Mapping urban green – The capabilities of remote sensing data with spatial resolutions from 10 meters to 10 centimeters

Kurzfassung

Urban green plays a vital role in the urban ecosystem, providing benefits for society, ecology and economy. Particularly in cities, urban green infrastructure mitigates the urban heat island effect, promotes air quality and biodiversity, and provides spaces for recreation and leisure, among others. Despite these positive effects, detailed spatial information on urban green is still limited in many cities in Germany as well as worldwide. Against this background, remote sensing provides a cost-effective source of data for area-wide derivation of detailed information on green infrastructure in cities. This contribution aims at the presentation of different sources of remote sensing data with spatial resolutions from 10 meters to 10 centimeters for mapping urban green. In this work, we present an approach for land cover and vegetation classification based on free and open data from the Copernicus Sentinel-2 mission. In addition, we demonstrate capabilities of satellite based remote sensing with very-high spatial resolution (VHR) of less than one meter for urban green mapping. The derived information from VHR data can also be combined with imagery of coarser spatial resolution for vegetation fraction mapping using regression techniques. Finally, we showcase aerial imagery and a derived canopy height model with highest spatial resolution of 10 centimeters for detection and delineation of single trees in cities. Throughout, the presented approaches retrieved vital accuracies in the order of 80 to 90 % overall accuracy. While satellite-based imagery from the Sentinel-2 mission is available through a free, full and open data policy for the entire globe, the availability of VHR imagery is still limited due to data costs and spatial coverage. The use of aerial imagery is facilitated by municipal and federal administrations, who conduct regular acquisition of such data and enable its use at reasonable costs or make the data available free of charge. The wide range of remote sensing-based information on urban green not only facilitates the municipal management of green spaces, but also enables sustainable urban planning and informed decision-making in cities.