Over the last decade, Volunteered Geographic Information (VGI) has emerged as a viable source of ... more Over the last decade, Volunteered Geographic Information (VGI) has emerged as a viable source of information on cities. During this time, the nature of VGI has been evolving, with new types and sources of data continually being added. In light of this trend, this paper explores one such type of VGI data: Volunteered Street View Imagery (VSVI). Two VSVI sources, Mapillary and OpenStreetCam, were extracted and analyzed to study road coverage and contribution patterns for four US metropolitan areas. Results show that coverage patterns vary across sites, with most contributions occurring along local roads and in populated areas. We also found that a few users contributed most of the data. Moreover, the results suggest that most data are being collected during three distinct times of day (i.e., morning, lunch and late afternoon). The paper concludes with a discussion that while VSVI data is still relatively new, it has the potential to be a rich source of spatial and temporal information for monitoring cities.
Over one billion people currently live in slums (informal settlements) with populations worldwide... more Over one billion people currently live in slums (informal settlements) with populations worldwide increasing; this number is only expected to grow in the coming decades. These communities are often recognized as the most vulnerable groups in society. In an effort to better address the plight of slum dwellers (e.g. the provision of better infrastructure and services) and to develop more effective and efficient policies, better information on slums needs to be collected and slum populations monitored. Five-step process for addressing the problem of slums We propose a five-step process for addressing this problem (Define, Data, Map, Analyze and Model).
Vampire bat-transmitted rabies was first recognized in Trinidad during a major outbreak reported ... more Vampire bat-transmitted rabies was first recognized in Trinidad during a major outbreak reported in 1925. Trinidad is the only Caribbean island with vampire bat-transmitted rabies. We conducted a literature review to describe the changing epidemiology of rabies in Trinidad and give a historical perspective to rabies prevention and control measures on the island. The last human case of rabies occurred in 1937 and although no case of canine-transmitted rabies was reported since 1914, sporadic outbreaks of bat-transmitted rabies still occur in livestock to date. Over the last century, seven notable epidemics were recorded in Trinidad with the loss of over 3000 animals. During the 1950s, several measures were effectively adopted for the prevention and control of the disease which led to a significant reduction in the number of cases. These measures include: vampire bat population control, livestock vaccination, and animal surveillance. However, due to lapses in these measures over the years (e.g., periods of limited vampire control and incomplete herd vaccination), epidemics have occurred. In light of the significant negative impact of rabies on animal production and human health, rabies surveillance in Trinidad should be enhanced and cases evaluated towards the design and implementation of more evidence-based prevention and control programs.
The purpose of this study was to determine via spectral separability using divergence measures th... more The purpose of this study was to determine via spectral separability using divergence measures the best individual and combinations of various numbers of bands for five land cover/ land use classes along the Blue Nile in Sudan. The data for this analysis were a stack of 15 layers including RADARSAT-2 C-band and PALSAR L-band quad-polarized radar registered with ASTER optical data, as well as four variance texture measures extracted from the RADARSAT-2 images. Spectral signatures were obtained for each class and examined by various separability measures. This examination is useful for better understanding the relative value of different types of remote sensing data and best band combinations for possible visual analysis and for improving land cover/ land use classification accuracy. Results show that the best single band for analysis was the RADARSAT-2 VH variance texture measure. The best pair of bands was the ASTER visible red and the RADARSAT-2 HV variance texture, which also included the PALSAR VH band for the best three band combination, all bands being very different data types. Further, based upon the divergence values, only eight bands are needed to achieve maximum separation between land cover/ land use classes. Beyond this point, classification accuracy is expected to decrease, with as few as six bands needed to reach viable classification accuracy.
