Sky View Factor Calculation in Urban Context: Computational Performance and Accuracy Analysis of Two Open and Free GIS Tools

The sky view factor (SVF) has an important role in the analysis of the urban micro-climate. A new vector-based SVF calculation tool was implemented in a free and open source Geographic Information System named OrbisGIS. Its accuracy and computational performance are compared to the ones of an existi...

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Main Authors: Jérémy Bernard, Erwan Bocher, Gwendall Petit, Sylvain Palominos
Format: Article
Language:English
Published: MDPI AG 2018-07-01
Series:Climate
Subjects:
GIS
Online Access:http://www.mdpi.com/2225-1154/6/3/60
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spelling doaj-65078dcf02464c37800c8a1a3258727c2020-11-24T22:26:30ZengMDPI AGClimate2225-11542018-07-01636010.3390/cli6030060cli6030060Sky View Factor Calculation in Urban Context: Computational Performance and Accuracy Analysis of Two Open and Free GIS ToolsJérémy Bernard0Erwan Bocher1Gwendall Petit2Sylvain Palominos3CNRS, UMR 6285 Vannes, FranceCNRS, UMR 6285 Vannes, FranceUniversité de Bretagne Sud, UMR 6285 Vannes, FranceUniversité de Bretagne Sud, UMR 6285 Vannes, FranceThe sky view factor (SVF) has an important role in the analysis of the urban micro-climate. A new vector-based SVF calculation tool was implemented in a free and open source Geographic Information System named OrbisGIS. Its accuracy and computational performance are compared to the ones of an existing raster based algorithm used in SAGA-GIS. The study is performed on 72 urban blocks selected within the Paris commune territory. This sample has been chosen to represent the heterogeneity of nine of the ten Local Climate Zone built types. The effect of the algorithms’ input parameters (ray length, number of directions and grid resolution) is investigated. The combination minimizing the computation time and the SVF error is identified for SAGA-GIS and OrbisGIS algorithms. In both cases, the standard deviation of the block mean SVF estimate is about 0.03. A simple linear relationship having a high determination coefficient is also established between block mean SVF and the facade density fraction, confirming the results of previous research. This formula and the optimized combinations for the OrbisGIS and the SAGA-GIS algorithms are finally used to calculate the SVF of every urban block of the Paris commune.http://www.mdpi.com/2225-1154/6/3/60local climate zoneurban climatesky view factormorphological indicatoropen scienceGIS
collection DOAJ
language English
format Article
sources DOAJ
author Jérémy Bernard
Erwan Bocher
Gwendall Petit
Sylvain Palominos
spellingShingle Jérémy Bernard
Erwan Bocher
Gwendall Petit
Sylvain Palominos
Sky View Factor Calculation in Urban Context: Computational Performance and Accuracy Analysis of Two Open and Free GIS Tools
Climate
local climate zone
urban climate
sky view factor
morphological indicator
open science
GIS
author_facet Jérémy Bernard
Erwan Bocher
Gwendall Petit
Sylvain Palominos
author_sort Jérémy Bernard
title Sky View Factor Calculation in Urban Context: Computational Performance and Accuracy Analysis of Two Open and Free GIS Tools
title_short Sky View Factor Calculation in Urban Context: Computational Performance and Accuracy Analysis of Two Open and Free GIS Tools
title_full Sky View Factor Calculation in Urban Context: Computational Performance and Accuracy Analysis of Two Open and Free GIS Tools
title_fullStr Sky View Factor Calculation in Urban Context: Computational Performance and Accuracy Analysis of Two Open and Free GIS Tools
title_full_unstemmed Sky View Factor Calculation in Urban Context: Computational Performance and Accuracy Analysis of Two Open and Free GIS Tools
title_sort sky view factor calculation in urban context: computational performance and accuracy analysis of two open and free gis tools
publisher MDPI AG
series Climate
issn 2225-1154
publishDate 2018-07-01
description The sky view factor (SVF) has an important role in the analysis of the urban micro-climate. A new vector-based SVF calculation tool was implemented in a free and open source Geographic Information System named OrbisGIS. Its accuracy and computational performance are compared to the ones of an existing raster based algorithm used in SAGA-GIS. The study is performed on 72 urban blocks selected within the Paris commune territory. This sample has been chosen to represent the heterogeneity of nine of the ten Local Climate Zone built types. The effect of the algorithms’ input parameters (ray length, number of directions and grid resolution) is investigated. The combination minimizing the computation time and the SVF error is identified for SAGA-GIS and OrbisGIS algorithms. In both cases, the standard deviation of the block mean SVF estimate is about 0.03. A simple linear relationship having a high determination coefficient is also established between block mean SVF and the facade density fraction, confirming the results of previous research. This formula and the optimized combinations for the OrbisGIS and the SAGA-GIS algorithms are finally used to calculate the SVF of every urban block of the Paris commune.
topic local climate zone
urban climate
sky view factor
morphological indicator
open science
GIS
url http://www.mdpi.com/2225-1154/6/3/60
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