What is a digital elevation model (DEM)?

A digital elevation model (DEM) is accurately described as a 3D representation of the terrain surface formed by elevation data. This model is typically raster-based and consists of a grid of elevation values that denote the height of the terrain relative to a reference level, usually mean sea level. The DEM provides a detailed overview of the topography and can be used for various applications such as hydrology, land-use planning, and environmental modeling. By representing terrain in three dimensions, DEMs enable users to visualize changes in elevation and slope, which is crucial for tasks such as flood modeling, landscape analysis, and infrastructure development.

The other choices do not represent the concept of a DEM accurately. For instance, while options discussing weather patterns, population data, or historical records are related to geospatial data, they do not embody the specific characteristics or uses of a digital elevation model.