The study of slums as social and physical constructs: challenges and emerging research opportunities
over 1 billion people currently live in slums, with the number of slum dwellers only expected to ... more over 1 billion people currently live in slums, with the number of slum dwellers only expected to grow in the coming decades. the vast majority of slums are located in and around urban centres in the less economically developed countries, which are also experiencing greater rates of urbanization compared with more developed countries. this rapid rate of urbanization is cause for significant concern given that many of these countries often lack the ability to provide the infrastructure (e.g., roads and affordable housing) and basic services (e.g., water and sanitation) to provide adequately for the increasing influx of people into cities. While research on slums has been ongoing, such work has mainly focused on one of three constructs: exploring the socio-economic and policy issues; exploring the physical characteristics; and, lastly, those modelling slums. this paper reviews these lines of research and argues that while each is valuable, there is a need for a more holistic approach for studying slums to truly understand them. By synthesizing the social and physical constructs, this paper provides a more holistic synthesis of the problem, which can potentially lead to a deeper understanding and, consequently, better approaches for tackling the challenge of slums at the local, national and regional scales.
Coral reefs are one of the most diverse marine ecosystems on Earth. They are renowned hotspots of... more Coral reefs are one of the most diverse marine ecosystems on Earth. They are renowned hotspots of species biodiversity and provide home to a large array of marine plants and animals. Over the past 100 years, many tropical regions' sea surface temperatures have increased by almost 1 °C and are currently increasing at about 1–2 °C per century. Corals have very specific thermal thresholds beyond which their temperature sensitive symbiont Zooxanthellae becomes affected and causes corals to bleach. Mass bleaching has already caused significant losses to live coral in many parts of the world. In the Caribbean, the problem of coral bleaching has especially been problematic, with as much as 90% bleaching in some parts of the Caribbean due to thermal anomalies in some instances. This paper looks at the key role that temperature plays in the health and spatial distribution of coral in the Caribbean. The relationship between coral and symbiont is examined along with some evolutionary strategies necessary to ensure the future survival of coral with the changing climate.
Various land use/cover types exhibit seasonal characteristics which can be captured in remotely s... more Various land use/cover types exhibit seasonal characteristics which can be captured in remotely sensed imagery. This study examined how different seasons of Radarsat-2 data influence land use/cover classification accuracies for two study sites. Two dates of Radarsat-2 C-band quad-polarized images were obtained for Washington, D.C., USA and Wad Madani, Sudan. Spectral signatures were extracted and used with a maximum likelihood decision rule for classification and thematic accuracies were then determined. Both despeckled radar and derived texture measures were examined. Thematic accuracies for the two despeckled image dates were similar with a difference of 3% for Washington and 6% for Sudan. Merging the despeckled images for both seasons increased overall accuracy by 2% for Washington and 9% for Sudan. Further combining the original radar for both seasons with derived texture measures increased overall accuracies by 9% for Washington and 16% for Sudan for final overall accuracy values of 73% and 82%.
This study examined the appropriateness of radar speckle reduction for deriving texture measures ... more This study examined the appropriateness of radar speckle reduction for deriving texture measures for land cover/use classifications. Radarsat-2 C-band quad-polarized data were obtained for Washington, D.C., USA. Polarization signatures were extracted for multiple image components, classified with a maximum-likelihood decision rule and thematic accuracies determined. Initial classifications using original and despeckled scenes showed despeckled radar to have better overall thematic accuracies. However, when variance texture measures were extracted for several window sizes from the original and despeckled imagery and classified, the accuracy for the radar data was decreased when despeckled prior to texture extraction. The highest classification accuracy obtained for the extracted variance texture measure from the original radar was 72%, which was reduced to 69% when this measure was extracted from a 5x5 despeckled image. These results suggest that it may be better to use despeckled radar as original data and extract texture measures from the original imagery.
