Shuttle Radar Topography Mission

The USGS SRTM data is based on NASA's SIR-C instrument. It is available in at the following versions:

• Version 1 (2003–2004) is almost the raw data.{{Cite web|date=|title=What's new|url=https://dds.cr.usgs.gov/srtm/version1/Whats_new.txt|url-status=live|archive-url=https://web.archive.org/web/20161230132420/https://dds.cr.usgs.gov/srtm/version1/Whats_new.txt|archive-date=2016-12-30|access-date=|website=USGS Data Distribution Service}}
• Version 2.1 (~2005) is an edited version of v1. Artifacts are removed, but voids are not yet filled. There are 1-arcsecond data over the US.{{cite journal|doi=10.1029/2005RG000183|title=The Shuttle Radar Topography Mission|date=2007|last1=Farr|first1=Tom G.|last2=Rosen|first2=Paul A.|last3=Caro|first3=Edward|last4=Crippen|first4=Robert|last5=Duren|first5=Riley|last6=Hensley|first6=Scott|last7=Kobrick|first7=Michael|last8=Paller|first8=Mimi|last9=Rodriguez|first9=Ernesto|last10=Roth|first10=Ladislav|last11=Seal|first11=David|last12=Shaffer|first12=Scott|last13=Shimada|first13=Joanne|last14=Umland|first14=Jeffrey|last15=Werner|first15=Marian|last16=Oskin|first16=Michael|last17=Burbank|first17=Douglas|last18=Alsdorf|first18=Douglas|journal=Reviews of Geophysics|volume=45|issue=2|pages=RG2004|bibcode = 2007RvGeo..45.2004F |citeseerx=10.1.1.102.9372|s2cid=140735782 }}
• Version 3 (2013), also known as SRTM Plus, is void-filled with ASTER GDEM and USGS GMTED2010. This release is available in global 1-arcsecond (30 meter) resolution since 2014.

The SRTM also carries the X-SAR instrument operated by the German Aerospace Center (DLR) and Italian Space Agency (ASI). The resulting dataset is usually called SRTM/X-SAR, or SRTMX for short. The grid resolution is high at 25 meters, but it has many gaps. The data was made public in May 2011.{{cite web |title=SRTM X-SAR - Digital Elevation Model (DEM) 10° Mosaics - Global |url=https://www.europeandataportal.eu/data/datasets/f4d4079a-ada3-41d0-ba95-630ba232e147?locale=en |website=European Data Portal |access-date=2021-02-14 |archive-date=2021-09-10 |archive-url=https://web.archive.org/web/20210910132029/https://data.europa.eu/data/datasets/f4d4079a-ada3-41d0-ba95-630ba232e147?locale=en |url-status=live }}{{cite web |title=SRTM |url=https://www.dlr.de/caf/en/desktopdefault.aspx/tabid-5515/9214_read-17716/ |website=DLR - Earth Observation Center |access-date=2021-02-14 |archive-date=2018-05-20 |archive-url=https://web.archive.org/web/20180520035726/http://www.dlr.de/caf/en/desktopdefault.aspx/tabid-5515/9214_read-17716/ |url-status=live }}

The terminology regarding versions and resolutions can be confusing. "SRTM1" and "SRTM3" refers to the resolutions in 1 and 3 arc-seconds, not the versions of the format. On the other hand, "SRTM4.1" refers to a specific filled version by CGIAR-CSI. It is recommended to add a "v" in front of the version number to disambiguate.

File:Srtm voidfilling grass gis.png.]]

The elevation datasets are affected by mountain and desert no-data areas. These amount to no more than 0.2% of the total area surveyed,Reuter H.I, A. Nelson, A. Jarvis, 2007, [https://www.researchgate.net/publication/220650064_An_Evaluation_of_Void-Filling_Interpolation_Methods_for_SRTM_Data An evaluation of void filling interpolation methods for SRTM data], International Journal of Geographical Information Science, 21:9, 983–1008 – 'the ‘finished’ grade version of the data (also referred to as Version 2) still contains data voids (some 836,000 km^2)'; 836,000 is 0.164% of the Earth's 5.1×10^8 km^2 surface but can be a problem in areas of very high relief. They affect all summits over 8,000 meters, most summits over 7,000 meters, many Alpine and similar summits and ridges, and many gorges and canyons. There are some SRTM data sources which have filled these data voids, but some of these have used only interpolation from surrounding data, and may therefore be very inaccurate. If the voids are large, or completely cover summit or ridge areas, no interpolation algorithms will give satisfactory results.

