Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Settlement Dynamics and Impacts on the Environment <s> Abstract A Tresholding technique was used to convert a prototype “city lights” data set from the National Oceanic and Atmospheric Administration's National Geophysical Data Center (NOAAINGDC) into a map of “urban areas” for the continental United States. Thresholding was required to adapt the Defense Meteorological Satellite Program's Operational Linescan System (DMSPIOLS)-based NGDC data set into an urban map because the values reported in the prototype represent a cumulative percentage lighted for each pixel extracted from hundreds of nighttime cloud screened orbits, rather than any suitable land-cover classification. The cumulative percentage lighted data could not be used alone because the very high gain of the OLS nighttime photomultiplier configuration can. lead to a pixel (2.7X2.7 km) appearing “lighted” even with very low intensity, nonurban light sources. We found that a threshold of %89% yielded the best results, removing ephemeral light sources and “blooming” of light onto water when adjacent to cities while still leaving the dense urban core intact. This approach gave very good results when compared with the urban areas as defined by the 1990 U. S. Census; the “urban” area from our analysis being only 5% less than that of the Census. The Census was also used to derive population.- and housing-density statistics for the continent-wide “city lights” analysis; these averaged 1033 persons/km 2 and 426 housing units/ king, respectively. The use of a nighttime sensor to determine the location and estimate the density of population based on light sources has proved feasible in this exploratory effort. However, issues concerning the use of census data as a benchmark for evaluating the accuracy of remotely sensed imagery are discussed, and potential improvements in the sensor regarding spatial resolution, instrument gain, and pointing accuracy are addressed. <s> BIB001 </s> Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Settlement Dynamics and Impacts on the Environment <s> Night-time imagery from the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) has been proposed as a useful tool for monitoring urban expansion around the world, but determining appropriate light thresholds for delineating cities remains a challenge. In this paper we present a new approach. We used DMSP stable lights and radiance-calibrated images to delimit urban boundaries for San Francisco, Beijing and Lhasa, cities with different levels of urbanization and economic development, and compared the results against boundaries derived from high-resolution Landsat Thematic Mapper (TM) imagery. Unthresholded DMSP images exaggerate and shift the extent of these urban areas. We then calculated light thresholds that minimized the discrepancies between the DMSP- and TM-derived urban boundaries for each city. Our comparison highlights the difficulty of using DMSP data across areas with disparate urban characteristics, but suggests the possibility of calibrating this data source for ... <s> BIB002 </s> Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Settlement Dynamics and Impacts on the Environment <s> Abstract Previous studies of DMSP-OLS stable night lights have shown encouraging agreement between temporally stable lighted areas and various definitions of urban extent. However, these studies have also highlighted an inconsistent relationship between the actual lighted area and the boundaries of the urban areas considered. Applying detection frequency thresholds can reduce the spatial overextent of lighted area (“blooming”) but thresholding also attenuates large numbers of smaller lights and significantly reduces the information content of the night lights datasets. Spatial analysis of the widely used 1994/1995 stable lights data and the newly released 1992/1993 and 2000 stable lights datasets quantifies the tradeoff between blooming and attenuation of smaller lights. For the 1992/1993 and 2000 datasets, a 14% detection threshold significantly reduces blooming around large settlements without attenuating many individual small settlements. The corresponding threshold for the 1994/1995 dataset is 10%. The size–frequency distributions of each dataset retain consistent shapes for increasing thresholds while the size–area distributions suggest a quasi-uniform distribution of lighted area with individual settlement size between 10 and 1000 km equivalent diameter. Conurbations larger than 80 km diameter account for 90% can often reconcile lighted area with built area in the 1994/1995 dataset but there is not one threshold that works for a majority of the 17 cities considered. Even 100% thresholds significantly overestimate built area for the 1992/1993 and 2000 datasets. Comparison of lighted area with blooming extent for 10 lighted islands suggests a linear proportionality of 1.25 of lighted to built diameter and an additive bias of 2.7 km. While more extensive analyses are needed, a linear relationship would be consistent with a physical model for atmospheric scattering combined with a random geolocation error. A Gaussian detection probability model is consistent with an observed sigmoid decrease of detection frequency for settlements <s> BIB003 </s> Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Settlement