FUNCTION findrange(lat1, lat2, startln, stopln, quadnum, areaopt, numfound, model)
double lat1; double lat2; long startln[2]; long stopln[2]; long quadnum; long areaopt; long *numfound; struct MODEL *model;
The starting latitude defining the specified range.
The ending latitude defining the specified range.
The line corresponding to the starting latitude. The second element will be set only if areaopt = 2 and the specified latitude range occurs twice in the image.
The line corresponding to the ending latitude. The second element will be set only if areaopt = 2 and the specified latitude range occurs twice in the image.
= 1: Quadrant 1 = 2: Quadrant 2 = 3: Quadrant 3 = 4: Quadrant 4 = 5: Any quadrant = 6: North pole = 7: South pole = 8: Both poles
= 0: Return the first area found. = 1: Return the second area found. = 2: Return both areas found.
The number of areas found.
Model and orbital information.
Spherical trigonometry is used to find the location of the desired latitude in relation to the satellite's location at a given time in the scene. This yields an approximate line number, which is then refined to find the exact latitude. Note that the scan lines are not parallel to the lines of latitude, and are consequently oriented differently depending if the pass is ascending or descending.
findrange() returns
E_SUCC --> Successful completion E_FAIL --> Operation failed