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  • 2014 Volume 16 Issue 3
    Published: 10 May 2014
      

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  • SANG Peng, TANG Xinming, AI Bo, WANG Huabin
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    Traditional methods of news retrieval which return a series of related news-list that sorted by time or events such as Baidu, are lack of intuitive description in both temporal and spatial dimensions, as well as spatio-temporal development that related to news events. This paper presented a method of multi-dimensional description and spatio-temporal visualization of online RSS news events, which helps readers understand the spatio-temporal development of the whole news event. Firstly, this method pulled news from several well-known websites such as Baidu, Sina and Google News based on RSS (Really Simple Syndication) service, and then used a multi-dimensional description method to mark the spatial and temporal dimensions of RSS news. The method of temporal dimensional description defines news publishing time as news' occurrence time, while the method of spatial dimensional description dynamically parses and identifies Chinese geographical name from news description, and then matches them with their geographical coordinates. Spatial dimensional description method is the primary content of this article. This approach has been separated into four stages to accomplish the analyzing process: (i) XSL Transformation, which uses XSL(eXtensible Stylesheet Language) to transform a news RSS document into a HTML(Hypertext Markup Language) document;(ii) Description Extraction, which uses the regular expression to extract the news description from news HTML document;(iii) Chinese place Name Extraction, which uses ICTCLAS to extract geographic name from description;And (iv) Geocoding, which uses Google Geocoder API to get the geographical coordinates of the place name. At last, this paper demonstrated the spatio-temporal visualization of news events and made a brief analysis by setting H7N9 hot news as an example. In the analysis, temporal visualization used transition color to show the changes between two time nodes according to the amount of news, and then used line chart to show the variation tendency of the total amount of news. Furthermore, spatial visualization clustered news by province and used different-sized plots to indicate the diffidence of news amounts between two provinces.

  • LIN Bingxian, ZHOU Liangchen, SHENG Yehua, LV Guonian
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    The archaeological sites are important places for the studying of ancient human activities. 3D modeling of archaeological sites could be helpful in the context of archaeological excavation unit representation and analysis, and therefore have great significance for the archaeological works such as ancient environmental restoration and historic preservation. Nevertheless, most of the archaeologists are still relying on hand drawings of the excavation units for their analysis and interpretation. These 2D representations are difficult to make an effective simulation of the archaeological site environment and cannot accurately repent the geometric and spatial relations of the cultural layers and the volumetric objects. In recent years, archaeologists have brought some new investigation technologies in 3D modeling of archaeological sites, but these methods cannot be applied to the archaeological sites in which excavation has been completed. To solve this problem, this paper presents a 3D modeling method of archaeological sites based on hand drawings. In this method, excavation unit is used as the basic modeling unit, and the cultural layers and the relics are modeled separately. Firstly, the excavation unit distribution diagrams and the excavation unit diagrams are used to establish the 3D models of archaeological cultural layers. Secondly, the relic diagrams are used to establish 3D models of archaeological relics. Thirdly, through 3D Boolean operations, these two models are integrated into complete 3D models of the archaeological sites. Finally, the 81-Dang east area, in Lixian County of Hunan Province has been chosen as the research region to verify the validity and practicality of this method. The research practice has proved that this method can make full use of the large amount of data accumulated in the traditional archaeological process, and is helpful to transform the qualitative descriptions of traditional archeology in macro scale to the quantitative description of modern digital archeology in microscopic scale.

