[PROJ] Help in setting proj parameters for an old map

[Pierre Abbat]

On Sunday, 2 February 2020 18.14.49 EST aborruso wrote:
> Hi,
> I have discovered these fantastic public domains maps
> https://legacy.lib.utexas.edu/maps/ams/italy_50k/
> 
> If you open a map you can read [1] that the projection is a Lambert Conic
> Conformal and you have also the lat_0, lon_0, the Spheroid, the x_0 and the
> y_0 of the map.
> 
> For a [2] LCC projection the lat_1 parameter (first standard parallel) is
> required and it's possible to set also a second standard parallel (lat_2).
> 
> First question:
> 
> - what's the right lat_1 for this map?
> - is it better to set also the lat_2? And if it's yes, what's the right one?

I pulled up the map of Castelnuovo di Garfagnana. On the right, about a 
quarter of the way down, are the data:
Origin: 45°54'N 14°E
False coordinates of origin: 800000,601000
Scale factor: 0.998992911
With Lambert conformal conic, two parallels and a scale of 1 are equivalent to 
one parallel somewhere between them and a scale less than 1. Since there is a 
scale, which is slightly less than 1, I think that there is one parallel, 
which is 45°54'N.

I tried searching for "zona nord italia lambert" and the like, but didn't find 
it. Hopefully an Italian surveyor will pipe up soon.

Pierre
-- 
When a barnacle settles down, its brain disintegrates.
Já não percebe nada, já não percebe nada.