4. October 2016

New 3D world map – Tan­DEM-X glob­al el­e­va­tion mod­el com­plet­ed

Crater landscape of the Nevada Test Site
Crater land­scape of the Neva­da Test Site
Image 1/4, Credit: DLR

Crater landscape of the Nevada Test Site

The 'Neva­da Test Site' was, from 1951, the venue for nu­mer­ous nu­cle­ar tests. The desert area, 100 kilo­me­tres north­west of Las Ve­gas, is dot­ted with ex­plo­sion craters.
La Avenida de los Volcanes in Ecuador
La Aveni­da de los Vol­canes in Ecuador
Image 2/4, Credit: DLR

La Avenida de los Volcanes in Ecuador

The ‘Av­enue of the Vol­ca­noes’ in Ecuador. The left third of the pic­ture is dom­i­nat­ed by Co­topaxi. At 5897 me­tres, this very reg­u­lar, con­i­cal stra­to­vol­cano is the sec­ond high­est moun­tain in Ecuador. In the sur­round­ing area, the sum­mits of the vol­ca­noes Ru­miñawi (4721 me­tres), Sin­cholagua (4900 me­tres), Pasa­choa (4200 me­tres) and Pich­in­cha (4784 me­tres) are vis­i­ble.
Richat Structure in Mauritania
Richat Struc­ture in Mau­ri­ta­nia
Image 3/4, Credit: DLR

Richat Structure in Mauritania

The Richat Struc­ture in Mau­ri­ta­nia. Through vol­canic ac­tiv­i­ty, sed­i­ment lay­ers from the primeval ocean were pushed to the sur­face in the Maur Adrar Desert. Sa­ha­ran winds erod­ed these over time, trans­form­ing the dif­fer­ent lay­ers of hard rock in­tru­sions in­to con­cen­tric rings and dips. The dis­tinc­tive for­ma­tion is a land­mark for as­tro­nauts.
Chuquicamata copper mine in Chile
Chuquica­ma­ta cop­per mine in Chile
Image 4/4, Credit: DLR

Chuquicamata copper mine in Chile

The Chuquica­ma­ta cop­per mine in north­ern Chile is the sec­ond largest open pit cop­per mine on Earth. The enor­mous ex­tent of the pit tes­ti­fies to the huge mass that has been re­moved. Cov­er­ing an area of about 13 square kilo­me­tres, the rock has been mined to a depth of over 850 me­tres. The city of Cala­ma can be seen in the cen­tre of the im­age, ap­prox­i­mate­ly 10 kilo­me­tres from the open pit.

The new three-dimensional map of Earth has been completed. Mountain peaks and valley floors across the globe can now be seen with an accuracy of just one metre. The global elevation model was created as part of the Tan­DEM-X Sci­ence Home satellite mission; it offers unprecedented accuracy compared with other global datasets and is based on a uniform database. The approximately 150 million square kilometres of land surface were scanned from space by radar sensors. "TanDEM-X has opened up a whole new chapter in the field of remote sensing. The use of radar technology based on two satellites orbiting in close formation is still unique and was key to the high-precision remapping of Earth. In this way, DLR has demonstrated its pioneering role and satisfied the prerequisites for the next major development step in satellite-based Earth observation – the Tandem-L radar mission," says Pascale Ehrenfreund, Chair of the Executive Board of the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR).

More than 1000 scientists around the world are already making use of the data from the mission. "With completion of the global TanDEM-X elevation model, we are once again anticipating a surge in scientific interest. Accurate topographical data is essential for all geoscientific applications," says Alberto Moreira, Principal Investigator of the TanDEM-X mission and Director of the DLR Microwaves and Radar Institute. The applications for this unique dataset range from climate and environmental research, surveying and mapping to infrastructure planning for urban development and road construction.

Expectations exceeded

The quality of the global elevation model has surpassed all expectations. Exceeding the required 10-metre accuracy, the topographic map has an elevation accuracy of a single metre. This is a result of excellent system calibration. The distance between the two satellites in formation flight, for example, is determined with millimetre precision. The global coverage achieved by TanDEM-X is also unparalleled – all land surfaces were scanned multiple times and the data was then processed to create elevation models. In this process, DLR's remote sensing specialists created a digital world map consisting of more than 450,000 individual models with pixel by pixel height detail – creating a special kind of three-dimensional mosaic.

This mission broke new ground in many areas. The close formation flight of the two satellites at a minimum distance of 120 metres has become as routine as the various manoeuvres required to continuously change the formation and adapt it to the requirements of the imaging geometry. A similar situation applies to bistatic radar operation; simultaneous data acquisition using two radar satellites was initially a major challenge, but was a necessity to ensure the high accuracy of the elevation models. DLR is now a world leader for this pioneering technology.

