TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurements) is an Earth observation radar mission that consists of a SAR interferometer built by two almost identical satellites flying in close formation. With a typical separation between the satellites of 120 m to 500 m a global Digital Elevation Model (DEM) has been generated.

The TanDEM-X 90m DEM is a product variant of the global Digital Elevation Model (DEM) acquired in the frame of the German TanDEM-X mission between 2010 and 2014, and has a reduced pixel spacing of 3 arcseconds (arsec), which corresponds to 90m at the equator. It covers all Earth’s landmasses from pole to pole.

This map shows all 8 original TanDEM-X Information Layers as specified in the Product Specification:

• TDM90 Elevation (DEM): The DEM elevation values represent the ellipsoidal heights relative to the WGS84 ellipsoid in the WGS84-G1150 datum.
• TDM90 Height Error Map (HEM): The height error map (HEM) values represent for each DEM pixel the corresponding height error in form of the standard deviation.
• TDM90 Amplitute Min/Mean (AMP/AM2): The amplitude mosaic AMP and AM2 layers are a by-product generated for further processings, e.g. water body detection or DEM filtering. They represent the mean (AMP) and minimum value (AM2) of all calibrated amplitude values from the contributing DEM scenes (in general between 2 and up to 10 scenes).
• TDM90 Consistency Map (COM): The consistency mask (COM) indicates DEM pixels, which have height inconsistencies among the contributing DEM scenes.
• TDM90 Coverage Map (COV): The coverage map (COV) indicates how many valid height values from different DEM acquisitions were available for mosaicking.
• TDM90 Layover & Shadow Mask (LSM): The layover and shadow mask (LSM) is based on the SRTM-C DEM and the GLOBE DEM regarding the TanDEM-X geometry of each individual scene.
• TDM90 Water Indication Mask (WAM): The water indication mask (WAM) layer represents the water bodies indentified during processing.