Cities are vital to the future of the global economy; at present, 70% of the world’s population live in cities. It is essential that our cities are sustainable, make minimal impact on the environment and offer increased quality of living for residents. Cities should be developed as whole systems, including urban planning, buildings and infrastructure.
Our cities are growing exponentially, but the land we have available is limited. Good planning allows cities to have a low environmental impact and encourages a high quality of life, as well as protecting residents against floods and other natural phenomena.
At the University of Leicester, we use a range of Earth observation techniques to aid urban planning. Our academics specialising in geography, physics and astronomy run projects that translate satellite data into usable information for businesses, monitoring tree coverage, land use and flood risk.
Managing the built environment
Urban areas are characteristically several degrees warmer than surrounding rural areas, a phenomenon known as the 'urban heat island' effect. In addition to the impacts of increased heat on the wellbeing of residents, it also intensifies air pollution, places a strain on water supply and increases energy consumption. Climate change has the potential to affect their frequency and magnitude, making it even more important to develop our understanding of the urban heat island effect.
Accurate thermal infrared data can be gained from satellite instruments, such as Landsat 7’s Enhanced Thematic Mapper, and used to map urban heat islands. The surface temperature information is combined with aerial photography, a transport network map and a land cover map in a computer based Geographical Information System (GIS). The GIS can be used in order to identify major ‘hot spots’ contributing to the urban heat island effect. This detailed thermal information is important for urban planning and management.
Automated tree mapping
Leicester City Council is using tree maps in order to measure the amount of tree canopy to plan healthier, more sustainable urban environments.
Traditional manual extraction of tree maps from aerial imagery is a labour intensive and time consuming process. We worked with local aerial photography company Bluesky to create tree maps using an automated classification scheme.
The procedure involves the use of high resolution aerial photography to provide information on land cover classes and LiDAR (Light Detection and Ranging) to provide accurate height data for the measurement of land cover structure. An aerial photograph of the same area is used to extract a greenness index, which is used to separate vegetation from non-vegetated areas. Objects are classified as trees using the elevation data and the greenness index derived from the aerial photograph.