An­i­ma­tion: Ele­phant Foot Glacier in north­ern Green­land
Glacier struc­tures in Crown Prince Chris­tian Land in the North­east Green­land Na­tion­al Park, the largest na­tion­al park in the world. The Ele­phant Foot Glacier is an al­most per­fect­ly formed ex­am­ple of a Pied­mont glacier that is part of a larg­er glacier net­work.
Credit: DLR

Between January 2010 and December 2015, the radar satellites transmitted more than 500 terabytes of data to Earth via the worldwide reception network. In parallel, systematic creation of elevation models began in 2014. Sophisticated processing chains analysed the data using highly accurate and efficient algorithms to generate the final elevation models. During this process, the data volume increased to a total of more than 2.6 petabytes and the computer systems constantly delivered top performance. "Processing this data was an exciting challenge for us," explains Richard Bamler, Director of The Re­mote Sens­ing Tech­nol­o­gy In­sti­tute (IMF). "We are now all the more fascinated by our initial scientific findings. Using the current elevation model, we have shown that in some regions of Earth, glaciers are losing up to 30 metres in thickness per year in the area of the glacier tongues."

Next steps

TerraSAR-X and TanDEM-X have long exceeded their specified service lives and continue operating faultlessly and in such an efficient way that they still have enough propellant for several more years. Completion of the 3D world map does not signify the end of the mission. Due to the special nature of the formation flight, further scientific experiments are scheduled. Moreira points out: “Earth as a system is highly dynamic, which is also reflected in its topography. Through frequent updates, we could capture such dynamic processes systematically in the future. This is the primary goal of the Tandem-L mission that we have proposed.”

New Synthetic Aperture Radar (SAR) methods will enable diverse data for exploration of the global ecosystem to be provided within short periods of time. The Tandem-L successor mission could provide a current elevation image of Earth’s entire landmass every eight days and thereby capture dynamic processes in a timely manner. This would also make it possible to contribute to the review of international climate and environmental agreements. New radar methods and innovative missions such as Tandem-L are set to contribute to gaining a better understanding of dynamic processes in order to protect and preserve Earth Completion of the TanDEM-X global elevation model has now paved the way for the next dimension of radar remote sensing.

An­i­ma­tion: Namib-Nauk­luft Na­tion­al Park
The Sos­susvlei pan in Namib-Nauk­luft Na­tion­al Park, Namib­ia. An ar­royo breaks through the sand dunes of the Namib. The in­ter­est­ing struc­ture of the im­age is the re­sult of var­i­ous dune shapes that can be seen in high­ly de­tailed three di­men­sions thanks to the Tan­DEM-X el­e­va­tion mod­el.
Credit: DLR

About the mission

TanDEM-X is being implemented on behalf of DLR using funds from the Federal Ministry for Economic Affairs and Energy (Bundesministerium für Wirtschaft und Energie). It is a Public Private Partnership (PPP) project operated in conjunction with Air­bus De­fence and Space. DLR is responsible for providing TanDEM-X data to the scientific community, mission planning and implementation, radar operation and calibration, control of the two satellites, and generation of the digital elevation model. To this end, DLR has developed the necessary ground-based facilities. The DLR Microwaves and Radar Institute, the The Ger­man Re­mote Sens­ing Da­ta Cen­ter (DFD) and the DLR Space Op­er­a­tions and As­tro­naut Train­ing (RB) in Oberpfaffenhofen are participating in the development and operation of the ground segment of TerraSAR-X and TanDEM-X. Scientific coordination is the responsibility of the DLR Microwaves and Radar Institute. Airbus Defence and Space built the satellites and is sharing the development and operating costs. The company is also responsible for the commercial marketing of the TanDEM-X data.

Access to the TanDEM-X Digital Elevation Model (DEM) is restricted – DLR supplies the data free of charge to scientific projects. Interested parties must, however, demonstrate the scientific nature of their project with a proposal and submit it to DLR. All information about this can be found on the project website. Prospective commercial users of the data should contact DLR’s project partner, Airbus Defence and Space, where they can purchase the data.

The TanDEM-X mission dataset has been created by a public-private partnership. On the basis of this cooperation, DLR provides the data to the scientific community, while their industrial partner, Airbus, is responsible for commercial distribution. It is planned that the DTM will be made generally available at a lower resolution, so that processing of the data will also be possible with standard computer technology.

  • Bernadette Jung
    Com­mu­ni­ca­tions Ober­paf­fen­hofen, Weil­heim, Augs­burg
    Ger­man Aerospace Cen­ter (DLR)

    Com­mu­ni­ca­tions and Me­dia Re­la­tions
    Telephone: +49 8153 28-2251
    Fax: +49 8153 28-1243
    Münchener Straße 20
    82234 Weßling
  • Prof. Dr.-Ing. Alberto Moreira
    Ger­man Aerospace Cen­ter (DLR)
    Mi­crowaves and Radar In­sti­tute
    Telephone: +49 8153 28-2306
    Fax: +49 228 447-747
    Münchener Straße 20
    82234 Oberpfaffenhofen-Weßling
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