Continuous fields have a number of characteristics not shared by discrete fields. Since the field changes continuously, we can talk of slope angle, slope aspect and concavity/convexity of the slope.
These notions are not applicable to discrete fields. The discussions in this subsection use terrain elevation as the prototype example of a continuous field, but all aspects discussed are equally applicable to other types of continuous fields. Nonetheless, we regularly refer to the continuous field representation as a DEM, to conform with the most common situation.