Digital terrain models (DTMs) are digital representations of the Earth's surface that include elevation data. They are often used in geographic information systems (GIS) and remote sensing applications for various purposes such as flood modeling, land use planning, transportation planning, and natural resource management. DTMs can be created using various data sources including LiDAR, photogrammetry, and radar, and can provide detailed and accurate representations of the Earth's surface for analysis and visualization. These models are essential tools for understanding and studying the shape and characteristics of the Earth's surface in different environments.