What does the acronym DEM stand for in GIS?

The acronym DEM stands for Digital Elevation Model. This term specifically refers to a 3D representation of a terrain's surface created from terrain data. DEMs are used in GIS to provide a digital representation of ground surface topography or terrain. They play a crucial role in various applications, including flood modeling, terrain analysis, and landscape visualization.

Digital Elevation Models can represent elevations in different formats, such as raster grids, where each cell in the grid has a specific elevation value. This allows for the analysis of elevation changes across large areas, which is vital for researchers and professionals working in fields such as environmental science, urban planning, and resource management.

The other options do not accurately define what a DEM is within the context of GIS. For example, "Detailed Earth Mapping" and "Digital Environment Model" suggest broader or different applications that do not specifically focus on the elevation data that a DEM provides. "Data Elevation Model" also fails to capture the established terminology and scope of a Digital Elevation Model. Thus, the correct answer reflects the widely recognized definition in the GIS community.