Please use this identifier to cite or link to this item:
Title: Modeling the effective emissivity of the urban canopy using sky view factor
Authors: Yang, J
Wong, MS 
Menenti, M
Nichol, J 
Keywords: Effective emissivity
Remote sensing
Urban geometry
Issue Date: 2015
Publisher: Elsevier
Source: ISPRS journal of photogrammetry and remote sensing, 2015, v. 105, p. 211-219 How to cite?
Journal: ISPRS Journal of Photogrammetry and Remote Sensing 
Abstract: Surface emissivity is a critical parameter for studying city-, meso-, and micro-scale climate and energy balance. The emissivity of complex surfaces e.g. a forest or an urban canopy is an effective surface property since it depends on both surface materials and geometry. This study presents a novel methodology for estimating effective emissivity using sky view factor retrieved from airborne Lidar data, building GIS data, and land use and land cover classification data. First, a high correlation between the effective emissivity retrieved from ASTER TIR bands 10-14 and the sky view factor was observed (r2=0.93, 0.99, 0.99, 0.97, 0.97). When the sky view factor decreases, the effective emissivity tends to increase, which is mainly due to multiple scattering (cavity effect), thus increases the effective emissivity. A simplified model which assumes that reflection and scattering only occurs within a single pixel was developed. Results showed that the correlations between the modeled and the spectral (band) emissivity retrieved from the ASTER multispectral TIR data (five spectral bands) are high (r2=0.93, 0.99, 0.98, 0.93, 0.97), and with low RMSE (0.019, 0.016, 0.012, 0.003 and 0.004 from band 10-14 respectively). The emissivity derived from this simplified model, however, tends to be overestimated in band 10-12. Thus, a refined urban emissivity model based on sky view factor (UEM-SVF) which considers the scattering and reflection from adjacent pixels was developed in this study. Results show a good agreement with ASTER spectral (band) emissivity: r2=0.90, 0.98, 0.96, 0.94 and 0.96, and very low RMSE (0.006, 0.003, 0.004, 0.002 and 0.004). This study illustrates that the UEM-SVF can be useful for estimation of land surface emissivity of complex surfaces, and can further be used for accurate land surface temperature retrieval.
ISSN: 0924-2716
DOI: 10.1016/j.isprsjprs.2015.04.006
Appears in Collections:Journal/Magazine Article

View full-text via PolyU eLinks SFX Query
Show full item record


Last Week
Last month
Citations as of Aug 10, 2018


Last Week
Last month
Citations as of Aug 18, 2018

Page view(s)

Last Week
Last month
Citations as of Aug 20, 2018

Google ScholarTM



Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.