Over the last decade, Volunteered Geographic Information (VGI) has emerged as a viable source of ... more Over the last decade, Volunteered Geographic Information (VGI) has emerged as a viable source of information on cities. During this time, the nature of VGI has been evolving, with new types and sources of data continually being added. In light of this trend, this paper explores one such type of VGI data: Volunteered Street View Imagery (VSVI). Two VSVI sources, Mapillary and OpenStreetCam, were extracted and analyzed to study road coverage and contribution patterns for four US metropolitan areas. Results show that coverage patterns vary across sites, with most contributions occurring along local roads and in populated areas. We also found that a few users contributed most of the data. Moreover, the results suggest that most data are being collected during three distinct times of day (i.e., morning, lunch and late afternoon). The paper concludes with a discussion that while VSVI data is still relatively new, it has the potential to be a rich source of spatial and temporal information for monitoring cities.
Over one billion people currently live in slums (informal settlements) with populations worldwide... more Over one billion people currently live in slums (informal settlements) with populations worldwide increasing; this number is only expected to grow in the coming decades. These communities are often recognized as the most vulnerable groups in society. In an effort to better address the plight of slum dwellers (e.g. the provision of better infrastructure and services) and to develop more effective and efficient policies, better information on slums needs to be collected and slum populations monitored. Five-step process for addressing the problem of slums We propose a five-step process for addressing this problem (Define, Data, Map, Analyze and Model).
Vampire bat-transmitted rabies was first recognized in Trinidad during a major outbreak reported ... more Vampire bat-transmitted rabies was first recognized in Trinidad during a major outbreak reported in 1925. Trinidad is the only Caribbean island with vampire bat-transmitted rabies. We conducted a literature review to describe the changing epidemiology of rabies in Trinidad and give a historical perspective to rabies prevention and control measures on the island. The last human case of rabies occurred in 1937 and although no case of canine-transmitted rabies was reported since 1914, sporadic outbreaks of bat-transmitted rabies still occur in livestock to date. Over the last century, seven notable epidemics were recorded in Trinidad with the loss of over 3000 animals. During the 1950s, several measures were effectively adopted for the prevention and control of the disease which led to a significant reduction in the number of cases. These measures include: vampire bat population control, livestock vaccination, and animal surveillance. However, due to lapses in these measures over the years (e.g., periods of limited vampire control and incomplete herd vaccination), epidemics have occurred. In light of the significant negative impact of rabies on animal production and human health, rabies surveillance in Trinidad should be enhanced and cases evaluated towards the design and implementation of more evidence-based prevention and control programs.
The purpose of this study was to determine via spectral separability using divergence measures th... more The purpose of this study was to determine via spectral separability using divergence measures the best individual and combinations of various numbers of bands for five land cover/ land use classes along the Blue Nile in Sudan. The data for this analysis were a stack of 15 layers including RADARSAT-2 C-band and PALSAR L-band quad-polarized radar registered with ASTER optical data, as well as four variance texture measures extracted from the RADARSAT-2 images. Spectral signatures were obtained for each class and examined by various separability measures. This examination is useful for better understanding the relative value of different types of remote sensing data and best band combinations for possible visual analysis and for improving land cover/ land use classification accuracy. Results show that the best single band for analysis was the RADARSAT-2 VH variance texture measure. The best pair of bands was the ASTER visible red and the RADARSAT-2 HV variance texture, which also included the PALSAR VH band for the best three band combination, all bands being very different data types. Further, based upon the divergence values, only eight bands are needed to achieve maximum separation between land cover/ land use classes. Beyond this point, classification accuracy is expected to decrease, with as few as six bands needed to reach viable classification accuracy.
The study of slums as social and physical constructs: challenges and emerging research opportunities
over 1 billion people currently live in slums, with the number of slum dwellers only expected to ... more over 1 billion people currently live in slums, with the number of slum dwellers only expected to grow in the coming decades. the vast majority of slums are located in and around urban centres in the less economically developed countries, which are also experiencing greater rates of urbanization compared with more developed countries. this rapid rate of urbanization is cause for significant concern given that many of these countries often lack the ability to provide the infrastructure (e.g., roads and affordable housing) and basic services (e.g., water and sanitation) to provide adequately for the increasing influx of people into cities. While research on slums has been ongoing, such work has mainly focused on one of three constructs: exploring the socio-economic and policy issues; exploring the physical characteristics; and, lastly, those modelling slums. this paper reviews these lines of research and argues that while each is valuable, there is a need for a more holistic approach for studying slums to truly understand them. By synthesizing the social and physical constructs, this paper provides a more holistic synthesis of the problem, which can potentially lead to a deeper understanding and, consequently, better approaches for tackling the challenge of slums at the local, national and regional scales.
