[GRASS-user] v.segment performance

[Markus Metz]

Hi Eric,

On Tue, Aug 6, 2019 at 8:23 PM Eric Patton <eric.r.patton at protonmail.com>
wrote:
>
> Hi,
>
>  I have a massive Delaunay polygon tessellation that I converted to lines
with v.type. I then stripped this vector of centroids using v.edit
tool=delete type=centroids, and added categories to the line segments with
v.category option=add. So far so good, this leaves me with about 670,000
vector line segments.
>
> I want to find the midpoint of each of these line segments and create a
new Delaunay tessellation using the line segment midpoints as the vertices
in the new tessellation.

The addon v.centerpoint [1] should be much faster than v.segment to get
line midpoints.

Markus M

[1]
https://github.com/OSGeo/grass-addons/tree/master/grass7/vector/v.centerpoint

> I have prepared a rules file to feed into v.segment to do this, using the
50% distance offset.
>
> I ran v.segment with the verbose flag and the only output I received
after 90 minutes is ‘Using native format’ ;  I’m not sure if the process is
going to run forever, or if I just need to be more patient, or if I am
trying to process too many points for this tool -  this is my first time
ever using this module, so I don’t know what to expect. Does anyone have
any experience using large vectors with v.segment?
>
> I thought the program might give some more output as to what’s happening.
htop shows The program is using one core out of eight at 100% so I suppose
it’s working normally.
>
> Thanks for any hints,
>
> ~ Eric.
>
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