[Qgis-user] topology checker - Check if point features are covered by line features

[Nicolas Cadieux]

Hi Marshal,

I looked at your data. The first problem is that none or your line nodes 
intersect with a point.  It looks close... but it's not close enough.  
By using "snap geometry location", I was able to create a new line that 
snaps to your point.  (called Topologie snapped_line in the file I will 
send you in private).  A "Select by location" or a "Join Attributes by 
location" confirms that the points now intersect the Topologie snapped 
line layer. The Join Attributes by location will permit you to find the 
problems as you can discard records that do not intersect.  This will 
give you what you want.

As for the topology Checker, it seems that a line cannot cover a point 
or a point cannot cover a line even if point and line nodes intersect 
(Can someone confirm this?).  I can only assume that QGIS works with the 
correct assumption that a point and a line does not have a surface to 
cover and therefore, cannot cover anything.  I assume, based on your 
observations that ESRI does not follow that assumption.

You can however create a 1 m buffer around your line (Topologie 
Buffered_line in the file).  Then, you can create the rule (polygon must 
contain point). That rule will work in the topology Checker.

Cheers!

Nicolas


On 2020-04-13 10:25 a.m., Nicolas Cadieux wrote:
> Hi,
>
> I don’t have QGIS in front of me.  I looked around on the the net and was surprised to see the «covered By » option for points and lines.  Unless a line is snapped, or intersects a point exactly on a Line node, it’s just about impossible to calculate if a line « covers » a point.  This is something easy to do with a polygon but not a line because of float point precision error.  You could buffer the lines and see if that helps. You could create a 1m buffer on the line (or the point).  Make sure both layers are in the same crs so that additional calculations don’t need to be done.
>
> You could at the « select by location » side.  I would look at « snap with » or «intersects with »options.
>
> Nicolas Cadieux
> Ça va bien aller!
>
>> Le 13 avr. 2020 à 06:11, Marshal Mappers <marshalmappers at gmail.com> a écrit :
>>
>> 
>> Hello everyone,
>> I want to use the topology checker to check if point features are covered by line features. For example are the bus stops covered by the bus lines.
>> Therefore I use the topology checker with the following rule: "points" must be covered by "lines". But I get the error for all points that "point is not covered by segment".
>> I even get the error for points that I edited on the line with snapping.
>> Here my questions:
>> 1. Is it possible to check if point features are covered by line features? With topology checker? In general?
>> 2. What does the rule: "points" must be covered by "lines"check? Under what cicumstances is a point feature covered by a line feature?
>>
>> I tried this in QGIS Versions 2.18.26; 3.4.15; 3.10.2
>> My OS ist Windows 10
>> I tried with shapefiles and geopackage layers
>> The CBS of point and line layers are the same. Here I tried the coordinate systems with epgs: 31468 (DHDN / 3---degree Gauss-Kruger zone 4) and 25832 (ETRS89 / UTM zone 32N).
>> If anyone could explain or point me to the right direction, that would be awesome.
>>
>> Thank you!
>>
>> Best regards
>>
>> Marshal
>> _______________________________________________
>> Qgis-user mailing list
>> Qgis-user at lists.osgeo.org
>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> _______________________________________________
> Qgis-user mailing list
> Qgis-user at lists.osgeo.org
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user