Coral reefs are one of the most diverse marine ecosystems on Earth. They are renowned hotspots of... more Coral reefs are one of the most diverse marine ecosystems on Earth. They are renowned hotspots of species biodiversity and provide home to a large array of marine plants and animals. Over the past 100 years, many tropical regions' sea surface temperatures have increased by almost 1 °C and are currently increasing at about 1–2 °C per century. Corals have very specific thermal thresholds beyond which their temperature sensitive symbiont Zooxanthellae becomes affected and causes corals to bleach. Mass bleaching has already caused significant losses to live coral in many parts of the world. In the Caribbean, the problem of coral bleaching has especially been problematic, with as much as 90% bleaching in some parts of the Caribbean due to thermal anomalies in some instances. This paper looks at the key role that temperature plays in the health and spatial distribution of coral in the Caribbean. The relationship between coral and symbiont is examined along with some evolutionary strategies necessary to ensure the future survival of coral with the changing climate.
Various land use/cover types exhibit seasonal characteristics which can be captured in remotely s... more Various land use/cover types exhibit seasonal characteristics which can be captured in remotely sensed imagery. This study examined how different seasons of Radarsat-2 data influence land use/cover classification accuracies for two study sites. Two dates of Radarsat-2 C-band quad-polarized images were obtained for Washington, D.C., USA and Wad Madani, Sudan. Spectral signatures were extracted and used with a maximum likelihood decision rule for classification and thematic accuracies were then determined. Both despeckled radar and derived texture measures were examined. Thematic accuracies for the two despeckled image dates were similar with a difference of 3% for Washington and 6% for Sudan. Merging the despeckled images for both seasons increased overall accuracy by 2% for Washington and 9% for Sudan. Further combining the original radar for both seasons with derived texture measures increased overall accuracies by 9% for Washington and 16% for Sudan for final overall accuracy values of 73% and 82%.
This study examined the appropriateness of radar speckle reduction for deriving texture measures ... more This study examined the appropriateness of radar speckle reduction for deriving texture measures for land cover/use classifications. Radarsat-2 C-band quad-polarized data were obtained for Washington, D.C., USA. Polarization signatures were extracted for multiple image components, classified with a maximum-likelihood decision rule and thematic accuracies determined. Initial classifications using original and despeckled scenes showed despeckled radar to have better overall thematic accuracies. However, when variance texture measures were extracted for several window sizes from the original and despeckled imagery and classified, the accuracy for the radar data was decreased when despeckled prior to texture extraction. The highest classification accuracy obtained for the extracted variance texture measure from the original radar was 72%, which was reduced to 69% when this measure was extracted from a 5x5 despeckled image. These results suggest that it may be better to use despeckled radar as original data and extract texture measures from the original imagery.
