MERIS IDL General Purpose Tools

Projecting a Look Up Table on a given geometry

Last modified: Wed Dec 05 10:45:15 2001.

• MAP2GEOM

Routine Descriptions

 NAME:
  MAP2GEOM

 PURPOSE:
  interpolates a Look-Up table indexed by theta_s, theta_v, and delta_phi on a given geometry.

 CATEGORY:
  MAPING

 CALLING SEQUENCE:
  map=map2geom(GEOMETRY=geometry,LUT=lut)

 INPUTS:
  None (all inputs are passed using keywords) 

 OPTIONAL INPUTS:
  NA     

 KEYWORD PARAMETERS:
  GEOMETRY - structure with 'THETA_S','THETA_V','DELTA_PHI' tags
             holding arrays of same dimensions (of dimension
             [N_column,N_line]) with sun zenith angles, viewing zenith angles and 
             azimuth difference angles values.

  LUT      - structure holding Look Up Table with 'lut.dims.theta_v', 'lut.dims.theta_s',
             'lut.dims.delta_phi' and 'lut.data' attributes following the structure 
             retrieved by the RD_MOM function.

 OUTPUTS:
  map - 3-dimensional array of size [N_column,N_line,N_wavelengths]
        where N_wavelengths is the number of bands of the LUT ; and
        N_column and N_line are given by the dimensions of the
        geometry tags (see above).

 OPTIONAL OUTPUTS:
  NA

 COMMON BLOCKS:
  NA

 SIDE EFFECTS:
  None

 RESTRICTIONS:
  None

 PROCEDURE:
  Performs a trilinear interpolation of the LUT on a given 3-dimensional geometry 
  given by theta_s, theta_v and delta_phi.

 EXAMPLE:

  The following procedure was used to project a MOM file on a MERIS L2RR image

   momfile='/megs_test/validation/Ocean/megs_4_2_SAT/momfiles/momfile_rn_chl0'
   s=rd_mom(filename=momfile)

   prdfile='/megs/megs.4.2/folders/sat_L02_4_2/pacific_30/files/l2_rr.prd'
   geometry=get_geometry(PRDFILE=prdfile,/FULL)

   map=map2geom(GEOMETRY=geometry,LUT=s)

 MODIFICATION HISTORY:
  created by Vincent Fournier-Sicre - vfs@acri.fr - December 1999

(See $IDL_LOCAL\Meris\map2geom.pro)