Image:Maps-for-free Sierra Nevada.png]]

File:SRTM1 Example Nevada.png

Groups of scientists have worked on algorithms to fill the voids of the original SRTM (v2.1) data. Three datasets offer global coverage void-filled SRTM data at full (3-arcsecond) resolution:

• The CGIAR-CSI version 4 provides the best global coverage using interpolation.{{cite web

|url=http://srtm.csi.cgiar.org/

|publisher=Consultative Group on International Agricultural Research

|access-date = 26 December 2023

|title=SRTM 90m Digital Elevation Data

|date=19 August 2008

|archive-date=16 October 2014

|archive-url=https://web.archive.org/web/20141016030443/http://srtm.csi.cgiar.org/

|url-status=live

}}

• The USGS HydroSHEDS dataset was generated for hydrological applications and is suitable for consistent drainage and water flow information. References are provided{{cite web

|url=http://hydrosheds.cr.usgs.gov/references.php

|publisher=United States Geological Survey

|access-date=10 October 2014

|title=USGS HydroSHEDS References

|date=5 September 2010

|archive-date=21 October 2014

|archive-url=https://web.archive.org/web/20141021005444/http://hydrosheds.cr.usgs.gov/references.php

|url-status=live

}} on the algorithms used and quality assessment.

{{cite web

|url = http://hydrosheds.cr.usgs.gov/

|publisher = United States Geological Survey

|access-date = 10 October 2014

|title = USGS HydroSHEDS

|date = 6 September 2010

|url-status = live

|archive-url = https://web.archive.org/web/20140928112952/http://hydrosheds.cr.usgs.gov/

|archive-date = 28 September 2014

}}

• The void-filled SRTM data from Viewfinder Panoramas by Jonathan de Ferranti

{{cite web

|url = http://www.viewfinderpanoramas.org/dem3.html

|publisher = Viewfinder Panoramas

|access-date = 26 December 2023

|title = DIGITAL ELEVATION DATA

|url-status = live

|archive-url = https://web.archive.org/web/20091210183954/http://www.viewfinderpanoramas.org/dem3.html

|archive-date = 10 December 2009

}} are high quality at full SRTM resolution. The data is filled using local survey maps and photographs. The OpenTopoMap website uses this fill. It has been partially updated for the 1-arcsecond release in the US.

In November 2013, LP DAAC released

{{cite web

|url = https://lpdaac.usgs.gov/news/nasa-shuttle-radar-topography-mission-srtm-version-30-srtm-plus-product-release/

|publisher = United States Geological Survey

|access-date = 26 December 2023

|title = NASA Shuttle Radar Topography Mission (SRTM) Version 3.0 (SRTM Plus) Product Release

|date = 30 November 2013

|url-status = live

|archive-url = https://web.archive.org/web/20131224234411/https://lpdaac.usgs.gov/node/539

|archive-date = 24 December 2013

}} the NASA Shuttle Radar Topography Mission (SRTM) Version 3.0 (SRTM Plus) Product collection with all voids eliminated. Voids were filled primarily from ASTER GDEM2, and secondarily from USGS GMTED2010 – or USGS National Elevation Dataset (NED) for the United States (except Alaska) and northernmost Mexico according to the announcement.

1-arc second global digital elevation model (30 meters) is available from the United States Geological Survey web site. The United States Government announced on September 23, 2014 over a United Nations Climate Summit that the highest possible resolution of global topographic data derived from the SRTM mission will be released to public.{{cite web|title=U.S. Releases Enhanced Shuttle Land Elevation Data|url=http://www2.jpl.nasa.gov/srtm/|website=JPL-Shuttle Radar Topography Mission|access-date=31 January 2015|url-status=live|archive-url=http://archive.wikiwix.com/cache/20080823022748/http://www2.jpl.nasa.gov/srtm/|archive-date=23 August 2008}} Before the end of the same year, a 1-arc second global digital elevation model (30 meters) was released. Most parts of the world have been covered by this dataset ranging from 54°S to 60°N latitude except for the Middle East and North Africa area.{{cite web|title=USGS Earth Explorer|url=http://earthexplorer.usgs.gov/|website=USGS-EarthExplorer|access-date=31 January 2015|url-status=live|archive-url=https://web.archive.org/web/20150206111800/http://earthexplorer.usgs.gov/|archive-date=6 February 2015}} Missing coverage of the Middle East was completed in August 2015.{{cite web|url=https://lpdaac.usgs.gov/nasa_shuttle_radar_topography_mission_srtm_global_1_arc_second_data_released_over_middle_east|title=NASA Shuttle Radar Topography Mission (SRTM) Global 1 arc second Data Released Over the Middle East - LP DAAC :: NASA Land Data Products and Services|website=lpdaac.usgs.gov|url-status=live|archive-url=https://web.archive.org/web/20150913200035/https://lpdaac.usgs.gov/nasa_shuttle_radar_topography_mission_srtm_global_1_arc_second_data_released_over_middle_east|archive-date=2015-09-13}}

In early June 2011, there were 750,000 confirmed users of SRTM topography dataset. Users in 221 countries have accessed the site.{{cite web |url=http://dapa.ciat.cgiar.org/dapas-srtm-topography-data-reaches-750000-users/ |title=DAPA's SRTM topography data reaches 750,000 users | DAPA |access-date=2011-06-24 |url-status=live |archive-url=https://web.archive.org/web/20110819172254/http://dapa.ciat.cgiar.org/dapas-srtm-topography-data-reaches-750000-users/ |archive-date=2011-08-19 }}

