Inspired Stone

February 18, 2011, 6:19 am
Filed under: cartography, Mountain | Tags: , , ,

My first steps into geographic analysis were to experiment with GIS and get the geographic data into a format I understood and could use. Now the fun starts.

I have a keen interest in the ridge lines of alpine terrain, which I’m sure is influenced by my passion for climbing. So my first idea was to develop an algorithm and computational routine to identify the ridge lines in an elevation map. I started with a small elevation map, shown below, covering the area immediately around Mt. Whitney. Lighter colors correspond with higher elevation (the summit of Mt. Whitney is at the center). Just looking at the image, it’s not difficult to identify the major ridge lines, like the ones I outlined in red. Telling a computer how to do the same thing is not easy.

In my first attempt, I wrote a short octave script that would find the locations where the elevation sloped downward in both east and west, or north and south (if it slopes downward in all four directions, than it’s a peak). The image below displays a white pixel wherever a ridge was identified. The result is mediocre. Of course there are minor ridges identified (like the ones on the west slope of Whitney, which are truly there), but the bigger problem is that even the major ridge lines are discontinuous.

Excitingly, I have found current research being done in this area.:

Taking a hint from the paper above and this group in Zurich, I think I should use some strategy like the Watershed algorithm. Here’s a peak at what I’m working on: