[Qgis-user] Recognize and apply custom CRS automatically

[Rahkonen Jukka (MML)]

Hi,

I have loads of historical maps which are georeferenced by using ground control points in a few different custom coordinate reference systems. I have saved each CRS into QGIS as custom projections. Everything works otherwise OK but each time when I open the map I must select the CRS of the new layer manually even the source data (GeoTIFFs and GDAL VRT files) contains the same CRS information. Is it somehow possible to make QGIS to recognize that the CRS of the map is one of the custom projections and apply that automatically? I have access to source data and I can edit the WKT of the CRS in all files if for example giving names to things that are currently "unknow" would help. One of the custom projection follows as an example, it is using the Bessel 1841 ellipsoid with 0 meridian at the observatory of Pulkovo.

GEOGCRS["unknown",
DATUM["Unknown based on Bessel 1841 ellipsoid",
ELLIPSOID["Bessel 1841",6377397.155,299.1528128,
LENGTHUNIT["metre",1,
ID["EPSG",9001]]]],
PRIMEM["unknown",30.32835833,
ANGLEUNIT["degree",0.0174532925199433,
ID["EPSG",9122]]],
CS[ellipsoidal,2],
AXIS["longitude",east,
ORDER[1],
ANGLEUNIT["degree",0.0174532925199433,
ID["EPSG",9122]]],
AXIS["latitude",north,
ORDER[2],
ANGLEUNIT["degree",0.0174532925199433,
ID["EPSG",9122]]]]

-Jukka Rahkonen-
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