• Interferometric Synthetic Aperture Radar
• Digital elevation model
• National Geospatial-Intelligence Agency
• Advanced Spaceborne Thermal Emission and Reflection Radiometer
• SRTM Water Body Data
• WorldDEM private data with higher resolution, from newer satellite TerraSAR-X-TanDEM-X

{{Reflist}}

• {{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 |page=4819 |doi=10.1080/01431160600835853 |bibcode=2006IJRS...27.4819N |s2cid=1939968 |issn=0143-1161 |url=http://www.iacm.forth.gr/_docs/pubs/4/Nikolakopoulos_et_al_2006.pdf |access-date=March 10, 2010 |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 }}
• {{cite journal|last1=Hirt|first1=C.|last2=Filmer|first2=M.S. |last3=Featherstone|first3=W.E.|date=2010|title=Comparison and validation of recent freely-available ASTER-GDEM ver1, SRTM ver4.1 and GEODATA DEM-9S ver3 digital elevation models over Australia|journal=Australian Journal of Earth Sciences|volume=57|issue=3|pages=337–347|url=http://espace.library.curtin.edu.au:80/R?func=dbin-jump-full&local_base=gen01-era02&object_id=137777|access-date=May 5, 2012|bibcode = 2010AuJES..57..337H |doi = 10.1080/08120091003677553 |hdl=20.500.11937/43846|s2cid=140651372|hdl-access=free}}
• {{cite journal|last1=Rexer|first1=M.|last2=Hirt|first2=C.|date=2014|title=Comparison of free high-resolution digital elevation data sets (ASTER GDEM2, SRTM v2.1/v4.1) and validation against accurate heights from the Australian National Gravity Database|journal=Australian Journal of Earth Sciences|volume=61|issue=2|pages=213–226|url=http://geodesy.curtin.edu.au/local/docs/Rexer_Hirt_2014_DEM_AJES_av.pdf|access-date=April 24, 2014|doi=10.1080/08120099.2014.884983|bibcode=2014AuJES..61..213R|url-status=dead|archive-url=https://web.archive.org/web/20160607102637/http://geodesy.curtin.edu.au/local/docs/Rexer_Hirt_2014_DEM_AJES_av.pdf|archive-date=June 7, 2016|hdl=20.500.11937/38264|s2cid=3783826|hdl-access=free}}
• Hennig, T., Kretsch, J, Salamonowicz, P, Pessagno, C, and Stein, W., The Shuttle Radar Topography Mission, Proceedings of the First International Symposium on Digital Earth Moving 2001, Springer Verlag, London, UK.

• {{cite journal |last1=Li |first1=P. |last2=Li |first2=Z. |last3=Muller |first3=J.-P. |last4=Shi |first4=C. |last5=Liu |first5=J. |title=A new quality validation of global digital elevation models freely available in China |journal=Survey Review |date=November 2016 |volume=48 |issue=351 |pages=409–420 |doi=10.1179/1752270615Y.0000000039|s2cid=129792781 }}

{{commonscat|NASA SRTM images}}

• [http://www2.jpl.nasa.gov/srtm/ Official NASA SRTM site] (SRTM V1 and V2)
• [https://lpdaac.usgs.gov/dataset_discovery/measures/measures_products_table NASA MEaSUREs Products] (SRTM V3 and more)
• [https://web.archive.org/web/20090622043357/http://dds.cr.usgs.gov/srtm/ NASA's server with SRTM data tiles] – Please read the accompanying documentation
• [http://www.ga.gov.au/topographic-mapping/digital-elevation-data.html Digital elevation data from Geoscience Australia] – arcsecond-resolution derived data covering Australia
• Void filled SRTM data at [http://www.cgiar-csi.org/data/srtm-90m-digital-elevation-database-v4-1 CGIAR-CSI] {{Webarchive|url=https://web.archive.org/web/20130207040342/http://www.cgiar-csi.org/data/srtm-90m-digital-elevation-database-v4-1 |date=2013-02-07 }}
• [http://www.hydrosheds.org/ USGS HydroSHEDS] – Full resolution SRTM-based DEM for hydrological applications
• Software that can read and process SRTM data: [http://www.hangsim.com/3dem/ 3dem], GRASS GIS, SAGA GIS, [http://www.mapwindow.com/ MapWindow GIS], [http://www.dgadv.com/dgtv DG Terrain Viewer/Void Killer], [http://vterrain.org/ Virtual Terrain Project]
• [http://www.viewfinderpanoramas.org/dem3.html Viewfinder Panoramas] – Unofficial SRTM data with voids corrected using topographic maps

{{Jet Propulsion Laboratory}}

Category:Digital elevation models

Category:Space synthetic aperture radar

Category:2000 in spaceflight

Category:Spacecraft instruments

Category:Topography techniques