What is navigation
Satellite imagery in its raw format is simply what the sensor
observes. To use the data quantitatively (or even to simply
overlay a map) requires the calculation of the Earth location
for each pixel. Generally, the Earth location is described in
How does one navigate imagery?
CLASS automatically navigates...
However, McIDAS Area files will need to be navigated by the user,
which depends on whether the data originates from the:
- GIF/JPG imagery by overlaying map coordinates on the image.
- netCDF files by providing latitude and longitude as variables
in the file
- Mode Files: GOES-1,2,3,4,5,6,7 (i.e., pre GOES-8)
- GVAR Files: GOES-8,9,10,11,12,... (GOES-Next in GVAR format)
Mode data was just recently made available from CLASS. A description
of the navigation will be included here at a later date.
NCDC scientists have brought this code up-to-date by upgrading it to
Fotran95 and also converting it to IDL.
- The GVAR navigation is described in the NESDIS Earth Location
User's Guide (ELUG) available from
- The ELUG describes a navigation algorithm which has been coded in Fortran 77 and is available
via ftp at the
GOES Project Science Office.
- This tool converts files in their raw format to netCDF.
Since it is a Java tool, it is compatible with most systems.
- The weather and climate toolkit
developed at NCDC will calibrate and remap CLASS-Area files to various
output formats, some of which can be used with GIS software.
- IDL - NCDC has a library of routines which can be used to
navigate GOES Area files. The routines are provided as part of a
which includes IDL code to read and navigate GOES GVAR McIDAS Area files.
- Fortran - If you are interested in the Fortran code for GVAR navigation, please contact
to request the code. The Fortran code has some compiler-specific calls
(Lahey Fortran 95) which may preclude it from working with all Fortran