Aerial Thermography for Energetic Modelling of Cities

Abstract

Abstract:The rising attention to energy consumption problems is renewing interest in the applications of thermal remote sensing in urban areas. The research presented here aims to test a methodology to retrieve information about roof surface temperature by means of a high resolution orthomosaic of airborne thermal infrared images, based on a case study acquired over Bologna (Italy). The ultimate aim of such work is obtaining datasets useful to support, in a GIS environment, the decision makers in developing adequate strategies to reduce energy consumption and CO2 emission. In the processing proposed, the computing of radiometric quantities related to the atmosphere was performed by the Modtran 5 radiative transfer code, while an object-oriented supervised classification was applied on a WorldView-2 multispectral image, together with a high-resolution digital surface model (DSM), to distinguish among the major roofing material types and to model the effects of the emissivity. The emissivity values were derived from literature data, except for some roofing materials, which were measured during ad hoc surveys, by means of a thermal camera and a contact probe. These preliminary results demonstrate the high sensitivity of the model to the variability of the surface emissivity and of the atmospheric parameters, especially transmittance and upwelling radiance.

Integration of Aerial Thermal Imagery, LiDAR Data and Ground Surveys for Surface Temperature Mapping in Urban Environments

“…This is mainly suggested by practical considerations about the estimation of the emissivity values for the different materials, because the use of a thermal camera for ground surveys, as discussed later, allows the determination of a single broadband value for each material. Differently from the study by Bitelli et al [9], however, the sky-view factor is fully considered here for the surface temperature retrieval.…”

“…This section summarizes the theoretical assumptions under the approach proposed in the Methods section. Following the formalism adopted by Bitelli et al [9], small letters indicate the spectral quantities (which are functions of the wavelength), while the broadband quantities, integrated or averaged over the spectral range to which the thermal camera is sensitive, are designated by capital letters.…”

“…The emissivity map, required for the correction of the entire mosaic of aerial images, was based on the object-oriented supervised classification presented in Bitelli et al [9], which was applied on a WorldView-2 multispectral image acquired in 2011, providing eight spectral bands at a resolution of 2 m. Five major roofing materials were distinguished: bitumen, clay, concrete, gravel and metal (Table 2). Where available, emissivity values were set according to field measurements, otherwise according to data published in the literature [9].…”

“…Starting from the conclusions by Bitelli et al [9], this work aims at achieving a better accuracy through the integration of LiDAR data and ground surveys for calibration purposes.…”

The evaluation and application of an urban land cover map with image data fusion and laboratory measurements

“…2014). Only a few studies applied high resolution thermal imagery for this purpose (Bitelli, G. et al 2015). Previously, for example Roman, K.K.…”