Advanced Navigation Certus OEM Reference Manual page 228

Certus Reference Manual • Certus Reference Information
11.5.2 Height
Any height data output by Advanced Navigation devices is the height referenced the WGS84 reference
ellipsoid. The WGS84 reference ellipsoid is a smooth mathematical model that approximates the form of the
surface of the earth. The ellipsoid height (as used by GNSS) is not referenced to mean sea level; the height
from the EGM96 geoid (orthometric height) approximates the height above mean sea level (MSL).
See Figure 114: Orthometric, ellipsoid and geoid height diagram below for a visual representation of geoid
height, ellipsoid height and orthometric height (height above mean sea level).
Note:
Ellipsoid height refers to the height of a point of interest referenced to the WGS84 reference ellipsoid.
Geoid height refers to the height of the EGM96 geoid referenced to the WGS84 reference ellipsoid at a
point of interest.
Orthometric height is the height at a point of interest referenced to the EGM96 geoid.
All heights can be either positive or negative dependant upon direction from the reference surface.
Figure 114: Orthometric, ellipsoid and geoid height diagram
The value required to convert the WGS84 ellipsoid height to orthometric height can be found in the geoid height
packet, see 10.4.34 Geoid Height Packet.
v2.4 Page 215 2024-12-17