel, and this provides a string of data distances calibrated with the distance travelled and the angle of rotation. This is a simple data set as two of the three vectors are relatively constant. The form of scanner used in the Nottingham Cave Survey produces a vast amount of data.

John,
the laser scan used a system of points, called a "point cloud".
The laser scanner is located at a point in th epassage and left to scan, this can take a long time (in a passage like that, perhaps 40 minutes). It is then moved along the passage so that it can still see some of the original points that were scanned, and set to scan again (another 40 minutes?) progression is in short steps like this until it has accumulated massive numbers of "points".

The scans are downloaded to a powerful PC with some very expensive software on it and this is set to try and identify the points that are common in each individual scan. If it is succesful then it will "stitch" the scans together. More likely is that a person will need to intervene on locating common points as software is not that good at spotting the same points from different angles. This process can take many days. One it is complete the finished image is rendered into a movie, again this requires powerful processing and still takes the computer many hours. The final result is very pleasing though.

The scanners are very expensive and not really suited to hostile underground.

The guy that knows about all this stuff in the UK is Kevin Dixon. He has scanned lots of stuff, including Gaping Gill, Titan and The Frozen Deep. He has also scanned the largest chamber in the world, Sarawak Chamber and the largest cave passage in the world, Deer Cave. This stuff is still way beyond the budgets of most cavers and the software is many, many thousands of pounds. It is still very labour intensive and processor intensive. It will be a long time before anything is developed by cavers to produce comparable scans on as budget. Kevin "borrowed" a scanner from Lecia to scan in Mulu (Sarawak Chamber and Deer Cave) but it was only a loan as the scanner was valued at something like a quarter of a million quids...

www.mulucaves.org/wordpress/articles/measuring-sarawak-chamber

cave-registry.org.uk/images/stories/TFD.mp4

www.scribd.com/doc/51213138/Kevin-Dixon-Laser-Scanning
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Last Edit: 7 years 9 months ago by LesW.
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Brief Report on the Survey weekend 7 years 9 months ago #11818

We saw that 3D film on the survey course, but the figues quoted were not as high as you suggest. My feeling is that this is the current top of the range 3D lasers, and the cost will come down as more people use it. It happens that UCET may have a way to borrow this kit (or similar) over weekends. I am not suggesting that we abandon the DistoX, but rather give it a jolly good go, whilst keeping an eye on other opportunities as they come along.

Do you know how we can contact Kevin Dixon?
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Brief Report on the Survey weekend 7 years 9 months ago #11819

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Kevin Dixon is "KDXN" on ukcaving.com so you can send him a personal message there
I also have an email address for him but am not posting it on a public forum.

John, you would do well to come to the cave technology symposium next year, it is in Wales as well (albeit a tad south of you...). There will almost certainly be talks on the latest technological developements with surveying (although not totally guaranteed if nothing new is about)

BCRA Cave Technology Symposium 2013. Weekend 20-21 April 2013, South Wales
bcra.org.uk/index.html#techsym
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Brief Report on the Survey weekend 7 years 9 months ago #11840

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NewStuff wrote:
LesW wrote:
Currently people are working on a variant of DistoX that works with a newer Disto and uses available components, however, so far they have yet to perfect it...

I'll await the results of this with interest. Any links I can look at?

No, they were working on a software & hardware to fit a newer Leica model but by the time they had got even a fraction of the way there leica had once again updated their model, software etc.

I think the truth is, at present there are 'enough' Distox's around to satisfy the people (amateur volunteers) who are doing the development - in short the demand probably isn't big enough.

I got a second hand Leica Disto A3 on ebay about two years ago and also managed to buy the last ever board Beat Heeb (yes, he's foreign!) ever made , again about 2 years ago.

Since then Kevin Dixon managed to source components to make about another 100 DistoX1 boards - exact copies of the Beat Heeb Boards.

Beat Heeb meanwhile was looking at development of a new board and software for the Leica DXT (the newer and water proof version of the A3) but while i believe it did get of the ground for a trial run, it hasn't been completed yet.

google DistoX and you'll get loads of info. :-)

Heres a paper by Beat (2009) which explains what a Disto X is

paperless.bheeb.ch/download/DistoX.pdf

and theres more info on his website paperless.bheeb.ch
-
Tim Watts
Last Edit: 7 years 9 months ago by timwatts.
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