Digital elevation model (DEM)

A map where every pixel holds the height of the ground, building a 3D picture of the terrain — mountains, valleys, and slopes — as a grid of elevation values.

Why it matters

DEMs underpin flood modeling, landslide risk, watershed mapping, and the correction of satellite images for terrain, making them a foundational dataset across Earth science and engineering.

Where you’ll meet it

• SRTM flew on the Space Shuttle and produced a near-global DEM still in wide use.
• ASTER GDEM combined many stereo image pairs into a global elevation product.
• NASADEM reprocessed and improved SRTM data into a refined modern DEM.

In plain terms

It’s like a topographic relief map turned into data — instead of squiggly contour lines, every spot simply knows how high it stands above sea level.