Thursday, 16 May 2013

Cave crawling with lasers....

Sometimes you think of a 'great idea'...but then you have to put it into practice. Like many good ideas, they are often far more painful than you might have predicted. When I say painful, it defeats explanation of the many bizarre ways I have found to inflict pain upon myself undertaking what seemed initially a simple procedure. Next time I suggest in a research group meeting 'why don't we simply scan the whole cave system?' either ignore me, or clump me on the head with a blunt object. The LiDAR scanning of a cave system that seems beautifully adapted to size 0 troglodytes is astoundingly hard, hot and positively grim labour.

Dr Bill Sellers tests his Sciatica within the cave system....

The chosen LiDAR tool was certainly the best kit we could have chosen for the task. The Z+F Imager is stunningly engineered and simple to use (the latter being very important for me!). This little beauty pulses an eye-safe laser that maps the 3D geometry of the cave, as we move it from scan station to scan station...some 50+ in the depths of the subterranean maze. Ideally this means we do not get in the way of the said laser when it rotates 180 degrees to scan its surroundings. When using the kit in the open, this is fine...but in a cave, this involves us working alone or in pairs at most (in this case, Bill Sellers and I). As the unit rotates, you have to move with the rotation, avoiding contact with the beam. This makes the later alignment of the 3D scans much easier and there is less tidying-up required of the said scans. In a cave, this involves twisting your body around corners in an attempt not to be scanned....if there is two of you, it is like playing a bizarre game of 3D 'Twister'. Needless to say, a few hours into the scanning, we were monumentally exhausted and ached in places that only maybe an Olympic Twister Champion might ache.

Z+F Imager about to spin its funky we rapidly retreat into the nooks and crannies of the cave!

There is a short delay before the Z+F unit kick-starts each scan, if there is a potential hide hole...this is the time when we scurry like giant gerbils in a stony cage towards stoney refuges in an attempt to avoid messing-up the scan...this is when we trip, scrape, bump, bash and abrade our heads, shoulders, knees and hips against the unforgiving walls of the cave. I am grateful the scanner does not record there there would be vast stretches of profanity that would blight each and very scan...requiring a major edit from the final data.

Our Cave-man natural history guide checks a LiDAR scan marker
By now you might have noticed that I have not mentioned where we are on the planet...other than the fact we are just north of the equator. This is simply to protect one of the most pristine cave systems that the members of our team have ever had the privilege to work within. At this point I would love to praise our local guide, who has been the all-seeing and all-knowing oracle on maters of natural history and a sump of information on the antediluvian realm we are spending so much time. We could not ask for a better guide...who seems to have super-human strength and abilities in terms of caving..not to mention his bat-like night vision. Alas, our splendid guide must remain anonymous, but we still want to thank him for his patience and humour.

Dr Bill Sellers hides in his 'hobbit laser avoidance hole' as I do the 180 degree LiDAR dance...
As with many of our travels, we get to meet many kind and generous folks and today was no exception. The neighbours on the adjoining land to the cave system offered iced tea and provided some of the best tasting water melon in my life. It is amazing how the sensory depravation of a cave system heightens your tastebuds! We even managed to tempt one of the neighbours underground to share some of our enthusiasm for our chosen task. Once we have the 3D maze of the caverns reconstructed from the LiDAR scans...we will also be able to invite you all into the wonderful cavern we have named 'Green Cave'.

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