Digital Models of the Earth: Adding the third dimension

August 31, 2018

Digital Models of the Earth: Adding the third dimension

Lidar-derived Digital Elevation Model over Zion National Park, Utah. Courtesy: USGS

By Ishveena Singh

To fully understand the planet we live in, we cannot rely on traditional flat imagery alone. An optimal management of Earth and its resources is exceedingly dependent upon how well we are able to visualize our world in three dimensions (3D), complete with all its dynamic features and topography. This realization led to the birth of a concept called Digital Earth, of which digital elevation model is a core component.

What is a digital elevation model?

A digital elevation model is an unmodified representation of Earth’s bare surface, which is supposedly devoid of any non-ground objects like buildings, bridges, or trees. Digital elevation data is captured using remote sensing techniques like LiDAR, aerial photogrammetry, radar-based satellite imagery, etc.

Many people use the term Digital Elevation Model (DEM) interchangeably with Digital Surface Model (DSM) or Digital Terrain Model (DTM). But that would not be accurate. Which brings us to the next section of this post…

What is the difference between DEM, DSM, and DTM?

DEM: As discussed above, DEM is an elevation model of Earth’s bare topography.

DSM: It is an elevation model that includes above-the-ground features, such as vegetation and man-made objects.

DTM: When data from DEM is processed further, you get DTM. Basically, DTM is DEM of much greater accuracy because its terrain data is augmented with additional information, such as contour lines obtained by land surveys.

In essence, you can call DEM a superset of both DSM and DTM.

What is a digital elevation model used for?

Knowledge of elevation and slope is not only useful but critical for understanding the changes taking place on Earth’s surface and making informed decisions about its resources and environment. For example, you cannot make sense of the variations in temperature, moisture, air particles, etc., of a region without knowing its exact topography.

Elevation data is also vital for modeling the flow of water for hydrological purposes and tracking the movement of glaciers. DEMs become even more necessary when you need to model flood waters in case of storms, avalanches or landslides. In the field of mineral exploration, DEMs can provide a telling picture of favorable regions of potential mineral deposits.

1-m LiDAR-derived digital elevation model (DEM) data is superimposed on a USGS topographic map of Glacier Peak in the United States for computationalmodeling of volcano hazards, such as volcanic mudflows that could travel downstream and affect nearby populated areas. Courtesy: USGS

Infrastructure planning and construction are also highly dependent on an understanding of precise elevation data. Other application areas include archaeology, intelligent transportation systems like Hyperloop, and precision farming and forestry. A not-so-obvious use case is that of flight and battle simulations – cannot afford any surprises there!

And of course, digital elevation models are an indispensable part of topographic studies, used in everything from correcting imperfections in satellite imagery to visualizing Earth’s surface in thematic maps – and some of these maps even double up as art. To see how stunning maps based on real elevation data can look, hop on here.

About the Author

Photo of Ishveena SinghIshveena is a geospatial enthusiast and a veteran of creating and managing compelling digital content for organizations and individuals. When she is not making magic at her desk, you are likely to find her exploring nature, eating her way through life, or binge-watching funny animal videos.


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