Yongxue Liu

Study on the complex network characteristics of urban road system based on GIS

Urban road system is the basic bone of urban transportation and one of the most important factors that influent and controls the urban configuration. In this paper, an approach of modeling, analyzing and optimizing urban road system is described based on complex network theory and GIS technology. The urban road system is studied on three focuses: building the urban road network, modeling the computational procedures based on urban road networks and analyzing the urban road system of Changzhou City as the study case. The conclusion is that the urban road network is a scale-free network with small-world characteristic, and there is still space for development of the whole network as a small-world network, also the key road crosses should be kept expedite.

An overview of the methods of GIS-based land-use suitability analysis

The land-use suitability mapping and analysis is one of the most useful applications of GIS for planning and management. There are four objectives of this paper: (a) to present a historical overview of methods and techniques of GIS-based land-use suitability analysis, (b) to overview multi-criteria synthetically overlay land-use evaluation models, (c) to discuss GIS-based land-use evaluation system, (d) to identify the trends, challenges and prospects of GIS-based land-use suitability analysis. There are two focused perspectives of GIS-based land-use suitability analysis in the paper, the techno-positivist perspective and the socio-political, public participation perspectives. It is organized into six chapters. Chapter 1 defines land-use suitability analysis, and provides an introduction to GIS-based land-use suitability analysis along with a historical perspective. Chapter 2 gives an overview of the development of methods and techniques of GIS-based land-use suitability analysis. The multi-criteria synthetically overlay land-use analysis models is discussed in chapter 3. Chapter 4 offers GIS-based land-use evaluation system. Chapter 5 introduces expert systems for GIS-based land-use suitability evaluation. The concluding chapter summarizes the main points of the papers and discusses problems and prospects from GIS-based land-use suitability analysis. Along with the in-depth development of land research and the constant advancement of GIS technology, GIS-based land-use suitability analysis will toward greater depth.

An image segmentation algorithm for SAR images based on wavelet packets frame transformation

SAR (synthetic aperture radar) images are strongly disturbed by speckle noises, which brings difficulty to the segmentation of the SAR images. Some model-based SAR image segmentation approaches (such as the Markov random field model, fractal model) are too complex and time consuming. We propose an new method to segment the SAR images fast in this paper. First we transform the original SAR intensity image into some subimages using the wavelet packets frame transformation. Then we analyze the energy distribution in the transformed subimages and find that the energy of the speckle noise is mainly concentrated in the high frequency subimages. So we segment the SAR image based on the gray level of the low frequency subimages using a threshold classifying method. The result shows that this method can get a satisfying segmentation result and time saving.

Classification of Landsat 7 ETM+ imagery in western mountainous area of Zhejiang based on gray-gradient co-concurrency matrix

Texture feature is becoming more and more important for classification of remote sensing image, especially in remote sensing image in mountainous area. An approach to classification of western mountainous area of Zhejiang land cover using ETM+ imagery is described in this paper. Firstly the gradient images of research area were obtained using different edge detection methods with Roberts, Sobel, Prewitt and Canny operator using ETM+ pan image. The results of four different edge detection methods were evaluated qualitatively and quantitatively. The qualitative evaluations mainly considered the visual effect so that the results of combining edge images with original image for qualitative evaluation, and the edge points,4-connected component quantities and 8-connected component quantities were adapted to quantitatively evaluate different edges. Then Canny operator was selected as the gradient operator according to the qualitative and quantitative evaluation results of different research areas edge images and fifteen texture features were obtained based on the Gray-Gradient Co-concurrency Matrix consequently through MATLAB programmer with the Canny operator. Finally, the classification results based on the spectral respond feature only and the texture feature with the spectral respond feature were evaluated separately. It shows that the texture features highlight the residents, rivers etc. which the geometric structure of space themselves are more obvious than others; enhancing the undulating the distinction between water and the shadow.

A fast preprocessing algorithm for massive MODIS 1B data

MODIS 1B data preprocessing consists of bowtie effect elimination and geometric correction. The paper proposes a fast preprocessing algorithm. First, partition the input image into small sub-images without bowtie effect. Secondly, do geometric correction to each sub-image. Finally, mosaic each sub-image in the output coordinate system and eliminate the bowtie effect in the process. The proposed algorithm shows both a better geometric performance and faster preprocessing speed. For the massive MODIS 1B data preprocessing, a parallel preprocessing method based on this algorithm above is further proposed. Analysis shows that real-time preprocessing for massive MODIS 1B data can be realized by the parallel algorithm.

Design and realization of high quality prime farmland planning and management information system

The article discusses the design and realization of a high quality prime farmland planning and management information system based on SDSS. Models in concept integration, management planning are used in High Quality Prime Farmland Planning in order to refine the current model system and the management information system is deigned with a triangular structure. Finally an example of Tonglu county high quality prime farmland planning and management information system is introduced.

