HPGN Datum? (fwd)

[Dean C. Mikkelsen]

Hi Didrik,

Try setting the pm (Prime Meridian) back to Paris. This projection was
originally defined using Paris as the PM.

Keep all the other values the same as you have....I'm checking my
numbers on the values again. This projection is defined with Clarke 1880
(IGN), where Clarke's values for a and b using his 1865 ratio of
39.370432 inches per metre to convert axes to metres. I had a typo with
CLRK66. Your axes definitions are correct.

I will check what version of PROJ.4 I am using.

Dean



-----Original Message-----
From: Didrik Pinte [mailto:dpinte at itae.be] 
Sent: April 26, 2005 1:02 AM
To: Dean C. Mikkelsen
Cc: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: RE: [UMN_MAPSERVER-USERS] HPGN Datum? (fwd)

Le mardi 26 avril 2005 à 00:57 -0700, Dean C. Mikkelsen a écrit :
> Hi Didrik,
> 
> In the epsg file, for NTF II, I get the following:
> 
> # NTF (Paris) / France II
> # Unable to translate coordinate system into PROJ.4 format.
> 
> I could not find your code 27572.
> 
> Let me suggest a work-around. It may not be popular, but it should
solve
> the problem for you. 
> 
> In the epsg file, add the following line of code:
> 
> <27572> +proj=lcc +lat_0=18.000000000 +lon_0=-77.000000000
+k=0.99987742
> +x_0=600000  +y_0=2200000 +ellps=clrk66  +towgs84=-168,-60,320,0,0,0,0
> +units=m  no_defs <>
> 
> This should resolve the problem.
> 
> Let me know what happens.
> 
> Kind regards,
> Dean

What version of proj do you use ?

Here is the output of my /usr/share/proj/epsg file :

# NTF (Paris) / Lambert zone II (corrected by DP : +pm=paris is wrong)
<27572> +proj=lcc +lat_1=46.7999999999999997 +lat_0=46.7999999999999997
+lon_0=2.3372291666666669 +k_0=0.99987742 +x_0=600000 +y_0=2200000
+a=6378249.2000000002 +b=6356514.9999041939
+towgs84=-168,-60,320,0,0,0,0 +units=m +no_defs  <>


What is the difference with the parameters you propose ?

Didrik