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Indian toposheets (pre-2000 series) of 1:50k scale are in Polyconic projection, with Everest 1956 spheroid and India-nepal datum. How do I create a custom CRS in QGIS to represent this, so that I can then reproject the topo corners (tic points) to UTM-WGS 84 and then geo-reference the toposheet.

marked as duplicate by AndreJ qgis Oct 5 '16 at 6:05

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    Found the answer: search for 37203 in the filter when specifying the output CRS in the Georeference add-on. EPSG=37203 is nothing but Everest 1956 with India-Nepal datum. – Sharad May 6 '14 at 14:49
  • technically 37203 is ESRI, not EPSG. – mkennedy May 6 '14 at 16:36
  • UPDATE: Actually using 37203 does not solve the problem. Although choosing this in ERDAS might work, the proj.4 definition of 37203 is incomplete, because it does not contain the delta-x, delta-y, delta-z shift information. So one still ends up with a 200-300m error if one uses 37203. Defining a custom CRS as: +proj=longlat +a=6377301.243 +b=6356100.2284 +towgs84=295.00,736.00,257.00,0,0,0,0 +no_defs solves the problem. – Sharad Jun 9 '14 at 7:55
  • @Sharad. UPDATE: Actually using 37203 does not solve the problem. Although choosing this in ERDAS might work, the proj.4 definition of 37203 is incomplete, because it does not contain the delta-x, delta-y, delta-z shift information. So one still ends up with a 200-300m error if one uses 37203. Defining a custom CRS as: +proj=longlat +a=6377301.243 +b=6356100.2284 +towgs84=295.00,736.00,257.00,0,0,0,0 +no_defs solves the problem. – Sharad Jun 9 '14 at 7:55 Thank you very much, New Custom CRS solved the problem by 95%. Further more Geo referencing is needed to achieve more accuracy. Than – manishankar madishetty Oct 4 '16 at 12:24
  • Please don't add "thank you" as an answer. Once you have sufficient reputation, you will be able to vote up questions and answers that you found helpful. - From Review – ArMoraer Oct 4 '16 at 12:59