Re: map projection in Ferret

[Ansley Manke <ansley.b.manke@xxxxxxxx>]

Hi Tony,
The mp_land and mp_fland scripts expect certain variables to be defined
by a call to an mp_projection script.  How about running one of the map
projection scripts, and then modifying the variables to not do any
projection?

  yes? use etopo60
  yes? set grid rose
  yes? go mp_mercator
 
  yes? show variables
   Created by DEFINE VARIABLE:
   >>> Definitions that replace any file variable of same name:
       MP_X = X
       MP_CENTRAL_MERIDIAN = (MP_X[I=@MAX] + MP_X[I=@MIN])/2
       MP_Y = Y
       MP_STANDARD_PARALLEL = (MP_Y[J=@MAX] + MP_Y[J=@MIN])/2
       PI = 3.14159265
       DEG2RAD = PI / 180.0
       MP_R = 1
       MP_LAMBDA0 = MP_CENTRAL_MERIDIAN * DEG2RAD
       MP_LAMBDA = MP_X * DEG2RAD
       MP_PHI = MP_Y * DEG2RAD
       X_PAGE = MP_R * (MP_LAMBDA-MP_LAMBDA0)
       Y_PAGE = MP_R *  LN(TAN(MP_PHI/2 + PI/4))
       MP_MASK = 1
 
    !! change y_page to just mp_phi

  yes? let Y_PAGE =  MP_R * MP_PHI
 
  yes? shade rose, x_page, y_page
  yes? go mp_fland

You could also write your own script mp_noprojection.jnl based on
a map projection script, with this definition.
 
Tony Jolibois wrote:

>          Hi all,
>
> With Ferret we can plot field in a lot of cartographic projection, 
> like Mercator, Bonne etc...
> But there is not the simplest of them, the "geographical projection", 
> x=longitude y=latitude ?
>
> I tryed to change one of the mp_$projection.jnl script in order to 
> have this geographical projection, but have problem with mp_fland and 
> mp_land, can anybody help me ?
>
> Thanks in advance,
> Tony