Distributed geospatial information processing: sharing distributed geospatial resources to support Digital Earth

Abstract

This paper introduces a new concept, distributed geospatial information processing (DGIP), which refers to the process of geospatial information residing on computers geographically dispersed and connected through computer networks, and the contribution of DGIP to Digital Earth (DE). The DGIP plays a critical role in integrating the widely distributed geospatial resources to support the DE envisioned to utilise a wide variety of information. This paper addresses this role from three different aspects: 1) sharing Earth data, information, and services through geospatial interoperability supported by standardisation of contents and interfaces; 2) sharing computing and software resources through a GeoCyberinfrastructure supported by DGIP middleware; and 3) sharing knowledge within and across domains through ontology and semantic searches. Observing the long-term process for the research and development of an operational DE, we discuss and expect some practical contributions of the DGIP to the DE.     

Improving geospatial query performance of an interoperable geographic situation‐awareness system for disaster response

Disaster response operations require fast and coordinated actions based on real‐time disaster situation information. Although crowdsourced geospatial data applications have been demonstrated to be valuable tools for gathering real‐time disaster situation information, they only provide limited utility for disaster response coordination because of the lack of semantic compatibility and interoperability. To help overcome the semantic incompatibility and heterogeneity problems, we use Geospatial Semantic Web (GSW) technologies. We then combine GSW technologies with Web Feature Service requests to access multiple servers. However, a GSW‐based geographic information system often has poor performance due to the complex geometric computations required. The objective of this research is to explore how to use optimization techniques to improve the performance of an interoperable geographic situation‐awareness system (IGSAS) based on GSW technologies for disaster response. We conducted experiments to evaluate various client‐side optimization techniques for improving the performance of an IGSAS prototype for flood disaster response in New Haven, Connecticut. Our experimental results show that the developed prototype can greatly reduce the runtime costs of geospatial semantic queries through on‐the‐fly spatial indexing, tile‐based rendering, efficient algorithms for spatial join, and caching, especially for those spatial‐join geospatial queries that involve a large number of spatial features and heavy geometric computation.     

A geospatial study of the drought impact on surface water reservoirs: study cases from Texas,USA

Satellite images have been used historically to measure and monitor fluctuations in the surface water reservoirs. This study integrates remote sensing and Geographic Information System (GIS) technologies to investigate the impact of drought on 10 selected surface water reservoirs in San Angelo and Dallas, Texas. Oscillations in summer and winter months throughout the 2005–2016 period were assessed using multispectral images from Landsat-5, ?7, and ?8, and changes in the reservoirs were characterized and correlated against local climate data of each reservoir. For quantitative comparisons of the time-series measurements, a robust density slicing approach was employed to classify the range of values of the raster cells in the near-infrared band of Landsat images for each lake into three desired classes (deep water, shallow water, and dry area) based on the natural breaks inherent in the dataset. Statistical analysis shows that the overall accuracy of the classification is about 94%, which demonstrates the efficiency of the density slicer to accurately estimate surface water area changes from an individual Landsat band. Shrinkage in the surface water area over the study period reveals the concrete impact that the drought along with other factors have on the 10 selected lakes. The San Angelo lakes located in west central Texas experienced a nearly consistent pattern of change during most of the study period; whereas the Dallas lakes in northeast Texas followed the oscillating pattern of drought and correlated closely to the local conditions. Shockingly, the extreme drought caused complete vanishing of several lakes, and consequently Texas had to remove them from its recreational plans. Our new findings can certainly help with the water resource management in Texas and our study approach can be adapted for monitoring lake oscillations in other areas across the world. This geospatial study demonstrates the societal benefits from incorporating remote sensing and GIS in investigating geo-environmental problems associated with severe climate changes.     

