共查询到20条相似文献，搜索用时 31 毫秒
1.
CHENGPenggen SHIWenzhong GONGJianya ZHOUGuoqing 《地球空间信息科学学报》2005,8(1):64-71
3D spatial data model and simulating are the core of 3D GIS can be adopted in different domains. A data model based on Quasi Tri-Prism Volume (QTPV) has been proposed. QTPV definition and its special cases have been discussed. Using QTPV and its special cases, irregular natural geological bodies and regular subsurface engineering can be described efficiently. The proposed model is composed of five primitives and six objects. Data structures and topological relationship of the fives primitives and three objects describing stratigraphy are designed in detail Some schemes are designed for the QTPV modelling of stratigraphy and subsurface engineering according to modelling data. The model manipulation method of QTPV cutting by an arbitrary plane is discussed. Using VC 6.0 programming language integrated with SQL database and OpenGL graphic library under windows environment, a system prototype 3DGeoMV has been developed. The experiment result shows that the QTPV model is feasible and efficient in modelling subsurface engineering. 相似文献
2.
3D spatial data model and simulating are the core of 3D GIS can be adopted in different domains. A data model based on Quasi Tri-Prism Volume (QTPV) has been proposed. QTPV definition and its special cases have been discussed. Using QTPV and its special cases, irregular natural geological bodies and regular subsurface engineering can be described efficiently. The proposed model is composed of five primitives and six objects. Data structures and topological relationship of the fives primitives and three objects describing stratigraphy are designed in detail. Some schemes are designed for the QTPV modelling of stratigraphy and subsurface engineering according to modelling data. The model manipulation method of QTPV cutting by an arbitrary plane is discussed. Using VC++ 6.0 programming language integrated with SQL database and OpenGL graphic library under windows environment, a system prototype 3DGeoMV has been developed. The experiment result shows that the QTPV model is feasible and efficient in modelling subsurface engineering. 相似文献
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KAREN K KEMP 《Transactions in GIS》1996,1(3):219-234
Linking a GIS to a spatially distributed, physically-based environmental model offers many advantages. However, the implementation of such linkages is generally problematic. Many problems arise because the relationship between the reality being represented by the mathematical model and the data model used to organize the spatial data in the GIS has not been rigorously defined. In particular, while many environmental models are based on theories that assume continuity and incorporate physical fields as independent variables, current GISs can only represent continuous phenomena in a variety of discrete data models. This paper outlines a strategy in which field variables are used to enable modellers to work directly with the spatial data as spatially continuous phenomena. This allows the manner in which the spatial data has been discretized and the ways in which it can be manipulated to be treated independently from the conceptual modelling of physical processes. Modellers can express their spatial data needs as representations of reality, rather than as elements of a GIS database, and a GIS-independent language for model development may result. By providing a formal linkage between the various models of spatial phenomena, a mechanism is created for the explicit expression of transformation rules between the different spatial data models stored and manipulated by a GIS. 相似文献
5.
An integration between a visual programming environment and GIS has been developed to create and run spatial models. The visual programming environment provides graphical objects to create flowchart-like models of spatial phenomena using GIS data. The integrated system is object-oriented and designed to lessen the technical burdens of GIS programming. The system capabilities are demonstrated using a hydrological model example, and the model execution speed is compared with an equivalent model implementation in a traditional raster-based modelling system. 相似文献
6.
This paper addresses two issues: the use of 'realistic' environments for the visualization of socio-economic data, and the use of virtual reality tools for the exploration of data from existing GIS databases. 'Realistic' is here used in a narrow sense to imply the reconstruction of real-world scenes in which major components of the physical environment are reconstructed to facilitate geographical visualization. A review of visualization techniques for geographically-referenced 3-D data is presented, and the translation of an existing urban GIS database into virtual reality modelling language (VRML) demonstrated for a study area in Cardiff, UK. This work shows that the export of conventional 2-D GIS data into virtual reality toolkits can be relatively straightforward, and offers exciting new avenues for visualization and exploration. We argue that some of the parameters of the true scene such as colour, building shape, and texture may be directly modified in order to represent otherwise unobservable socio-economic characteristics, in the spirit of exploratory data analysis. These issues are of particular importance in the context of current advances towards the dynamic linkage of GIS and virtual reality modelling. 相似文献
7.
