Geolocate OLS swath data, return geodetic latitude and longitude.
Author: Ethan R. Davis
Date: 30 November 1994
Earth-centered coordinate system:
x-axis goes through zero longitude at the equator.
y-axis goes through 90 degrees longitude at the equator.
z-axis goes through the north pole.
The plane tangent to the earth surface at the subsatellite point
will be called the tangent plane.
Method:
- Calculate the subsatellite point.
- Calculate the satellite point.
- Calculate the parametric equation for the line from
the satellite to the scan point.
- Calculate north and west in the tangent plane.
- Calculate heading vector in tangen plane.
- Calculate scan line vector in tangent plane.
- Calculate the scan angle.
- Calculate the scan point in the tangent plane
(i.e., the point where the line-of-sight and the
tangent plane intersect).
- Calculate the intersection of the line-of-sight and the
earth surface (elliptical model). This is done by
solving the quadratic equation that is found when the
equations for the line-of-sight are substituted into the
equations for an ellipse.