Hello,
I would like to measure distances between points in a constrained space,
such as distances between cities, but only taking into account distances
by land, and so excluding any water bodies. Concretely, this means
finding those cities in a first set of cities which are at least 150km
from the nearest city in the a second set of cities.
At this stage, I only see the possibility of creating a cost surface
with cell values on land masses equal to the resolution and null cells
on water masses and then using r.cost with null_cost set to a very high
level and start_points to the second set of cities, then v.what.rast to
sample the result at the location of the cities of the first set. Does
that sound reasonable ? At the moment I'm getting very weird values, but
I'll have to double-check my operations.
Does anyone see a way of doing this with vector operations ?
Moritz
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