地理信息系统(GIS)发展动态及其在林业中的应用

一、地理信息系统的发展动态 1.面向对象(object oriented)技术研究 面向对象方法为人们在计算机上直接描述物理世界提供了一条适合于人类思维模式的方法。面向对象技术在GIS中的应用,即面向对象的GIS,已成为GIS的发展方向。这是因为空间信息较传统数据库处理的一维信息更为复杂、琐碎.面向对象的方法为描述复杂的空间信息提供了一条直观、结构清晰、组织有序的方法,因而备受重视。

城市地下管网三维整体自动建模方法

为解决城市地下空间数字化建设中地下管网整体、批量、精细化的三维可视化表达。以当前城市相关部门所探测的二维管线数据为基础,通过建立三维管网模型数据标准,管线及其附属设施自动生成、管线与连接部件自动套合的三维建模方法和算法,利用"Sweep+Mesh"进行管网批量造型处理,采用C++语言结合DirectX进行程序实现。完成三维管网整体自动建模,并开发三维可视化软件原型系统。通过三维管网整体自动建模,大大减少人工三维手动建模的时间和成本,更为管网大数据的瓦片金字塔制作奠定基础,为三维数字城市建设,特别是在三维视角下进行地下管线的管理、规划、设计和施工提供关键技术的解决方案。

电子政务中地理信息系统应用模型探讨

GIS(地理信息系统)在政府机关的应用是政府GIS的专门研究领域。当今GIS发展相对成熟,因此,GIS能否在电子政务中充分发挥它最大的功能,很大程度上取决于GIS模型的应用。本文通过对电子政务中专业信息的分析,在对地理信息建模系统研究的基础上提出了两种基本的模型。

Relocation Selection for Poverty Alleviation:Factor Analysis and GIS Modeling

Resettlement is considered a major policy measure in two major Chinese policy programs,the "Great Development of the West" and poverty alleviation in the new century,and the "New Countryside Development".The selection of the target location of resettlement sites for poverty-stricken villages is of critical importance to the success of resettlement projects,yet the selection process is challenged by the need for analyzing a variety of contributing factors,and the need for many rounds of tedious data processing.So in this paper we present an in-depth analysis of the major factors and data processing model concerning mountainous povertystricken villages,which also takes a major part of China's poor villages.Our analysis shows the following factors bear the most importance in resettlement selection:1) topography:candidate areas should have slope less than 25 degrees and altitude less than 2400 meters.2) accessibility:close to market conventions places and transportation facilities.3) farming resources:with abundant land and water resources.4) non-intrusiveness:interests of receiving villages should be considered and negative impact minimized.A simple measure could be having the candidate area 1000 m away from the receiving residents.5) Minimal ecological and political footprint:candidate areas shall not conflict with nature conservation areas or nationally planned key land use projects.6) Social and cultural compatibility:residents will better off if relocated in the same county,considering language,religion,ethnic culture and other factors.Taking Makuadi,Lushui County of Nujiang Prefecture as a case study,we demonstrate how GIS analysis and modeling tools can be used in the selection process of resettlement projects in mountainous areas.

Modelling spatial vagueness based on type-2 fuzzy set

The modelling and formal characterization of spatial vagueness plays an increasingly important role in the imple- mentation of Geographic Information System (GIS). The concepts involved in spatial objects of GIS have been investigated and acknowledged as being vague and ambiguous. Models and methods which describe and handle fuzzy or vague (rather than crisp or determinate) spatial objects, will be more necessary in GIS. This paper proposes a new method for modelling spatial vagueness based on type-2 fuzzy set, which is distinguished from the traditional type-1 fuzzy methods and more suitable for describing and implementing the vague concepts and objects in GIS.

Land-Cover Change Monitoring in Obuasi, Ghana： An Integration of Earth Observation, Geoinformation Systems and Stochastic Modelling

For over twenty years, Obuasi Municipality, Ghana, has experienced land-cover change arising from gold mining and urbanisation. This project quantified the land-cover changes that have taken place and projected likely future land-cover. An integration of EO （earth observation）, GIS （geographical information science） and Stochastic Modelling was examined. Post-classification Change Detection employed Landsat TM or ETM＋ images in 1986, 2002 and 2008. Subsequently, Markov Chain Analysis projected the land-cover distribution for 2020. Seven broad land-use and land-cover classes were identified and mapped, namely： built-up areas, mine sites tailing ponds barren land forestland farmland and rangeland. The results obtained for the 2008 to 2020 projection revealed a continuous expansion of built-up areas （1.63%）, mine sites （0.89%） and farmland （3.4%）, and a reduction of forestland （4.17%） and rangeland （2.59%）. Despite the advent of very high resolution satellite imagery, this use of EO and GIS technology focussed on low-cost and lower resolution satellite imagery, coupled with Markov Modelling and was found to be beneficial in describing and analysing land-cover change processes in the study area, and was hence potentially useful for strategic planning purposes.

Sensitivity studies of a high accuracy surface modeling method

The sensitivities of the initial value and the sampling information to the accuracy of a high accuracy surface modeling(HASM) are investigated and the implementations of this new modeling method are modified and enhanced. Based on the fundamental theorem of surface theory, HASM is developed to correct the error produced in geographical information system and ecological modeling process. However, the earlier version of HASM is theoretically incomplete and its initial value must be produced by other surface modeling methods, such as spline, which limit its promotion. In other words, we must use other interpolators to drive HASM. According to the fundamental theorem of surface theory, we modify HASM, namely HASM.MOD, by adding another important nonlinear equation to make it independent of other methods and, at the same time, have a complete and solid theory foundation. Two mathematic surfaces and monthly mean temperature of 1951–2010 are used to validate the effectiveness of the new method. Experiments show that the modified version of HASM is insensitive to the selection of initial value which is particular important for HASM. We analyze the sensitivities of sampling error and sampling ratio to the simulation accuracy of HASM.MOD. It is found that sampling information plays an important role in the simulation accuracy of HASM.MOD. Another feature of the modified version of HASM is that it is theoretically perfect as it considers the third equation of the surface theory which reflects the local warping of the surface. The modified HASM may be useful with a wide range of spatial interpolation as it would no longer rely on other interpolation methods.