  • WANG Zheng, WANG Yingjie
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    The flow line method occupies a very important position in cartography. It is able to synthetically express the direction of actions, the movement routes, the increase or decrease of the number, and the quality change of spatial entities or phenomena. Flow line method is a difficult subject in computer graphics, which has not been satisfactorily resolved. The traditional fixed-line method is linear symbols. However, there are many limitations in the practical application of linear symbols. To solve this problem, the author proposed the correlation algorithm of curve line symbol and developed a WEB-side system for the moving line method with respect to adaptive cartography, which is based on the open source software MapServer. This article is mainly consisted of three parts: the flow line symbolic algorithm, the database management system, and the map display system. The flow line symbolic algorithm was discussed based on the map display system developed by the Visual Studio 2010 platform, which was consisted of curve symbolic algorithm, obstacles avoiding algorithm, and confluence and difference algorithm. The database management system was established based on the shape file format of spatial data and Oracle environment attribute data. The map display system was used for WEB-side adaptive map display and other interactive functions. In the article, the floating population data was used as an example to verify and describe the system functions of the thematic map display, the hazard avoidance, and the confluence and difference calculations. According to the thematic map, we could analyze the floating population data easily, accurately, and intuitively. This provides great assistances in data supporting and decision making for other studies of floating population and related disciplines. In addition to the floating population, the system is also adapted to the data presentation and analysis of economic development, social factors, military combat, natural phenomena, and so on. It can accomplish the functions including curve symbol drawing, obstacle avoidance, and confluence and difference calculations. That is, the flow line symbol algorithm is a great help for the visualization of temporal expression data, and it has broad application prospects.

  • WANG Yanhui, LI Yue
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    With the development of mobile communication technologies, the demands of location-based spatial information services are more and more extensive in order for scientists to effectively obtain rich spatial information in mobile internet era anytime and anywhere, and SVG (Scalable Vector graphics) is becoming a hot application on data representation and organization in Location Based Services (LBS). However, few past researches focused on image quality assessment of the conversion from different spatial data format to SVG format. So in this context, according to the unique demand on SVG_based representation and organization for spatial data in LBS, this research put forward the conversion method and quality assessment method from multiple formats to SVG format. Firstly, by using of the directly loaded raster images and by running the vector data conversion programme, a valid conversion is achieved from multi-source spatial data formats to SVG format. Secondly, from the combination of qualitative and quantitative view, the comparison between the image quality before and after the conversion is analyzed. And, based on the design of corner detection index and evaluation processes, a Harris_corner detector method is proposed and verified to evaluate the transform result. The test shows that SVG_based representation is suited for spatial data in LBS, especially for the vector data, and the SVG image after conversion for either raster or vector data has a high image quality. As the JPG raster image is concerned, compared with the original image, the accuracy of the converted SVG image changed little, but the resolution of the converted SVG image is less than the original one. On the other hand, the accuracy and clarity of the converted vector data is similar to the original vector data. And the conversion of raster data is less effective than that of vector data, which shows that the corner detection technique on SVG transform is feasible. Further, it verifies a reliable SVG_based mobile location service information expression and spatial organization model, and helps to popularize and strengthen SVG application in LBS.

  • SHAO Hua, JIANG Nan, HU Bin, ZHU Jin
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    With the rapid development of modeling methods, the scale and depth complexity of the 3D urban scenes have increased significantly. One of the methods to increase the system efficiency is to build multi-level 3D models. However, the simplification algorithms of 3D models are unsatisfactory in real-time rendering because of the complexity of 3D urban models. Sort-First rendering clusters are broadly used when single PC cannot meet the requirements of real-time rendering, which is more suitable for high resolution and large screen rendering. The current researches are weak at quantitative analysis and self-adaptive load balancing. To overcome these difficulties, we studied the influencing factors of the performance by analyzing the speed-up ratio model of Sort-First rendering clusters, including node size, rendering resolution, network speed, task partitioning and so on. We also improved an existing load balancing method by using the rendering time and the transmission time as the feedbacks for adjusting the task partition instead of simply using the rendering time. Based on this, a necessary condition to achieve the highest speed-up ratio is proposed in an ideal situation that the load is completely balanced and the triangles are uniformly distributed on the screen. This quantitative expression of the condition may help us find out the bottleneck of the parallel rendering system and rationalize the configuration. We further point out that adding more rendering nodes might not help improve the performance if the rendering load is not very heavy, and the benefits of parallel system will decrease while the node size is large. A real-time parallel rendering experiment based on Sort-First was performed, which included 4 rendering nodes and used a large scale urban model. The results verify the above analysis and indicate that our improvement has increased the performance to a certain extent. Furthermore, our research could provide a reference for building Sort-First rendering clusters to reduce the abuse of the computer resources.

