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Author Zhao, M.; Zhou, Y.; Li, X.; Cheng, W.; Zhou, C.; Ma, T.; Li, M.; Huang, K. url  doi
openurl 
  Title Mapping urban dynamics (1992–2018) in Southeast Asia using consistent nighttime light data from DMSP and VIIRS Type Journal Article
  Year 2020 Publication Remote Sensing of Environment Abbreviated Journal Remote Sensing of Environment  
  Volume (down) 248 Issue Pages 111980  
  Keywords Remote Sensing  
  Abstract The long-term urban dynamics at regional and global scales is essential to understanding the urbanization processes and environmental consequences for providing better scientific insights and effective decision-making. The time series of consistent nighttime light (NTL) data generated by integrating the Defense Meteorological Satellite Program-Operational Linescane System (DMSP-OLS) and the Suomi National Polar-Orbiting Partnership Visible Infrared Imaging Radiometer Suite (NPP-VIIRS) provide a longer consistent record of the nightscape beyond a single dataset for monitoring urban dynamics. In this study, we developed a new framework based on the spatial variation of NTL gradient (SVNG) to map urban dynamics in Southeast Asia using the consistent NTL data (1992–2018). First, we identified the potential urban clusters in the region using the cluster-based segmentation approach in 2018. Second, we applied the SVNG framework in each potential urban cluster to extract the initial annual urban extent from corresponding time-series NTL images (1992–2018). Finally, we performed a temporal consistency check on the initial urban extent to obtain the final urban sequence in Southeast Asia. The evaluation on the spatiotemporal patterns and consistency of urban dynamics using other urban products indicates that the SVNG framework can effectively capture the urban dynamics in areas with different development levels and patterns. Moreover, we investigated urban dynamics in Southeast Asia at the local, national, and regional scales. This study opens new research avenues for monitoring and understanding the long-term urban dynamics and the pathways of urban growth from local to global scales.  
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  Corporate Author Thesis  
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  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0034-4257 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number GFZ @ kyba @ Serial 3114  
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Author Li, X.; Levin, N.; Xie, J.; Li, D. url  doi
openurl 
  Title Monitoring hourly night-time light by an unmanned aerial vehicle and its implications to satellite remote sensing Type Journal Article
  Year 2020 Publication Remote Sensing of Environment Abbreviated Journal Remote Sensing of Environment  
  Volume (down) 247 Issue Pages in press  
  Keywords Remote Sensing; Skyglow; Instrumentation  
  Abstract Satellite-observed night-time light in urban areas has been widely used as an indicator for socioeconomic development and light pollution. Up to present, the diurnal dynamics of city light during the night, which are important to understand the nature of human activity and the underlying variables explaining night-time brightness, have hardly been investigated by remote sensing techniques due to limitation of the revisit time and spatial resolution of available satellites. In this study, we employed a consumer-grade unmanned aerial vehicle (UAV) to monitor city light in a study area located in Wuhan City, China, from 8:08 PM, April 15, 2019 to 5:08 AM, April 16, 2019, with an hourly temporal resolution. By using three ground-based Sky Quality Meters (SQMs), we found that the UAV-recorded light brightness was consistent with the ground luminous intensity measured by the SQMs in both the spatial (R2 = 0.72) and temporal dimensions (R2 > 0.94), and that the average city light brightness was consistent with the sky brightness in the temporal dimension (R2 = 0.98), indicating that UAV images can reliably monitor the city's night-time brightness. The temporal analysis showed that different locations had different patterns of temporal changes in their night-time brightness, implying that inter-calibration of two kinds of satellite images with different overpass times would be a challenge. Combining an urban function map of 18 classes and the hourly UAV images, we found that urban functions differed in their temporal light dynamics. For example, the outdoor sports field lost 97.28% of its measured brightness between 8: 08 PM – 4:05 AM, while an administrative building only lost 4.56%, and the entire study area lost 61.86% of its total brightness. Within our study area, the period between 9:06 PM and 10:05 PM was the period with largest amount of light loss. The spectral analysis we conducted showed that city light colors were different in some urban functions, with the major road being the reddest region at 8:08 PM and becoming even redder at 4:05 AM. This preliminary study indicates that UAVs are a good tool to investigate city light at night, and that city light is very complex in both of the temporal and spatial dimensions, requiring comprehensive investigation using more advanced UAV techniques, and emphasizing the need for geostationary platforms for night-time light sensors.  
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  Corporate Author Thesis  
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  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0034-4257 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number GFZ @ kyba @ Serial 3014  
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Author Li, M.; Koks, E.; Taubenböck, H.; van Vliet, J. url  doi
openurl 
  Title Continental-scale mapping and analysis of 3D building structure Type Journal Article
  Year 2020 Publication Remote Sensing of Environment Abbreviated Journal Remote Sensing of Environment  
  Volume (down) 245 Issue Pages 111859  
  Keywords Remote Sensing  
  Abstract Urban land use is often characterized based on the presence of built-up land, while the land use intensity of different locations is ignored. This narrow focus is at least partially due to a lack of data on the vertical dimension of urban land. The potential of Earth observation data to fill this gap has already been shown, but this has not yet been applied at large spatial scales. This study aims to map urban 3D building structure, i.e. building footprint, height, and volume, for Europe, the US, and China using random forest models. Our models perform well, as indicated by R2 values of 0.90 for building footprint, 0.81 for building height, and 0.88 for building volume, for all three case regions combined. In our multidimensional input variables, we find that built-up density derived from the Global Urban Footprint (GUF) is the most important variable for estimating building footprint, while backscatter intensity of Synthetic Aperture Radar (SAR) is the most important variable for estimating building height. A combination of the two is essential to estimate building volume. Our analysis further highlights the heterogeneity of 3D building structure across space. Specifically, buildings in China tend to be taller on average (10.35 m) compared to Europe (7.37 m) and the US (6.69 m). At the same time, the building volume per capita in China is lowest, with 302.3 m3 per capita, while Europe and the US show estimates of 404.6 m3 and 565.4 m3, respectively. The results of this study (3D building structure data for Europe, the US, and China) are publicly available, and can be used for further analysis of urban environment, spatial planning, and land use projections.  