A feasibility study in progress to integrate health and air quality information is presented. The methods of using integrated GIS and air quality dispersion modelling tools to assess the effect of the environment on health are discussed. The main aim is to model human personal exposure to air pollutants and compare the predictions to respiratory health data for asthmatics in a health telematics project. The MEDICATE project develops and tests the feasibility of using a health telematic system for asthmatics. Key to this is the determination of the real-time health (lung function) response to the ambient environment. For this, air quality information is related to respiratory measurements by modelling personal exposure through a GIS. The methods of integrating environmental modelling and assessment tools (GIS) in this case are examined. ESRI's ArcView is used to locate and compile environmental information about the patients' locations and lifestyles in the study areas (London and Barcelona). A dispersion modelling extension to ArcView, ADMS Urban, is used to interrogate the spatial environmental databases (e.g. emission inventories) to model air pollution concentrations. Patients' personal exposure is modelled by time-weighted estimates of their exposure to ambient air quality at each defined location. Lung function data can be compared on a time-wise basis with these air quality indicators to see if there is a relationship on an hourly, daily or lagged-day basis. The aim of this paper is to propose a methodology and discuss the integration and practicalities of using air quality assessment tools (inventories, dispersion modelling and a GIS) in assessing the impacts of the environment on human health. 相似文献
8.
There is a growing requirement for GIS to incorporate dynamic analytic models. At the same time, there is a need to distribute results of dynamic GIS using the Internet. Therefore, this paper sets out to explore the implementation of dynamic environmental models using Internet-based geocomputation techniques. An overview discusses shortcomings of current Internet GIS techniques for dynamic modelling based on the idea that bidirectional and sustained communication is required between the client and the server sides. Thus an applet-servlet approach is explored to demonstrate the modelling process of a chosen hydrological model, TOPMODEL, which requires frequent and efficient client-server interactions. This approach overcomes the inherent shortcomings of the current Common Gateway Interface (CGI) and more primitive Java applet techniques. We present an effective and generic way to implement dynamic modelling and visualization processes in an Internet environment. This allows users to benefit from Internet-based geocomputation techniques to gain insights into computation and representation of dynamic spatial phenomena. 相似文献
9.
The PCRaster Software and Course Materials for Teaching Numerical Modelling in the Environmental Sciences 总被引：4，自引：0，他引：4
Derek Karssenberg Peter A. Burrough Raymond Sluiter & Kor de Jong 《Transactions in GIS》2001,5(2):99-110
Teaching numerical modelling in the environmental sciences not only needs good software and course material but also an understanding of how to program the models in the computer. Conventional environmental modelling procedures require computer science and programming skills, which may detract from the important understanding of the environmental processes involved. An alternative strategy is to build a generic toolkit or modelling language that operates with concepts and operations that are familiar to the environmental scientist. PCRaster is such a spatio-temporal environmental modelling language developed at Utrecht University, the Netherlands. It is used for teaching modelling in classrooms and over the Web (distance learning) at three levels: (1) explaining environmental processes and models, where models with a fixed structure of model equations are evaluated by changing model parameters, (2) teaching model construction, where students learn to program spatial and temporal models with the language, and (3) teaching all phases of scientific modelling related to field research. So far, we have received positive responses to these courses, largely because the software provides a set of easily learned functions matching the conceptual thought processes of a geoscientist that can be used at all levels of teaching. 相似文献
10.
Fulong Wu 《Journal of Geographical Systems》1999,1(3):199-218
The purpose of this paper is to argue for a novel use of geographical information system (GIS) as an exploratory device for
understanding complex space-time processes. Conventionally, a GIS has been configured as a spatial database management system.
