An object-based classification approach for mapping "migrant housing" in the mega-urban area of the Pearl River Delta (China)

Urban areas develop on formal and informal levels. Informal development is often highly dynamic, leading to a lag of spatial information about urban structure types. In this work, an object-based remote sensing approach will be presented to map the migrant housing urban structure type in the Pearl River Delta, China. SPOT5 data were utilized for the classification (auxiliary data, particularly up-to-date cadastral data, were not available). A hierarchically structured classification process was used to create (spectral) independence from single satellite scenes and to arrive at a transferrable classification process. Using the presented classification approach, an overall classification accuracy of migrant housing of 68.0% is attained

A gabor filter-based protocol for automated image-based building detection

Detecting buildings from high-resolution satellite imagery is beneficial in mapping, environmental preparation, disaster management, military planning, urban planning and research purposes. Differentiating buildings from the images is possible however, it may be a time-consuming or complicated process. Therefore, the high-resolution imagery from satellites needs to be automated to detect the buildings. Additionally, buildings exhibit several different characteristics, and their appearance in these images is unplanned. Moreover, buildings in the metropolitan environment are typically crowded and complicated. Therefore, it is challenging to identify the building and hard tolocate them. To resolve this situation, a novel probabilistic method has been suggested using local features and probabilistic approaches. A local feature extraction technique was implemented, which was used to calculate the probability density function. The locations in the image were represented as joint probability distributions and were used to estimate their probability distribution function (pdf). The density of building locations in the image was extracted. Kernel density distribution was also used to find the density flow for different metropolitan cities such as Sydney (Australia), Tokyo (Japan), and Mumbai (India), which is useful for distribution intensity and pattern of facility point f interest (POI). The purpose system can detect buildings/rooftops and to test our system, we choose some crops with panchromatic high-resolution satellite images from Australia and our results looks promising with high efficiency and minimal computational time for feature extraction. We were able to detect buildings with shadows and building without shadows in 0.4468 (seconds) and 0.5126 (seconds) respectively

Advances in remote sensing applications for urban sustainability

Abstract: It is essential to monitor urban evolution at spatial and temporal scales to improve our understanding of the changes in cities and their impact on natural resources and environmental systems. Various aspects of remote sensing are routinely used to detect and map features and changes on land and sea surfaces, and in the atmosphere that affect urban sustainability. We provide a critical and comprehensive review of the characteristics of remote sensing systems, and in particular the trade-offs between various system parameters, as well as their use in two key research areas: (a) issues resulting from the expansion of urban environments, and (b) sustainable urban development. The analysis identifies three key trends in the existing literature: (a) the integration of heterogeneous remote sensing data, primarily for investigating or modelling urban environments as a complex system, (b) the development of new algorithms for effective extraction of urban features, and (c) the improvement in the accuracy of traditional spectral-based classification algorithms for addressing the spectral heterogeneity within urban areas. Growing interests in renewable energy have also resulted in the increased use of remote sensing—for planning, operation, and maintenance of energy infrastructures, in particular the ones with spatial variability, such as solar, wind, and geothermal energy. The proliferation of sustainability thinking in all facets of urban development and management also acts as a catalyst for the increased use of, and advances in, remote sensing for urban applications

Survey of Vegetation cover Changes in Forcados Area of the Niger Delta

Time Lapse Analysis revealed that Water class changed slightly across the three epochs. The water class was 312.39km2 in 1988, 312.55km2 in 1998 and 312.81km2 in 2008. Mature forest (Forest I) occupied 69.96 km2 1988 and decreased continuously to 55.59 km2 in 1998 and 41.9km2 in 2008. Forest II (Secondary forest) was 3.43km2 in 1988. This increased to 21.56km2 in 1998 and 31.41km2 in 2008. Mangrove class which covered 15.97km2 in 1988 decreased to 10.76 km2 in 1998 and 10.22km2 in 2008. Stressed Vegetation occupied 2.42km2 in 1988, and increased to 2.6 km2 in 1998 and then increased to 3.33 km2 in 2008. Urban/Industrial/Sand class increased across the epochs; from 1.94km2 in 1988 to 3.05 km2 in 1998, and 6.44km2 in 2008. The major changes are the decline in the areal coverage of mature forest by about 21% between 1988 and 1998 and 40% from 1988-2008; phenonmenal increase of secondary forest by over 800% between 1988 and 2008; decline in the areal coverage of mangrove vegetation by about 37% from 1988-2008; and progressive increase in the area occupied by stressed vegetation by 7% from 1988-1998 and 38% from 1988-2008. The results of this study underscore the need for a field study to verify the results obtained from the unsupervised image classification carried out in this work. That some major changes have taken in the biophysical environment around Forcados between 1988 and 2008 is not in doubt from this study