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  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0034-4257 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number GFZ @ kyba @ Serial 2918  
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Author Wang, J.; Zhou, M.; Xu, X.; Roudini, S.; Sander, S.P.; Pongetti, T.J.; Miller, S.D.; Reid, J.S.; Hyer, E.; Spurr, R. url  doi
openurl 
  Title Development of a nighttime shortwave radiative transfer model for remote sensing of nocturnal aerosols and fires from VIIRS Type Journal Article
  Year 2020 Publication Remote Sensing of Environment Abbreviated Journal Remote Sensing of Environment  
  Volume (down) 241 Issue Pages 111727  
  Keywords Remote Sensing  
  Abstract The launch of the Visible Infrared Imaging Radiometer Suite (VIIRS) on board the Sumo-NPP satellite in 2011 ushered in a new era of using visible light and shortwave radiation at night to characterize aerosol and fire distributions from space. In order to exploit the full range of unprecedented observational capabilities of VIIRS, we have developed a nighttime shortwave radiative transfer model capability in the UNified and Linearized Radiative Transfer Model (UNL-VRTM). This capability is based on the use of additional source functions to treat illumination from the Moon, from fires, and from artificial lights. We have applied this model to address fundamental questions associated with the VIIRS sensing of aerosol and fire at night. Detailed description of model developments and validation (either directly with surface measurements of lunar spectra or indirectly through cross validation) are presented. Our analysis reveals that: (a) when convolution with the broad-range (500–900 nm) relative spectral response (RSR) function of the VIIRS Day-Night Band (DNB) is omitted, AOD retrieval from the DNB have uncertainties up to a factor of two in conditions with low or moderate AOD (<0.5 in mid-visible); (b) using a wavelength independent spectrum for the surface illumination source can lead to an AOD bias of −10% over surfaces illuminated by light-emitting diodes and fluorescent lamps, and −30% illuminated by high-pressure sodium lamps; and (c) a DNB-equivalent narrow band for AOD retrieval over the surfaces illuminated by the three types of bulbs studied in this paper is found to be centered at 585 nm at which the look-up table can be generated for AOD retrieval from DNB. Furthermore, while uncertainty in AOD retrievals from the DNB decreases as AOD increases, fire characterization can be affected by AOD; for a smoke-scenario AOD of 2.0, the DNB and SWIR (1.6 μm) radiances can be reduced by 50% depending on the fire area fraction and temperature within VIIRS pixel. DNB is overall more sensitive to smaller and cooler fires than SWIR and can be used to retrieve AOD over bright surfaces. Finally, three-dimensional (3D) radiative transfer effects and the non-collimated nature of most artificial light sources are neglected in this 1D radiative transfer (plane-parallel) model, resulting in possibly large uncertainties (e.g., the inability to reproduce side-illumination of clouds by city lights) that should be studied in future.  
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  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0034-4257 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number GFZ @ kyba @ Serial 2863  
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Author Zheng, Q.; Weng, Q.; Wang, K. url  doi
openurl 
  Title Correcting the Pixel Blooming Effect (PiBE) of DMSP-OLS nighttime light imagery Type Journal Article
  Year 2020 Publication Remote Sensing of Environment Abbreviated Journal Remote Sensing of Environment  
  Volume (down) 240 Issue Pages 111707  
  Keywords *instrumentation; Remote Sensing  
  Abstract In the last two decades, the advance in nighttime light (NTL) remote sensing has fueled a surge in extensive research towards mapping human footprints. Nevertheless, the full potential of NTL data is largely constrained by the blooming effect. In this study, we propose a new concept, the Pixel Blooming Effect (PiBE), to delineate the mutual influence of lights from a pixel and its neighbors, and an integrated framework to eliminate the PiBE in radiance calibrated DMSP-OLS datasets (DMSPgrc). First, lights from isolated gas flaring sources and a Gaussian model were used to model how the PiBE functions on each pixel through point spread function (PSF). Second, a two-stage deblurring approach (TSDA) was developed to deconvolve DMSPgrc images with Tikhonov regularization to correct the PiBE and reconstruct PiBE-free images. Third, the proposed framework was assessed by synthetic data and VIIRS imagery and by testing the resulting image with two applications. We found that high impervious surface fraction pixels (ISF > 0.6) were impacted by the highest absolute magnitude of PiBE, whereas NTL pattern of low ISF pixels (ISF < 0.2) was more sensitive to the PiBE. By using TSDA the PiBE in DMSPgrc images was effectively corrected which enhanced data variation and suppressed pseudo lights from non-built-up pixels in urban areas. The reconstructed image had the highest similarity to reference data from synthetic image (SSIM = 0.759) and VIIRS image (r = 0.79). TSDA showed an acceptable performance for linear objects (width > 1.5 km) and circular objects (radius > 0.5 km), and for NTL data with different noise levels (<0.6σ). In summary, the proposed framework offers a new opportunity to improve the quality of DMSP-OLS images and subsequently will be conducive to NTL-based applications, such as mapping urban extent, estimating socioeconomic variables, and exploring eco-impact of artificial lights.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0034-4257 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number GFZ @ kyba @ Serial 2940  
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