Products
In a first service, Urban Atlas maps (present ‘2010’ and historical ‘2003’) and the change map for Rosetta City (Egypt) are created using VHR (very high resolution) optical imagery (Quickbird (0,7m resolution), 2003 and WorldView-2 (0,5m resolution), 2010).
The Urban Atlas maps help to understand the past and present developments in the city. Land use and changes are analysed by the creation of statistics, graphics and indicators. The Urban Atlas provides an up-to-date digital urban reference layer. It provides a spatial view on the distribution of urban infrastructure and can thus be used as an input for urban planning. The map is a necessary step towards a good planning and management of the cities.
Figure : Urban Atlas maps; Rosetta (Egypt) (1/10.000) (background change map: Quickbird 2003)
In a second service, HR (high resolution) Landsat images of years 2011, 2002, 1984 (30m resolution) and 1972 (60m resolution) are used to develop urban extent and land cover maps; these provide an assessment of the regions’ land cover changes. A pixel-based classification approach in combination with manual delineation of masks (e.g. urban extent maps) is used to carry out this HR land cover mapping.
The HR urban extent and land cover maps, produced by EUROSENSE, enable an urban change analysis over the last 40 years. These maps can be used to monitor land cover conversion and general land take trends over several time periods.
Figure : HR Land cover maps (1972-1984-2002-2011) showing the cover conversion and general land take trends over a time period of 40 years (background: Landsat imagery)
Lessons Learned
Although the thematic detail of the Urban Atlas is highly dependent on the availability of ancillary data (of which the acquisition is often difficult and time consuming), visual image interpretation of VHR data already offers a valuable amount of info on the land use. As the used legend is easily adaptable, the availability of reliable ancillary information (high scale topographic maps, GCP’s…) will lead to a more detailed map while still maintaining the same thematic accuracy.
The area of interest (Rosetta, Egypt) is known to be highly affected by coastal erosion during the past decades. A pattern of coastal erosion (the regression of the shore line) could already be detected by using the HR Land cover maps. Earth Observation can be a valuable tool to do a more detailed and quantitative analysis.
The SCARABE project is one of the service trials of the Gazelle project (http://plangazelle.info). This project belongs to the EOMD programme (Earth Observation Market Development) which is devoted to foster the use of geoinformation products and services within new markets and sectors. The aim of Gazelle is to analyse the current situation of EO sector in the Mediterranean Africa (Algeria, Egypt, Libya, Morocco and Tunisia) in order to draw a Strategic Plan to steer activities during the following 5 years. The project is financed by ESA and lead by Indra (Spain).