Remote sensing technology has long been used to detect and map crop diseases.Airborne and satellite imagery acquired during growing seasons can be used not only for early detection and within-season management of some...Remote sensing technology has long been used to detect and map crop diseases.Airborne and satellite imagery acquired during growing seasons can be used not only for early detection and within-season management of some crop diseases,but also for the control of recurring diseases in future seasons.With variable rate technology in precision agriculture,site-specific fungicide application can be made to infested areas if the disease is stable,although traditional uniform application is more appropriate for diseases that can spread rapidly across the field.This article provides a brief overview of remote sensing and precision agriculture technologies that have been used for crop disease detection and management.Specifically,the article illustrates how airborne and satellite imagery and variable rate technology have been used for detecting and mapping cotton root rot,a destructive soilborne fungal disease,in cotton fields and how site-specific fungicide application has been implemented using prescription maps derived from the imagery for effective control of the disease.The overview and methodologies presented in this article should provide researchers,extension personnel,growers,crop consultants,and farm equipment and chemical dealers with practical guidelines for remote sensing detection and effective management of some crop diseases.展开更多
Detailed and precise urban land-cover maps are crucial for urban-related studies. However, there are limited ways of mapping high-resolution urban land cover over large areas. In this paper, we propose an operational ...Detailed and precise urban land-cover maps are crucial for urban-related studies. However, there are limited ways of mapping high-resolution urban land cover over large areas. In this paper, we propose an operational framework to map urban land cover on the basis of Ziyuan-3 satellite images. Based on this framework, we produced the first high-resolution(2 m) urban land-cover map(Hi-ULCM) covering the 42 major cities of China. The overall accuracy of the Hi-ULCM dataset is 88.55%, of which 14 cities have an overall accuracy of over 90%. Most of the producer’s accuracies and user’s accuracies of the land-cover classes exceed 85%. We further conducted a landscape pattern analysis in the 42 cities based on Hi-ULCM. In terms of the comparison between the 42 cities in China, we found that the difference in the land-cover composition of urban areas is related to the climatic characteristics and urbanization levels, e.g., cities with warm climates generally have higher proportions of green spaces. It is also interesting to find that cities with higher urbanization levels are more habitable, in general. From the landscape viewpoint, the geometric complexity of the landscape increases with the urbanization level.Compared with the existing medium-resolution land-cover/use datasets(at a 30-m resolution), HiULCM represents a significant advance in accurately depicting the detailed land-cover footprint within the urban areas of China, and will be of great use for studies of urban ecosystems.展开更多
The commercial high-resolution imaging satellite with 1 m spatial resolution IKONOS is an important data source of information for urban planning and geographical information system (GIS) applications. In this paper, ...The commercial high-resolution imaging satellite with 1 m spatial resolution IKONOS is an important data source of information for urban planning and geographical information system (GIS) applications. In this paper, a morphological method is proposed. The proposed method combines the automatic thresholding and morphological operation techniques to extract the road centerline of the urban environment. This method intends to solve urban road centerline problems, vehicle, vegetation, building etc. Based on this morphological method, an object extractor is designed to extract road networks from highly remote sensing images. Some filters are applied in this experiment such as line reconstruction and region filling techniques to connect the disconnected road segments and remove the small redundant. Finally, the thinning algorithm is used to extract the road centerline. Experiments have been conducted on a high-resolution IKONOS and QuickBird images showing the efficiency of the proposed method.展开更多
城市林木树冠覆盖(urban tree canopy,UTC)既是衡量一个城市生态状况的标志性指标,也是衡量森林城市建设成就的关键指标,其中的潜在林木树冠覆盖(possible urban tree canopy,简称PUTC)又与城市森林建设目标的科学制定息息相关。在国外...城市林木树冠覆盖(urban tree canopy,UTC)既是衡量一个城市生态状况的标志性指标,也是衡量森林城市建设成就的关键指标,其中的潜在林木树冠覆盖(possible urban tree canopy,简称PUTC)又与城市森林建设目标的科学制定息息相关。在国外文献与实践案例研究的基础上,以北京市六环外1km以内范围为研究对象,利用2002和2013年的0.5m分辨率航、卫片影像,通过其解译的地表覆盖数据,对其两个年度的潜在林木树冠覆盖的区域分布和动态变化进行分析,并利用人口密度、道路密度和现实林木树冠覆盖率等指标,以村(社区)为单元对其潜在林木树冠覆盖的优先度进行了分析评价。结果显示,11年间,研究区域的PUTC从40882.18hm^2减少到了18845.82hm^2,空间分布也呈现出沿环路越是靠近城市中心区域,其分布也越少的格局,从其类型上看,随着时间的推移,其类型的丰富度也越来越低,到2013年,则呈现出荒草地类型绝对占优的格局。PUTC的斑块数量从109892个减少为7793个,但斑块平均面积从2002年的0.37hm^2增加到了2013年的2.36hm^2,斑块大小格局也从2002年的小斑块占绝对优势演变为各种类型"平分秋色"的状况。以PUTC为核心的村(社区)区域潜力评价结果显示,整个研究区域在2002年时低潜力和中潜力区域范围最大,分别占到了研究区域的32.39%和28.83%,2013年时潜力格局改变为极低潜力和低潜力区域面积最大,分别占研究区域总面积的25.83%和50.94%。极高优先度和高优先度区域应该是北京城市未来重点发展城市森林的区域,目前的潜在优先度评价结果表明,其面积占比分别达到了研究区域面积的13.11%和41.79%,其中极高优先度区域主要分布在构成城市核心区的东城区和西城区,因此北京城区未来的林木树冠发展策略应该走植被潜在斑块与不透水地表潜在斑块共同开发之路。展开更多
文摘Remote sensing technology has long been used to detect and map crop diseases.Airborne and satellite imagery acquired during growing seasons can be used not only for early detection and within-season management of some crop diseases,but also for the control of recurring diseases in future seasons.With variable rate technology in precision agriculture,site-specific fungicide application can be made to infested areas if the disease is stable,although traditional uniform application is more appropriate for diseases that can spread rapidly across the field.This article provides a brief overview of remote sensing and precision agriculture technologies that have been used for crop disease detection and management.Specifically,the article illustrates how airborne and satellite imagery and variable rate technology have been used for detecting and mapping cotton root rot,a destructive soilborne fungal disease,in cotton fields and how site-specific fungicide application has been implemented using prescription maps derived from the imagery for effective control of the disease.The overview and methodologies presented in this article should provide researchers,extension personnel,growers,crop consultants,and farm equipment and chemical dealers with practical guidelines for remote sensing detection and effective management of some crop diseases.
