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Real Time Mosaics

Luca Mellano(1) and Luigi Scozzafava(1)

(1) CHELYS srl, Via Erasmo Gattamelata 3, 00176 Rome, Italy

Abstract

The importance of satellite data is becoming greater every day thanks to technological progress that has made technology which once could only be obtained through the use of supercomputers, available to the general public. Today, public networks (Internet) allow us to transmit huge amounts of data in a way that permits the distribution of satellite images which, due to their dimensions, could only be distributed on physical media (DVD, Tapes, etc.) until a few years ago. At present, new 3D visualization tools (Google Earth™, NASA WorldWind, etc.) allow us to depict information with a completely new appearance and to interact with it in a more intuitive way. All this, in addition to an increased sense of global awareness, has increased interest in images of our planet as seen from space. Natural or environmental disasters, global warming, deforestation, desertification and meteorological phenomena can now be observed directly and at the same moment in which they occur. Satellite missions have now collected enough data to comprehend the evolution of such phenomena over time. Now, everyone has the possibility to realize how our planet has changed and is changing. The relevance of this data is not of interest only to scientists and researchers but also to a public made up of a continuously growing number of users that now can and want to understand what is happening. For years, the European Space Agency has represented a point of reference in this sector with a commitment to research and to the sharing of information that has allowed the development of services linked to taking advantage of the data from the satellite missions it manages. In the field of earth observation and distributing satellite imagery, Chelys has developed and provided ESA with a system that generates high resolution images in real time, MIRAVI. This has allowed ESA to take advantage of high resolution images as never before, making them available just a few minutes after the data reaches the Earth. Everything is accessed through a fast and intuitive web interface. The speed of generation and the systematic generation of the images (every satellite pass is elaborated in a data-driven way as soon as is it downloaded to ground, therefore there is no need to ask for processing) has allowed us to create an additional service for generating Mosaics in real time (MOSRI). The themed mosaic is made of the projection (usually cylindrical) of many images which are combined together in order to obtain a continuous, homogeneous map of a determined zone on Earth (or of the entire Earth). The mosaics generated by MOSRI system are of two essential types: mosaics at medium or high resolution without cloud cover mosaics at medium or high resolution with cloud cover For every single image generated by the Envisat/MERIS sensor, the MOSRI software proceeds to calculate the projection, remove the clouds and make a combination with the images elaborated previously. The two types of mosaics are available just a few seconds after the generation of the Miravi images and can be viewed as single images or “navigated” using software like Google Earth™ o NASA WorldWind. In particular, using these two tools, it is possible to combine dynamic images generated in real time with themed historicized mosaics in order to be able to analyze variations which have occurred over time due to natural causes (seasons) or to climatic changes and disasters (floods, desertification, deforestation, global warming, etc.).

 

Workshop presentation

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry