Performing digital terrain mapping (DTM) is essential to human safety (as evidenced by the horrors of the recent tsunami in Asia) and to the environment, because it is instrumental in allowing at least some warning of short- or long-term changes that may signal significant disruptions. The authors concentrate on the mathematics of DTM as well as acquisition techniques and data analysis. They cover DTM data generation, including georeferencing technology and photogrammetric data sources, DRM data structures include storage and compression techniques and choosing the appropriate models, DTM manipulation such as data gridding, KRIGING, generalization and quality control, mapping and engineering applications, and applications in environmental modeling.