[Proj] +towgs84 approximation error

Noel Zinn (cc) ndzinn at comcast.net
Sat Mar 25 11:09:24 EST 2017

Jochem, yes, the original challenge was to demonstrate that the 7 parameters 
of a Helmert transformation derived in a small area are squandered due to 
the high correlations with the rotations (regardless of how the rotations 
are approximated, or not) and that 7 coefficients could be "spent" better in 
2 or 3 regression equations depending upon the dimensionality of the 
experiment, but we'd have to decide how to handle the geoid, or not.  Is 
this your understanding?  -Noel

Noel Zinn, Principal, Hydrometronics LLC
+1-832-539-1472 (office), +1-281-221-0051 (cell)
noel.zinn at hydrometronics.com (email)
http://www.hydrometronics.com (website)

-----Original Message----- 
From: Jochem
Sent: Saturday, March 25, 2017 10:02 AM
To: proj at lists.maptools.org
Subject: Re: [Proj] +towgs84 approximation error


Noel, I read your email again, and I think I misunderstood your suggestion
for the "challenge". It is not about the strict/approximate formulas, but
only about correlated/uncorrelated parameters, right? Then we can do it
exactly as you suggested. I still see it as an experiment. I am really
interested in the outcome, not in winning.

Kind regards, Jochem

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