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  • 2009 Volume 11 Issue 5
    Published: 25 October 2009
      

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  • ARTICLES
    XIAO Tong, LIU Jiyuan, SHAO Quanqin
    2009, 11(5): 557-565.
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    As the largest nature reserve of China,"Three River Sources" Nature Reserve plays an important role in protecting ecological security.The change of NPP,which is a vital indicator for ecosystems,is still concerned by us.We utilize NPP,which is simulated by GLOPEM model,to calculate the difference of NPP between both inside and outside of the protected areas.We define the buffer region of a protected area as the outside.The outsides we defined are used to calculate mean value of NPP to subtract from the mean NPP of insides.Also we calculate the difference in three periods,i.e.1988-2008,1988-2004 and 2004-2008.If the differences of insides and outsides in 1988-2004 are lower than the value in 2004-2008,we define it as turning better,especially when the value in 1988-2004 is negative but is positive in 2004-2008,we call it notable better.After that,we find that there are 13 protected areas better and 2 notable better than before,and only 5 protected areas become worse than before.In the 5 regions there is a snow-mountain protected area,although the result in this region is worse than before,it does not mean the ecosystem is worse,in contrary it means the environment is turning better because of the spread of main ecosystem decrease the NPP.We conclude that in this region,since the implementation of ecosystem engineering,NPP rise obviously with the rate of 0.47 gC m-2 yr-1,and most protected areas are turning better.
  • ARTICLES
    SUN Xiaoyu, SU Fenzhen, LV Tingting, GAO Yi
    2009, 11(5): 566-571.
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    A method to extract marine hydrographic characteristics based on line process is introduced in this paper.The program written in Visual C++ has already integrated in MaXplorer,which is a marine geographic information system platform developed by China.By this method,time series MODIS-SST data were used to extract sea surface warm front of Kuroshio in East China Sea.The seasonal change of the warm front location was analyzed based on the extracted results above.It showed that the seasonal change of the warm front location of the top layer of Kuroshio is not very evident in East China Sea in general,except in the area of about 30°N and the area near the northeast of Taiwan Island.Because the change of sea surface temperature(SST) in East China Sea in summer is relative small at an average temperature of 28℃,it is difficult to determine the locations of the warm front.The warm front locations in other seasons were occurred along the shelf break near the isobath of 200 meters.In north-eastern of Taiwan Island there is a clear curve which showed a cyclone pattern then an anticyclone pattern.The locations of warm front in winter were occurred in the relatively east part while in autumn,showed a relatively complicated route.
  • ARTICLES
    CHEN Chuanfa, YUE Tianxiang
    2009, 11(5): 572-576.
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    A digital elevation model(DEM) is a representation of terrain elevation as a function of geographic location.DEM inevitably contains errors,which are spatial variable and correlated.The usual error model is Root Mean Square Error(RMSE),whereas it is a global variable,and can not show the DEM error of each grid.In order to overcome the deficiency of RMSE,Dongzhi Tableland was employed as a test region,and an error surface about 6.25km2 was constructed based on the conditional stochastic simulation model(CSS).Water and soil loss level determination was taken as an example to validate the importance of CSS.The results indicated that the uncertainties in derived slope of the Dongzhi Tableland tend to be found in flatter areasthe slope error range is bigger than DEM error range,which indicates that the DEM error is magnifiedprobabilistic and fuzzy model shows that almost all grids are influenced by the DEM error in water and soil loss level determination.As a tool for DEM error analysis,conditional stochastic model can improve the user assessment of DEM error.
  • ARTICLES
    XU Jinlin, ZHA Xuan
    2009, 11(5): 577-584.
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    Soil erosion risk assessment is crucial to soil and water conservation monitoring,harnessing and so on.With the increase of national attention on the ecological environment and the development of science of soil and water conservation,research of soil erosion risk assessment is becoming more and more important.By consulting the published researches on soil erosion risk assessment,an improved method of soil erosion risk assessment was adopted in this paper.Firstly,distribution of soil erosion degree by various impact factors including altitude,gradient,land use type and soil types were calculated by GIS and statistic analysis.Secondly,integrative index of different soil erosion degree by impact factors were computed.Then the soil erosion risks by different impact factors for every subbasin were calculated by weighting impact factors corresponding to each degree of integrative index of soil erosion.Thirdly,soil erosion risk by every impact factor was classified into three levels and the corresponding maps were finished.The integrative degree of soil erosion risk also was classified by cluster analysis.Finally,comparing distribution of different soil erosion intensity with the distribution of soil erosion risk,the studied area was regionalized with various soil and water conservation aims.The results were that:(1) the method was reasonable and suitable for actual conditions,and it avoided subjectivity in weight decision.(2) The relationship between soil erosion and impact factors in Anxi County,Fujian Province were discussed.The intensity of soil erosion in <500m altitude zone,3~15°gradient zone,dry land and other wood land,acid skeleton soil and acid stone soil was greater than other grades of corresponding impact factors.(3) According the spatial distribution of soil erosion risk,the possibility of erosion of every subbasin and different effect of impact factors were clearly showed.The distribution of soil erosion risk and intensity of soil erosion are basically in accordance.(4) By comparing consistent and discrepancy of the distribution of soil erosion risk and intensity of soil erosion,zoning of soil and water conservation areas was more pertinent.Preventing and treating areas,controlling areas,preventing areas and reserve areas were confirmed and characterized so as to provide scientific basis for departments of water conservancy and agriculture which could make scientific and reasonable decisions and take some effective countermeasures for soil erosion controlling.