数字地理空间框架建设的形势与任务

数字地理空间框架建设是推进国土资源信息化和构建数字中国的重要基础性工作,是测绘部门面临的紧迫任务。本文总结了十一五以来数字地理空间框架建设取得的主要进展,分析了存在的主要问题和面临的机遇挑战,研究提出了下一步数字地理空间框架建设的基本思路、主要任务和对策措施。     

Modeling sprawl of unauthorized development using geospatial technology: case study in Kuantan district,Malaysia

Abstract

The paper explores a framework combining remote sensing and GIS-cellular automata (CA) concepts aimed at improving the modeling of unauthorized land use sprawl. Remote sensing data have been used in urban modeling and analysis, the use of high-resolution remote sensing data in assessing unauthorized development is quite unexplored. This work has demonstrated systematic combination utilization of geospatial analyses tools to acquire a new level of information to enable urban modeling and sprawl analysis in assisting urban sustainable management. In this study, Kuantan city, Malaysia was selected in simulation of the unauthorized land use with CA concept for a period of 15 years (2000–2015), with main input time-series land use observation from 1995 to 2005. The 2000 and 2005 land use input was also used as calibrated and test assessment of the simulation. The results show excellent agreement between in-situ changes of the unauthorized land use classes and the corresponding simulated classes within the same periods. In conclusion, CA model can lead to new levels of understanding of how urban areas grow and change as in view of digital earth aspiration.     

植被指数对旱灾的响应研究—以中国西南地区2009年—2010年特大干旱为例

基于中国西南地区5个省(市)2001年—2010年期间由中分辨率成像光谱仪MODIS影像资料反演得到的归一化植被指数NDVI产品数据和区内气象站点的连续观测资料,提取了研究区内各气象站点印迹区的NDVI值,计算了降水距平百分率Pa和D指数(降水量与潜在蒸散量之差)这两种气象干旱指数。依据全国植被类型图(2000年版),对研究区内的主要植被类型在季节时间尺度上开展了这两种气象干旱指数与距平NDVI的相关性分析。研究结果表明:距平NDVI对D指数的最大响应滞后约一个月,在此尺度上表现出明显的线性相关性,所选取的6个季度的相关系数均接近或大于0.7,显著性水平小于0.01;对干旱敏感的植被类型如旱地和草地等,表现出更显著的相关性,其相关系数分别达到了0.83和0.71(平均);在干旱季节,D指数与距平NDVI表现出较为一致的空间分异规律,而Pa指数仅在旱情比较严重的情况下或对干旱比较敏感的植被类型区与距平NDVI表现出一致性分布。     

AR技术在GIS可视化中的应用及方法研究

地理数据的增强现实可视化技术,是地理信息科学可视化的一个重要的发展方向之一。首先,笔者详细地综述了国内外AR技术在GIS可视化领域的应用。针对基于真实视频影像表达地理数据的问题,笔者构建了该可视化系统的概念模型;并以户外山区地形数据和影像数据为基础,详细地阐述了AR技术可视化地理数据的原理和方法;最后,实现了以视频影像为载体的地理数据AR可视化方法。与传统地理数据的可视化方式相比,AR可视化表达方式更简单直观,真实感更强。     

Change vector analysis for disaster assessment: A case study of Hurricane Andrew

Abstract

Remote sensing is a powerful and accurate means of collecting data for wildlife management, particularly for large areas which are difficult of access and feature delicate ecosystems.

Giant panda habitat in the People's Republic of China was evaluated by visual interpretation of multitemporal LANDSAT MSS images. The resulting map, combined with ground survey data, provides important information upon which management decisions can be planned.

This case study illustrates that remote sensing techniques can make a significant contribution to the management programme for the conservation of a threatened animal species.     

Access to Geospatial Data in 2003: A Global Survey of Public Policy and Technological Factors

Access to global geospatial data, and the way these data are being used, has changed dramatically in the past decade. This is true for a variety of reasons, many of them not readily apparent. This article will explore some of the essential changes in this sphere since the early 1990s, as seen from the perspective of a commercial distributor and service bureau involved with international maps and related data.     