  • SHIWei, SU Fenzhen, ZHOU Chenghu
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    A waterway is any navigable body of water. Waterways can include natural water area such as rivers, lakes, seas, oceans, and artificial water area such as canals and harbor. In order for a waterway to be navigable, it must be deep and wide enough and has suitable hydrology to allow vessels passing safely. In the sea, waterways usually connect mainland or islands. Especially, in the water area filling with reefs, they will be the only passage and the lifeline of the transportations and supplies. The islands and reefs also can influence the security of the waterways in that area. Consider the relationships between islands and waterways, it can not only influence the security of the waterways, but also reflect the value of the islands. In this paper, a spatial configuration model of islands and waterways based on Voronoi diagram was proposed to describe the spatial relationships between islands and waterways. The intensity of waterways controlled by islands was used to indicate the security state ofA waterway is any navigable body of water. Waterways can include natural water area such as rivers, lakes, seas, oceans, and artificial water area such as canals and harbor. In order for a waterway to be navigable, it must be deep and wide enough and has suitable hydrology to allow vessels passing safely. In the sea, waterways usually connect mainland or islands. Especially, in the water area filling with reefs, they will be the only passage and the lifeline of the transportations and supplies. The islands and reefs also can influence the security of the waterways in that area. Consider the relationships between islands and waterways, it can not only influence the security of the waterways, but also reflect the value of the islands. In this paper, a spatial configuration model of islands and waterways based on Voronoi diagram was proposed to describe the spatial relationships between islands and waterways. The intensity of waterways controlled by islands was used to indicate the security state of the waterways and reflect the value of the islands. Then the data of 43 islands and three waterways were used to calculate the intensity and extent of the three waterways controlled by the islands and the spatial configuration of islands and waterways is analyzed. The results of this research showed: (1) the relationship of spatial configuration is a key factor of the intensity and extent of the waterways controlled by the islands. (2) Under the spatial interaction conditions, the more prominent on the location advantage of islands, the more outstanding on the effect of the control. This study provided a new vision of the security of waterways and the value of islands. The method is easy and useful to evaluate the security of waterways and the value of islands.

  • LIU Kang, DUAN Yingying, LU Feng
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    Urban road traffic is spatially autocorrelated. The change of the traffic on a certain road will alter the surrounding roads' traffic status. Understanding the spatial autocorrelation of road traffic is essential for traffic planning and traffic prediction. However, unban road traffic is heterogeneous in spatial, which means that the traffic interactions between neighboring roads are not always isotropy. The spatial heterogeneity of urban traffic makes the measurement of spatial autocorrelation more complex, thus only uses spatial adjacency to define the traffic autocorrelated roads cannot well reveal the characteristics of spatial autocorrelation in urban road traffic. It is worth mentioning that urban roads have topological and geometric properties, which are neglected in the previous research. The aim of our research is to analyze the spatial autocorrelation of urban road traffic based on the topological and geometric properties of urban roads. We first investigated the spatial clustering characteristics of urban roads using community detection algorithm, and then depicted the spatial heterogeneity of the traffic interaction by measuring the importance of road segments with the use of the roads' generalized geometric forms. Based on those analyses, we proposed a novel approach to cluster together the roads whose traffic is spatially autocorrelated. Experiment results for the road network of Beijing indicate that the proposed approach performs better than the approaches that only consider the spatial adjacency or topological structure, which further implies that our approach can capture the spatial autocorrelation characteristics of urban road traffic more reasonably.

  • HUANG Jin, GAO Xing, WANG Wei
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    Firstly, this paper gives a simple review of the research of full waveform inversion (FWI) which emerged in the 80's of the 20th century. Aimed at the increasingly quantitative and precision requirement of the seismic exploration, a viewpoint is proposed in this paper that FWI should combine with other data processing steps or techniques in the future. In terms of the data processing of seismic exploration or from the standpoint of the final geological interpretation, a combination with other data process steps or techniques would be the development trend of FWI. Finally, author holds a discussion about the development of FWI, especially focusing on the key problems of FWI research, including the seismic wavefield modeling, inversion initial velocity model picking, object function style selecting, optimization algorithm choosing and its application in the anisotropic medium. By using Laplace FWI to obtain inversion-based initial velocity model, making full use of the advantages of combining the wave equation method which benefited from parallel computing and ray tracing to simulate the seismic wavefield, and selecting the form of inversion objective function and optimization algorithm flexibly to update velocity model parameters, it could be concluded that the practical use of FWI will be accelerated greatly, especially its application in the anisotropic medium.

