I was looking for some advice on how to calculate topographic exposure (TOPEX) in ArcGIS. Jamie Popkin posted a tutorial on how to perform the calculations using GRASS (http://jamiepopkin.blogspot.de/2011/01/calculating-togographic-exposure-with.html). I am looking to calculated Distance Limited TOPEX for eight directions (10,60,90,140,190,240,270,320) with ArcGIS. Any clues? Additionally, there is a script for ArcView3.2 available from http://faculty.forestry.ubc.ca/mitchell/downloads.htm. I tried contacting Dr. Mitchell himself, but no response yet. Any advice besides just doing it in grass is greatly appreciated!
I took a look at the TOPEX model available at http://faculty.forestry.ubc.ca/mitchell/downloads.htm and this is, in fact, not an ArcView 3.2 avenue script but rather a standalone compiled commandline program that can be run at the windows cmd. There is a "topex.txt" file that provides instructions. The program requires data in an arc grid format.
I am extremely sorry it took me soo long to reply. I saw that jevans02 ran the model and everything worked for him, so I did not put in too much thought into getting back to you. Anyways, in the end, I just used qGIS, but after I tried the "compiled command line program" from http://faculty.forestry.ubc.ca/mitchell/downloads.htm. I have not tested it recently, but when I tried a year ago, I asked a friend of mine to also test it (between the 2 of us on 3 systems in Germany and in the Netherlands), and we still got a similar message after following the read-me to a T). Maybe we just can't follow instructions. 😉
As of last year, these functions were not available in ArcEditor which "is now referred to as ArcGIS for Desktop Standard." qGis has a built in function **that I am too lazy to look at right now, but you could also do it using the aforementioned link to Jamie Popkin's website and instead of using perl to do "simple" trigonometry, calculate the cardinal angles using excel.
If you have any further trouble, shoot me a message! I hope you got it all figured out by now! With kindest regards, Eric
