What type of model includes only the elevations of terrain without objects?

The Digital Terrain Model (DTM) is specifically designed to represent the bare ground surface of the Earth, including its elevation, without any objects such as vegetation or buildings. This makes it uniquely suited for analyzing terrain characteristics, slope, and drainage patterns, as it captures only the elevation data necessary for understanding the landscape itself.

In contrast, a Digital Surface Model (DSM) includes not only the elevation data of the ground but also any objects on the surface, such as trees and buildings, which can complicate analyses focused solely on the underlying terrain. A Hillshade Model, while it derives from elevation data, is a visualization that simulates how terrain would appear under a specific light source, effectively displaying shadows and highlights but not serving as a foundational elevation dataset. A Point Cloud represents a collection of data points in space and may include various features from the surface, making it unsuitable for representing just terrain elevations.

This specificity of the Digital Terrain Model to capture only ground elevations is what distinguishes it from the other types of models listed.