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I am trying to define a custom CRS in QGIS 3.4 to work on some data in Central Asia. I want to use the Albers Equal Area Conic but change the parameters so that the transformation works best for my study area.

I first tried to go via "Settings" --> "Custom CRS". I defined the name and the +projstring as +proj=aea +lat_1=21 +lat_2=49 +lat_0=37 +lon_0=87 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs. But when I click "Ok", nothing happens.

I don't get an error message or any feedback, there's just no response. (I tried QGIS 3.10 as well, but the same problem occurred.) This looks like a bug to me or is there something I missed?

If this cannot be reproduced, I could also go the Python way, but I'm not so familiar with that. I've read through some documentation and found the following pieces of code but I'm not sure if they are in the right order or if something is missing:

my_crs = QgsCoordinateReferenceSystem()
my_crs.createFromProj4("+proj=aea +lat_1=21 +lat_2=49 +lat_0=37 +lon_0=87 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs")
my_crs.saveAsUserCrs("Albers_Central_Asia")
  • works for me in QGIS 3.4.6 – nmtoken Nov 12 at 8:11
  • Could you give me the detailed workflow for this, please? You first click the green "plus", then add name and proj-string and click "ok"? Because that way it does not work for me... – Florian Mlehliv Nov 12 at 8:26
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  1. add new profile. : Settings -> User Profiles -> New profile

  2. use new profile and try creating custom projections.

  • Wow, thanks a lot! I hadn't even thought about that! Sometimes it can be so simple. – Florian Mlehliv Nov 21 at 7:46
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Settings > Custom Projections > Green Plus

Add name and parameters > OK

Custom Projection in QGIS 3.4.6

Creates a custom projection (in my case called USER:100030)

custom projection USER:100030

  • Thanks for the details! This is exactly how I've been doing it. So it seems to be a bug... Do you perchance also know how to write this in Python? – Florian Mlehliv Nov 12 at 8:41
  • I installed QGIS under Linux and was able to create the CRS using your workflow. I still don't know what the problem was, though. – Florian Mlehliv Nov 12 at 10:17
  • My example is Linux based too. I've tried since on Windows with 3.6.3 version and it works just the same – nmtoken Nov 13 at 14:03
  • Strange... However, now I'm stuck on trying to export the custom crs to Windows. I've tried to save a raster with this crs and open it on Windows, but there it appears to have no projection. Does this work for you? Or is there another way to export a projection? – Florian Mlehliv Nov 13 at 14:09
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    You can do a direct edit of the .../share/proj/other.extra file to add custom projections – nmtoken Nov 13 at 14:35

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