I opened the code and it has it right in header:
TOTAL COST = [(WALKING ENERGY ) + (LAMBDA*FRICTION)]
maybe this is how it should go into the man page
Helena
On Oct 10, 2008, at 2:21 PM, Michael Barton wrote:
I've been emailing with Helena to try to understand exactly how
lambda and a friction surface interacts with information about
topography (extracted from a DEM) in r.walk. It seems a good idea to
put this back on the list. Perhaps I'm the only one a little in the
dark, but maybe it can help others.
On Oct 10, 2008, at 10:40 AM, Helena Mitasova wrote:
To clarify for me, is it
total cost = (movement time cost + lambda) * friction costs
OR
total cost = movement time cost + (lambda * friction costs)
I did not look into the code but if there are no brackets in the
code, this second interpretation applies.
For anyone familiar with the code, is this the case? If so, should I
be thinking in time units for creating a friction map? If I
remember, r.walk normally outputs in seconds to traverse the cell.
So, should the friction map be in additional seconds to traverse the
cell? Or is friction a weighting factor (i.e., multiplicative rather
than additive)?
Thanks
Michael
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