Feature request #2332

please add +towgs parameters

Added by Paolo Cavallini almost 10 years ago. Updated over 6 years ago.

Status:Closed
Priority:Low
Assignee:-
Category:Projection Support
Pull Request or Patch supplied:No Resolution:
Easy fix?:No Copied to github as #:12392

Description

Standard EPSG code for Italian projections (3003 and 3004) do not include datum; as a result, reprojection is always wrong by about 100 m. Can we add 4 more projection definition to our SRS database?
It should only be added the +towgs84 parameter so that we'll have:

3003 corrected, mainland: same as 3003, with
+towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68

3004 corrected, mainland: same as 3004, with
+towgs84=-104.1,-49.1,-9.9,0.971,-2.917,0.714,-11.68

3003 corrected, Sardinia: same as 3003, with
+towgs84=-168.6,-34.0,38.6,-0.374,-0.679,-1.379,-9.48

3004 corrected, Sicily: same as 3004, with
+towgs84=-50.2,-50.4,84.8,-0.690,-2.012,0.459,-28.08

In GRASS this has been solved by a similar approach:
http://freegis.org/cgi-bin/viewcvs.cgi/*checkout*/grass/src/libes/gis/datumtransform.table?rev=HEAD&content-type=text/plain
I think this can be done now, as it does not impact anything else, and it would make life a lot easier for Italian users (remember, the second largest QGIS user community!).
Details in http://www.crs-geo.eu/

New custom codes should be in the 32,768-100,000 range; 39031, 39032, 39041, 39042 should be ok.

History

#1 Updated by Giovanni Manghi almost 10 years ago

Italy is not the only case, there are obviously others (in my case I'm referring to Portugal).

My suggestion is to implement this #1908 and then just maintain the list of datum association (3 and 7 parameters transformation).

Ex:
http://trac.osgeo.org/grass/browser/grass/branches/releasebranch_6_4/lib/gis/datumtransform.table

http://trac.osgeo.org/grass/browser/grass/branches/releasebranch_6_4/lib/gis/datum.table

Missing/correct definitions for Portugal

  • [D73HG] HAYFORD-GAUSS DATUM 73

http://www.igeo.pt/produtos/Geodesia/Inf_tecnica/sistemas_referencia/Datum_73.htm

+proj=tmerc +lat_0=39.66666666666666 +lon_0=-8.131906111111112 +k=1 +x_0=180.598 +y_0=-86.98999999999999 +ellps=intl +towgs84=-239.749,88.181,30.488,0.263,0.082,1.211,2.229

  • [DLXHG] HAYFORD-GAUSS DATUM LISBOA (IGP)

http://www.igeo.pt/produtos/Geodesia/Inf_tecnica/sistemas_referencia/Datum_Lx.htm

+proj=tmerc +lat_0=39.66666666666666 +lon_0=-8.131906111111112 +k=1 +x_0=0 +y_0=0 +ellps=intl +towgs84=-288.885,-91.744,126.244,-1.691,0.410,-0.211,-4.598

  • [DLXHGMIL] HAYFORD-GAUSS DATUM LISBOA (Militar)

+proj=tmerc +lat_0=39.66666666666666 +lon_0=-8.131906111111112 +k=1 +x_0=200000 +y_0=300000 +ellps=intl +towgs84=-288.885,-91.744,126.244,-1.691,0.410,-0.211,-4.598

#2 Updated by Giovanni Manghi almost 10 years ago

making some addition, please wait before adding

#3 Updated by Giovanni Manghi almost 10 years ago

it seems there is a little confunsion about official towgs parameters for Portugal. I will try to gather the right infos in time for the dev meeting.

#4 Updated by Giovanni Manghi over 9 years ago

see also #1908

#5 Updated by Giovanni Manghi almost 8 years ago

  • Target version changed from Version 1.7.0 to Version 1.7.4

#6 Updated by Giovanni Manghi over 7 years ago

  • Target version changed from Version 1.7.4 to Version 2.0.0

#7 Updated by Pirmin Kalberer about 7 years ago

  • Target version changed from Version 2.0.0 to Future Release - Nice to have

#8 Updated by Giovanni Manghi over 6 years ago

  • Status changed from Open to Feedback
  • Assignee deleted (nobody -)
  • Pull Request or Patch supplied set to No

3003 and 3004 they now include those parameters, please leave feedback.

#9 Updated by Paolo Cavallini over 6 years ago

  • Status changed from Feedback to Closed

Also available in: Atom PDF