Historical Background of DEM

 The concept and development of Digital Elevation Models (DEMs) have evolved significantly over the past century, driven by advances in cartography, remote sensing, photogrammetry, and computing power. Initially, terrain elevation was represented through topographic contour maps, meticulously created through field surveys and manual interpretation of aerial photographs. These early efforts provided critical elevation information but were time-consuming, labor-intensive, and lacked the flexibility and precision offered by digital models. The idea of transforming analog elevation data into digital raster format first gained momentum in the mid-20th century, as geographic and military organizations began to digitize terrain data for analytical modeling. One of the earliest known digital elevation models was developed by the U.S. Geological Survey (USGS) in the 1970s, where elevation data was stored in grid format and used for terrain visualization and basic topographic analysis.

The 1990s saw a surge in DEM development with the advent of satellite remote sensing, enabling elevation capture at global scales. However, a true turning point came in 2000 with the launch of the Shuttle Radar Topography Mission (SRTM)—a joint project by NASA, the National Geospatial-Intelligence Agency (NGA), and the German and Italian space agencies. This mission used radar interferometry onboard the Space Shuttle Endeavour to scan the Earth’s surface and produce what became the first nearly-global DEM, covering most of the land surface between 60°N and 56°S. The SRTM provided elevation data at 90-meter resolution globally, and later at 30-meter resolution for the U.S., revolutionizing the accessibility and quality of global terrain data. For the first time, researchers, planners, and developers could download accurate, standardized elevation data for most parts of the world—an unprecedented milestone in the field of GIS.

Following SRTM, a range of missions contributed to the global DEM landscape. The ASTER GDEM (Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model) was launched by NASA and Japan’s METI, providing global elevation data at approximately 30-meter resolution using stereo imaging techniques. Another advancement came from the TanDEM-X and TerraSAR-X missions by the German Aerospace Center (DLR), which used radar interferometry to produce one of the most accurate and detailed global DEMs to date, with 12-meter resolution and 2-meter vertical accuracy. Meanwhile, airborne technologies such as LIDAR (Light Detection and Ranging) became widely adopted for high-resolution terrain modeling, especially in urban and forested environments.

Today, DEMs are an indispensable part of GIS and remote sensing workflows, embedded in everything from flood simulation models and transportation planning to mobile navigation apps and virtual globe platforms. The growing number of open-access DEM repositories and cloud-based GIS services has further democratized their use, making them accessible not only to governments and scientists but also to students, NGOs, and hobbyists. Understanding the historical evolution of DEMs provides valuable context for their current capabilities and limitations. For learners seeking to engage with DEMs using real data and modern tools like ArcGIS and ERDAS, the Complete Remote Sensing and GIS - ArcGIS – ERDAS course serves as an ideal starting point, combining historical insight with practical, hands-on experience in terrain analysis.