IMPACT OF URBANIZATION ON THE DUNE ECOSYSTEM: CASE OF THE CITY OF ‎ECHATT AND SIDI MBAREK (EL TARF)‎

Context and backgroundThroughout history, the severity of coastal impacts has varied depending on social and environmental factors. Human activities in general have caused large-scale environmental and morphological changes, and our study area is not outside this context.Goal and Objectives:This study aims to reveal the evolution of urban fabric of the city of Echatt and sidimbarek and their degree of influence on the state of dune cordon last 37 years.Methodology:The methodology followed during this study is based on satellite and topographic data as well as on measurements and observations made in the field. In order to study the evolution of urban fabric of the study area.The approach adopted is based on a study of several satellite images and google Earth pro images at different dates in order to determine the extent of changes that occurred between 1984 and 2021.Results:The results show an increase in coastal urbanization at varying rates amounting to 11.92 ha/year between (1984-2000), 4.95 ha/year between (2000; 2010) and 9. 92 ha/year between (2010,2021); and landscape changes that have developed at different rates over time due to the exploitation of the dune cordon of the city of echatt and sidimbarek in an irrational way that can lead to a total removal of vegetation cover, because according to the results obtained, more than half of the vegetation cover of the coastal dunes has been removed in 37 years Thematic maps and results obtained at different periods show that the forest landscape has gradually converted into dry land despite the entry into force of the Algerian Coastal Law 02-02 on the protection and enhancement of the coast, which aimed at the protection of the coast and sustainable use of its resources.

Progress and Methodological Approaches in Urban Trees and Forests Research in Africa

The numerous benefits of urban trees and forests are being increasingly recognised globally but grossly under studied in the developing world. This paper reviewed the methodological approaches to urban trees and forests assessments in Africa in relation to the growing number of publications in the field between 2012 and 2017. It adopted a comprehensive search of online publications related to urban trees and forests in the Google Scholar, Springer, Science Direct, Scopus, IEEE, Tailor and Francis and African Journals databases. Number of publications increased steadily from 2 in 2012 to a cumulative total of 44 in 2017, most of which were however, from South Africa, Nigeria and Ghana with little contributions from Kenya and Rwanda. Although remote sensing may facilitate detailed studies of urban trees, most researchers used the traditional and time-consuming field surveys and to some extent, interview and questionnaire surveys. African cities are highly diverse in both native and exotic tree species but the exotic species dominate in many areas. Urban trees in Africa provide both tangible and intangible benefits which include provision of income, fruits, medicines, fuelwood and recreation opportunities. Others are micro-climate modification, erosion and desertification control, pollutants removal, spirituality and aesthetics. Advances in urban tree assessments such as the use of i-Tree Eco and i-Tree Streets, high resolution remote sensing images and LiDAR should be explored. Governmental and private organizations need to be more committed to urban trees research and management through enhanced funding. Keywords: Africa; Urbanization; Urban Trees; Urban Forests; Diversity; Remote Sensing DOI: 10.7176/JEES/9-9-05 Publication date:September 30th 201

From quantitative to qualitative analysis of Land-Take. The application of a Composite Indicator for targeted policies of Land Take reduction

The processes of land take and soil sealing tend to receive more attention as threats to soil resources and Ecosystem Services (ES) provided by soil grow. The objectives of this paper are: 1) to assess the extent of land take (intended as the of artificial surfaces) in the Province of Lodi (Northern Italy) by evaluating the accuracy associated to the different scales of the cartography used; 2) to assess the effects of land take on the selected ES (in particular, supporting and regulating services). In case of study the ES assessed was the potential agricultural productivity, evaluated the Land Capability Classification1 as proxy and integrated with additional information regarding the increase of impervious surfaces. Thus, the construction of an experimental Composite Indicator on Land Take has been provided. The results have shown that important underestimation of land take occurs when Corine Land Cover2 (CLC) is used at local level in Italy but, at the same time, when used in Country, CLC seems to be sufficient to assess the general amount of Land Take. Moreover, when a shift from the neutral assessment to practical policy orientation of Land Take reduction is requested, a higher degree of additional qualitative information necessary to steer planning options. The Composite Indicator is aimed to help policy makers and planners to adopt suitable measures by applying European guidelines and protocols for Land Take government

Assessing responses of grasslands to grazing management using remote sensing approaches

Grazing caused grassland degradation has occurred worldwide in recent decades. In spite of numerous efforts that have been invested to explore the mechanism of grassland responses to grazing management, the major challenge remains monitoring the responses over large area. This research evaluates the synthetic use of remote sensing data and the Milchunas-Sala-Lauenroth (MSL) model for grazing impact assessment, aiming to explore the potential of remotely sensed data to investigate the responses of grasslands to various grazing intensities across different grassland types. By combining field collected biophysical parameters, ground hyperspectral data and satellite imagery with different resolutions, this research concluded that 1) sampling scale played an important role in vegetation condition assessment. Adjusted transformed soil-adjusted vegetation index (ATSAVI) derived from remote sensing imagery with 10m or 20m spatial resolution was suitable for measuring leaf area index (LAI) changes in post-grazing treatment in the grazing experimental site; 2) canopy height and the ratio of photosynthetically to non-photosynthetically active vegetation cover were identified as the most sensitive biophysical parameters to reflect vegetation changes in mixed grasslands under light to moderate grazing intensities; 3) OSAVI (Optimised soil adjusted vegetation index) derived from Landsat Thematic Mapper (TM) image can be used for grassland production estimation under various grazing intensities in three types of grasslands in Inner Mongolia, China, with an accuracy of 76%; and 4) Grassland production predicted by NCI (Normalized canopy index) showed significant differences between grazed and ungrazed sites in years with above average and average growing season precipitation, but not in dry years, and 75% of the variation in production was explained by growing season precipitation (April-August) for both grazed and ungrazed sites