Performance evaluation and work-load estimation for geographic information systems

Abstract

Agencies acquiring GIS hardware and software are faced with uncertainty at two levels: over the degree to which the proposed system will perform the functions required, and over the degree to which it is capable of doing so within proposed production schedules. As the field matures the second concern is becoming more significant. A formal model of the process of acquiring a GIS is presented, based on the conceptual level of defining GIS sub-tasks. The appropriateness of the approach is illustrated using performance data from the Canada Land Data System. It is possible to construct reasonably accurate models of system resource utilization using simple predictors and least squares techniques, and a combination of inductive and deductive reasoning. The model has been implemented in an interactive package for MS-DOS systems.     

A modified binary space partitioning tree for geographic information systems

We present a reactive data structure, that is, a spatial data structure with detail levels. The two properties, spatial organization and detail levels, are the basis for a geographic information system (GIS) with a multi-scale database. A reactive data structure is a novel type of data structure catering to multiple detail levels with rapid responses to spatial queries. It is presented here as a modification of the binary space partitioning tree that includes the levels of detail. This tree is one of the few spatial data structures that does not organize space in a rectangular manner. A prototype system has been implemented. An important result of this implementation is that it shows that binary space partitioning trees of real maps have O(n) storage space complexity in contrast to the theoretical worst case O(n² ), with n the number of line segments in the map.     

信息时代移动社会理论构建与城市地理研究

以信息技术进步为核心的信息革命已经成为推动国家、区域与城市社会经济发展及其快速转型的重要动力,并持久、深刻地冲击和改变着工业革命以来人类对社会经济及其空间结构形成的固有认识。当前,移动通信技术的进步及其应用,与高速铁路的加快建设、城市区域化的加速和智慧城市的建设一起,正将世界带入一个全新的移动信息时代。由于时间和空间概念的重新定义,全新时空观的出现,使得以空间问题为核心内容的城市地理学面临着根本性的变革。在移动信息技术的支撑下,城市地理学的研究范式、方法和内容都开始发生巨大的变化,传统的理论框架已逐渐不能满足当前研究的需要。本文重点分析了移动信息技术影响下的地理空间与网络信息空间的变化,提出了基于移动信息技术的移动社会理论框架。进而对移动信息时代城市地理学的研究方法、研究重点进行了探讨,希望运用城市地理学的研究更好地服务于移动信息时代的城市与区域的发展、规划与管治。     

Usability evaluation for geographic information systems: a systematic literature review

The growing dissemination of geographic information systems (GIS) in recent years has increased the availability and use of geospatial tools. Despite this trend in GIS, usability is often not considered, and studies on usability are relatively rare. However, it has been shown that the effectiveness, efficiency and user satisfaction of these tools when used for geospatial tasks may be impacted by their design and terminology. In this article, we present a comprehensive review of the relevant literature. We analyze and compare publications of GIS usability evaluations, the methods that were used, and the findings reported. We thus produce a more detailed picture of GIS usability evaluations. Our contributions are (1) an overview of methods applied in case studies for evaluating the usability of GIS; (2) the identification of gaps and resulting weaknesses of previous studies; and (3) challenges and opportunities for future GIS usability studies. Our findings reveal a lack of usability guidelines for GIS, a lack of methods for analyzing complex workflows, and a lack of usage studies over longer periods of time. These contributions can help GIS developers and designers to improve the usability of their systems.     

OutDet: an algorithm for extracting the outer surfaces of building information models for integration with geographic information systems

The integration of Building Information Modelling (BIM) and geographic information systems (GIS) is a promising but challenging topic to solve problems in construction industry. However, loading and rendering rich BIM geometric data and large-scale GIS spatial information in a unified system is still technologically challenging. Current efforts mainly simplify the geometry in BIM models, or convert BIM geometric data to a lower level of detail (LOD). By noticing that only exterior features of BIM models are visible from outdoor observation points, culling BIM interior facilities can dramatically reduce the computational burden when visualizing BIM models in GIS. This study explores the outline detection problem and presents the OutDet algorithm, which selects representative observation points, transforms & projects the BIM geometric data into the same coordinate system, and detects the visible facilities. Empirical study results show that OutDet can cull a large portion of unnecessary features when rendering BIM models in GIS. The use of outlines of BIM models is not an alternative but rather a supplementary approach for current solutions. Jointly using LOD and outer surface can help improve the efficiency of integrated BIM-GIS visualization.Because OutDet retains BIM geometry and semantics, it can be applied to more BIM-GIS applications..     

