Using geospatial technology to strengthen data systems in developing countries: The case of agricultural statistics in India     

《Applied geography (Sevenoaks, England)》2013

Despite significant progress in the development of quantitative geography techniques and methods and a general recognition of the need to improve the quality of geographic data, few studies have exploited the potential of geospatial tools to augment the quality of available data methods in developing countries. This paper uses data from an extensive deployment of geospatial technology in India to compare crop areas estimated using geospatial technology to crop areas estimated by conventional methods and assess the differences between the methods. The results presented here show that crop area estimates based on geospatial technology generally exceed the estimates obtained using conventional methods. This suggests that conventional methods are unable to respond quickly to changes in cropping patterns and therefore do not accurately record the area under high-value cash crops. This finding has wider implications for commercializing agriculture and the delivery of farm credit and insurance services in developing countries. Significant data errors found in the conventional methods could affect critical policy interventions such as planning for food security. Some research and policy implications are discussed.  相似文献   

Comparison of existing methods for building triangular irregular network,models of terrain from grid digital elevation models     

JAY LEE 《International journal of geographical information science》2013,27(3):267-285

Abstract

Triangulated irregular networks (TINs) are increasingly popular for their efficiency in data storage and their ability to accommodate irregularly spaced elevation points for many applications of geographical information systems. This paper reviews and evaluates various methods for extracting TINs from dense digital elevation models (DEMs) on a sample DEM. Both structural and statistical comparisons show that the methods perform with different rates of success in different settings. Users of DEM to TIN conversion methods should be aware of the strengths and weaknesses of the methods in addition to their own purposes before conducting the conversion.  相似文献   

Watermarking of digital geospatial datasets: a review of technical,legal and copyright issues     

Carlos López 《International journal of geographical information science》2013,27(6):589-607

Gathering data accounts for more than 80% of the cost of any GIS project. Fast Internet connections and digital datasets threaten the investments of data producers through data piracy. Outside the GIS community this problem has been known for a long time, and possible solutions exist for digital imagery, formatted text, 3D meshes and so on, showing possible links to typical spatial data. This is largely achieved through embedding hidden information in a dataset without producing perceptible changes in the data, a process known as watermarking. The producer can recover the embedded information on request in order to produce evidence of ownership in a court, so the overall strategy relies on a legal basis rather than technical ones. This paper analyses the state-of-the-art for watermarking protection in digital geographical datasets. Digital imagery is demonstrably a more mature area than geographical information, even with multiple commercial vendors offering watermarking protection. 2D vector and point datasets have received less attention from the research community; however, 3D meshes have been considered by the CAD community and a handful of techniques are available for that case, and they are reviewed here.  相似文献   

Developing geographic information infrastructures: the role of access policies     

B. van Loenen 《International journal of geographical information science》2013,27(2):195-212

Within societies, information availability is a key issue affecting society's well‐being. For geographic information, a geographic information infrastructure (GII) facilitates availability and access to geographic information for all levels of government, the commercial sector, the non‐profit sector, academia, and ordinary citizens. Although the importance of access policies in the development of a GII is commonly understood, research that has assessed the impact of access policies on this development is scant. This article adds this perspective. Based on information acquired from case‐study and literature research, the author argues that open‐access policies do not always promote GII development and in specific instances are counter‐productive. These findings may explain why many nations still adhere to cost‐recovery policies instead of following access policies recommended by research. The article provides alternatives for changing current policies into new access policies that promote GII development.  相似文献   

An adaptive approach to selecting a flow‐partition exponent for a multiple‐flow‐direction algorithm     

C. Qin  A.‐X. Zhu  T. Pei  B. Li  C. Zhou  L. Yang 《International journal of geographical information science》2013,27(4):443-458