  • DONG Nan, WANG Liming, MA Mingjuan
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    Urban potential is a quantitative indicator to measure the urban spatial interaction. It is used to describe the interaction force exerted to any place in the region, while taking into consideration that the interaction force is produced jointly by all the other surrounding cities. Urban population potential is the potential that is measured and indicated by urban population. GIS usually uses points to represent the spatial locations of cities and uses the point attribute field to store their urban population information. Therefore, the most convenient way to simulate urban population potential is to build a spatial analysis model based on the relevant point data. Obviously, this method has some disadvantages: on one hand, urban point data represented by latitude-longitude pattern in national fundamental geographic information datasets does not coincide with the urban population centroids in reality;on the other hand, most cities are usually composed of a variety of mutually separated urban land-use patches and these patches interact with each other within their urban precincts. To overcome the impacts of these disadvantages, this study has designed a simulation technology solution of urban population potential based on urban land-use patches. It takes the independent urban patches as the basic spatial analysis units and propose a method to divide grades for those urban patches in Beijing-Tianjin-Hebei region. Then, a time-consuming grid surface of Beijing-Tianjin-Hebei region is established. The numerical simulation of the urban population potential in Beijing-Tianjin-Hebei region is realized by making use of ArcGIS platform and modeling techniques of python accordingly. The method based on urban land-use patches could overcome the deficiency that the urban points do not coincide with urban population centroids in reality and it could reflect the spatial interactions of urban interior patches. Moreover, the simulation of urban population potential has further satisfied the requirements toward refinement.

  • GUO Limin, ZHOU Tinggang, SU Yingchun
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    Among the influencing factors of regional resources integration and coordinated development, a reasonable division of city hinterland plays a key role. Based on the weighted Voronoi diagram, we put urban centricity intensity and comprehensive transportation accessibility as the weights into the breaking point model, and then revised the urban population scale in the model. As such we constructed a new urban hinterland definition model based on the weighted Voronoi model. To verify this new model, we took 36 central cities in Chengdu-Chongqing Economic Circle as an example to do a test. The result shows that, in our test area, the hinterland extent of each city does not match the administrative region extent well. To make it clearer, we divided these cities into three categories according to the ratio of the hinterland size and the administrative region size of each city. Cities, whose ratio is greater than 100%, have good conditions of hinterland outward extending and have great influence on the development of the surrounding cities. When the ratio is smaller than 60%, it indicates that the influence of the surrounding cities is much stronger than that of the central city itself. Once the ratio is between 60% and 100%, the central cities make little sense to the development of the surrounding cities. Furthermore, Chengdu City of Sichuan Province and Chongqing Municipality are both well-known as the most powerful cities in this region, however, their hinterland extents are not the biggest of all the hinterlands in the region. This phenomenon shows that the extent and size of a city hinterland is not completely positively related to its comprehensive strength, and it should be defined by the comprehensive strength of both the central city and the surrounding cities. Finally, this article completes a redefinition of city hinterland for each city in Chengdu-Chongqing Economic Circle, and it is expected to afford a certain reference to the future urban construction and city planning.

