Augmented Projection-Based SRFs
Simulations usually require three dimensions.
Some coordinate systems bound to an ERM are three dimensional by definition.
Map projections (two-dimensional) are commonly augmented with a vertical axis to create a three dimensional orthogonal rectilinear system.
Various vertical measures are used for these augmentations, such as:
- Mean sea level height, orthometric height, geodetic height, pressure altitude, and others.
These augmentations are in different units than the other two axes so that the the resulting CS may not be orthonormal.
This practice adds additional geometric distortions (now in the third dimension).