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I am georectifying scanned versions of Survey of India maps, which are in Everest spheroid and india_nepal datum. The exact parameters are:

+proj=longlat +a=6377301.243 +b=6356100.2284 +towgs84=295,736,257,0,0,0,0 +no_defs

I encountered two issues, one minor and one more significant.

  1. I define a custom CRS using these parameters. Give it a name "Everest_India_Nepal_custom". Save the CRS. Use it when georectifying a toposheet. Save the toposheet with this new CRS. (gtif file). But when I reopen that gtif file in a new project, its properties show the CRS parameters, but do not show the custom name I had given for ease of recognition. When saving it said :User 100001: Everest... But when opeining it says "User 100009: *Generated CRS....". So it does not remember the name I gave. Although the name still shows up in CRS options.

  2. bigger problem: if I try to validate this custom CRS by using the "calculate" button at the bottom of the custom CRS window, i get rubbish. But the CRS definition is correct, and it works--when my rectified topo is placed on google earth, it sits perfectly (error <10m).

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  • Should probably be bug reports.
    – underdark
    Jun 9 '14 at 9:06
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For the first issue, add a +wktext at the end of your proj string. This will preserve your custom CRS including the name.

Otherwise QGIS tries to find a suitable CRS in the EPSG database from the WKT definition in the file, and create a new custom CRS if nothing matches.

For the second one, I can not help you much. I don't use that calculator.

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  • Great! I have had this problem for some time. Using +wktext did the trick. Where can I find information about this parameter? I searched in the proj.4 parameters list and didn`t find anyting
    – Ernesto561
    Aug 27 '17 at 20:15
  • Just one thing, it doesn't work in all cases. I am rasterizing some lines using the GDAL Rasterize tool and the CRS of the result is a generated CRS. The CRS for the lines layer and the project is the same custom CRS.
    – Ernesto561
    Aug 28 '17 at 4:06
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    @Ernesto561 see osgeo-org.1560.x6.nabble.com/… . For your remaining problem, it might be better to open a new question, adding more details about the CRS you use, and the output you get. You may link here.
    – AndreJ
    Aug 28 '17 at 5:17
  • I asked a new question here: gis.stackexchange.com/questions/253475/…
    – Ernesto561
    Aug 28 '17 at 15:53

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