  • ZHANG Meimei, ZHANG Rongqun, HAO Jinmin, AI Dong
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    Wetland landscape spatio-temporal dynamic development process is more important than the ultimate form of its spatial pattern. Only clearly understand wetland dynamic development process, the theory and decision support of wetland resources protection and sustainable utilization can be provided. In this paper, Yinchuan Plain wetland landscape evolution driving force analysis model was established, full considering the causal relationship between the geographical phenomena in space and time. The transform rules of cellular automata (CA) were built with the model of artificial neural network (ANN), which reduced the man-made subjective factors, and improved the accuracy. Comparing the prediction results with actual wetland types, it concludes that the prediction accuracy reaches about 84.24%. Three driving force factors as annual precipitation, population density and agriculture gross output value were selected for the scenarios simulation of wetland landscape pattern. The scenarios simulation results show that, average annual rainfall has more significant driving force to natural wetland, in the process of reduced by 10% to increased by 10%, the area of river and lake wetlands continues to increase, with river wetland increased 26.3844 km2 and lake wetland 22.4100km2. Rice paddies and ponds maintain a steady growth. Population density has more significant driving force to artificial wetland. With the growth rate of population density changing from 8 ‰ to 18.7 ‰, rice paddies and ponds expanded greatly, i.e. 19.4364 km2 and 18.2088 km2, respectively. But the area of natural wetlands (river and lake wetlands) decreased gradually, and the construction land increased markedly. Total agricultural output also has more significant driving force to artificial wetlands, but slow reverse inhibition force to natural wetlands. When the growth rate of total agricultural output changes from 4.5% to 6.5%, artificial wetlands such as rice paddies and ponds expand rapidly, increasing 21.5604 km2 and 19.1880 km2, respectively;river and lake wetlands decrease slowly;and the construction land and the Yellow River washland remain basically unchanged.

  • GONG Guoli, LIU Jiyuan, SHAO Quanqin
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    China is one of the countries suffering severely from soil wind erosion in the world, especially in the typical northern steppe. Xilingol League in Inner Mongolia is a part of the typical steppe zone. Ever since Beijing-Tianjin Dust Storms Sources Control Project was established in 2002, the grassland degradation situation has been controlled. The change of vegetation coverage can affect the ecological function of windbreak and sand-fixation. In order to prepare the prevention and control measures for regional ecological restoration, to understand the practical significances of sustainable development of grassland ecosystem, and to control soil wind erosion, in this study, based on the meteorology and remote sensing data, combined with grassland degradation and recovery in Xilingol League, the Revised Wind Erosion Equation (RWEQ) was applied to quantitatively evaluate the spatio-temporal variations of soil conservation service function since the 1990s and to reveal the effects of the change of vegetation coverage on soil wind erosion control service. The results are shown as follows. The intensity of soil wind erosion was low in the most regions of Xilingol League, Especially in the eastern, central and southern regions, with higher vegetation coverage, lower wind field intensity, and abundant rainfall. The wind erosion regions with medium and higher soil wind erosion intensity were mainly distributed in the western desert steppe and Otindag Sandy Land, and the area of these regions decreased progressively as the erosion intensity increased. The distribution pattern of soil retention was similar to soil wind erosion modulus. The distribution characteristics of the soil retention rate were similar to the vegetation coverage, indicating a gradually increasing trend from northwest to southeast. Under the comprehensive influence of the warming-drying climate and the implementation of Beijing-Tianjin Dust storm Source Control Project, the vegetation coverage decreasing regions dominated by slight and micro erosion intensity turned into vegetation coverage increasing grassland dominated by slight and micro erosion intensity;the grassland having mild, medium or severe degree of vegetation coverage reduction turned into the grassland with balanced vegetation coverage. The decrease or increase of vegetation coverage can significantly intensify or mitigate the soil wind erosion. Additionally, the soil retention rate showed a significant positive relationship with the grassland vegetation coverage in the spring seasons in most regions(r>0.6, p<0.05).

  • ZHANG Jianchen, WANG Yanhui
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    The problem that population data is usually missing in small scale areas such as administrative villages which are always mentioned in population distribution studies and related researches. In this context, we took the Hefeng County in Hubei Province as the study area and analyzed the correlation between land use type index and population density. The simulation of the village-level population distribution is performed using Geographically Weighted Regression (GWR) method, grid method and BP neural network method respectively. Then, from the perspective of global-local and linear-nonlinear, the comparative precision validation was taken to verify the simulation accuracy of the population in villages with missing population data, which utilizes cross-validation method between the simulated population and the actual population. Results show that: (1) in all kinds of land use types, the main factors affecting population distribution are farmland, woodland, urban industrial land, and transportation land;(2) with regard to the three simulation methods we concerned, the errors of the simulated total population using these methods are all less than 3% for the 30 invested villages. By comparing the ratios of estimated values to the actual values of population in each village, and taking 10% as the tolerance, the reliability of GWR method is 43.33%, while grid method is 76.67% and BP neural network is 86.67 %. It shows that the BP neural network method is the optimal method among the three methods for the study area, and grid method is better than GWR method. In addition, the prediction accuracy of nonlinear regression is higher than that of linear regression;(3) population spatial distribution in the study area shows a high spatial positive correlation and a "high–high"agglomeration type which is also the main type in the study area;moreover, it shows that the population densities of the county are not spatially independent but intensively agglomerated.

