1. An image registration process comprising: extracting a two-dimensional set of features ( 36 ) from a two-dimensional image ( 30 ); extracting a three-dimensional set of features ( 38 ) from a three-dimensional image ( 32 ); mathematically projecting the three-dimensional set of features into a two-dimensional set of projected features ( 44 ) using a projection geometry; first registering the two-dimensional set of features and the two-dimensional set of projected features; and second registering the two-dimensional image and a mathematical projection of the three-dimensional image using parameters derived from the first registering.