4

I am trying to spatially join point layers of some 12,000 women interviewed in Egypt to Egypt's polygon layers (administrative districts boundaries) using QGIS 2.2 and need some advice. I am a QGIS self-learner.

I have read many QGIS manuals, but I cannot complete the spatial join successfully. I have added the vector layers of both Egypt's women's GPS points and Egypt's polygons (district boundaries). I used the UTF-8 encoding. Whenever I attempt to join attributes by location, the following message appears "Input layers have non-matching CRS". However, when I check the CRS of both layers, I found it the same (EPSG:4326 - WGS 84).

Improve this question
7
  • How have you checked the CRSs? Are you able to view both layers properly overlayed?
    – MickyInTheSky
    May 29, 2014 at 7:56
  • I have checked the CRSs by right clicking each layer, choosing the Properties tab, then choosing the General tab. I cannot view both layers properly overlayed. However, I can see each layer properly when I separately open it.
    – Amira El-Shal
    May 29, 2014 at 8:07
  • Tho QGIS is trying to use EPSG:4326 in both layers, they are actually not the same. You should check with your data origin what is the real CRS of the files. For Spatial join work properly both layers must overlap.
    – Alexandre Neto
    May 29, 2014 at 8:41
  • which Spatial Join tool are you using in QGIS?
    – HDunn
    May 29, 2014 at 8:44
  • I click the Vector tab, then click the Data Management Tools tab, then select "Join attributes by location".
    – Amira El-Shal
    May 29, 2014 at 8:59

1 Answer 1

Reset to default
3

After being reasonably certain of the correctness of the CRSs (check also the on-fly projection option) you could use the spatial query plugin

Improve this answer
4
  • I know the CRS of one shapefile but the coordinate system of the second layer is unknown, and there is no *.prj file. How I can identify its CRS?
    – Amira El-Shal
    May 29, 2014 at 10:53
  • 1
    You can define it with the following Qgis command: Vector--> Data Management Tools--> Define Current projection
    – MickyInTheSky
    May 29, 2014 at 10:57
  • I could not save the women's locations to a new layer, using the CRS of the administrative districts boundaries, because I do not know the CRS of the boundaries. No *.prj file is there and I do not have access to the supplier in the meantime. I just know the CRS of the women's locations. Therefore, I tried to save the boundaries to the CRS of the interview locations then do the spatial join, but it did not work either. What is your advice?
    – Amira El-Shal
    May 29, 2014 at 11:42
  • it's very hard to do a spatial join with a layer with unknown CRS. I would recommend you open a new post
    – MickyInTheSky
    May 29, 2014 at 12:00

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.