The development and applications of geographic information systems for urban and regional planning in the developing countries

Abstract

In the past 10 years, geographic information systems (GIS) have been widely used in urban and regional planning in the developed countries in Australia, North America and Europe. However, the use of GIS in urban and regional planning in the developing countries is limited and still at an early stage of development. This paper examines the current use of GIS in urban and regional planning in the developing countries in Asia. The major hindrances in the use of GIS in the developing countries is related not so much to the technology of GIS but more to data availability, leadership, organization structure and planning practice. For GIS to be more useful to urban and regional planning in the developing countries the development of a sustainable strategy in developing GIS and staff training is needed. International assistance agencies and GIS software companies can play an active role in making GIS available and usable to the planners in the developing countries.     

An improved wide furrow micro-catchment for large-scale implementation of water-harvesting systems in arid areas

A new water harvesting (WH) micro-catchment technique [Wide Furrow with Back-placed transplanting area (WFB)], implemented using a specially developed inexpensive plow, was experimented and compared to a popular technique [the Deep Furrow (DF)] under East Mediterranean arid environment. Both WH micro-catchments with 4, 8, and 12 m long runoff area were planted with 1, 2, and 6-month old Atriplex seedlings. A multi-criterion method for comparison was employed, where the following parameters were evaluated: Sedimentation thickness and infiltration rate inside the micro-catchments; stored water in the soil profile; seasonal WH efficiency; plant productivity over two years; and the ease of mechanizing the implementation system. The DF technique showed higher WH efficiency and greater soil water storage, however, the WFB technique showed thinner sedimentation, higher infiltration rates and comparable plant productivity. Both techniques increased the wetting period of the top soil layers significantly and provided the soil reservoir with available water for more than one season. Using WFB technique and employing 1–2-month old Atriplex transplants facilitate mechanized transplanting and/or seed drilling for mixed cropping as well as mechanized maintenance of the micro-catchments, which will presumably encourage large-scale implementation and improve the sustainability of the WH structures.     

Ontologies of geographic information

This article explores the notion of a system of ontologies specifically designed for the needs of an information science. A framework for geographic information ontologies is outlined that focuses on geographic information constructs rather than on the direct representation of real-world entities or on linguistic terms. The framework takes the form of a generative hierarchy anchored by the notion of intentionality at one end and of a spatiotemporal field of potentially relevant information at the other. Two theoretical notions are used in the generation of the hierarchy. The first is the principle of semantic contraction, whereby, starting from a level of geographic information constructs specified so as to reflect user intentionality, semantically coherent domains of properties are removed over several steps until only the rudiments of a spatiotemporal information system are left. The second notion is that of object of discourse, which allows entities to be represented as the composites of geographic information constructs at the higher levels of the hierarchy, explicitly reflecting the connections between the purpose, function, appropriate internal constitution, and ensuing categorization of the entities represented. The framework's main contribution is thus twofold: first, it allows the notions of user purpose and object function to be directly built into geographic representations; second, it proposes a hierarchy of ontological levels that are linked by systematic semantic relations. Further, the framework presents an integrated view of object and field representations. It may also provide a novel perspective on a number of issues of ongoing interest in geographic information science.     

Automated geographic context analysis for volunteered information

Several studies show the impacts of (geo)social media and Volunteered Geographic Information (VGI) during crisis events, and have found intrinsic value for rescue teams, relief workers and humanitarian assistance coordinators, as well as the affected population. The main challenge is how emergency management and the public can capitalize on the abundance of this new source of information by reducing the volume to credible and relevant content.In this paper, we present the GeoCONAVI (Geographic CONtext Analysis for Volunteered Information) approach and a prototype system, designed to retrieve, process, analyze and evaluate social media content on forest fires, producing relevant, credible and actionable VGI usable for crisis events. The novelty of the approach lies in the enrichment of the content with additional geographic context information, and use of spatio-temporal clustering to support scoring and validation. Thus, the system is focusing on integrating authoritative data sources with VGI. Evaluation in case studies shows that the prototype system can handle large amounts of data with common-off-the-shelf hardware, produces valuable results, and is adaptable to other types of crisis events.     

