I am a very beginner with QGIS. I would like to know how to align two shapefiles in QGIS. The image below shows the mismatch:

enter image description here

  • Welcome to GISSE, the shps seemed to be aligned, but one is more simplified. What are the sources of this data? – artwork21 Feb 26 '16 at 12:48
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    are the shapefiles of same extent? – hfawad Feb 26 '16 at 12:48
  • Hi artwork21 and HFawad. Yes they are of same extent. And I had them on maps.data.ug – Landry Feb 27 '16 at 19:05

I'm no expert, But there could also be a projection problem. Do both files have the same projection?

If the files don't have the same projection GIS programs may try and project display them on the fly resulting in slight miss alignment of the files.

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  • Also, I know Qgis has some topology rules, and you could use those to go through the boundaries manually matching them. – Stefan Bosman Feb 27 '16 at 13:47
  • Thank you Stefan. Yes the two shape files have the same projection. However this still result in the slight miss alignment of the files. How can I use the topology rules? – Landry Feb 27 '16 at 19:07

The black outlined polygon shapefile extends into the ocean (presumably, could be lake though) whereas the purple polygon shapefile extends to the shoreline. The difference in boundary is common with administrative boundaries.

There are some areas in the north (assuming north is up) that the boundaries do not align which should be similar. This would be caused by the digitization of the shoreline. you can imagine that precision, accuracy, etc all play a role in how accurate a shapefile is created and can thus cause some small level of difference in the boundary match.

See the image below - where the peach coloured line is the administrative boundary and the blue line is the shoreline boundary respectively.

enter image description here.

If you require that they both have the same boundary line I would suggest completing a spatial join or copying the table features into the geometry.

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  • Dear MDHald, thank you for your comment. I perform the spatial join but the two shape files are still miss aligned. how do we copy the table features into the geometry? – Landry Feb 27 '16 at 19:34
  • @landry - I can add to the answer Monday - but for now - the basics are that you set up the tables to have the same schema by making the field names the same data type and field name. Then you select all your content from one shape file and copy. Then paste the content to the other shapefile. I will add pictures and such on Monday to show how to do it. – MDHald Feb 27 '16 at 23:11

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