#2563: r.grow.distance: define max distance
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Reporter: mlennert | Owner: grass-dev@…
Type: enhancement | Status: new
Priority: normal | Milestone: 7.1.0
Component: Raster | Version: svn-trunk
Keywords: r.grow.distance maximum distance | Platform: Unspecified
Cpu: Unspecified |
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It would be nice if r.grow.distance allowed to define a maximum distance.
The module could then stop calculating once this maximum distance is
attained (e.g. similar to r.cost's max_cost option). This should probably
accelerate the module if only short distances are needed from the starting
points.
#2563: r.grow.distance: define max distance
----------------------------------------------+-----------------------------
Reporter: mlennert | Owner: grass-dev@…
Type: enhancement | Status: new
Priority: normal | Milestone: 7.1.0
Component: Raster | Version: svn-trunk
Keywords: r.grow.distance maximum distance | Platform: Unspecified
Cpu: Unspecified |
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Comment(by glynn):
Replying to [ticket:2563 mlennert]:
> It would be nice if r.grow.distance allowed to define a maximum
distance. The module could then stop calculating once this maximum
distance is attained (e.g. similar to r.cost's max_cost option). This
should probably accelerate the module if only short distances are needed
from the starting points.
It wouldn't have the slightest effect upon performance. r.grow.distance
doesn't operate in order of increasing distance. It operates row-by-row in
two passes, from top-to-bottom then bottom-to-top, recording the distance
to the closest point seen so far.
Replying to [comment:1 glynn]:
> Replying to [ticket:2563 mlennert]:
> > It would be nice if r.grow.distance allowed to define a maximum
distance. The module could then stop calculating once this maximum
distance is attained (e.g. similar to r.cost's max_cost option). This
should probably accelerate the module if only short distances are needed
from the starting points.
>
> It wouldn't have the slightest effect upon performance. r.grow.distance
doesn't operate in order of increasing distance. It operates row-by-row in
two passes, from top-to-bottom then bottom-to-top, recording the distance
to the closest point seen so far.
Ok, so the only way to limit the distance is to determine the smallest
region that would include the max distance.