[Qgis-user] Finding Points which do not overlay

[Carlos Cerdán]

Hi Henrik:

If you still don't solve your issue, perhaps you can try this:

1. If you don't have it, Calculate X and Y coords. for your two layers

2. Make a table union, in layer properties

3. Create two new fields for calculate difference of coordinates (Xi - Xj)
and (Yi - Yj)

4. Calculate the absolute distance between points in a new field, with the
two previous.

5. This last field is your criterion about absolute difference between
points.

Good luck

Carlos Cerdán




2014-09-19 9:35 GMT-05:00 henrik_f <henrik.feltens at gmx.de>:

> Hey,
> So I will get right to the problem I have.
> I have two different Layers with the same content from different times. Now
> I want to know which points changed their location and which have been
> added
> or deleted so I just wanted to find the points which do not overlay by
> using
> Vector -> Geoprocessing Tools -> Difference
> (I wasnt sure if the one I was looking for was Symetrical Differnce so I
> tried both)
> I then realzied that not a single point was overlaying due to the fact that
> the points that should have the same location were all seperated by about 3
> meters.
>
> Pictures: In the first picture you see a red point. Out of these kind of
> points I want to make a new layer. The second picture is a zoomed in
> version
> of the area highlighted in the first one.
>
> <http://osgeo-org.1560.x6.nabble.com/file/n5162929/Pic1.png>
> <http://osgeo-org.1560.x6.nabble.com/file/n5162929/Pic2.png>
>
>
> Here is my question: How do I find the points which are not in distance of
> 3m to each other?
> I made some attempts with buffers and the difference tool again but non
> worked.
> Does anyone have an idea?
>
> Greetings
> Henrik
>
>
>
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