Research of the relationship between space accessiblity and urban land price by point-based space syntax

Studies on economic geography assume that the space accessibility, which means the connectivity of one location with the others, can be considered as the crucial factor determining the land price in case that we can not take account of all factors. Space syntax was widely developed to study the accessibility of urban system recently. The traditional lines-based space syntax theory is not so in reason that every single point along each line has the same syntactical attributes, so it is more logical to use characteristic points to represent the urban system instead. This paper tries to analyze the space accessibility of urban system with point-based space syntax, and then find the inherent relationship between space accessibility and urban land price. The approach of this paper was to get the sample points of land price, calculate the syntactical variables of the sample points depend on interpolation with characteristic points, and find the relationship between space accessibility and urban land price from correlation analysis. The test area is Luqiao, Zhejiang Province, a developed area close to the East Sea of China. The result showed that the total integration and land price had rather strong correlation. It can be concluded that the space accessibility is one of the fatal factor influencing the urban land price, and the integration is the direct variable to describe it. However, more issues have to be discussed: the definition of characteristic points was not so clear and some preferences were factitious, etc. They need to be implemented in the wider context of accessibility covering both geographic and geometric elements through further researches.

Tidal flat stability analysis based on GIS & RS technology: A case study in Dongsha sandbank, offshore the coast of Jiangsu province

Stability of the tidal flat in silt-muddy coast is the ability to keep its terrain from erosion under the ocean dynamic processes. Evaluating the stability of the tidal flat is one of the most important issues insediment dynamics research field , and has been attached more and more importance. Dongsha Sandbank is one of the largest sandbanks of the radial sand ridges, and serves as an important barrier to the inner sandbank and has a direct impact on the process of Tiaozini Sandbank merging into mainland. To evaluate the stability of Dongsha Sandbank will provide guidance for coastal zone environmental protection (such as environmental protection and coast protection, etc.) to make a rational use of tidal flat resources for sustainable development. In the study, 63 scenes of remotely sensed imageries from 1973 to 2007 were collected, taken by different sensors such as MSS, TM, ETM+, SPOT, ASTER and CBERS. GIS & RS technology was used in the stability analysis of Dongsha Sandbank tidal flat based on field investigation, RS classification and overlay analysis. Major relate factors such as sediment dynamic environment, tidal channel and tidal creek system were discussed in the paper. Some conclusion can be summarized as follows :( 1) Integral stability of Dongsha Sandbank tidal flat has been gradually declined from 1973 to 2007. This trend was embedded in two aspects: both area of stable tidal flat and maximum value of stability coefficient degraded. (2) Tidal flat with high stability is mainly distributed on the sand ridges of Dongsha Sandbank, and has an integrally contractive trend: in the mid-continental region, one region with high stability coefficient has been broken into two small parts-- the northern part has a southwards movement while the southern has a northern wards movement; within the north part, stability of the tidal flat reduced with the northwards movement of the shoreline; in the west part, the tidal flat is in an unstable state due to the lateral swing of Xiyang Tidal Channel and strengthen of tidal creek activity; and in the south part, the tidal flat has a low stability due to the unstable flow path of Doufuzhayaomen Tidal Channel.

Research on scenario simulation of land-use planning based on CA model: A case study in Kunming metropolitan area

Rapid urbanization and the following conversions of land-use have caused series of social and environment problems. To construct a model of land-use conversions has been considered as a powerful tool to analyze the reason, process and results of the conversions, and to make land-use planning and interrelated policies. Cellular Automata (CA) is a kind of bottom-up model which has advantages in simulation method as well as simulation results. However, there are some weaknesses in supporting the land-use planning. The way to extend the usage of CA model in this field is to model dynamic spatial processes of different urban future planning scenarios. An improved CA model is designed in order to meet the new requirement of land-use planning scenario simulation. After the design of CA model, scenario simulation of Kunming metropolitan area will be demonstrated and discussed. In the application, 3 different targets, different density patterns and different planning regulation are provided for the CA model to bring out different scenario simulation results. The results show that this model can be used to recognize the different effects of different land-use planning. It provides a more directly aspect to evaluate the land-use planning, and finally supports the government to construct the new round of land-use planning.

Theory of ontology and land use ontology construction

It mainly presents the problems of data share in land use database construction. How to accurately define geographic classification expression and how to quickly and accurately express the user demand are plaguing problems of information system developer. The introduction of ontology and relevant technologies address the problem with a brand new perspective and provide a strong theoretical and methodological support. From the relevant ontology theoretical study, this paper summarizes the essence of the concept of ontology; and explores the type, role, method, formalization expression and tools of ontology. On the basis of existing research, the paper brings forward 5-step method of ontology building and then uses this method to build ontology in land use database construction. It also puts forward the notion model of land use database based on ontology.