Satellite Remote Sensing

Satellite Remote Sensing

By detecting and monitoring the physical characteristics of an area, Remote sensing measure its reflected and emitted radiation at a distance. Special cameras collect remotely sensed images, which help "sense" things about the Earth.

Cameras on satellites take images of large areas on the Earth's surface, allowing us to see much more than we can see when standing on the ground.

Different part of the spectrum are sensed with different sensors, as an example the MultiSpectral Instrument (MSI) Instrument on boards Sentinel 2 satellite allows to acquire data with 13 bands in the visible, near infrared, and short wave infrared part of the spectrum.

Optical imaging 

Optical products, thanks to their high revisit time and open accessibility in the case of Sentinel or Landsat missions,  allows the continuos monitoring of the Land Cover of the urban areas and to study the interaction between the urbanized environment and its rural surrondings.

Thermal imaging sensors measure the radiation emitted by a surface and allow the creation of mosaics describing the object's temperature.

Thanks to the TIRS sensor mounted on Landsat 8 & 9 and in particular thanks to Band 10 and Band 11 the Land Surface Temperature (LST) can be retrieved and utilized for further analysis and monitoring of the status of a city.  Analyzing the time series of retrieved LST, robust estimation of the hotspots within the city can  be identified.

Hyperspectral satellite sensors: PRISMA  & EnMAP

Hyperspectral sensors enable the acquisition of images with hundreds of spectral bands in the visible and non-visible spectral ranges. By analysing the spectral signatures of the objects and applying machine learning algorithms, information is extracted for geological applications (i.e. mineral mapping and monitoring of polluted sites), urban green mapping (i.e. tree species, identification of invasive species, health status analysis and quantification of biophysical metrics), urban material classification (i.e. roof and ground materials, presence of pollutant like asbestos), water quality analysis and so on. 

The high-resolution space and spectral satellites have changed the way we consider the environment and the environmental phenomena. This is the case of PRISMA (Hyperspectral Precursor of the Application Mission), a cutting-edge Earth observation system, equipped with electro-optical tools, which integrates a hyperspectral sensor with a medium-resolution camera, sensitive to all colors (panchromatic). 

EnMAP provides unique data needed to address major environmental challenges related to human activities and climate change. The mission’s main objective is to provide high-quality, regional scale hyperspectral data to improve our understanding of coupled environmental processes and to assist in the sustainable management of Earth’s resources. Despite being a primarily scientific mission, EnMAP has clear potential to evolve into an operational service.

Satellite and Airborne Data Fusion

To take advantage of the high geometric and temperature resolution of the airborne-based products and the high revisit time of satellite images, a downscaling procedure to improve the geometric resolution of satellite thermal data is developed. The method would allow, accepting some error on the estimation of LST, to retrieve airborne-like thermal products for every cloudless revisit acquisition of a thermal satellite.