J.M. Roques writes:
Has someone already used Grass with the lambert (1,2 or 3) projection used in France/ Belgium ?
If yes can this someone (i will be forever endebted to such a nice person) send me a copy of the file WIND or WIND_DEFAULT of its LOCATION/MAPSET directory?
or at least, some hints on the procedure for creating the relevant WIND file
Yes, I have used the Lambert-III projection in GRASS. It took me quite a
while to figure out what the necessary parameters were. Basically, you
should create a PROJ_INFO file under $LOCATION, looking like this:
name: Lambert Conformal Conic
ellps: clrk80
proj: lcc
lon_0: 2.337800
lat_0: 44.10000
lat_1: 43.2
lat_2: 45.0
x_0: 600000
y_0: 3200000
As you will notice, lon_0 is the meridian of Paris. lat_0, lat_1 and
lat_2 are the parallels needed, and x_0 and y_0 the false easting and
northing.
I don't know what GRASS actually *does* with this information, but it is
absolutely essential if you want to convert data from say Lambert-II to
Lambert-III using proj.
for Lambert-II you need
lat_0: 46.8
lat_1: 45.36
lat_2: 48.24
and for Lambert-I you need
lat_0: 49.5
lat_1: 48.06
lat_2: 51.03
For Belgium I am not absolutely sure (I never checked it), but I think you
need
ellps: intl
lon_0: 4.35693972
lat_0: 50.5
lat_1: 49.833333
lat_2: 51.166667
x_0: 150000
y_0: 5400000
I hope this is sufficient information for you; mail me if you need
additional clarification.
Philip Verhagen
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