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I am trying to georeference rasters from Vietnam in QGIS which have printed coordinates in VN2000.

I am using the following custom CRS settings for the province.

+proj=tmerc +lat_0=0 +lon_0=108.25 +k=0.9999 +x_0=0 +y_0=500000 +ellps=WGS84 +towgs84=-191.90441429,-39.30318279,-111.45032835,0.00928836,-0.01975479,0.00427372,0.252906278 +units=m +no_defs

The rasters appear in the incorrect location when georeferenced.

This has been solved. The definition of the false easting above is incorrect. The definition should read +x_0=500000 +y_0=0

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  • epsg.io says it's epsg:3405 and it would be a projected crs – Andreas Müller Sep 4 '18 at 18:31
  • Thanks Andreas. I'm not a GIS expert but the translation and rotation parameters on the epsg.io site do not match the official Vietnamese government directive. See this site (in Vietnamese): vanban.chinhphu.vn/portal/page/portal/chinhphu/… Also, there are 63 provinces, each with guidance on central meridian values. See this link: tnmtcaobang.gov.vn/uploads/laws/files/tt973.pdf I have not managed to georeference a raster using this information and I am wondering if anyone can shed light on this. – CMurray Sep 4 '18 at 20:34
  • We need more details about how did you do the georeferencing. – user30184 Sep 4 '18 at 21:30
  • I created a CRS in QGIS using Proj4 and the meridian, translation, rotation and scaling data from the above government publications. I then georeferenced my image using the new CRS, however, this incorrectly places the image. I am not certain that the transformation equations used by QGIS are compatible with the above government data. One publication in Vietnamese seems to suggest the signs in the rotation matrix in the transformation equation has opposite signs to the QGIS implementation. I have inverted the signs in the Proj4 CRS rotation definition but this does not fix the issue. – CMurray Sep 5 '18 at 15:52
  • Has anyone successfully implemented this CRS? My Proj4 definition is outlined below: +proj=tmerc +lat_0=0 +lon_0=108.25 +k=0.9999 +x_0=0 +y_0=500000 +ellps=WGS84 +towgs84=-191.90441429,-39.30318279,-111.45032835,-0.00928836,0.01975479,-0.00427372,0.252906278 +units=m +no_defs – CMurray Sep 5 '18 at 15:53

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