Urban surfaces studied by VIS/NIR imaging from UAV: Possibilities and limitations

Abstract

The present research approach aims at analyzing the relation between material properties and their thermal behavior using airborne multispectral imaging in VIS/NIR and IR with sensors mounted on Unmanned Aerial Vehicle (UAV). As a follow up to a pilot study from spring 2016, a survey including several flights spanned over three days, from early morning before sunrise until late evening after sunset, was carried out in Athens in June 2017. The camera specifications for the survey in 2017 were different than the ones used in 2016. The performance of the cameras was evaluated, taking into account atmospheric correction. The images have been combined to form maps of surface temperature distribution and material physical properties. The VIS/NIR images were used to classify the different surface materials, to compute a map of estimated albedo, and to construct a 3D-model of the area. By combining thermal maps with material classification, albedo information and local weather data, thermal material properties could be characterized for the various materials. The derived properties from this dataset yield valuable information for improved simulation models of urban climate.