Therefore, the capabilities of data input, storage, retrieval, manipulation and display have been well developed, whereas
the analytical and dynamic processing and modelling capabilities are under-developed. The importance of integrating GIS with
dynamic and analytical models has been widely recognised. Extending the use of GIS into spatial simulation represents a plausible
research direction. On the other hand, the usefulness of conventional deductive model becomes limited when dealing with complex
space-time processes. In essence, the inherent complexity calls for a simulation approach. The new nonlinear modelling paradigm,
for example, cellular automata (CA), opened a way in which behaviourally-richer dynamics and more micro-spatial data could
be incorporated into understanding space-time processes. It is argued therefore that GIS can be used as a platform – a controlled
environment or laboratory – for exploring complex space-time processes. The discussion of GIS-based simulation in this paper
is illustrated with a primitive simulation of the evolution of urban spatial structure.
Received: 2 July 1997/Accepted: 19 November 1998 相似文献
11.
V. M. Chowdary Yatindranath S. Kar S. Adiga 《Journal of the Indian Society of Remote Sensing》2004,32(1):59-73
Assessment of the environmental impact of Non Point Source (NPS) pollutants on a global, regional and localized scale is the
key component for achieving sustainability of agriculture as well as preserving the environment. The knowledge and information
required to address the problem of assessing the impact of NPS pollutants like Nitrogen (N), Phosphorus (P), etc., on the
environment crosses several sub-disciplines like remote sensing, Geographical Information System (GIS), hydrology and soil
science. The remote sensing data, by virtue of its potential like synopticity, multi-spectral and multi-temporal capability,
computer compatibility, besides providing almost real time information, has enhanced the scope of automation of mapping dynamic
elements, such as land use/land cover, degradation profile and computing the priority categorisation of sub-watersheds. The
present study demonstrates the application of remote sensing, GIS and distributed parameter model Agricultural Non-Point Source
Pollution Model (AGNPS) in the assessment of hazardous non-point source pollution in a watershed. The ARC-INFO GIS and remote
sensing provided the input data to support modelling, while the AGNPS model predicted runoff, sediment and pollutant (N and
P) transport within a watershed. The integrated system is used to evaluate the sediment pollution in about 2700 ha Karso watershed
located in Hazaribagh area of Jharkhand State, India. The predicted values of runoff and sediment yield copared reasonably
well with the measured values. It is important to emphasize that this study is not intended to characterise, in an exhaustive
manner. Instead, the goal is to illustrate the implications and potential advantages of GIS and remote sensing based Hydrology
and Water quality (H/WQ) modelling framework. 相似文献
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传统应用型地理信息系统软件开发主要通过商用地理信息系统软件的二次开发语言来实现,造成系统可移植性差、界面不友好、数据库软件不兼容等缺点;池州市公交查询系统采用VB和组件GIS相结合的方法进行开发,一方面利用组件强大的GIS功能,实现池州市公交站点查询、线路查询、公交换乘查询等功能,另一方面利用VB设计出良好的用户界面以... 相似文献
14.
地理空间数据的互操作研究是近年来地理信息系统 (GIS)研究中的一个热点 ,本文针对这个问题结合新一代互联网置标语言XML(eXtensibleMarkupLanguage)在互操作以及GIS领域的运用 ,做这样一种理论与实践的探索 ,主要介绍一种可互操作地理空间对象IGO(InteroperableGeospatialObjevts)概念模型 ,来讨论它对空间互操作的解决方法 .并且着重探讨了XML基础上的GIS互操作问题 ,阐明XML对于实现空间互操作的重要意义 ,指出不仅要在元数据层实现互操作 ,同时应致力于空间数据的基于XML的互操作研究。 相似文献
15.
During the HAPEX-Sahel experiment (1991–94), water redistribution processes were studied at the meso-scale (10 000 km2 ) near Niamey, Niger. A project now under way at ORSTOM aims at modelling the regional water balance through a spatial approach combining GIS data organization and distributed hydrological modelling. The main objective is to extend the surface water balance, by now available only on a few, small (around 1 km2 ) unconnected endoreic catchments, to a more significant part of the HAPEX-Sahel square degree, a 1500 km2 region called SSZ that includes most of the environmental and hydrology measurement sites. GIS architecture and model design consistently consider data and processes at the local, catchment scale, and at the regional scale. The GIS includes spatial and temporal hydrological data (rainfall, surface runoff, ground water), thematic maps (topography, soil, geomorphology, vegetation) and multi-temporal remote sensing data (SPOT, aerial pictures). The GIS supports the simulation of the composite effect at the regional scale of highly variable and discontinuous component hydrologic processes operating at the catchment scale, in order to simulate inter-annual aquifer recharge and response to climatic scenarios at the regional scale. 相似文献
16.