  • LI Jingyao, SHI Runhe, YIN Ruijuan
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    As one of the main greenhouse gases, global atmospheric carbon dioxide has increased one third over the past one hundred years, becoming the focus of global warming research. Using satellite remote sensing technology and radiative transfer model to retrieve atmospheric carbon dioxide has become the most important means to obtain the global carbon dioxide concentration data. However, the input parameters of radiative transfer model inevitably carry some errors, which will influence the retrieval accuracy more or less, so this influence must be quantified and considered in the retrieval algorithm. In this paper, the radiances of 17 infrared carbon dioxide retrieval channels located in 15μm wave band of the Aqua/AIRS infrared detection instrument are simulated by the fast radiative transfer model RTTOV10. The temperature profile, ozone profile, water vapor profile, surface temperature and emissivity are considered as the influence factors. And the sensitivities of the outgoing radiance to the errors of these input parameters are calculated. Then the comparison between these sensitivities and that to 0.5% change of atmospheric carbon dioxide concentration is made. Analysis shows that: temperature profile errors have the biggest influence on carbon dioxide retrieval, and these errors should be less than 0.5k. The total sensitivity of all channels to ozone profile errors are about one third of that to carbon dioxide, making ozone profile errors take the second place. The sensitivities to errors of water vapor profile and surface temperature show the same trend which is only high at channel 738.1 cm-1 and 738.4 cm-1. Errors of surface emissivity are negligible at all channels, because the sensitivities due to them are far less than that to carbon dioxide. Finally, for each channel, these parameters are divided into three classes which are high sensitive parameters, low sensitive parameters and non-sensitive parameters, providing a reference for carbon dioxide retrieval channel selection and algorithm design.

  • XU Rong, ZHANG Zengxiang, WEN Qingke, LIU Fang
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    A mechanism error model for the lake surface area derived from the different spatial resolution data is presented. The model is based on the assumption that the differences of lake surface areas estimated by remote sensing images with different spatial resolutions are mainly determined by the mixed pixels on the water-land boundary but not the central part of the lake water surface. The elliptical (including circular), triangular, and hexagonal areal ground features are analyzed to illustrate the relationships between areas extracted from images with different spatial resolutions. It is found that for these three kinds of areal ground features, the calculated relationships accord with the same law. It is proved that this assumption works for the areas of many internal homogeneous features derived from images with different spatial resolutions. Lake surface is a certain internal heterogeneous feature, thus the surface areas derived from the different spatial resolution accord with the similar relationship. Taking the lake surface area data derived from images with high spatial resolution as reference, a mechanism model for the error of the lake surface area estimated through low spatial resolution data is established. In order to validate this model, it is applied to the data of Ebinur Lake, including lake surface areas based on SPOT VGT and ETM+. The relationship between areas extracted from VGT and ETM+ is analyzed, and it is found that the relationship could be described by the error model. To calculate the parameters of the model, the least square method is applied based on the area data derived from VGT and ETM+. According to this model, the calculation values are obtained based on the area data extracted from VGT, and compared with the area derived from VGT. It is shown that this mechanism model is applicable to Ebinur Lake, and its principle is correct. The model simulates the error of the lake surface area extracted from low spatial resolution data, and estimates the value of error successfully. Therefore, it is capable to calibrate the lake surface area derived from low spatial resolution data with the high spatial resolution data. Three sets of data are employed for demonstrating the correction capability of the model, and the result shows that the precision of the lake surface area derived from VGT are improved significantly after correction. For further evaluation, the areas of Ebinur lake and Yake Kumu Lake estimated by MODIS are calibrated with the areas estimated by TM/ETM+, and the similar results are obtained. With the gradual accumulation of the sample data, the correction effect of the model can be improved. It is helpful for estimating the lake water area more accurately in a large region.

