<HTML dir=ltr><HEAD><TITLE>[Proj] grid based transformation</TITLE>
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<DIV dir=ltr><FONT face="Times New Roman" color=#000000 size=2>Francesco,</FONT></DIV>
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<DIV dir=ltr><FONT size=2>The code is easy to find; for both Mincurve for the NADCON algorithm (from <A href="http://www.ngs.noaa.gov">www.ngs.noaa.gov</A>), as well as the NTv2 method for the Canadian/Australian nations and elsewhere. The NTv2 method of variable grid spacing was discussed on this forum in the past several weeks along with links to all of the source code. The major problem, though, is where are you going to find the data? These techniques depend on data, and for a regional or national datum transformation based on a grid system ... you need ALL the control point coordinates on BOTH datums. That's a pretty tall order for many countries. Professor Charles Merry did it for the Union of South Africa some years ago when they upgraded to the Hartbeeshoek System.</FONT></DIV>
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<DIV dir=ltr><FONT size=2>You have access to everything in the files of IGM - Firenze?</FONT></DIV>
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<DIV dir=ltr><FONT size=2>Wow!</FONT></DIV>
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<DIV><FONT size=2>Clifford J. Mugnier, C.P., C.M.S.<BR>LSU Student ASCE Chapter Faculty Advisor<BR>and<BR>Past National Director (2006-2008),<BR>Photogrammetric Applications Division<BR>American Society for Photogrammetry and Remote Sensing <BR>and <BR>Chief of Geodesy,<BR>CENTER FOR GEOINFORMATICS <BR>Department of Civil Engineering <BR>Patrick F. Taylor Hall 3223A<BR>LOUISIANA STATE UNIVERSITY <BR>Baton Rouge, LA 70803<BR>Voice and Facsimile: (225) 578-8536 [Academic] <BR>Voice and Facsimile: (225) 578-4474 [Research] <BR>Honorary Life Member of the <BR>Louisiana Society of Professional Surveyors <BR>Member Emeritus of the ASPRS <BR>Member of the Americas Petroleum Survey Group<BR>======================================================<BR></FONT><A href="https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.lsu.edu/exchweb/bin/redir.asp?URL=https://email.ls" target=_blank><FONT face="Times New Roman, Times"><FONT size=2>http://www.asprs.org/resources/GRIDS/</FONT></A></FONT><BR><FONT face="Times New Roman, Times" size=2>======================================================</FONT></DIV></DIV></DIV>
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<FONT face=Tahoma size=2><B>From:</B> proj-bounces@lists.maptools.org on behalf of francesco<BR><B>Sent:</B> Thu 31-Jul-08 14:12<BR><B>To:</B> Proj@lists.maptools.org<BR><B>Subject:</B> [Proj] grid based transformation <BR></FONT><BR></DIV>
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<P><FONT size=2>Hello everyone,<BR><BR>I wanted to know if grid based transformations can be somehow implemented for other reference systems other than NAD ... I am up to programming if someone gives me hints on where to look for the code that uses the grid parameters.<BR><BR>Cheers,<BR><BR>Francesco Pirotti<BR>Dip.to TESAF<BR>Università di Padova<BR>tel. 049-8272710 349 5539261<BR><BR><BR>_______________________________________________<BR>Proj mailing list<BR>Proj@lists.maptools.org<BR><A href="http://lists.maptools.org/mailman/listinfo/proj">http://lists.maptools.org/mailman/listinfo/proj</A><BR></FONT></P></DIV></BODY></HTML>