Natural Conversational Interfaces to Geospatial Databases 总被引：1，自引：0，他引：1
Natural (spoken) language, combined with gestures and other human modalities, provides a promising alternative for interacting with computers, but such benefit has not been explored for interactions with geographical information systems. This paper presents a conceptual framework for enabling conversational human‐GIS interactions. Conversations with a GIS are modeled as human‐computer collaborative activities within a task domain. We adopt a mental state view of collaboration and discourse and propose a plan‐based computational model for conversational grounding and dialogue generation. At the implementation level, our approach is to introduce a dialogue agent, GeoDialogue, between a user and a geographical information server. GeoDialogue actively recognizes user's information needs, reasons about detailed cartographic and database procedures, and acts cooperatively to assist user's problem solving. GeoDialogue serves as a semantic ‘bridge’ between the human language and the formal language that a GIS understands. The behavior of such dialogue‐assisted human‐GIS interfaces is illustrated through a scenario simulating a session of emergency response during a hurricane event. 相似文献
17.
A classification of water erosion models according to their geospatial characteristics 总被引：3，自引：0，他引：3
《International Journal of Digital Earth》2013,6(3):229-250
In this article, an extensive inventory in the literature of water erosion modelling from a geospatial point of view is conducted. Concepts of scale, spatiality and complexity are explored and clarified in a theoretical background. Use of Geographic Information Systems (GIS) is pointed out as facilitating data mixing and model rescaling and thus increasing complexity in data-method relations. Spatial scale, temporal scale and spatial methodologies are addressed as the most determining geospatial properties underlying water erosion modelling. Setting these properties as classification criteria, 82 water erosion models are identified and classified into eight categories. As a result, a complete overview of water erosion models becomes available in a single table. The biggest share of the models is found in the category of the mechanistic pathway-type event-based models for watershed to landscape scales. In parallel, geospatial innovations that could be considered as milestones in water erosion modelling are highlighted and discussed. An alphabetical list of all models is also listed in the Appendix. For manipulating scale efficiently, two promising spatial theories are suggested for further exploitation in the future such as hierarchy theory and fractals theory. Regarding erosion applications, uncertainty analysis within GIS is considered to be necessary for further improving performance of erosion models. 相似文献
18.
Ananta Man Singh Pradhan 《国际地球制图》2018,33(8):810-829
This study employed GIS modelling to ascertain landslide susceptibility on Mt. Umyeon, south of Seoul, South Korea. In this study, an effective contributing area (ECA) for certain drainage time was purposed as a temporal causative factor and then used for modelling in combination with spatial causative factors such as elevation, slope, plan curvature, drainage proximity, forest type, soil type and geology. Landslide inventory map of 163 landslide locations was prepared using aerial photographic interpretation and field verifications after that digitized using GIS environment in 1:5000 scale. A presence-only-based maximum entropy model was used to establish and analyse the relationship between landslides and causative factors. Before final modelling, a jackknife test was performed to measure the variable contributions, which showed that the slope was the most significant spatial causative factor, and ECA with a drainage time of 12 h was the most significant temporal causative factor. The performances of the final models, with and without significant ECA, were assessed by plotting a receiver operating characteristic curve to be 75.5 and 81.2%, respectively. 相似文献
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GIS中文查询系统中SQL语句的形成 总被引：3，自引：1，他引：2
由于GIS中文查询语句与SQL语句相差很大,直接转化非常困难,所以需要有某种中间逻辑形式语言。本文首先分析了查询语句的句型和基于此句型的栈式中间语言结构,然后重点研究了这种中间语言到SQL语句的转换。在此对SQL语句的结构中的查询条件段、查询目标段、分组段的判断策略进行了研究,难点在于嵌套结构的判断,在此借助中间关系进行转换,系统设计了相应的转换算法,并对算法进行了测试,测试表明系统所提出的转换策略和算法对大多数查询语句能转换为相应的SQL语句,为该课题的进一步研究奠定了基础。 相似文献