Problem with r.cost?
W. Fredrick Limp
fred at cast.uark.edu
Mon Nov 1 16:06:57 EST 1993
Recently Jianping Xu responded to a question from Rick Thompson about
changes in r.cost from 4.0 to 4.1. Thanks for this info. I may have
missed something but it does not appear that the 4.1 documentation
discusses this. Xu discussion is useful but I wonder if we could
have a more detailed discussion from someone (the reviser?) as
to the specifics... r.cost is a very valuable module and I, for
one, would like to be sure that I know what it is doing.
Some specifics listed below...
> > Hello Grassers,
> > Does anyone know why r.cost is behaving so much differently in 4.1 than
> > in 4.0. The manual entry in 4.0 makes sense, but after using 4.1 r.cost,
> Several reasons:
> 1. 4.0 r.cost figures the cumulative_cost for a to_cell by simply adding
> its cost to the from_cell's; while 4.1 r.cost does it
> by adding the average_cost of the 'from' and 'to' cells to the
> from_cell's cumulative_cost.
----- I follow this...
> 2. *Absolute* cell resolutions are taken into accout by 4.0 r.cost
> ('normalized' to 100m), not by 4.1 r.cost.
------- This is not clear. What does "taken into account" really imply
> 3. 4.1 r.cost takes more 'neighboring' cells into accout as your
> request, while 4.0 r.cost doesn't. And ...
----- I assume this refers to the knights move or perhaps not ????
> Jianping Xu
> jianp at ocean.rutgers.edu
W. Fredrick Limp, Director FAX: (501) 575-3846
CAST, Center for Advanced Spatial Technologies TEL: (501) 575-6159
12 Ozark Hall, University of Arkansas
Fayetteville AR 72701 fred at cast.uark.edu
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