Web 2.0 technologies and the wide dissemination of relatively inexpensive, location aware devices... more Web 2.0 technologies and the wide dissemination of relatively inexpensive, location aware devices have reshaped the way in which geospatial data have traditionally been collected and disseminated. Individuals, most with no mapping experience, are voluntarily contributing to the growth of digital datasets that span a wide range of land use and land cover (LULC) themes (Stefanidis et al., 2013), a role traditionally held by governments and private sector businesses. This volunteered geographic information (VGI—Goodchild, 2007) represents a rich source of information on people, place and their intertwined relationship with society, presenting new opportunities for research and a better understanding of the complex world that we live in. OpenStreetMap (OSM) represents one of the best examples of the success of VGI. As noted by Arsanjani et al. in the introductory chapter of their book, ''OpenStreetMap in GIScience: Experiences, Research and Applications,'' OSM was first introduced as a tool for overcoming traditional barriers to the use of quality geospatial information such as cost and accessibility, providing a free and editable source of global geospatial data. Launched in 2004, and building on similar technologies and concepts such as Wikipedia at the time, OSM soon grew from a system supported by a few registered users to a digital geospatial ecosystem in its own right. At the time of writing this review, February 2016, there were almost 2.5 million registered OSM users, with the number of users continuing to grow daily (OpenStreetMap, 2016). Not only is OSM growing as a leading repository of geospatial data, the community has also been expanding into other areas such as the creation of a humanitarian network and supporting the development of open source software. These qualities, among others, have attracted the attention of many academics, researchers, businesses and governments to increasingly accept OSM as a potential source of quality geospatial information. Such a myriad of interests has resulted in a host of applications which use OSM data, along with various innovations which seek to improve the quality of these data and the way users interact with and access this information. Given the phenomenal growth of OSM, its applications, communities, and OSM possibly being considered as the next geographic big data source (Goodchild, 2013), not surprisingly, questions have been raised on issues surrounding the suitability of OSM to support different types of activities. ''OpenStreetMap in GIScience: Experiences, Research and Applications'' is timely divided into four different but related sections which seek to address these scientific lines of inquiry. Each section represents a broad, but major contributing state of the art and cutting edge area of research, highlighting the contribution of OSM work to GIScience. Environment and Planning B: Planning and Design 0(0) 1–3
ISPRS International Journal of Geo-Information, 2020
Over the last decade, Volunteered Geographic Information (VGI) has emerged as a viable source of ... more Over the last decade, Volunteered Geographic Information (VGI) has emerged as a viable source of information on cities. During this time, the nature of VGI has been evolving, with new types and sources of data continually being added. In light of this trend, this paper explores one such type of VGI data: Volunteered Street View Imagery (VSVI). Two VSVI sources, Mapillary and OpenStreetCam, were extracted and analyzed to study road coverage and contribution patterns for four US metropolitan areas. Results show that coverage patterns vary across sites, with most contributions occurring along local roads and in populated areas. We also found that a few users contributed most of the data. Moreover, the results suggest that most data are being collected during three distinct times of day (i.e., morning, lunch and late afternoon). The paper concludes with a discussion that while VSVI data is still relatively new, it has the potential to be a rich source of spatial and temporal information for monitoring cities.
The last several decades have witnessed a shift in the way in which news is delivered and consume... more The last several decades have witnessed a shift in the way in which news is delivered and consumed by users. With the growth and advancements in mobile technologies, the Inter-net, and Web 2.0 technologies users are not only consumers of news, but also producers of online content. This has resulted in a novel and highly participatory cyber-physical news awareness ecosystem that fosters digital activism, in which volunteers contribute content to online communities. While studies have examined the various components of this news awareness ecosystem, little is still known about how news media coverage (and in particular digital media) impacts digital activism. In order to address this challenge and develop a greater understanding of it, this paper focuses on a specific form of digital activism, that of the production of digital geographical content through crowdsourcing efforts. Using refugee camps from around the world as a case study, we examine the relationship between news coverage (via Google news), search trends (via Google trends) and user edit contribution patterns in OpenStreetMap, a prominent geospatial data crowdsourcing platform. In addition , we compare and contrast these patterns with user edit patterns in Wikipedia, a well-known non-geospatial crowdsourcing platform. Using Google news and Google trends to derive a measure of thematic public awareness, our findings indicate that digital activism bursts tend to take place during periods of sustained build-up of public awareness deficit or surplus. These findings are in line with two prominent mass communication theories: agenda setting and corrective action, and suggest the emergence of a novel stimulus-awareness-activism framework in today's participatory digital age. Moreover, these findings further complement existing research examining the motivational factors that drive users to contribute to online collaborative communities. This paper brings us one step closer to
Slums are a global urban challenge, with less developed countries being particularly impacted. To... more Slums are a global urban challenge, with less developed countries being particularly impacted. To adequately detect and map them, data is needed on their location, spatial extent and evolution. High-and very high-resolution remote sensing imagery has emerged as an important source of data in this regard. The purpose of this paper is to critically review studies that have used such data to detect and map slums. Our analysis shows that while such studies have been increasing over time, they tend to be concentrated to a few geographical areas and often focus on the use of a single approach (e.g., image texture and object-based image analysis), thus limiting generalizability to understand slums, their population, and evolution within the global context. We argue that to develop a more comprehensive framework that can be used to detect and map slums, other emerging sourcing of geospatial data should be considered (e.g., volunteer geographic information) in conjunction with growing trends and advancements in technology (e.g., geosensor networks). Through such data integration and analysis we can then create a benchmark for determining the most suitable methods for mapping slums in a given locality, thus fostering the creation of new approaches to address this challenge.