Dynamics and Impacts on the Environment <s> Mapping human settlements from remotely sensed data at regional and global scales has attracted increasingly attention but remains a challenge. The thresholding technique is a common approach for settlement mapping based on the DMSP-OLS data. However, this approach often omits the areas with small proportional settlements such as towns and villages and overestimates urban extents, resulting in information loss of spatial patterns. This paper explored an integrated approach based on a combined use of multiple remotely sensed data to map settlements in southeastern China. Human settlements for selected sites were mapped from Landsat ETM+ images with a hybrid approach and they were used as reference data. The DMSP-OLS and Terra MODIS NDVI data were combined to develop a settlement index image. This index image was used to map a pixel-based settlement image with expert rules. A regression model was established to estimate fractional settlements at the regional scale, which the DMSP-OLS and MODIS NDVI data were used as independent variables and the settlement data derived from ETM+ images were used as a dependent variable. This research indicated that a combination of DMSP-OLS and NDVI variables provided a better estimation performance than single DMSP-OLS or NDVI variable, and the integrated approach for settlement mapping at the regional scale was promising. Compared to the results from the traditional thresholding technique, the estimated fractional settlement image in this paper greatly improved the spatial patterns of settlement distribution and accuracy of settlement areas. This paper provided a rapid and accurate approach to estimate fractional settlements from coarse spatial resolution images at the regional scale by combining a limited number of medium spatial resolution images. This research is especially valuable for timely updating settlement databases at regional and global scales with limited time, labor, and cost. <s> BIB004 </s> Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Settlement Dynamics and Impacts on the Environment <s> Fundamental questions regarding the human-environment-sustainability problematic remain contested. What are the relative roles of population, consumption, and technology with respect to sustainability? How can sustainability be measured? Numerous metrics have been developed to address these controversial questions including ideas of carrying capacity, environmental sustainability indices, and ecological footprints. This work explores the question: is pavement a proxy measure of human impact on the environment? We explore and evaluate the use of satellite derived density grids of constructed area (aka ‘pavement’ or ‘impervious surface’) in the calculation of national and subnational ‘ecological footprints’. We generated a global constructed area density grid for the 2000—2001 period using satellite observed nighttime lights and a population count grid from the US Department of Energy. Satellite data inputs to the population product include MODIS landcover, SRTM topography and high-resolution imagery. Calib... <s> BIB005 </s> Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Settlement Dynamics and Impacts on the Environment <s> Mapping urban areas at regional and global scales has become an urgent task because of the increasing pressures from rapid urbanization and associated environmental problems. Satellite imaging of stable anthropogenic lights from DMSP-OLS provides an accurate, economical, and straightforward way to map the global distribution of urban areas. To address problems in the thresholding methods that use empirical strategies or manual trial-and-error procedures, we proposed a support vector machine (SVM)-based region-growing algorithm to semi-automatically extract urban areas from DMSP-OLS and SPOT NDVI data. Several simple criteria were used to select SVM training sets of urban and non-urban pixels, and an iterative classification and training procedure was adopted to identify the urban pixels through region growing. The new method was validated using the extents of 25 Chinese cities, as classified by Landsat ETM+ images, and then compared with two common thresholding methods. The results showed that the SVM-based algorithm could not only achieve comparable results to the local-optimized threshold method, but also avoid its tedious trial-and-error procedure, suggesting that the new method is an easy and simple alternative for extracting urban extent from DMSP-OLS and SPOT NDVI data. <s> BIB006 </s> Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Settlement Dynamics and Impacts on the Environment <s> This paper provides an approach for rapid and accurate estimation of built-up areas on a per pixel-basis using a integration of two coarse spatial resolution remote sensing data namely DMSP-OLS and MODIS NDVI. The DMSP-OLS data due to its free availability, high temporal resolution and wide swath was used for regional level mapping of built-up areas. However, due to its low radiometric resolution, the built-up areas cannot be estimated accurately from the DMSP-OLS data. In present study, the DMSP-OLS data was combined with MODIS NDVI data to develop an Human Settlement Index (HSI) image, which estimated the fraction of built-up area on a per pixel