How to Define projection and enter the Geographic Transformation parameters from SGL-GEO to WGS84 in QGIS?
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I think this is brand new in QGIS 2.2 : sourcepole.ch/ntv2-transformations-with-qgis– DPSSpatial_BoycottingGISSEFeb 27, 2014 at 19:45
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1 Answer
Define the SGL-GEO projection by clicking the Settings > Custom CRS ,
Add a new CRS and add the parameters ,
Once you have your SGL-GEO projection defined, go to the Raster > Projections > Warp(reproject) and make the tranformation between SGL-GEO and WGS84.
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You would include a +towgs84 statement. The transformation values would be dx,dy,dz,rx,ry,rz,ds where the translations are in m, rotations in arc-seconds, and ds is in parts-per-million. Note: PROJ4/GDAL uses the Position Vector versionfor a 7-parameter datum transformation (which affects the rotation values).– mkennedyFeb 27, 2014 at 22:16
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I'm assuming SGL = Singapore Land Authority whose transformation parameter values are NOT publicly available and thus must be defined.– mkennedyFeb 27, 2014 at 23:05
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If you're talking about the parameters of the CRS to be defined I should mention that the parameter string I've put in the example is just for the show, it's up to Kwai Hai to write that string.– AkheloesFeb 27, 2014 at 23:12
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I think that's obvious. I just wanted to mention +towgs84 since it's not in the screenshot and it has a 'gotcha' if you're not familiar with its usage.– mkennedyFeb 28, 2014 at 0:51