With volunteered geographic information (VGI) platforms such as OpenStreetMap (OSM) becoming incr... more With volunteered geographic information (VGI) platforms such as OpenStreetMap (OSM) becoming increasingly popular, we are faced with the challenge of assessing the quality of their content, in order to better understand its place relative to the authoritative content of more traditional sources. Until now, studies have focused primarily on developed countries, showing that VGI content can match or even surpass the quality of authoritative sources, with very few studies in developing countries. In this paper, we compare the quality of authoritative (data from the Regional Center for Mapping of Resources for Development (RCMRD)) and non-authoritative (data from OSM and Google's Map Maker) road data in conjunction with population data in and around Nairobi, Kenya. Results show variability in coverage between all of these datasets. RCMRD provided the most complete, albeit less current, coverage when taking into account the entire study area, while OSM and Map Maker showed a degradation of coverage as one moves from central Nairobi towards rural areas. Furthermore, OSM had higher content density in large slums, surpassing the authoritative datasets at these locations, while Map Maker showed better coverage in rural housing areas. These results suggest a greater need for a more inclusive approach using VGI to supplement gaps in authoritative data in developing nations.
With volunteered geographic information (VGI) platforms such as OpenStreetMap (OSM) becoming incr... more With volunteered geographic information (VGI) platforms such as OpenStreetMap (OSM) becoming increasingly popular, we are faced with the challenge of assessing the quality of their content, in order to better understand its place relative to the authoritative content of more traditional sources. Until now, studies have focused primarily on developed countries, showing that VGI content can match or even surpass the quality of authoritative sources, with very few studies in developing countries. In this paper, we compare the quality of authoritative (data from the Regional Center for Mapping of Resources for Development (RCMRD)) and non-authoritative (data from OSM and Google's Map Maker) road data in conjunction with population data in and around Nairobi, Kenya. Results show variability in coverage between all of these datasets. RCMRD provided the most complete, albeit less current, coverage when taking into account the entire study area, while OSM and Map Maker showed a degradation of coverage as one moves from central Nairobi towards rural areas. Furthermore, OSM had higher content density in large slums, surpassing the authoritative datasets at these locations, while Map Maker showed better coverage in rural housing areas. These results suggest a greater need for a more inclusive approach using VGI to supplement gaps in authoritative data in developing nations.