basis. The resultant HSI image conveys more information than both the individual datasets. These temporal HSI images were then used for monitoring urban growth in Indo-Gangetic plains during the 2001–2007 time period. Thus, the present research can be very useful for regional level monitoring of built-up areas from coarse resolution data within limited time and minimal cost. <s> BIB007 </s> Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Settlement Dynamics and Impacts on the Environment <s> Timely and accurate information about the dynamics of urban expansion is vital to reveal the relationships between urban expansion and the ecosystem, to optimize land use patterns, and to promote the effective development of cities in China. Nighttime stable light data from the Defense Meteorological Satellite Program's Operational Line-scan System (DMSP-OLS) Nighttime Lights Time Series dataset provide a new source of information that can quickly reveal the dynamics of urban expansion. However, the DMSP-OLS sensor has no on-board calibration, which makes it difficult to directly compare time series data from multiple satellites. This study developed a new method for systematically correcting multi-year multi-satellite nighttime stable lights data and rapidly extracting the dynamics of urban expansion based on this corrected data for China from 1992 to 2008. The results revealed that the proposed method effectively reduced abnormal discrepancy within the nighttime stable light data and improved continuity and comparability. The dynamics of urban expansion in China from 1992 to 2008 were extracted with an average overall accuracy of 82.74% and an average Kappa of 0.40. <s> BIB008 </s> Application of DMSP/OLS Nighttime Light Images: A Meta-Analysis and a Systematic Literature Review <s> Settlement Dynamics and Impacts on the Environment <s> Urban land accounts for a small fraction of the Earth's surface area but rapid increases in urban land have a disproportionate influence on the environment. China is a living laboratory in urbanization and has witnessed fast urban growth in recent decades. The timely and accurate mapping of urban land in China is an urgent and basic issue toward clarifying the urbanization process and revealing its environmental impacts. Nighttime stable light (NSL) data obtained by the Defense Meteorological Satellite Program's Operational Linescan System (DMSP/OLS) can provide an economical way to map urban land nationwide. However, it is difficult to apply existing methods to accurately extract urban land from DMSP/OLS NSL data covering the entirety of China due to China's large area and substantial regional variation. A stratified support vector machine (SSVM)-based method used to map the urban land in China in 2008 at a national scale using DMSP/OLS NSL and SPOT normalized difference vegetation index data is presented. The results show that measurement of urban land in China in 2008 using SSVM achieves an average overall accuracy of 90% and an average Kappa of 0.69. The success of this research demonstrates the great potential of SSVM for clarifying the urbanization process in continental and global research. (C) 2013 Society of Photo-Optical Instrumentation Engineers (SPIE) <s> BIB009
The first category of applications was the mapping of settlements (Figure 3) , including urban areas BIB008 BIB001 BIB003 , built-up areas BIB007 , impervious surfaces areas BIB005 , and urban boundaries BIB002 . This category included subcategories I and II (Table 6) , and appeared in 40 papers. The major challenges of this research topic were distinguishing settlement light from short-term light, and reducing the blooming effect at the city edge, which may exaggerate the extent of settlement. The first strategy was the threshold method originally proposed by Imhoff BIB001 , which compared changes in polygon perimeter along the increase in threshold. The best threshold yielded the highest accuracy with urban areas from U.S. census data; however, the optimal threshold in this study, 89% for American cities, is not a universal value for other cities around the world, especially in developing countries where the average light intensity is weaker than in developed countries BIB005 . In addition, the level of development in countries such as China is spatially heterogeneous, and thus different regional thresholds are required to increase mapping accuracy BIB009 . The threshold based on calibrated radiance is easier to interpret than that based on stable light data BIB002 . BIB008 ). Another strategy is to integrate other sources of remote-sensing information to increase the mapping accuracy. For instance, Lu et al. BIB004 combined nighttime images and MODIS NDVI data to map human settlements in southeastern China. The results showed that the regression method integrating DMSP and NDVI data produced a more accurate estimation and spatial distribution of urban settlements than the results based on each dataset individually. Cao et al. BIB006 proposed a semi-automatic algorithm based on the support vector machine technique to extract urban areas by combining nighttime images with SPOT VGT data. They found that the new method achieved comparable results with localized thresholds in 25 Chinese cities and avoided the time-consuming procedure of finding the local optimal thresholds.