The mountain calls –
the satellite responds

Nearly as beautiful as being there:
3D maps for alpinists

Off to the mountains. But where are the best hiking routes, skiing regions, or mountain bike tours? And how are things on the spot? What is the height profile of a tour, are the inclines not too steep?

Previously the task was to decipher existing hiking maps with the expert’s eye without overlooking details. To derive the correct conclusions on
the respective incline from the contour lines. Or to go there and see for
oneself – hit or miss.

Now Earth observation by satellites lays the foundation for better “deciphering” of mountains, i.e. with 3D maps and 3D apps, not
only used by mountaineers.

The most beautiful regions of the Alps – photo-realistic in 3D: available as “3D Outdoor Guides” by 3D RealityMaps. Their premium version includes 4,000 edited tours. Thus possible: before starting the tour, checking whether route and height profile match one’s own stamina. Mountain rescue also benefits from these 3D maps. The technology behind it? German space research, first deployed on Mars and then on the Mount Everest.

Mighty in 3D: Mount Everest. The “roof of the world”, since 2011 available as interactive 3D map with a resolution of 50 centimetres – both online and as app. All set for digital ascent. To create the 3D images, a cooperation between the DLR Institute of Robotics and Mechatronics (software for the 3D models), 3D RealityMaps (depiction software), and DigitalGlobe (data from the optical Earth observation satellites WorldView 1 and WorldView 2) had been established, complemented by images taken by the German satellite system RapidEye. The trick of the DLR software: 2D satellite images from different viewing angles are put on top of each other, and subsequently 3D surface models are calculated.

Apps for skiing areas: 3D-piste plan with opening hours as app, shown here for the Dolomiti Superski skiing area with 1,200 piste kilometres. Thanks to 3D, one can well assess if a blue piste is really harmless. And through routing plus inclusion of webcams and opening hours, a day in the mountains can be better planned.

Finding locations for renewable energies from space: the generation of electricity and heat with renewable energies is to be greatly extended. However, there is no sound data available regarding suitable locations. The Cop4EE project develops the solution: automated location search and assessment based on satellite data. In this way, wind power plants, solar plants, cultivation areas for energy crops as well as locations for biogas plants and district heating networks could be planned and discussed quickly and transparently. The picture shows an evaluation for the surroundings of Bitburg. For instance, the yellow fields show suitable locations for photovoltaics.

Is the winter trip worth it?
Is there any snow?

Snow heights are traditionally measured with a metre stick – or more
state-of-the-art with a firmly installed snow height sensor. Both methods are
very precise; however, they are nothing but spot tests. Even snowdrifts
may result in false measuring results. Especially the monitoring of snow
height trends – important for travel planning and in particular for climate
research – continuously requires reliable data on large regions or all over the
world to detect long-term changes based on time series.

With technically sophisticated combinations of optical, temperature and
radar data from space – and the suitable mathematical models – meteorologists can measure the extension of snow and ice surfaces as well as their changes in order to draw up a world map of snow coverage, for example – even where nobody measures the snow parameters (for instance type and age of snow), like in Siberia or the Tibetan high plateau.

The data for this purpose is provided, for example, by the instruments on board the Sentinel satellites of ESA’s Copernicus programme. In addition, this data enables supporting large-scale snow situation reports and forecasts for winter athletes.

Effective avalanche warning: a Norwegian project, co-financed by ESA, uses satellite data (Sentinel-1) for automated software-aided detection of avalanches. The trick: the huge number of avalanche data, in combination with other data (temperature, hillslope), enables a functioning avalanche forecast, with a precision of up to 82 per cent. It has been in operation in Norway since winter 2017. The service should be made possible worldwide. That could save many lives; in the Alps alone, about 100 persons die every year in avalanche disasters.

Making power predictions based on snow data: in the mountains, there are many hydropower stations that are fed by lakes. There, melting water accumulates. If energy providers monitor the snow occurrence and calculate the melting rate using weather data, they can predict how much power the hydropower stations will deliver within the next days – depending on the snow melt. This information is also valuable for early warning of flood water. It is established by Vista from Wessling near Munich, a company cooperating with DLR and ESA and using satellite data (e.g. radar data from Sentinel-1 and optical data from Sentinel-2).