  • TIAN Jing, WANG Juanle, LI Yifan, ZHOU Yujie, GUO Haihui, ZHU Junxiang
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    Global and regional land use/cover data processed by remote sensing images is a supportive part for the researches related to environment and so on. Mongolia Plateau includes all of Mongolia, parts of southern Russia and northern China. Study on land use/cover changes in Mongolia Plateau has important practical and scientific significance to discover the resources, environmental and ecological characteristics of this area and even in northeast Asia area, and also it is beneficial to enhance international cooperation in regional resources utilization, ecological and environmental protection and sustainable development. According to the land use/cover mapping requirement in Mongolia Plateau, a land cover classification approach was designed based on QUEST (Quick Unbiased and Efficient Statistical Tree) decision tree method in the representative area of Mongolia Plateau, where includes Tov Province and Ulaanbaatar City in Mongolia. Land cover classification dataset in this area was captured using Landsat TM images, through QUEST automatic classification and visual interpretation. Results show that the total area of steppe occupies 70.88%, followed by forest accounting for 14.83%, barren 10.73%, cropland 2.98%, water 0.31%, built area 0.27%, and wetland 0.02%. 139 GPS verification points for accuracy assessment were collected by fieldwork, which was held in August 2013. Accuracy assessment found that land cover overall accuracy is up to 72.66% in class I, while the overall accuracy in class II is obviously descent, mainly due to the confusion of real steppe and desert steppe. This was caused by the different understanding of these two steppe types between scientists from China and Mongolia. In general, the QUEST decision tree method used in this paper is proved to be feasible for higher accuracy land cover classification mapping in this area.

  • SHI Tingting, YANG Xiaomei, ZHANG Tao, LIU Li, TIAN Wenjun
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    Due to the spatiotemporal heterogeneity of regional precipitation, and sparseness and uneven spatial distribution of meteorological stations in Fujian Province, the overall accuracy of the regional precipitation spatiotemporal interpolation is limited. Tropical Rainfall Measurement Mission (TRMM) 3B42 rainfall estimates can directly provide spatially distributed precipitation estimations over global areas, which are used to make up the drawbacks of observed data of rain gauge stations. At the same time, Bayesian Maximum Entropy (BME) is used to improve the accuracy of spatial interpolation because BME can use the soft data with uncertainty and accurate hard data to perform the spatial interpolation. Based on annual and monthly precipitation data of 20 meteorological stations from 2000 to 2012, the BME with TRMM as soft data and the Ordinary Kriging (OK) are employed to analyze the spatiotemporal characteristics of multi-yearly precipitation in Fujian Province, and the results of interpolation methods are compared. The results indicate that BME with TRMM as soft data performs are better in reflecting the local spatial disparity. Comparing the calculation results of two interpolation methods, the MAE and RMSE values of BME with TRMM as soft data are smaller than OK with hard data only. The results show that BME could effectively reduce the absolute error by taking account of using TRMM rainfall estimates as soft data. In conclusion, BME makes the spatiotemporal analysis results of precipitation more objectively because of the integration of hard and soft data. The study also provides new opportunities in application of TRMM rainfall estimates.

  • XU Yuanjing, ZHANG Zengxiang, WANG Xiao, WEN Qingke, LIU Fang, LI Na
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    Shandong is one of the largest aquaculture producing provinces in China,and its aquaculture land changes significantly in both quantity and spatial distribution in the recent 30 years. This paper chose the coastal aquaculture land use in Shandong Province as the research object. In order to extract the aquaculture land use information, the interactive visual interpretation method incorporating spatial and spectral information from multi-source image objects was applied to Landsat TM/ETM+, CBERS-02B and HJ-1 images which were acquired in the late 1980s, 2000, 2005 and 2010 covering the coastal area of Shandong Province. Furthermore, to reveal the spatial pattern of Shandong coastal aquaculture land use evolution, we adopted different models including the single land use dynamic index, the gravity center, the landscape fragmentation and multi-model analysis of spatial information such as changes in the distribution area statistics. Results show that: from the late 1980s to 2010, Shandong coastal aquaculture area has increased, but the increase rate varies slightly in different periods; the dynamic degree from the late 1980s to 2000 is about 16.95%, which is the largest. It decreases gradually after 2000. The changes of aquaculture land use indicate the spatial heterogeneity. The aquaculture area in Dongying city keeps growing fast, followed by Binzhou city and Weihai city. But the growth rate in Qingdao city and Weifang city has dropped after a period of increment. For nearly 30 years, the fragmentation degree of the aquaculture area has increased by 4.5 times, and the gravity center of the aquaculture area has migrated to the northwest. The increased aquaculture land is mainly transformed from the construction land, sea water bodies and the agriculture land. The loss in aquaculture land is mainly turned into construction land and other forms of water bodies.

