Editing Digital elevation model (section)

===Satellite mapping===
One powerful technique for generating digital elevation models is [[interferometric synthetic aperture radar]] where two passes of a radar satellite (such as [[RADARSAT-1]] or [[TerraSAR-X]] or [[Cosmo SkyMed]]), or a single pass if the satellite is equipped with two antennas (like the [[Shuttle Radar Topography Mission|SRTM]] instrumentation), collect sufficient data to generate a digital elevation map tens of kilometers on a side with a resolution of around ten meters.<ref>{{cite web|url=http://www.intelligence-airbusds.com/worlddem/|title=WorldDEM(TM): Airbus Defence and Space|website=www.intelligence-airbusds.com|access-date=2018-01-05|archive-date=2018-06-04|archive-url=https://web.archive.org/web/20180604103046/http://www.intelligence-airbusds.com/worlddem/|url-status=dead}}</ref> Other kinds of [[stereoscopic]] pairs can be employed using the [[digital image correlation]] method, where two optical images are acquired with different angles taken from the same pass of an airplane or an [[Earth Observation Satellite]] (such as the HRS instrument of [[SPOT (satellites)|SPOT5]] or the [[VNIR]] band of [[Advanced Spaceborne Thermal Emission and Reflection Radiometer|ASTER]]).<ref name=Nikolakopoulous>{{cite journal|last1=Nikolakopoulos |first1=K. G. |last2=Kamaratakis |first2=E. K |last3=Chrysoulakis |first3=N. |date=10 November 2006 |title=SRTM vs ASTER elevation products. Comparison for two regions in Crete, Greece |journal=International Journal of Remote Sensing |volume=27 |issue=21 |pages=4819–4838 |issn=0143-1161 |url=http://www.iacm.forth.gr/_docs/pubs/4/Nikolakopoulos_et_al_2006.pdf |access-date=June 22, 2010 |doi=10.1080/01431160600835853 |bibcode=2006IJRS...27.4819N |s2cid=1939968 |url-status=dead |archive-url=https://web.archive.org/web/20110721081314/http://www.iacm.forth.gr/_docs/pubs/4/Nikolakopoulos_et_al_2006.pdf |archive-date=July 21, 2011 }}</ref>

The [[SPOT (satellites)|SPOT 1 satellite]] (1986) provided the first usable elevation data for a sizeable portion of the planet's landmass, using two-pass stereoscopic correlation. Later, further data were provided by the [[European Remote-Sensing Satellite]] (ERS, 1991) using the same method, the [[Shuttle Radar Topography Mission]] (SRTM, 2000) using single-pass SAR and the [[Advanced Spaceborne Thermal Emission and Reflection Radiometer]] (ASTER, 2000) instrumentation on the [[Terra satellite]] using double-pass stereo pairs.<ref name=Nikolakopoulous/>

The HRS instrument on SPOT 5 has acquired over 100 million square kilometers of stereo pairs.