The present invention is directed to a method of positioning perspective
terrain on a SVS (Synthetic Vision System) based on a navigation
solution, the vertical component of which is calculated utilizing a
terrain database and sensing unit (which provides height above terrain).
The terrain database provides elevation of terrain above MSL. A sensor,
such as a GNSS sensor, may be utilized to calculate the navigation
solution. In alternative embodiments, the navigation solution is
calculated differently based upon the phase of flight. In one, the
vertical component calculation utilizes the sensing unit at or below the
sensing unit's rated altitude. In another, vertical component calculation
blends the sensing unit with the sensor. The blending may be based upon
percentages based upon altitude or utilize filtering such as Kalman
filtering. The present invention is particularly advantageous for close
to ground operations, insuring perspective terrain will stay consistent
with the real world.