Details
| Original language | English |
|---|---|
| Pages (from-to) | 90-102 |
| Number of pages | 13 |
| Journal | Landscape and urban planning |
| Volume | 170 |
| Early online date | 16 Nov 2017 |
| Publication status | Published - Feb 2018 |
Abstract
Computational fluid dynamics (CFD) techniques, such as large-eddy simulation (LES), are widely used in urban ventilation studies. Unfortunately, realistic building data required in CFD studies are not always available. In this study, LES of urban ventilation is used to assess building height extraction from different satellite images. As a case study, three sets of digital elevation data extracted from satellite images in an urban area of Mong Kok, Hong Kong, are assessed. Simulations of velocity ratio from the LES model are first validated by wind tunnel measurements, yielding a recommended local roughness length of 0.02 m. Wind characteristics in urban elevations extracted from two single satellite images and the fused result are then compared with those from realistic data in the same area, using identical LES settings. It is found that building height data retrieved from the WorldView-2 optical (stereo) images are of poor quality, as they underestimate higher buildings, which are deemed to be more important for pedestrian-level velocity ratios. The TerraSAR-X synthetic aperture radar (SAR) image and the fused results of SAR and stereo images are sufficient for CFD simulations of urban ventilation. This fusion provides a slight improvement over SAR images alone in reproducing urban geometric parameters, and it is superior in simulating more accurate wind profiles in the urban canopy.
Keywords
- Building height extraction, High-density urban area, Large-eddy simulation, Urban ventilation
ASJC Scopus subject areas
- Environmental Science(all)
- Ecology
- Environmental Science(all)
- Nature and Landscape Conservation
- Environmental Science(all)
- Management, Monitoring, Policy and Law
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In: Landscape and urban planning, Vol. 170, 02.2018, p. 90-102.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Evaluation of satellite-derived building height extraction by CFD simulations: A case study of neighborhood-scale ventilation in Hong Kong
AU - Wang, Weiwen
AU - Xu, Yong
AU - Ng, Edward
AU - Raasch, Siegfried
N1 - Publisher Copyright: © 2017 Elsevier B.V.
PY - 2018/2
Y1 - 2018/2
N2 - Computational fluid dynamics (CFD) techniques, such as large-eddy simulation (LES), are widely used in urban ventilation studies. Unfortunately, realistic building data required in CFD studies are not always available. In this study, LES of urban ventilation is used to assess building height extraction from different satellite images. As a case study, three sets of digital elevation data extracted from satellite images in an urban area of Mong Kok, Hong Kong, are assessed. Simulations of velocity ratio from the LES model are first validated by wind tunnel measurements, yielding a recommended local roughness length of 0.02 m. Wind characteristics in urban elevations extracted from two single satellite images and the fused result are then compared with those from realistic data in the same area, using identical LES settings. It is found that building height data retrieved from the WorldView-2 optical (stereo) images are of poor quality, as they underestimate higher buildings, which are deemed to be more important for pedestrian-level velocity ratios. The TerraSAR-X synthetic aperture radar (SAR) image and the fused results of SAR and stereo images are sufficient for CFD simulations of urban ventilation. This fusion provides a slight improvement over SAR images alone in reproducing urban geometric parameters, and it is superior in simulating more accurate wind profiles in the urban canopy.
AB - Computational fluid dynamics (CFD) techniques, such as large-eddy simulation (LES), are widely used in urban ventilation studies. Unfortunately, realistic building data required in CFD studies are not always available. In this study, LES of urban ventilation is used to assess building height extraction from different satellite images. As a case study, three sets of digital elevation data extracted from satellite images in an urban area of Mong Kok, Hong Kong, are assessed. Simulations of velocity ratio from the LES model are first validated by wind tunnel measurements, yielding a recommended local roughness length of 0.02 m. Wind characteristics in urban elevations extracted from two single satellite images and the fused result are then compared with those from realistic data in the same area, using identical LES settings. It is found that building height data retrieved from the WorldView-2 optical (stereo) images are of poor quality, as they underestimate higher buildings, which are deemed to be more important for pedestrian-level velocity ratios. The TerraSAR-X synthetic aperture radar (SAR) image and the fused results of SAR and stereo images are sufficient for CFD simulations of urban ventilation. This fusion provides a slight improvement over SAR images alone in reproducing urban geometric parameters, and it is superior in simulating more accurate wind profiles in the urban canopy.
KW - Building height extraction
KW - High-density urban area
KW - Large-eddy simulation
KW - Urban ventilation
UR - http://www.scopus.com/inward/record.url?scp=85034456520&partnerID=8YFLogxK
U2 - 10.1016/j.landurbplan.2017.11.008
DO - 10.1016/j.landurbplan.2017.11.008
M3 - Article
AN - SCOPUS:85034456520
VL - 170
SP - 90
EP - 102
JO - Landscape and urban planning
JF - Landscape and urban planning
SN - 0169-2046
ER -