[data models]
Often abbreviated to DTM. The representation of continuous elevation values over a topographic surface by an array of z-values that may be irregularly spaced to incorporate the elevation of significant topographic features—including mass points and breaklines—to better characterize the true shape of the bare-earth terrain and referenced to a common datum. With a DTM, the distinctive terrain features are more clearly defined and precisely located, and contours generated from DTMs more closely approximate the real shape of the terrain.