Articles for "TanDEM-X"

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Space | 22. March 2021 | posted by Manfred Gottwald

Using principles from painting – creating 3D-effect satellite images in true colour

Die physische Karte des Nördlinger Ries, abgeleitet aus einem farbkodierten, schräg beleuchteten digitalen Höhenmodell von TanDEM-X
Credit: © DLR
A physical map of the Nördlinger Ries, derived from a colour-coded, diagonally illuminated digital elevation model created using data acquired by TanDEM-X

How can an impression of three-dimensionality be created using a two-dimensional medium? In art, this question arose centuries ago. Certain painting techniques have since evolved to simulate effects of light and shadow, creating a 3D effect for the viewer. Such effects are referred to as trompe-l'œil – they 'deceive the eye'.

Earth observation satellites with multispectral sensors provide images in natural colours when their red, green and blue (RGB) channels are combined. However, they tend to appear somewhat 'flat'. To turn them into attractive, three-dimensional representations, they must first be 'transformed' into three dimensions. This can be achieved if we use proven methods from art as a guide in science, but this requires elevation information. read more

Space | 09. September 2020 | posted by Mattia Marconcini

World Settlement Footprint - Where do humans live?

Credit: DLR (CC-BY 3.0)
WSF2015 - Subset including India and vast part of Eastern and South Eastern Asia

After three years of meticulous data processing and comprehensive quality control, the World Settlement Footprint 2015 is now available. With a resolution of 10 metres, the new world map reveals settlement structures on Earth in 2015. read more

Space | 25. October 2019 | posted by Bernadette Jung

TerraSAR-X/TanDEM-X Science Meeting 2019: Monitoring very slow landslides from space


left image: ALOS-2 data (JAXA); centre image: modified Copernicus Sentinel data; right image: Terra-SAR-X data (DLR); prozessing each: by Gamma Remote Sensing and SUPSI

Loderio landslide (Switzerland): The colored dots mark the deformations over the course of a year. Three radar satellites and results in comparison: ALOS-2 PALSAR-2 data from 2014 to 2018 (left), Sentinel-1 data from 2014 to 2018 (center) and TerraSAR-X data from 2014 to 2017 (right). The data were processed using a special procedure called multi-temporal SAR interferometry.

Global change is no more a secret – neither is the annual TerraSAR-X and TanDEM-X Science Meeting at DLR Oberpfaffenhofen! High-level experts from all over the world presented the latest state of research from 21 to 24 October 2019 and point the way for future technologies in satellite-based remote sensing. Data source and mutual starting point are the two radar satellite missions TerraSAR-X and TanDEM-X. They provide indispensable data for environmental and climate research, for a better understanding of our earth. The applications are correspondingly diverse. The main research areas include forest, ocean, urbanization, ice cover, glacier, geohazards, agriculture, archaeology and technology development.

In the DLR-Blog we introduce some of the work presented at this year's science meeting. The short examples provided outline how the data of the German radar satellites support researchers worldwide

Over Switzerland, hazards due to slope instabilities affect about six percent of the territory. Particularly in the Alpine areas, landslides repeatedly lead to disasters. It is therefore of outstanding importance to continuously monitor the rate of movement of landslides for risk assessment and to survey their activity over time. Satellite SAR interferometry (InSAR) is one option for surface deformation monitoring over large areas. Recently, various nationwide maps of land deformation have thus been released in Norway, Germany and the United Kingdom. In Switzerland there is also high interest in creating deformation maps and time series of surface movement using InSAR.

Invisible danger

The very high spatial resolution of TerraSAR-X data allows for observing "invisible" or very slow landslides as shown in the latest research by Tazio Strozzi, Rafael Caduff and Andrea Manconi from Gamma Remote Sensing AG and Christian Ambrosi from the University of Applied Sciences and Arts of Southern Switzerland (SUPSI).

They report: Our work was based on large datastacks on the Loderio landslide of in the Canton of Ticino. The Loderio landslide is an example of a very slow but large and active landslide – with movements rates of a few centimeters per year. We used multi-temporal interferometric approaches to process the radar data. Thereby we obtained meaningful results for satellite-based monitoring of landslides in the Alps.

Sparse urbanization, large vegetated areas, snow cover, shadows and layover, atmospheric stratification and summer turbulences pose major challenges for InSAR processing. In particular, we investigated the potential and limitations of current satellite SAR data with different carrier frequencies (L-, C- and X-band), ground resolutions (around 10, 20 and 2 meters), time intervals (46, 6 and 11 days) and acquisition strategies (global versus on-demand, free versus commercial data) for operational monitoring of the Alps.

