One of my users called me the other day asking if there was any way to convert our DTM surface into a DEM surface, as a client had called them asking if it was possible. The short answer to the question was yes, but let me review the fundamental differences in these formats before getting into the how-to of this task. Both formats exist for the same fundamental reason – to capture a representation of the earth’s surface. What differs is the way each stores that data.
This is a bit of an oldie, but goodie. Civil 3D Pipe Label Styles can give me the Invert In or the Invert Out of a pipe, but not the invert between point a and point b. That limitation is never really an issue until you go to label the invert of a crossing pipe.