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I used the georeferencer with QGIS 3.2 and I imported an image with the following EXIFS

ExifTool Version Number         : 11.09
File Name                       : 
Directory                       : 
File Size                       : 660 MB
File Modification Date/Time     : 2018:08:16 09:57:14+02:00
File Access Date/Time           : 2018:08:16 09:56:50+02:00
File Creation Date/Time         : 2018:08:13 15:02:00+02:00
File Permissions                : rw-rw-rw-
File Type                       : TIFF
File Type Extension             : tif
MIME Type                       : image/tiff
Exif Byte Order                 : Little-endian (Intel, II)
Image Width                     : 8213
Image Height                    : 8426
Bits Per Sample                 : 16 16 16 16 16
Compression                     : Uncompressed
Photometric Interpretation      : BlackIsZero
Strip Offsets                   : (Binary data 82908 bytes, use -b option to extract)
Samples Per Pixel               : 5
Rows Per Strip                  : 1
Strip Byte Counts               : (Binary data 50555 bytes, use -b option to extract)
Planar Configuration            : Chunky
Extra Samples                   : Unknown (0 0 0 0)
Sample Format                   : Unsigned; Unsigned; Unsigned; Unsigned; 1
Pixel Scale                     : 0.0995571757896536 0.0995571757896668 0
Model Tie Point                 : 0 0 0 671039.99110524 6670610.39921535 0
GDAL No Data                    : 0
Geo Tiff Version                : 1.1.0
GT Model Type                   : Projected
GT Raster Type                  : Pixel Is Area
GT Citation                     : RGF93 / Lambert-93
Geog Citation                   : RGF93
Geog Angular Units              : Angular Degree
Geog To WGS84                   : 0 0 0
Projected CS Type               : Unknown (2154)
Proj Linear Units               : Linear Meter
Image Size                      : 8213x8426
Megapixels                      : 69.2
-- press RETURN --

The CRS is RGF93 as expected, the I georeferenced it using QGIS 3.2 raster georeferencer and specifying RGF93 as output CRS and I get those EXIFS on the output image

ExifTool Version Number         : 11.09
File Name                       : 
Directory                       : 
File Size                       : 660 MB
File Modification Date/Time     : 2018:08:16 10:29:24+02:00
File Access Date/Time           : 2018:08:16 10:29:16+02:00
File Creation Date/Time         : 2018:08:16 10:29:16+02:00
File Permissions                : rw-rw-rw-
File Type                       : TIFF
File Type Extension             : tif
MIME Type                       : image/tiff
Exif Byte Order                 : Little-endian (Intel, II)
Image Width                     : 8195
Image Height                    : 8443
Bits Per Sample                 : 16 16 16 16 16
Compression                     : Uncompressed
Photometric Interpretation      : BlackIsZero
Strip Offsets                   : (Binary data 83074 bytes, use -b option to extract)
Samples Per Pixel               : 5
Rows Per Strip                  : 1
Strip Byte Counts               : (Binary data 50657 bytes, use -b option to extract)
Planar Configuration            : Chunky
Extra Samples                   : Unknown (0 0 0 0)
Sample Format                   : Unsigned; Unsigned; Unsigned; Unsigned; 1
Pixel Scale                     : 0.100054163708167 0.100054163708167 0
Model Tie Point                 : 0 0 0 671039.531463217 6670614.55702631 0
GDAL No Data                    : 0
Geo Tiff Version                : 1.1.0
GT Model Type                   : Projected
GT Raster Type                  : Pixel Is Area
GT Citation                     : unnamed
Geographic Type                 : User Defined
Geog Citation                   : GCS Name = GRS 1980(IUGG, 1980)|Datum = unknown|Ellipsoid = GRS80|Primem = Greenwich| Geog Geodetic Datum             : User Defined
Geog Angular Units              : Angular Degree
Geog Ellipsoid                  : User Defined
Geog Semi Major Axis            : 6378137
Geog Inv Flattening             : 298.257222101
Geog Prime Meridian Long        : 0
Geog To WGS84                   : 0 0 0
Projected CS Type               : User Defined
Projection                      : User Defined
Proj Coord Trans                : Lambert Conf Conic 2SP
Proj Linear Units               : Linear Meter
Proj Std Parallel 1             : 49
Proj Std Parallel 2             : 44
Proj False Origin Long          : 3
Proj False Origin Lat           : 46.5
Proj False Origin Easting       : 700000
Proj False Origin Northing      : 6600000
Image Size                      : 8195x8443
Megapixels                      : 69.2
-- press RETURN --

They are not the same at all and I don't get any mention of the EPSG:2154 CRS, why is that ? I already had the problem with QGIS 2.18. Is there a way to prevent this ?

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  • Tags you are referring are not EXIF tags but GeoTIFF tags sno.phy.queensu.ca/~phil/exiftool/TagNames/GeoTiff.html. The source image is using citation tags but if you look at the other parameters epsg.io/2154 your georeferenced image is using the correct parameters for that CRS. Thus the result is correct even there is no reference to the shortcut code EPSG:2154 or the name of the CRS. Everything should works just fine. What is the exact problem that you have had?
    – user30184
    Aug 16 '18 at 9:08
  • Problem is that a software then tries to read the exifs to get the CRS but cannot when the image has been georeferenced, QGIS on the contrary reads it well. The fact is that QGIS didn't changed the GeoTiff tags this way prior to version 2.9 (they are not modified whith georeferencer on version 2.8)
    – Clement
    Aug 16 '18 at 9:13
  • Try to clean the image by making a copy gdal_translate -of GTiff -a_srs EPSG:2154 input.tif output.tif. If it works I can suggest better way to do it with gdal_edit.
    – user30184
    Aug 16 '18 at 9:20
  • Well if you then save the same image with CRS 2154 the image is cleaned and the EXIF look like the first set The question is not how to correct those EXIF, it's to know why the georeferencer is behaving like this in most recent versions and why did it changed.
    – Clement
    Aug 16 '18 at 9:41
  • Don't call the tags as EXIF because they are not. I would ask your second question from QGIS mailing list. Browsing the change log of source code is another option. Bug report for the third party software is also recommended, it should not interpret the citation tags only.
    – user30184
    Aug 16 '18 at 9:49

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