Most multiple‐flow‐direction algorithms (MFDs) use a flow‐partition coefficient (exponent) to determine the fractions draining to all downslope neighbours. The commonly used MFD often employs a fixed exponent over an entire watershed. The fixed coefficient strategy cannot effectively model the impact of local terrain conditions on the dispersion of local flow. This paper addresses this problem based on the idea that dispersion of local flow varies over space due to the spatial variation of local terrain conditions. Thus, the flow‐partition exponent of an MFD should also vary over space. We present an adaptive approach for determining the flow‐partition exponent based on local topographic attribute which controls local flow partitioning. In our approach, the influence of local terrain on flow partition is modelled by a flow‐partition function which is based on local maximum downslope gradient (we refer to this approach as MFD based on maximum downslope gradient, MFD‐md for short). With this new approach, a steep terrain which induces a convergent flow condition can be modelled using a large value for the flow‐partition exponent. Similarly, a gentle terrain can be modelled using a small value for the flow‐partition exponent. MFD‐md is quantitatively evaluated using four types of mathematical surfaces and their theoretical ‘true’ value of Specific Catchment Area (SCA). The Root Mean Square Error (RMSE) shows that the error of SCA computed by MFD‐md is lower than that of SCA computed by the widely used SFD and MFD algorithms. Application of the new approach using a real DEM of a watershed in Northeast China shows that the flow accumulation computed by MFD‐md is better adapted to terrain conditions based on visual judgement.  相似文献   

素质教育背景下地理教师的GIS素质构建     

牛继强  刘明华  徐丰  杨秀花 《地理空间信息》2013,11(1):163-165,16

在对地理教师地理科学素质现状分析的基础上,对地理教师在教学、科研、生活中应具备的地理信息科学素质进行了研究,并从师范教育、继续教育2个角度探讨了构建地理教师地理信息科学素质的方法。  相似文献   

地理信息共享的非技术理论基础探讨     

余旭  何建邦  曹彦荣  孔爱婷 《测绘软科学研究》2013,(6):19-22

地理信息共享涉及信息共享的政策、管理、标准、技术和法律等一系列问题,是地理信息系统研究的一个重要方面。地理信息共享研究视角总体上包括技术视角和非技术视角,本文基于已有的理论,从非技术视角探讨了地理信息共享的理论基础。  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987111001137   总被引：12，自引：1，他引：11  

N.S. Magesh  N. Chandrasekar  John Prince Soundranayagam 《地学前缘(英文版)》2012,3(2):189-196

Integration of remote sensing data and the geographical information system(GIS) for the exploration of groundwater resources has become a breakthrough in the field of groundwater research, which assists in assessing,monitoring,and conserving groundwater resources.In the present paper, various groundwater potential zones for the assessment of groundwater availability in Theni district have been delineated using remote sensing and GIS techniques.Survey of India toposheets and IRS-1C satellite imageries are used to prepare various thematic layers viz.lithology,slope,land-use,lineament, drainage,soil,and rainfall were transformed to raster data using feature to raster converter tool in ArcGIS.The raster maps of these factors are allocated a fixed score and weight computed from multi influencing factor(MIF) technique.Moreover,each weighted thematic layer is statistically computed to get the groundwater potential zones.The groundwater potential zones thus obtained were divided into four categories,viz.,very poor,poor,good,and very good zones.The result depicts the groundwater potential zones in the study area and found to be helpful in better planning and management of groundwater resources.  相似文献   

一种专用矢量地图浏览服务器设计     

李晓林  李霖 《测绘工程》2011,20(4):46-49,54

以地图符号形式表达地理要素是GIS地理信息可视化的有效手段.目前Web GIS发布系统在复杂地图符号的表达能力、地图的快速发布和运行效率等方面存在一定的不足.为此,应用IE浏览器内容扩展技术,结合地图符号表达的特征,设计出面向基础地理数据的地图浏览服务器,给出地理数据类型可兼容的快速发布矢量地图文档结构.据此,开发基于...  相似文献   

地理信息网络服务的发展研究     

蔡畅  崔铁军  葛文 《测绘软科学研究》2011,9(1):35-39

随着体系结构、软件层次和自身需求的变化,GIS逐步发展为地理信息网络服务并得到迅速的推广。从标准化、语义化和3维化的角度总结了当前地理信息服务的发展状态,并指出下一代地理信息网络服务必然是基于以上三者的能够实现主动服务和统一多维服务的新一代地理信息服务。  相似文献