An integrated virtual geographic environmental simulation framework: a case study of flood disaster simulation

Dynamic flood disaster simulation is an emerging and promising technology significantly useful in urban planning, risk assessment, and integrated decision support systems. It is still an important issue to integrate the large assets such as dynamic observational data, numerical flood simulation models, geographic information technologies, and computing resources into a unified framework. For the intended end user, it is also a holistic solution to create computer interpretable representations and gain insightful understanding of the dynamic disaster processes, the complex impacts, and interactions of disaster factors. In particular, it is still difficult to access and join harmonized data, processing algorithms, and models that are provided by different environmental information infrastructures. In this paper, we demonstrate a virtual geographic environments-based integrated environmental simulation framework for flood disaster management based on the notion of interlinked resources, which is capable of automated accumulating and manipulating of sensor data, creating dynamic geo-analysis and three-dimensional visualizations of ongoing geo-process, and updating the contents of simulation models representing the real environment. The prototype system is evaluated by applying it as a proof of concept to integrate in situ weather observations, numerical weather and flood disaster simulation models, visualization, and analysis of the real time flood event. Case applications indicate that the developed framework can be adopted for use by decision-makers for short-term planning and control since the resulting simulation and visualization are completely based on the latest status of environment.     

A Geospatial Approach to Understand the Dynamics of Shifting Cultivation in Champhai District of Mizoram,North-East India

The dynamics of crop-fallow rotation cycles of shifting cultivation has been poorly understood in northeastern part of the country although it is one of the major land use systems in the hilly states of this region. The present study was conducted to understand the dynamics of shifting cultivation through the use of Landsat time-series data from 1999 to 2016 in Champhai district of Mizoram. We mapped the current jhum fields and abandoned areas of each imagery of the study period and performed a post classification comparison to assess the crop-fallow rotation cycle/jhum cycle. The chrono-sequential change of slash and burn area over the past 17 years showed a decreasing trend with the greater part of the shifting cultivation area being occupied by 2nd year crop fields, covering 48.81% of total jhum land. On average, 114.46 km² area were annually slashed for current jhum, out of which 33.41% continued with current jhum 2nd year cropping and only 3.27% of jhumias continued with 3rd year cropping. The shifting cultivation patches were mostly confined to moderately steep slopes (15°–30°). East facing aspect was mostly preferred and North facing aspect was least preferred. During the study period, 10 years jhum cycle covered the maximum area followed by 9 years and 11 years jhum cycle. The end result of this study proved that the prevalent jhum cycle in Champhai district is 8–11 years with a fallow period of 6–9 years.     

Acceptance of open source geospatial software: Assessing QGIS in South Africa with the UTAUT2 model

Geospatial information and technologies are widely used in South Africa, initially mostly with proprietary software but today, mature, open source alternatives such as QGIS are available. We wanted to find out if and why South African users accepted QGIS, globally the most widely used free and open source GIS. We adapted the extended unified theory of acceptance and use of technology model to test several hypotheses regarding the acceptance and use of QGIS in South Africa. 205 registered members of the Geo‐Information Society of South Africa completed a structured questionnaire. Results show that habit has the most significant influence on behavioural intention to use QGIS, followed by facilitating conditions, price value and social influence. Performance expectancy, effort expectancy, hedonic motivation and access to source code played no significant role. The findings show that adoption of QGIS in South Africa is not primarily influenced by benefits attributed to open source software, such as cost benefits, customizability, improved reliability, quality and security. The results are useful for developers of any GIS product and for choosing a GIS product for an organization, because they provide insight into the behavioural intentions of users.     

基于DMSP/OLS灯光数据的快速城市化过程的生态效应评价研究——以环渤海城市群地区为例

快速有效地评估城市化过程带来的生态环境后果,对于优化城市土地利用格局、降低和防范城市生态环境风险,非常必要。因此本文综合利用DMSP/OLS夜间灯光数据和SPOT/VGT时间序列数据等多源遥感信息,以NDVI与时间的积分值来表征一定时间段内的植被初级生产力,探讨了环渤海城市群地区城市化过程对植被初级生产力的季节性变化影响。发现：（1）研究区全年总的平均初级生产力总体表现为城市地区低于非城市地区的特征。（2）研究区平均初级生产力一般是在8月份最高,而在1月份最低;同时,一个生长季内,平均初级生产力总体呈现为4-11月城市地区低于非城市地区,而12月到次年3月则是城市地区要高于非城市地区的趋势,但这种趋势在各土地覆盖类型间也存在很大的不同。（3）研究区全年总的平均初级生产力,城市地区NDVI为110.23d/km^2,而非城市地区为123.94d/km^2,两者相差13.71d/km^2,即城市化过程已经在一定程度上减弱了研究区的植被初级生产力。     