Combining geographic information systems and ethnography to better understand and plan ocean space use

Agencies in the US with oversight for marine renewable energy development idealistically have sought space where this new use might proceed unhindered by other uses. Despite experiential evidence of spatial overlap among existing ocean uses, a lack of documentation made the identification of potential space-use conflicts, communication between existing and potential ocean users, and the design of mitigation exceedingly challenging.We conducted a study along the US Atlantic and Pacific coasts to gather and document available spatial information on existing use through a compilation and organization of geographic information system (GIS) data. Stakeholder group meetings were used to vet the collected spatial data, and ethnographic interviews were conducted to gather knowledge and cultural perspectives. Results show extensive coverage and overlap of existing ocean space uses and provide a visualization of the social and cultural landscape of the ocean that managers can use to determine which stakeholders to engage.Marine resource managers are encouraged to recognize that marine space use is dynamic and multi-dimensional and as such research thereof requires a balance between the efficiency of GIS and the stories captured and told by ethnographic research. There are important linkages within and across fisheries and other uses, communities and interests, and across the land–sea interface. Therefore, it is important to use techniques demonstrated in this research that (1) integrate ethnographic and geospatial data collection and analysis; (2) engage stakeholders throughout the process; and (3) recognize the unique qualities of each geographic location and user group to support sound decision-making.     

VGTrust: measuring trust for volunteered geographic information

Volunteered Geographic Information (VGI) has emerged as a large, up-to-date, and easily accessible data source. VGI can allow authoritative mapping agencies to undertake continuous improvement of their own data, adding a currency dimension previously unattainable due to high associated costs. VGI also benefits scientific and social research by facilitating quick and low-cost research data capture by the public. VGI, however, through its diversity of authorship, presents a quality assurance risk to the use of this data. This research presents a formulaic model that addresses VGI quality issues, by quantifying trust in VGI. Our ‘VGTrust’ model assesses information about a data author, and the spatial and temporal trust associated with the data they create, to produce an overall VGTrust rating metric. This metric is both easy to understand and interpret. A facilitated case study, ‘Building Our Footprints’ is presented which tests the feasibility of VGTrust model in a real-world data capture exercise run by Land Information New Zealand, New Zealand’s mapping organisation. By overcoming the trust issues in VGI, this research will allow the integration of VGI and authoritative data and potentially expand the application of VGI, thereby leveraging the power of the crowd for productive and innovative re-use.     

A simple method for estimating basin-scale groundwater discharge by vegetation in the basin and range province of Arizona using remote sensing information and geographic information systems

Groundwater is a vital water resource in the arid to semi-arid southwestern United States. Accurate accounting of inflows to and outflows from the groundwater system is necessary to effectively manage this shared resource, including the important outflow component of groundwater discharge by vegetation. A simple method for estimating basin-scale groundwater discharge by vegetation is presented that uses remote sensing data from satellites, geographic information systems (GIS) land cover and stream location information, and a regression equation developed within the Southern Arizona study area relating the Enhanced Vegetation Index from the MODIS sensors on the Terra satellite to measured evapotranspiration. Results computed for 16-day composited satellite passes over the study area during the 2000 through 2007 time period demonstrate a sinusoidal pattern of annual groundwater discharge by vegetation with median values ranging from around 0.3 mm per day in the cooler winter months to around 1.5 mm per day during summer. Maximum estimated annual volume of groundwater discharge by vegetation was between 1.4 and 1.9 billion m³ per year with an annual average of 1.6 billion m³. A simplified accounting of the contribution of precipitation to vegetation greenness was developed whereby monthly precipitation data were subtracted from computed vegetation discharge values, resulting in estimates of minimum groundwater discharge by vegetation. Basin-scale estimates of minimum and maximum groundwater discharge by vegetation produced by this simple method are useful bounding values for groundwater budgets and groundwater flow models, and the method may be applicable to other areas with similar vegetation types.     

Video support in teaching about geographic information systems: a review of six videotapes

Abstract

Abstract. The growing interest in teaching about geographic information systems (GIS) raises a number of issues concerning the effectiveness of conventional instructional methods. To convey basic GIS concepts and applications better requires much more emphasis upon visual media. One such medium is that of VHS (or Beta) videotapes. Six currently-available GIS-oriented videotapes are reviewed for this purpose. Their contents are summarized and an evaluation is made of the usefulness of each in classroom-based GIS instruction.     