Technology from outer space: 3D images, first on Mars, subsequently on Earth

The basics for 3D visualisation of the Earth’s surface have emerged from DLR’s space research. Initially, the task was to map Mars (using the high-resolution stereo camera HRSC developed by the DLR Institute of Planetary Research). If the climate there was more convenient, and the trip was not that elaborate, Mars would be a paradise for alpinists. Take the mountain “Olympus Mons” alone. With a height of 26,000 metres, it is the highest mountain of our solar system. However: there is no beautiful summit, which seems to be rather flat despite of its height due to its diameter of 600 kilometres.

A novel procedure for 3D processing of stereo images has been developed at DLR’s Institute of Robotics and Mechatronics. 3D RealityMaps GmbH participated in the development as an industry partner.

The technology:
detecting ice and snow from space

Humans can easily recognise snow with their eyes. And so can satellites – but more precisely. Certain kinds of snow and ice, such as glacier ice, for example, reflect the light in the infrared range as well. By superposition and evaluation of satellite images taken in small wavelength ranges of light, software is capable of recognising what is snow, what is corn snow, and what is glacier ice. This enables automated monitoring of glaciers or, unfortunately, mostly their shrinking and disappearing caused by global warming, respectively. With data from the Sentinel satellites, today snow detection is possible.

From 2023, the detection will further improve: with the instrument METImage, some kind of camera. It has been designed mainly for capturing clouds; however, it is also capable of detecting ice and snow.

METImage is a multi-spectral, imaging radiometer, developed by
Airbus Defence and Space on behalf of the DLR. It will be carried on board a weather satellite (EUMETSAT Polar System – Second Generation). In
20 spectral channels at the same time and at a resolution of 500 metres, METImage will capture a band with a width of 2,670 kilometres, providing, among other things, important information on clouds, cloud coverage, and land surfaces, as well as on ocean, ice, and land surface temperatures. In this way, weather and climate forecasts will arrive at a new quality level.

Other satellites also provide data regarding the monitoring of snow and ice:

TanDEM-X: volume and mass changes of glaciers and ice caps
GRACE, GRACE-FO: imminent mass changes of glaciers and ice caps
Sentinel-1 and -2, TerraSAR-X and TanDEM-X: expansion and flow speed of glaciers
Sentinel-1 and -2: expansion and movement snow fields
Sentinel-3: measuring of elevation (and monitoring of changes in thickness) of glaciers and icebergs
Sentinel-1, TerraSAR-X and TanDEM-X: grounding lines of shelf ice
CryoSat-2: changes in height, sea ice expansion, and thickness

You don’t feel like snow anymore? Satellites can also detect spring

Not everyone fond of nature or mountains loves snow. Those who plan the first spring hike want to see the eagerly awaited green and first blossoms, and do not want to walk through grey snow residues. But where are the blossoms?

Spring can be detected from space. The catchword: net primary production. Satellite images show where and how much biomass was generated, i.e., how many leafs, buds, blossoms, and grasses have grown. Presently possibilities are created for consistent monitoring of biomass. This will help farmers to predict the yield from their fields more precisely and to avoid under- and overfertilisation.

The German Remote Sensing Data Center (DFD) of the DLR uses so-called vegetation models, i.e., methods that detect plant growth from space precisely – since the data has been previously compared to the results of field experiments.

This technology also enables striking insights: DFD scientists have calculated whether unused straw waste could be an interesting source of renewable energies. By means of the map for global “straw potential” drawn up by the DLR, it was rendered possible to detect the worldwide distribution and availability of energy from straw biomass. For the exemplary year of 2012, a global straw potential of about 55 million terajoules has been calculated. Theoretically, this would be sufficient for Germany to cover its entire primary energy requirements over a period of four years (or for the USA over half a year).

The mountain calls – the satellite responds

Nearly as beautiful as being there:3D maps for alpinists