Map compiling and map updating

Context

Highly developed areas of the world have been mapped to a very high accuracy and precision, using ground and aerial surveying methods which are on the whole expensive and labour intensive. However, particularly in the frontier regions where an impact from human development is being felt, the land's topography is still poorly mapped and any existing maps are out-of-date or of insufficient scale. A cost-effective method is required for the production of new maps, and updating old ones.

The world's mapping industries are currently experiencing rapid technological and organisational change. Increasingly, information is needed in digital formats enabling sophisticated analysis to be undertaken, producing products such as digital terrain models, over which land cover information can then be draped. Digital data are also of great value in the rapidly expanding market for GISs, which are now being used extensively to integrate data from different sources for land management, monitoring and planning.

Contents

The various techniques used in cartography which utilise SAR data are covered in:

• Updating maps using SAR

Other applications which monitor land use, and projects which derive agricultural statistics are covered in Monitoring Land Use, Forestry and Agriculture. Under suitable conditions, the bathymetry of shallow seas can be mapped using SAR - refer to Coastal Zone Monitoring and Management for more details. Geological mapping is carried out using SAR - the exploitation of mineral and hydrocarbon deposits using these techniques is covered in Exploitation of Natural Resources.

Updating maps using SAR

Illustration: Land surveying equipment

The cartography market has always been important in the development of commercial applications of EO data, and ERS is no exception. The use of ERS-1 SAR data is providing a marked improvement in the accuracy of maps produced for developing countries. The SAR data are being combined with data from optical sensors such as SPOT to help increase the thematic and in particular the geolocation accuracy of the latter. The use of interferometric techniques for the production of digital elevation models is potentially a major application of SAR data. Topographic maps are being compiled from ERS data for areas of the world not previously mapped because of their remote location and high frequency of cloud coverage. This information is of value to a range of activities, from managing land-use development to planning logistics of deposit exploration.

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