基金supported by the National Natural Science Foundation of China (41771360 and 41971295)the National Program for Support of Top-notch Young Professionals, the Hubei Provincial Natural Science Foundation of China (2017CFA029)the National Key Resarch & Development Program of China (2016YFB0501403)。
文摘Detailed and precise urban land-cover maps are crucial for urban-related studies. However, there are limited ways of mapping high-resolution urban land cover over large areas. In this paper, we propose an operational framework to map urban land cover on the basis of Ziyuan-3 satellite images. Based on this framework, we produced the first high-resolution(2 m) urban land-cover map(Hi-ULCM) covering the 42 major cities of China. The overall accuracy of the Hi-ULCM dataset is 88.55%, of which 14 cities have an overall accuracy of over 90%. Most of the producer’s accuracies and user’s accuracies of the land-cover classes exceed 85%. We further conducted a landscape pattern analysis in the 42 cities based on Hi-ULCM. In terms of the comparison between the 42 cities in China, we found that the difference in the land-cover composition of urban areas is related to the climatic characteristics and urbanization levels, e.g., cities with warm climates generally have higher proportions of green spaces. It is also interesting to find that cities with higher urbanization levels are more habitable, in general. From the landscape viewpoint, the geometric complexity of the landscape increases with the urbanization level.Compared with the existing medium-resolution land-cover/use datasets(at a 30-m resolution), HiULCM represents a significant advance in accurately depicting the detailed land-cover footprint within the urban areas of China, and will be of great use for studies of urban ecosystems.
文摘The commercial high-resolution imaging satellite with 1 m spatial resolution IKONOS is an important data source of information for urban planning and geographical information system (GIS) applications. In this paper, a morphological method is proposed. The proposed method combines the automatic thresholding and morphological operation techniques to extract the road centerline of the urban environment. This method intends to solve urban road centerline problems, vehicle, vegetation, building etc. Based on this morphological method, an object extractor is designed to extract road networks from highly remote sensing images. Some filters are applied in this experiment such as line reconstruction and region filling techniques to connect the disconnected road segments and remove the small redundant. Finally, the thinning algorithm is used to extract the road centerline. Experiments have been conducted on a high-resolution IKONOS and QuickBird images showing the efficiency of the proposed method.
文摘城市林木树冠覆盖(urban tree canopy,UTC)既是衡量一个城市生态状况的标志性指标,也是衡量森林城市建设成就的关键指标,其中的潜在林木树冠覆盖(possible urban tree canopy,简称PUTC)又与城市森林建设目标的科学制定息息相关。在国外文献与实践案例研究的基础上,以北京市六环外1km以内范围为研究对象,利用2002和2013年的0.5m分辨率航、卫片影像,通过其解译的地表覆盖数据,对其两个年度的潜在林木树冠覆盖的区域分布和动态变化进行分析,并利用人口密度、道路密度和现实林木树冠覆盖率等指标,以村(社区)为单元对其潜在林木树冠覆盖的优先度进行了分析评价。结果显示,11年间,研究区域的PUTC从40882.18hm^2减少到了18845.82hm^2,空间分布也呈现出沿环路越是靠近城市中心区域,其分布也越少的格局,从其类型上看,随着时间的推移,其类型的丰富度也越来越低,到2013年,则呈现出荒草地类型绝对占优的格局。PUTC的斑块数量从109892个减少为7793个,但斑块平均面积从2002年的0.37hm^2增加到了2013年的2.36hm^2,斑块大小格局也从2002年的小斑块占绝对优势演变为各种类型"平分秋色"的状况。以PUTC为核心的村(社区)区域潜力评价结果显示,整个研究区域在2002年时低潜力和中潜力区域范围最大,分别占到了研究区域的32.39%和28.83%,2013年时潜力格局改变为极低潜力和低潜力区域面积最大,分别占研究区域总面积的25.83%和50.94%。极高优先度和高优先度区域应该是北京城市未来重点发展城市森林的区域,目前的潜在优先度评价结果表明,其面积占比分别达到了研究区域面积的13.11%和41.79%,其中极高优先度区域主要分布在构成城市核心区的东城区和西城区,因此北京城区未来的林木树冠发展策略应该走植被潜在斑块与不透水地表潜在斑块共同开发之路。