Traditionally urban morphology has been the study of cities as human habitats through the analysi... more Traditionally urban morphology has been the study of cities as human habitats through the analysis of their tangible, physical artefacts. Such artefacts are outcomes of complex social and economic forces, and their study is primarily driven by traditional modes of data collection (e.g. based on censuses, physical surveys, and mapping). The emergence of Web 2.0 and through its applications, platforms and mechanisms that foster user-generated contributions to be made, disseminated, and debated in cyberspace, is providing a new lens in the study of urban morphology. In this paper, we showcase ways in which user-generated ‘big data’ can be harvested and analyzed to generate snapshots and impressionistic views of the urban landscape in physical terms. We discuss and support through representative examples the potential of such analysis in revealing how urban spaces are perceived by the general public, establishing links between tangible artefacts and cyber-social elements. These links may be in the form of references to, observations about, or events that enrich and move beyond the traditional physical characteristics of various locations. This leads to the emergence of alternate views of urban morphology that better capture the intricate nature of urban environments and their dynamics.
Over 1 billion people currently live in slums, with the number of slum dwellers only expected to ... more Over 1 billion people currently live in slums, with the number of slum dwellers only expected to grow in the coming decades. The vast majority of slums are located in and around urban centres in the less economically developed countries, which are also experiencing greater rates of urbanization compared with more developed countries. This rapid rate of urbanization is cause for significant concern given that many of these countries often lack the ability to provide the infrastructure (e.g., roads and affordable housing) and basic services (e.g., water and sanitation) to provide adequately for the increasing influx of people into cities. While research on slums has been ongoing, such work has mainly focused on one of three constructs: exploring the socio-economic and policy issues; exploring the physical characteristics; and, lastly, those modelling slums. This paper reviews these lines of research and argues that while each is valuable, there is a need for a more holistic approach for studying slums to truly understand them. By synthesizing the social and physical constructs, this paper provides a more holistic synthesis of the problem, which can potentially lead to a deeper understanding and, consequently, better approaches for tackling the challenge of slums at the local, national and regional scales.
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signatures were extracted and used with a maximum likelihood decision rule for classification and thematic accuracies were then determined. Both despeckled radar and derived texture measures were examined. Thematic accuracies for the two despeckled image dates were similar with a difference of 3% for Washington and 6% for Sudan. Merging the despeckled images for both seasons increased overall accuracy by 2% for Washington and 9% for Sudan. Further combining the original radar for both seasons with derived texture measures increased overall accuracies by 9% for Washington and 16% for Sudan for final overall accuracy values of 73% and 82%.
obtained for Washington, D.C., USA. Polarization signatures were extracted for multiple image components, classified with a maximum-likelihood decision rule and thematic accuracies determined. Initial classifications using original and despeckled scenes showed despeckled radar to have better overall thematic accuracies. However, when variance texture measures were extracted for several window sizes from the original and despeckled imagery and classified, the accuracy for the radar data was decreased when despeckled prior to texture extraction. The highest classification accuracy obtained for the extracted
variance texture measure from the original radar was 72%, which was reduced to 69% when this measure was extracted from a 5x5 despeckled image. These results suggest that it may be better to use despeckled radar as original data and extract texture measures from the original imagery.
signatures were extracted and used with a maximum likelihood decision rule for classification and thematic accuracies were then determined. Both despeckled radar and derived texture measures were examined. Thematic accuracies for the two despeckled image dates were similar with a difference of 3% for Washington and 6% for Sudan. Merging the despeckled images for both seasons increased overall accuracy by 2% for Washington and 9% for Sudan. Further combining the original radar for both seasons with derived texture measures increased overall accuracies by 9% for Washington and 16% for Sudan for final overall accuracy values of 73% and 82%.
obtained for Washington, D.C., USA. Polarization signatures were extracted for multiple image components, classified with a maximum-likelihood decision rule and thematic accuracies determined. Initial classifications using original and despeckled scenes showed despeckled radar to have better overall thematic accuracies. However, when variance texture measures were extracted for several window sizes from the original and despeckled imagery and classified, the accuracy for the radar data was decreased when despeckled prior to texture extraction. The highest classification accuracy obtained for the extracted
variance texture measure from the original radar was 72%, which was reduced to 69% when this measure was extracted from a 5x5 despeckled image. These results suggest that it may be better to use despeckled radar as original data and extract texture measures from the original imagery.