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Cavechat.org
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The Official Caving Forum of the National Speleological Society
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Re: Rigging question
Well I tend to read up on the knots, but sometimes i just dont practice them if I see no foreseeable use for them with what I do. But you are right, everyone should have a wide range of hitches and knots in their bag of tricks. I know the munters hitch, played with it a few times, but really havent used it. some people rappel short distances with it right?clove hitch, well that one doesnt move at all right? Thanks for helping.
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Re: Rigging question
Sorry chad. It's actually two different hitches. The munter, which I'm sure you've seen or used. And the mule knot which is basically a slip knot used to lock off a munter hitch or other belay device. The mule knot is usually compounded by an overhand lock off, much like how you lock off a rack. So it might help to look them both up seperately, I don't know. DO learn them both though. I'm continually amazed at the number of accomplished climbers and cavers who don't know how to use these hitches. They are essential. Right up there with the figure 8 on a bight for me. Ok. Enough soapboxin' latah gatah
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Re: Overlaying a COMPASS line plot to ArcGIS
You can right click on your cave shapefile in ArcCatalog and assign a coordinate system- that'll be the one your cave coordinates are in. If you want to know the relationship between the cave and the surface, you'll need data that represents the surface. That's where the DEM comes in.I'd suggest spending some time with the ESRI tutorials. If they didn't come with the copy you have, they are available online as well. It'd save me a whole bunch of typing too.
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Re: Rigging question
Ok, I will now have to read up on how to tie the munter mule. never had to use it so i never practiced that one. Maybe then I will understand more, lol. This is the downfall of usually rigging on bomber trees. I never have to tie anything fancy so i am rather limited on situations i have had to tie off with. Thanks for the advice. Good stuff.
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Re: Overlaying a COMPASS line plot to ArcGIS
John Lovaas wrote:If you are interested in finding places in the cave survey that are close to the surface, you might try writing a SQL query with the Select by Attribute tool. I'm working in 9.1, so everything I am suggesting may be totally archaic and useless.
Each cave survey station has an elevation attribute, as does each cell of a digital elevation model. You'd export a shapefile of the cave survey stations, and set your fixed station's elevation- it might best if they are in the same units as your DEM. I'm just guessing there.
I can't help you with the specifics of the query, but I'd be looking for DEM cells, witihin some defined horizontal distance to the nearest cave survey station (some kind of buffer function?) , that have an elevation attribute that is equal to/less than "X" (how far to you want to dig?), when compared to the elevation attribute of the nearest survey station.
Good times. ;-)
I really have no reason to dig but I would rather just like to know how much dirt and rock is above my head at any given point in the cave. Also I would like to know how close certain areas are to the surface just to see if there may be other entrances to the cave in that direction. I'm almost certain that there is another entrance to this cave and I would like to know where the most probable place for one would be.
I tried exporting a shape file but everytime I did so, ArcGIS told me that my coordinates were unknown. So I assume it's something to do with the coordinates...but I don't know what else I can do to make them correct...I'm not exactly sure what you mean by DEM...Could you elaborate on that please?
I'm not extremely familiar with compass... I've only used Compass for one "real" cave and that's the one im working on currently...
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