Digital bushwacking

[Artsay]

Nice! A fellow GIS geek! If you haven't already, hillshade your DEM in 3D Analyt. The effect is similar to what you're doing but greyscale. Then you can add a transparency to your DEM, lay it on top, and get a cool effect. I like using hillshade because it's easy to still read the DEM but the clifflines POP!

Here's a raw hillshade of PMRP:

Hillshade.jpg (490.68 KiB) Viewed 4635 times

[toad857]

nice, that's cool. I bet you could use aerial photos to "skin" the surface, or just overlay them for a cool effect.

I think i'm going to try to map out big south fork... the cliffs out there are incredible... just hard to find

[Artsay]

Your'e exactly right with the skin analogy! It looks coolest with the DEM, though, which is essentially the technique used for relief mapping. In ArcMap, set your transparency on the DEM to 70% or so and order it on top of the hillshade in the TOC (also, go to properties of the DEM, Display tab, and set resampling to bilinear interpolation to smooth the image resolution) . Oh yea, you can bring in all the RRG data I've created by bringing in the ArcGIS Online service. Go to your File menu, Add Data from ArcGIS Online, and search "Red River Gorge" (case sensitive). All crag locations, regions, roads, trails....you name it. Have fun! PM me if you want to talk GIS, I love this stuff.

[captain static]

I like to use Kentucky Digital Ortho Quarter Quadrangle aerial photography because it is referenced to USGS mapping and provides good resolution of ground features. For example go to http://kymartian.ky.gov/doqq/doqsouth.htm click on Irvine & then M48 which is the Zachariah Quad. Then click on SW11 which is a photo that shows the Motherlode, Choco Factory, Sore Heel Areas.

[Howie Feltersnatch]

nice, that's cool. I bet you could use aerial photos to "skin" the surface, or just overlay them for a cool effect.

I think i'm going to try to map out big south fork... the cliffs out there are incredible... just hard to find

They have already been mapped and are available through a variety of free/cheap sources. They are just very hard to get to and are of a much poorer quality than the corbin sandstone found in the northern cumberland and the denser sandstone found in the southern portion (obed/chattanooga).

[epitaph]

First post, couldn't help myself...

Good to see some climbing-minded folks who are thinking about raster analysis in GIS. I started climbing around a year ago and have a background in GIS. I am currently employed as a spatial programmer.

The USGS NED data that you're getting for KY in this area is very likely SRTM or ASTER based and the resolution isn't nearly as high as you would think. They approximate it at 1/3 of an arc second, which is pretty optimistic, it's closer to 1 arc second most likely, somewhere in the vicinity of 30m, be it SRTM or ASTER data (though resolution can vary widely within the data sets). The way the data is processed and interpolated to make a smooth, continuous DEM often gives a false sense of precision (side note: you can see in Artsay's picture the "tin-ning" effect from using a triangulated irregular network to process the source data into a DEM). Kentucky has an active program that aims to capture much higher resolution elevation data using LiDAR, but that's about all I know about it (think down to a few feet in terms of resolution -- tons of data, but disturbingly accurate). I did a research project using LiDAR to find landslides in Northern Kentucky and Cincinnati when pursuing a GIS certificate, but have since stopped following the progress of the LiDAR program in Kentucky. See: http://kygeonet.ky.gov/kyfromabove/

For anyone who doesn't have access to a machine with ArcGIS, most of these simpler surface analysis methods are accessible in the free open-source software GRASS, but it can be a bear to setup and use. I created an assignment to use in a Geomorphology class that I was a Teaching Assistant for that could be of assistance to anyone trying to use GRASS to search for cliffs. It's kind of out of date already, but it might be worth a once over if anyone wants to get into using these kinds of tools to explore. See: http://trishock.com/academic/pdf/landsl ... gnment.pdf

I might have to get it running on my home workstation again to play with this -- especially if they run some <1m resolution LiDAR fly overs for the DBNF region...

[edit]

Still thinking about this today.

While hillshade maps can provide a visual tool for finding cliff line, and slope can help identify steep cliffs, what may be more useful is finding where there is exposed rock. If the Kentucky LiDAR hit return data is released publicly, it would be a very interesting project to take the hit return data and see if you can use it to help distinguish rock from foliage. The general idea is that, as the LiDAR is collected, it sends out thousands of pulses of light every second. How the data comes back to the sensor can tell you a lot of what's on the ground. So, for example, if you're running LiDAR collection over a forest, you might be getting returns of the tops of trees and the ground, so if you were looking to create a DEM from the data, you may be interested in looking at the lower return values that more accurately represent the forest floor rather than the canopy.

[Andrew]

good first post

[climb2core]

y'all are working too hard at this GIS stuff.


http://www.satelliteviews.net/cgi-bin/g ... nty&sdb=Go

Click on physical and zoom in a bit. Shows relief real nice.

[toad857]

I think you're missing the point--these techniques can be used to automatically tell you where every cliff in Kentucky is. It takes 5 minutes of data analysis, rather than 50 years of bushwacking. Even terrain maps you have to pour over and analyze them manually. This stuff, on the other hand, can be used to cut out all the fat.

Epitaph: What you described sounds kind of like image classifcation in ArcGIS. I've used it with satellite imagery to train the program to recognize "forest" vs. "open" habitat, and it seems to work pretty well. Exposed rock is probably pretty stark compared to forest, at least in satellite images. But the overhung stuff wouldn't appear at all. Not sure about lidar data, but it sounds promising.

[epitaph]

toad857 is correct -- if a climber wants to find new prospective cliff line, you could run a series of analyses that rank potential cliffs based on some criteria that you could then scope out in person. While the analysis will never tell you "there is climbing here", it can narrow down the targets significantly into a manageable amount. Your ranking might include slope, aspect if you're concerned about sun and shade, proximity to a known trail or road to minimize bushwacking, total relief of 50 ft (you don't want climbs that are too short, perhaps), and that its location is on accessible land that allows bolted development (if you had the boundaries of PMRP, for example). Then you could take your top 5 potential locations and scout them out. What you're really trying to do is take known locations of climbing and try to find other areas that have similar characteristics. Finding the best criteria is the challenge (though slope surely must be a very important parameter).

toad857, about the raster classification that you did to help distinguish forest from open habitat -- was the source data thermal? I've seen such data classically used in environmental applications (finding honeysuckle, for example). One would think that bringing in ASTER data (emissivity, thermal) could also help distinguish rock from forest canopy. During my research using LiDAR I started to see what I believed to be indices of honeysuckle growth on cleared slopes within the data as well, though it's purely speculation and I never pursued it systematically.

Also, Artsay, thanks for sharing the data sets on ArcGIS online. For some reason when I load them in ArcGIS, it only loads the Bing roads base map and none of the feature classes. I've had problems with ArcGIS online before, though. It shows up in the online viewer using ArcGIS online, just doesn't seem to come down in the package. Any ideas on why this is? I appreciate any help. See: http://img833.imageshack.us/img833/5003/captureeqd.png