Seven possible states of geospatial data with respect to map projection and definition: a novel pedagogical device for GIS education

ABSTRACT

Conceptually, the theory and implementation of “map projection” in geographic information system (GIS) technology is difficult to comprehend for most introductory students and novice users. Compounding this difficulty is the concept of a “map projection file” that defines map projection parameters of geo-spatial data. The problem of the “missing projection file” appears ubiquitous for all users, especially in practice where data is widely shared. Another common problem is inadvertent misapplication of the “Define Projection” tool that can result in a GIS dataset with an incorrectly defined map projection file. GIS education should provide more guidance in differentiating the concepts of map projection versus projection files by increasing understanding and minimizing common errors. A novel pedagogical device is introduced in this paper: the seven possible states of GIS data with respect to map projection and definition. The seven possible states are: (1) a projected coordinate system (PCS) that is correctly defined, (2) a PCS that is incorrectly defined, (3) a PCS that is undefined, (4) a geographic coordinate system (GCS) that is correctly defined, (5) a GCS that is incorrectly defined, (6) a GCS that is undefined, and (7) a non-GCS. Recently created automated troubleshooting tools to determine a missing map projection file are discussed.     

重大自然灾害空间信息协同服务机制研究

结合重大自然灾害应急管理的业务需求,分析了国外数据共享实践经验与案例,基于国家灾害管理实践工作经验,提出了中国建设重大自然灾害空间信息协同服务机制的构想。在进行职责任务划分的基础上,设立了包括指令中枢、数据中枢和信息中枢的立体化体制架构,并结合国家灾害管理业务工作的实际情况,制定了服务机制的业务关系流程,设定应急与常规相结合的运行模式,并对所需的保障配套机制进行了研究和分析。目前,重大自然灾害空间信息协同服务机制已经在国家灾害管理部门得到了一定范围的实践和检验,取得了较好的应用效果和社会经济效益。     

Free software: A review,in the context of disaster management

This article examines the nature of freely available geospatial software and information systems in the context of disaster management. The use of geospatial data is crucial to effective disaster management, from preparedness to response and recovery. However, to make efficient use of available data and information – before, during and after a disaster – reliable software is required. The software applications examined in this paper range from Geographical Information Systems, to the processing of remotely sensed images, crowd-source mapping, web applications and content management systems. Trends and challenges are considered, and guidelines are given, to foster and encourage the provision of information by Freeware and Open Source Software. Free geoinformatics can help to optimize the limited financial, technological and manpower resources that many organisations face, providing a sustainable input to analytical activities.     

Visualisation techniques to support public interpretation of future climate change and land-use choices: a case study from N-E Scotland

Mitigating and adapting to climate change includes a requirement to evaluate the role of future land uses in delivering robust integrated responses that are sensitive to local landscape contexts. In practice, this emphasises the need for community engagement, planning and inclusive decision-making. Community engagement may be potentially facilitated by the use of spatially explicit quantitative scenarios of land-use change in combination with interactive visualisation. This requires a coherent framework to integrate spatial data modelling, analytical capabilities and visualisation tools in a format that will also engage diverse public audiences. These challenges were explored with a case study of virtual landscapes from N-E Scotland that was used to test preferences for scenarios of future land use. Visualisations employed texture-based rendering rather than full photo-realistic rendering to facilitate interactivity and this provided additional scope for audiences to explore multiple future scenarios compared to the present landscape. Interactive voting in a virtual landscape theatre suggested preferences for visual diversity, good stewardship and perceived naturalness that should be considered in developing planned responses to change. Further investigation of preferences was conducted using interactive 3D features located within the landscape. Study findings are reviewed against objectives for inclusive engagement in the Digital Earth agenda and used to make further recommendations on the use of scenarios and visualisation tools. In particular, technical advances in user engagement need to be developed in conjunction with emerging good practice that addresses ethical, behavioural and inclusion issues so that the content is presented in as transparent and unbiased format as possible.