  • ZOU Chuncheng, ZHANG Youshui, HUANG Huanhuan
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    With the economic development, urbanization has been accelerating in recent years in Fuzhou City, Fujian Province of China. Rapid change on land surface property and its patterns may lead to change of thermal properties in urban areas of Fuzhou City. One of the main impacts of rapid urbanization is the effect of urban thermal environment. Landscape patches in a region are different in size, shape and spatial arrangements, which contribute to the spatial heterogeneity of landscape and are linked to the distinct behaviour of urban thermal environments. Studies on landscape metrics extracted from discretized percent impervious surface area data are comparatively rare. This research, which investigated the relationship of landscape metrics and urban thermal environments in Fuzhou City, Fujian Province, China, is based on both the analysis of land surface temperature (LST) in relation to normalized difference vegetation index (NDVI), and the percent impervious surface area (FISA). Two Landsat TM/ETM+ images acquired on June 15 1989 and March 4, 2001 were used to estimate LST, NDVI, and impervious surface area (ISA). This was extracted by applying linear spectral mixture analysis. We analyzed the relationship between the above-mentioned components of urban ecosystem. Using threshold value method and range method to discretize percent ISA into different categories. Landscape metrics such as cohesion, AI, LPI, etc. are calculated based on different FISA categories. The result showed that there is a positive linear relationship between LST and impervious surface over the region. The correlation coefficient is .66(1989) and .71(2001). To find the relationship between landscape metrics and LST, we analyzed landscape metrics from three aspects: shape, area and structure. The study indicated that landscape metrics are sensitive to the variation of FISA and LST. Therefore, the integration of FISA and landscape metrics provided a feasible way to describe the spatial distribution and temporal variation in urban thermal patterns in a quantitative manner.

  • GUO Haihui, WANG Juanle, ZHOU Yujie, WU Xiaona, HOU Haiqian
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    Moorburn was occurred frequently in Poyang Lake Nanji Wetland National Nature Reserve, which affected biodiversity and regional ecological environment to some extend. The traditional moorburn information extraction methods have their respective advantages, but it is not suitable for rapid and emergency moorburn monitoring. So it is an urgent demand to extract moorburn information for environmental management in Poyang Lake Nature Reserve in a quick, convenient and accurate way. This paper focused on the moorburn incident in Poyang Nanji Nature Reserve Area of Poyang Lake located. The environmental mitigation satellite data were adopted in Lake Nanji wetland in early January 2012, taking Xinjian County as the study area. The research was based on object-oriented remote sensing image analysis theory. Firstly, the image was multi-scale segmented and merged. The scale of the image segmentation and merging of 35 and 80 respectively. Then, the rule set of moorburn extraction was built based on the spectral information, spatial feature, and texture feature of image. The spectral information rules were built based on Hue, NDVI, MTVI and the principal components after the principal component analysis. The space characteristic rules were built based on area and roundness. The rules of texture feature were built based on texture mean and texture entropy. Finally, the moorburn information was extracted, and the extraction result is tested with confusion matrix. Accuracy test shows that overall accuracy is 99.38%, and Kappa is 0.89. It demonstrates that the object-oriented method is a kind of effective, accurate and fast method for the extraction of moorburn information, and it can avoid salt and pepper broken figure spot in traditional methods. The difference of moorburn information and other features is bigger in the first principal component after the PCA transformation in spectral characteristics and the texture entropy of texture features. But the difference is very small in space characteristics. The method can provide data support and technical reference for environmental protection, nature reserve management and moorburn management in the Poyang Lake area.