I wonder if there is somewhere an explanation for the parameters that can be set when running the Algorithm "Join Attributes by Location" in QGIS 2.18.

I had a look here:

but there is no explanation. Any hints?

  • 1
    A more recent version of the docs for QGIS 2.14 has a bit more information.
    – Joseph
    Nov 11, 2016 at 11:16
  • 2
    Which of the parameters is not clear to you?
    – Joseph
    Nov 11, 2016 at 11:23
  • 2
    In the Version I am using (2.18) on windows you can select stuff like intersect, within, overlap, cross, ... Further there is a threshold to be set etc. I can check here pro.arcgis.com/en/pro-app/tool-reference/data-management/… …. But I wonder if there is something from QGIS since I am not sure if ESRI and QGIS use exactly the same terminology
    – four-eyes
    Nov 11, 2016 at 12:20

3 Answers 3


Join Attributes by Location concatenates the following set of methods to compare geometries:

  • intersects if the intersection of both geometries is not empty


  • contains if the second geometry is completely contained into the first one


  • disjoint if the intersection of both geometries is the empty set


  • equals if they are spatially identical


  • touches if the only points in common between both geometries lie in the union of their boundaries


  • overlaps if the intersection of both geometries results in a value of the same dimension of both geometries and is different from both the first and the second geometry


  • within if the first geometry is completely contained into the second one


  • crosses if the intersection of both geometries results in a value whose dimension is less than the maximum dimension of both geometries and the intersection value includes points interior to both geometries, and the intersection value is not equal to either the first or the second geometry



  • Does the last exemple for "touches" is right ? it include several points is that allowed for touches in the case of line and polygon ?
    – J.R
    May 11 at 11:47

Don't think the QGIS docs has something as detailed as what is shown in the link in your comment (here is the link for English speakers). I would assume the terminology would be pretty much similar if not the same.

However, the tool uses the QgsGeometry Class which for each geometric predicate has the following basic description:

  • intersects - Test for intersection with a geometry (uses GEOS)
  • contains - Test for if geometry is contained in another (uses GEOS)
  • disjoint - Test for if geometry is disjoint of another (uses GEOS)
  • equals - Test for if geometry equals another (uses GEOS)
  • touches - Test for if geometry touch another (uses GEOS)
  • overlaps - Test for if geometry overlaps another (uses GEOS)
  • within - Test for if geometry is within another (uses GEOS)
  • crosses - Test for if geometry crosses another (uses GEOS)

To elaborate on the answers given above, the geometric predicates of QGIS (via GEOS) utilise the spatial predicate definitions of DE-9IM. The following link provides the detailed explanation of each of the common predicates: https://en.wikipedia.org/wiki/DE-9IM#Spatial_predicates


I found this a very easy to understand (with a nice image) the predicates:


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.