[OSRS-PROJ] Lambert Conformal Conic 1SP

Gerald I. Evenden gerald.evenden at verizon.net
Sun Feb 9 21:22:07 EST 2003

On Sun, 2003-02-09 at 16:52, Clifford J Mugnier wrote:
> The fully conformal Lambert has its developed surface in either a tangent
> case or a secant case.  Period.  If we consider a tangent case, then the
> scale factor at the latitude of origin is equal to unity.  If we consider a
> secant case, then the scale factor at the latitude of origin is less than
> unity.  Period.

The inference, if not outright assertation, is that scale is not
specified for the tangential form of LLC.  That seems peculiar
as I have specs for Costa Rica Norte y Sud, Cuba Norte y Sud as
well as several other central American countries that use LLC
tangential with k_0 specified.  k_0 with tangential is merely an
alternative to secant usage and totally up to local cartographers in

Also, latitude of origin for the secant form is arbitrary and does
not necessarily have to be at the point of unity scale factor.
Unity scale factor occurs at the two standard parallels for
secant LLC.

As an aside, changing the formulas for secant to tangent only
requires the replacement of one equation.


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