[Qgis-user] Update attribute of road segment when it has been surveyed

[Nicolas Cadieux]

Hi,

It’s not clear to me what you are looking for but it seems you have information from points that you would like to have updated based on the lines.  This is impossible because they are not touching (a very hard thing to do btw).  You could snap the points to the line.  Look for “snap“ in Processing.

Another way is to make a buffer with the lines or with the points.  A 30cm buffer would permit you to do a spatial query where you have up to 30cm error between a line and a point.  

If you are also looking for an algorithm to fix your linear network, I have just posted a QGIS 3.20 model called fix directional network downloadable from the QGIS plugin site (look for the hub tab in https://plugins.qgis.org/  That could help find errors in the linear part of the network.  The YouTube video below will help using the model.

https://youtu.be/v61PafSByvM

Nicolas Cadieux
https://gitlab.com/njacadieux

> Le 27 sept. 2021 à 09:27, Roland Spielhofer <rspiel at gmx.net> a écrit :
> 
> 
> Hi,
> I have a road network that is surveyed for road distress.
> The network is a line vector layer.
> I also have a point layer representing the driven trajectories of the survey vehicle.
> I am looking for a method to update a field of the network layer when [some] points of the trajectory are "near" the line.
> As the trajectory is quite precise, the distances between lines and points are small and there are no obvious outliers.
>  
> What I don't have is the algorithm how to classify the lines if the points of the trajectory are near the line.
>  
> Any help appreiciated!
>  
> Roland
>  
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