[Proj] Lambert Conformal Conic

Gerald I. Evenden geraldi.evenden at gmail.com
Mon Apr 27 11:30:00 EST 2009


Snyder's formulary and presumable USGS Lambert CC computations *do not* use 
any series and thus not impacted by various hassles involving series degree 
or constants.  The only "constants" employed by various proj system and GCTP 
are simply those of the ellipsoid, defining parallels (or central parallel 
and scale factor).

If you are simply using Lambert Conformal Conic with no French or other 
annotation I would use any form of *proj* (+proj=lcc) or GCTP.  No series in 
these systems.

On Monday 27 April 2009 12:11:09 pm Irwin Scollar wrote:
> It's important to learn that some of the constants for Lambert
> Conformal Conic are not correct in various sources, but the intent of
> my posting was to ask those better versed in numerical matters on
> this list than I am, which of the methods for which I gave references
> give the most accurate results in those cases where I have no
> "official" formulae like I do in the case of France, but where I do
> have official values for the parallels of latitude, false Eastings
> and Northings and the ellipse.
>
> For France, in order to get the same results within the limits of
> floating point accuracy, I must use the maths supplied by the IGN.
> However, for places where I've not found such official formulae,
> perhaps one of the other formulae in the references I cited  have the
> lowest average error out at the projection limits.
>
> Irwin Scollar
>
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