[OSRS-PROJ] Projection of historic maps WW II - Italy
neteler at itc.it
Fri Jun 6 10:50:10 EDT 2003
Dear List members,
I would appreciate assistance for the following problem:
Currently I try to define a map projection for a map from 1945,
Northern Italy. The map was made by the US Army Engr. Top. Co.
in Lambert Conic Orthomorphic. It is based on a map from 1931
done by Istituto Geografico Militare and was enhanced by aerial
photo surveys in 1944.
Given on the (scanned) paper map is:
- prime meridian Monte Mario (old!): 12d27'7.1E (in PROJ: 12d27'8.4E)
- "spheroid": Bessel
- Origin: 14E, 45:54N
- False Easing: 800000 meters
- False Northing: 601000 meters
- The map provides the LCC grid and coordinates as well as
Lat/Long corners in reference to Monte Mario 12d27'7.1E (given as
"West from Rome" and Equator.
This projection I am defining in GRASS GIS which is based on the latest
PROJ from CVS. The parameters in GRASS style are (PROJ_INFO file)
name: Lambert Conformal Conic
The towgs84 parameter will be certainly wrong.
Using these values I achieve as accuracy a shift 70m eastwards and
170m northwards. For verification GIS data in Gauss-Boaga projection
from different providers were using (vector street map and orthophotos).
These maps I have reprojected into above LCC projection and compared to
the scanned and geocoded map from 1945:
For illustration there is a screenshot of a zoomed area:
To improve the accuracy, I am seeking assistance to find out:
- which Bessel definition should be used (is above right for these 1945 maps?)
- which datum was used in 1945 (Italian or US or ...)
- how to define a different prime meridian: 12d27'7.1E instead of 12d27'8.4E
(can I define a custom prime meridian?)
Thanks in advance
PROJ.4 Discussion List
See http://www.remotesensing.org/proj for subscription, unsubscription
and other information.
More information about the Proj