Our results show that the L-band has an advantage when it comes to temporal decorrelation over vegetated areas and relatively fast movements. The long-wave frequency range is less affected here than are the C- and X-bands. For this reason, the fastest moving part of the Loderio landslide could only be detected with PALSAR-2 data from the Japanese earth observation satellite ALOS-2. On the other hand, the C- and X-band are more sensitive to the very slow moving sectors of the landslide. Then TerraSAR-X data are preferred: they offer a high-precision spatial resolution, so we obtain a higher density of measurement points and are thus able to study local phenomena.

Space | 12. December 2018 | posted by Manfred Gottwald

TanDEM-X image of Hiawatha Glacier

Credit: DLR
TanDEM-X radar amplitude image of the region around Hiawatha Glacier. The apparent texture is due to the surface structure of the ice and its dynamics.

Glaciers abound on Greenland's coastline; fed by the Greenland ice sheet, they flow towards the Arctic Ocean. In the northwest, Hiawatha Glacier is located at 78.8 degrees north, 67 degrees west. It emerges from a semi-circular lobe at the ice sheet margin and forms a narrow tongue with a length of 10 kilometres extending onto the ice-free Inglefield Land. Hiawatha Glacier’s northern neighbour, the large Humboldt Glacier, is much more widely known. The front of the Humboldt Glacier is over 100 kilometres wide where it flows into the Nares Strait. The TanDEM-X image shows the region around Hiawatha Glacier.

Recently, however, Hiawatha Glacier has received worldwide attention. Some years ago, radar measurements performed as part of NASA’s Operation IceBridge, a campaign to monitor changes in the polar ice caps, revealed a circular depression in the ground underneath the ice where Hiawatha Glacier emerges from the ice sheet. Subsequent surveying by an international research team using a more advanced airborne radar system on board the Polar 6 aircraft operated by the Alfred Wegener Institute (AWI) yielded a more detailed view of that bowl-shaped feature. With a diameter of 31 kilometres and a depth of more than 300 metres, it resembles impact craters on Earth or the solid surface of other celestial bodies. read more

Space | 10. October 2017 | posted by Kathrin Höppner

Larsen C – A giant in motion

Credit: Copernicus data (2017) / ESA
Displacement of the iceberg at the Larsen-C ice shelf between July and October 2017

The A68 iceberg has been making headlines again after calving from the Larsen-C in July 2017. What happened? It moved and shrunk minimally. And while that may not be unusual, it is still worth a blog post.

Close examination of satellite image sequences from the last two months reveals the striking events unfolding there. Remember, the 5800 square kilometre iceberg is seven times the size of Berlin and is permanently moving. The iceberg has collided repeatedly with the ice shelf, dislodging smaller pieces of ice. read more

Space | 19. October 2016 | posted by Bernadette Jung

How researchers use the latest Earth observation data – Part two

Elevation model of the mangrove forest region in the Sundarbans

In the second part of the series on the TerraSAR-X and TanDEM-X Science Meeting in Oberpfaffenhofen, we present further applications for satellite data. This time, for example, biomass is determined with the help of 'Earth observers from space'. Up until Thursday, 20 October 2016, international scientists will use the congress to show their research results on satellite-based Earth observation and to exchange ideas.

High above the swamp

Wet, warm and salty – the perfect habitat for mangroves. These tropical trees only feel at home in seawater or the brackish water of rivers. Together with other water-loving plants and shrubs, they can spread across entire forests or swamps. They offer protection against land loss through coastal erosion along seaboards and act as buffers to block storm surges and tsunamis. Around the world, mangrove forests account for an expanse of roughly 150,000 square kilometres. This equates to an enormous quantity of biomass – plant constituents that act as natural carbon reservoirs and that influence the climate. But exactly how much biomass is stored in these forests? And what about the inaccessible areas? read more

Space | 19. October 2016 | posted by Bernadette Jung

How researchers use the latest Earth observation data - Part one

KIOST inertial DEM
Elevation model of coastal area

Researchers from across the globe are in Oberpfaffenhofen for the TerraSAR-X and TanDEM-X Science Meeting. For four days, from 17 to 20 October 2016, they have the opportunity to present their results from the data acquired by the two Earth observation satellite missions and exchange information. Here, approximately 200 presentations give an overview of the latest research in satellite-based Earth observation. The radar data are used in various scientific fields, from climate research to geosciences to forestry, infrastructure planning and remote sensing methodology.

Covering the Science Meeting, the Space Blog presents some of the work presented. The short examples provided outline how the data of the German radar satellites support researchers worldwide. read more

Space | 30. July 2013 | posted by Ralph Kahle

Formation swapping - Comic about the TanDEM-X mission

An exciting manoeuvre awaits us. In early August (6–8 August 2013), the two TanDEM-X mission satellites will be reversing their formation. Until now, the TanDEM-X satellite has been circling around its twin, TerraSAR-X, in an anti-clockwise direction; after the reversal, it will circle clockwise. read more