Hi Stephan,
Thanks for your message. I got intersection point with your method. I
did not succeed to add cat to the error v.clean with v.category
(database connection is missing ?). Anyway, another problem is I cannot
copy attribute table v.patch. So I have to do a v.what on my original
river lines to get its name and v.to.db to get coordinates. It's quite a
long process, and my data counts numerous lines (river our roads,
between 500 upto 2000 lines)... I will try
Another way could be to use v.buffer for transect lines and use this
buffer as transect with v.overlay. I keep the attribute table and I can
get coordinate with v.to.db. Do you think it is suitable ?
I think v.profile should be the way, but this function is not available yet.
Regards,
Frank
Le 27/04/2022 à 23:02, Stefan Blumentrath a écrit :
Hi Frank,
Yes, you are right. To get the intersection point you patch the line
maps (v.patch), use v.clean on the patched maps and sve the
intersection points (errors option in v.clean). Then you add
categories to the generated points with v.category…
That just for correction of my earlier suggestion. Your approach with
v.profile seems way more appropriate.
If all your lines have the same cat value, you could create new,
induvial cat values with v.category, before you run v.profile (I have
not looked at your dataset yet…)?
Cheers
Stefan
*From:*Frank David <[email protected]>
*Sent:* onsdag 27. april 2022 19:23
*To:* Stefan Blumentrath <[email protected]>; GRASS user list
<[email protected]>
*Subject:* Re: [GRASS-user] multiple
Hi Stephan,
I'm not very used to v.overlay, but it seems to be used with area and
not with lines crossing lines, isn't it ?
Frank
Le 27/04/2022 à 09:14, Stefan Blumentrath a écrit :
Hi Frank,
My general approach would be like this:
v.overay to intersect transects and lines
v.to.points use=start to get transect start points
v.distance to get distance from transect start point to point where lines
cross
With v.distance you need to try whether it is sufficient to compute
distance to the nearest point only or if you need to compute distance to all
intersection points within the distance equal to the length of the transect...
If the latter is the case you would need to filter out lines with distances
that are not along a transect.
Hope that helps.
v.distance can produce lines, so you could check visually if the approach
works as expected.
Just a suggestion.
Cheers
Stefan
-----Original Message-----
From: grass-user<[email protected]>
<mailto:[email protected]> On Behalf Of Frank David
Sent: tirsdag 26. april 2022 20:01
To: GRASS user list<[email protected]>
<mailto:[email protected]>
Subject: [GRASS-user] multiple
Hello,
I need to identify vector lines (like roads, rivers) crossed by a transect
and get distance from the beginning of the transect. For the moment I'm using
v.profile but it returns only the first item. Is there any way to get all
crossed lines ?
Thank for your help,
Frank
_______________________________________________
grass-user mailing list
[email protected]
https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.osgeo.org%2Fmailman%2Flistinfo%2Fgrass-user&data=05%7C01%7CStefan.Blumentrath%40nina.no%7Caf69c18ee50c48d0e93508da27afbd3a%7C6cef373021314901831055b3abf02c73%7C0%7C0%7C637865933270370389%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000%7C%7C%7C&sdata=nldQo6FwP%2FW2SFmeQdPQCw2GKnR%2B2Dr%2FbyaTrjuteg8%3D&reserved=0
<https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.osgeo.org%2Fmailman%2Flistinfo%2Fgrass-user&data=05%7C01%7CStefan.Blumentrath%40nina.no%7C1240fd7d1fc9422c513408da287297be%7C6cef373021314901831055b3abf02c73%7C0%7C0%7C637866769889954957%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=1NJMtzy00JhCzzWX%2BjN7y5kiLER8wa21Xp40ceYKOYU%3D&reserved=0>
_______________________________________________
grass-user mailing list
[email protected]
https://lists.osgeo.org/mailman/listinfo/grass-user
