[GRASSLIST:10754] Re: GRASS topographic position functionality beyond r.param.scale?

[Trevor Wiens]

On Sat, 4 Mar 2006 20:14:44 -0800
Graham Watt-Gremm <sunyata at uvic.ca> wrote:

> Hi Ian (and/or GRASS user list),
> Did you ever get a response to this query, or develop something  
> yourself? I would like to get at the (unidentified Arc/Info) slope  
> position algorithm used by Wimberly and Spies (2001, Ecology 82(5): 
> 1443-1459), where topographic position grades from 0 at valley bottom  
> to 100 at ridge top. I am thinking along the lines of using some of  
> the output from r.flow (flowline segments in each cell a function of  
> transformed distance from valley bottom), though I have no experience  
> with this module. Does anyone have any suggestions?
> 
> Cheers and thanks,
> 
> Graham Watt-Gremm
> Rocky Mountain Repeat Photography Project
> School of Environmental Studies
> University of Victoria
> sunyata at uvic dot ca
> 
> [GRASSLIST:1410] GRASS topographic position functionality beyond  
> r.param.scale?
> 
> Ian Allan iallan at geocode.com.au
> Mon, 06 Oct 2003 12:29:41 +1000
> 
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> 
> Hi
> 
> Can anyone suggest a technique for determining topographic position that
> would provide more information than r.param.scale? In particular, I'm
> interested in mapping upper slopes, mid slopes and lower slopes.
> 
> Many thanks
> 
> Ian Allan
> 

Another option to consider is the topographic convergence index
calculated by r.terraflow (if you have C++ support included).

T
-- 
Trevor Wiens 
twiens at interbaun.com

The significant problems that we face cannot be solved at the same 
level of thinking we were at when we created them. 
(Albert Einstein)