[Proj] grid based transformation

[Clifford J Mugnier]

Francesco,
 
The code is easy to find; for both Mincurve for the NADCON algorithm (from www.ngs.noaa.gov), 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.
 
You have access to everything in the files of IGM - Firenze?
 
Wow!
 
Clifford J. Mugnier, C.P., C.M.S.
LSU Student ASCE Chapter Faculty Advisor
and
Past National Director (2006-2008),
Photogrammetric Applications Division
American Society for Photogrammetry and Remote Sensing 
and 
Chief of Geodesy,
CENTER FOR GEOINFORMATICS 
Department of Civil Engineering 
Patrick F. Taylor Hall 3223A
LOUISIANA STATE UNIVERSITY 
Baton Rouge, LA  70803
Voice and Facsimile:  (225) 578-8536 [Academic] 
Voice and Facsimile:  (225) 578-4474 [Research] 
Honorary Life Member of the 
Louisiana Society of Professional Surveyors 
Member Emeritus of the ASPRS 
Member of the Americas Petroleum Survey Group
======================================================
http://www.asprs.org/resources/GRIDS/
======================================================

________________________________

From: proj-bounces at lists.maptools.org on behalf of francesco
Sent: Thu 31-Jul-08 14:12
To: Proj at lists.maptools.org
Subject: [Proj] grid based transformation 



Hello everyone,

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.

Cheers,

Francesco Pirotti
Dip.to TESAF
Università di Padova
tel. 049-8272710 349 5539261


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