Re: [GRASS-user] Create line perpendicular to other line at specific point

2019-11-08 Thread Markus Neteler
On Fri, Nov 8, 2019 at 10:02 AM Johannes Radinger
 wrote:
>
> Hi all,
> I've vector lines representing rivers and a set of points. Now, I'd like to 
> create short lines (e.g. 150 m) that are perpendicular to the river lines and 
> cross at the coordinates of the points vector.

A similar (?) code is available in the v.civil addon:

https://grass.osgeo.org/grass7/manuals/addons/v.civil.html#transversal

Perhaps it could be separated out into a separe module?

Or, I see that Micha has some code to offer as well.

best,
Markus
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Re: [GRASS-user] Create line perpendicular to other line at specific point

2019-11-08 Thread Micha Silver

  
  
I have a python script from some years ago that should prepare
  "station lines" perpendicular to stream reaches at regular
  intervals. If you're interested in trying, I'll gladly send it. I
  originally wrote the script to work in python 2, so if it's
  helpful, I should do the changes needed for python 3.


Regards, Micha  



On 08/11/2019 11:02, Johannes Radinger
  wrote:


  
  
Hi all,

I've vector lines representing rivers and a set of points.
  Now, I'd like to create short lines (e.g. 150 m) that are
  perpendicular to the river lines and cross at the coordinates
  of the points vector. This is basically to create transects
  similar to the tool v.transect. However v.transect creates the
  perpendicular lines at regular intervals and I'd like to
  create them only for the locations of the points on the river
  line. Is there any straight forward tool to accomplish this? I
  could retrieve the azimuth of the river lines at each point
  (using v.to.db), but how can I extrude a point into a line
  with a given length and azimuth? Any suggestions?


cheers,
Johannes
  
  
  
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-- 
Micha Silver
Ben Gurion Univ.
Sde Boker, Remote Sensing Lab
cell: +972-523-665918
https://orcid.org/-0002-1128-1325
  

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[GRASS-user] Create line perpendicular to other line at specific point

2019-11-08 Thread Johannes Radinger
Hi all,
I've vector lines representing rivers and a set of points. Now, I'd like to
create short lines (e.g. 150 m) that are perpendicular to the river lines
and cross at the coordinates of the points vector. This is basically to
create transects similar to the tool v.transect. However v.transect creates
the perpendicular lines at regular intervals and I'd like to create them
only for the locations of the points on the river line. Is there any
straight forward tool to accomplish this? I could retrieve the azimuth of
the river lines at each point (using v.to.db), but how can I extrude a
point into a line with a given length and azimuth? Any suggestions?

cheers,
Johannes
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