Planning of recreational trails in protected areas: Application of regression tree analysis and geographic information systems

One of the most important tasks for managers of many natural protected areas is achieving a balance between conservation of nature and recreational opportunity. This paper presents a framework based on geographic information system (GIS) and regression tree analysis of optimized recreational trail location for flexible, user-defined input parameters. The method utilizes: (1) the GIS to create a database containing field data and existing GIS/cartographic materials; (2) regression tree analysis to establish the relationships between indicators of degradation and environmental and use-related factors for existing trails, as well as to predict trail degradation for potential new trials; (3) least-cost path algorithm within a GIS framework to optimize trail route.The framework was applied to the Gorce National Park in the south of Poland. A large sample (>4500) of the field collected data about degradation of the existing trail network was linked with data about soil, geology, geomorphology and relief, and with information about the type and amount of recreational use. Based on the existing relationship, predicted trail degradation was calculated and routes for two examples of trails (hiking and motorized) were designated. The proposed methodology is objective and quantitative, and can also include knowledge of local stakeholders. The framework has the potential to design new trails (or to re-route old ones), characterized by the best possible solution for recreational and conservation functions to coexist, by routing visitors through trails with the lowest possible impact.     

Volunteered geographic information quality assessment using trust and reputation modelling in land administration systems in developing countries

This article presents an innovative approach to establish the quality and credibility of Volunteered Geographic Information (VGI) such that it can be considered in Land Administration Systems (LAS) on a Fit for Purpose (FFP) basis. A participatory land information system can provide affordable and timely FFP information about land and its resources. However, the establishment of such a system involves more than just technical solutions and administrative procedures: many social, economic and political aspects must be considered. Innovative approaches like VGI can help address the lack of accurate, reliable and FFP land information for LAS, but integration of such sources relies on the quality and credibility of VGI. Verifying volunteer efforts can be difficult without reference to ground truth: a novel Trust and Reputation Modelling methodology is proposed as a suitable technique to effect such VGI data set validation. This method has been applied to successfully demonstrate that VGI can produce accurate and reliable data sets which can be used to conduct regular systematic updates of geographic information in official systems. It relies on a view that the public can police themselves in establishing proxy measures of VGI quality thus facilitating VGI to be used on a FFP basis in LAS.     

多维统一GIS构建与实现的几何代数方法

针对时空GIS发展所面临的时空表达不统一,高维扩展困难等问题,基于以多维统一和坐标无关为特征的几何代数理论,建立多维统一GIS构建的层次体系与方法。利用几何代数对象构造中几何维度与Grassmann维度的一致性,实现整合维度结构与几何关系的多维地理对象自适应表达。利用几何代数算子的特征内蕴与结构明晰特性,构建多维统一计算模型以及可支撑复杂地理计算的多维统一分析框架,进而建立基于几何代数的多维统一GIS系统架构与实现方案。对上述关键技术加以实现并进行了相关应用案例分析。结果显示,基于几何代数构建的多维统一GIS有望突破现有时空GIS的不足,可为以多维统一表达与运算为特征GIS的发展提供新的数学工具与实现途径。     

Developing geographic information infrastructures: the role of access policies

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.     

Vague cognitive regions in geography and geographic information science

Cognitive regions are regions in the mind, reflecting informal ways individuals and cultural groups organize their understanding of earth landscapes. Cognitive region boundaries are typically substantially vague and their membership functions are substantially variable – the transition from outside to inside the region is imprecise or vague, and different places within the region are not equally strong or clear as exemplars of the region. Methods for assessing and cartographically depicting cognitive regions, as with other vague geographic regions, have traditionally implied an inappropriate level of boundary sharpness and membership uniformity, such as when boundaries are mapped as precise lines. Research in recent decades has explored methods for assessing and depicting boundary vagueness and membership variability, either within or across individuals, but has still assumed homogeneity and regularity in the vagueness and variability. In this article, we present two studies that assess the cognitive regions of ‘Northern’ and ‘Southern’ California, and, for comparison, ‘Northern’ and ‘Southern’ Alberta. The first study uses a standard boundary-drawing task; the second uses a novel task in which participants rate cells of a high-resolution grid laid over an outline map. This technique allows us to assess and depict vagueness and nonuniformity that is heterogeneous and irregular across different areas. Differences in the conceptualization of ‘Northern’ and ‘Southern’ regions in California, as compared to those in Alberta, point to thematic influences on cognitive regions in California but not in Alberta. As is often true with cognitive regions, Northern and Southern California are about attitude, not just latitude.