[netCDF #EVL-272024]: Standard Coordinate Transforms to Geo-locating gridded data

> Hi
> 
> Using TOOL UI, Looking at the GRIB file, I am not clear about certain points 
> and do observe the following:
> 
> A.
> 
> :grid_mapping_name = "vertical_perspective";
> 
> *************************
> char Space_View_Perspective_or_Orthographic;
> :grid_mapping_name = "vertical_perspective";
> :longitude_of_projection_origin = 0.0; // double
> :latitude_of_projection_origin = 0.0; // double
> :height_above_earth = 35747.054550299996; // double
> :earth_shape = "Earth oblate spheroid with axes specified by producer";
> :GRIB_param_Angle = 0; // int
> :GRIB_param_Dx = 1207.0; // double
> :GRIB_param_Dy = 1189.0; // double
> :GRIB_param_GDSkey = -256423982; // int
> :GRIB_param_Lap = 0.0; // double
> :GRIB_param_Lop = 0.0; // double
> :GRIB_param_Nr = 6610700.0; // double
> :GRIB_param_Nx = 1237; // int
> :GRIB_param_Ny = 1237; // int
> :GRIB_param_Quasi = "false";
> :GRIB_param_ResCompFlag = 0; // int
> :GRIB_param_Winds = "True";
> :GRIB_param_Xo = 0.0; // double
> :GRIB_param_Xp = 619.0; // double
> :GRIB_param_Yo = 0.0; // double
> :GRIB_param_Yp = 619.0; // double
> :GRIB_param_grid_name = "Space View Perspective or Orthographic";
> :GRIB_param_grid_shape = "Earth oblate spheroid with axes specified by 
> producer";
> :GRIB_param_grid_shape_code = 3; // int
> :GRIB_param_grid_type = 90; // int
> :GRIB_param_major_axis_earth = 6378.14; // double
> :GRIB_param_minor_axis_earth = 6356.7554; // double
> 
> B. In variables:
> float Pixel_scene_type(time=1, y=1237, x=1237);
> :units = "";
> :long_name = "Pixel scene type";
> :missing_value = -9999.0f; // float
> :grid_mapping = "Space_View_Perspective_or_Orthographic";
> :GRIB_param_discipline = "Space_Products";
> :GRIB_param_category = "Image_format_products";
> :GRIB_param_name = "Pixel_scene_type";
> :GRIB_param_id = 2, 3, 0, 8; // int
> :GRIB_product_definition_type = "Satellite product";
> :GRIB_level_type = 0; // int
> 
> :grid_mapping = "Space_View_Perspective_or_Orthographic";
> 
> *************************
> 
> Do we need to define all these parameters for MSGnavigation perspective?

you dont need anything starting with GRIB.

> 
> Is it possible to provide an example of MSG navigation perspective instead of 
> vertical perspective?

this is an MSG projection. open the file in the "CoordSys" tab, in the middle 
table, select then right click on the row, you get contect menu, select "Show 
CoordSys" you get:

Coordinate System = time y x
  Time    int time(time=1);
     :units = "Minute since 2007-05-22T11:45:00.000Z";
     :standard_name = "time";
     :_CoordinateAxisType = "Time";

  GeoY    float y(y=1237);
     :standard_name = "projection_y_coordinate ";
     :units = "km";
     :_CoordinateAxisType = "GeoY";

  GeoX    float x(x=1237);
     :standard_name = "projection_x_coordinate ";
     :units = "km";
     :_CoordinateAxisType = "GeoX";

 Coordinate Transforms
  SpaceViewPerspective_Projection type=Projection
    grid_mapping_name = MSGnavigation
    longitude_of_projection_origin = 0.0
    latitude_of_projection_origin = 0.0
    semi_major_axis = 6356.7548828125
    semi_minor_axis = 6378.14013671875
    height_from_earth_center = 42163.97265625
    scale_x = 35.785831451416016
    scale_y = -35.785831451416016
    impl.class= ucar.unidata.geoloc.projection.sat.MSGnavigation


it looks like you have the projection correct in your file (not positive) but 
you need to get the coordinates. look at what coordinates are in the grib file 
by going to lowest table and selecting on "GeoX", then right clicking and 
choose "show values". do same for "GeoY". You probably need similiar or 
identical coordinates.

John

Ticket Details
===================
Ticket ID: EVL-272024
Department: Support netCDF Java
Priority: Normal
Status: Closed