What is generally expressed in orthometric height in surveying and map data?

Orthometric height is a measure commonly used in surveying to refer to the height of a point above the geoid, which is an equipotential surface representing mean sea level across the globe. This height reflects the real-world elevation of terrain and is crucial for various applications such as construction, mapping, and civil engineering.

Elevation determination involves calculating the height of features relative to a reference surface, like the geoid, which aligns with orthometric heights. This method provides accurate representations of how high something is in relation to sea level, making it essential for various engineering and surveying activities where precise elevation data is required.

The other options address different concepts not directly linked to the definition of orthometric height. Geoidal separation is the difference between the ellipsoidal height and the orthometric height, geometric height refers to the height measured along a vertical line to an ellipsoidal model, and satellite position involves positional data derived from satellite systems rather than height determination with respect to a geoid.