  • ARTICLES
    YANG Fenghai, SUN Yankun, YU Taiyi, HOU Shutao, SHEN Nengzhan
    2009, 11(5): 585-596.
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    Spatial interpolation of average 10-day air temperatures were conducted at the scale of 1km×1km in Heilongjiang Province with CoKriging method through data exploring,error fitting,accuracy evaluating and model comparing.In this course,ground elevation and aspect data that are the local factors bringing on the spatial variation of air temperature were used to consider the autocorrelation of 10-day period air temperature and its relation to them,adopting 10 years of average 10-day air temperature data of 80 weather stations from 1997 to 2006 as interpolation variables.Cross-validation results show that the averages of mean,root-mean-square,average standard,mean standardized and root-mean-standardized errors are 0.0024℃,0.774℃,0.682℃,0.0006 and 1.124 respectively.According to the principle of geostatistics,this interpolation accuracy can meet the demand of climate change research all over the province in a macro level.On the basis of 10-day surface air temperature,average monthly and yearly surface air temperature have been work out.By the use of interpolation and calculation data of average 10-day air temperature and all data from weather stations as data source,spatiotemporal variation characteristics of average 10-day period,monthly and yearly air temperature have been analyzed to show that their spatial variation of air temperature in the Southeast are less than in other regions and,temporal variation of 11-13th,12-14th and 19-21st 10-day period are a smooth downward trend,15-17th,26-28th and 27-29th 10-day period are steadily rising trend,average air temperature in July are slightly downward trend,a slight upward trend in September and November,and about 1℃ higher between 5-9 months.The mean value of average annual air temperature is 2.9 ℃ fluctuating between 2.5-3.3 ℃ and being a little rising but no obvious trend.Change ratio of some average 10-day air temperature become lower and stable between spring and summer,higher between summer and autumn,indicating the shift of boundary among seasons.All of the air temperature data attained above by interpolation and calculation can be put into a geodatabase by which spatiotemporal variation of air temperature has been analyzed in order to lay a foundation to air temperature change monitoring,land capability evaluation,agricultural regionalization and crop yield estimation for related research in the future.
  • ARTICLES
    YANG Yu, LI Yunmei, LE Chengfeng, SUN Deyong, HUANG Changchun
    2009, 11(5): 597-603.
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    Semi-empirical models are the main models to retrieve chlorophyll-a concentration in remote sensing.The water is so turbid and eutrophic in Taihu Lake that the accuracy of some semi-empirical models varies highly.The datasets were collected over a considerable range of optical properties,trophic status,and geographical locations in Taihu Lake.So,it is very useful to find a model which can retrieve chlorophyll-a concentration in a good accuracy and has the best ability to adapt time changing.This study applied a recently developed model of the form 1/Rrs(λ1)-1/Rrs(λ2)×Rrs(λ3) where Rrs(λi) is the remote-sensing reflectance at the wavelength λi.The objectives of this paper are(a) to build the reflectance first-derivative model、reflectance ratio model and three-band model using the data measured from June to October in 2005 to find which model is the best,(b) to find out the special bands which are suitable in Taihu Lake for the three-band model,and(c) to examine these three models by the dataset measured in November in 2006 and 2007.Strong linear relationships were established between analytically measured chlorophyll-a concentration and both the three-band model 1/Rrs(λ666)-1/Rrs(λ693)×Rrs(λ734) and the two-band model R(λ705)/R(λ680).Accuracy for all these models were measured by R2 and RMSE.The result is that the three-band model is the best one of them.Its normal RMSE is less than 20% of the change which was shown in the dataset.And it has the best ability to adapt time changing that the normal RMSE of 2006 and 2007 is 11.17 and 9.74 respectively.We can also find that the bands used in the three-band model are available from some satellites.So,the three-band model has a good future to retrieve chlorophyll-a concentrations.
  • ARTICLES
    MA Liuqing, SONG Guanfu, GUO Hui, ZHOU Qin
    2009, 11(5): 604-609.
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    Walkthrough in massive terrain and image data is a key technology and a difficult problem of GIS,VR and Digital Earth,etc.Hardware-friendly LOD methods become popular with the development of computer hardware technology,such as SOAR,Chunked LOD,GeoClipmap etc.More and more LOD methods take account into large texture data.Based on current LOD algorithms and the development of computer hardware technology,the data block partition and the quadtree algorithm were used to establish pyramid.At the same time,large data accessing was improved by synchronous loading,LOD was controlled by texture resolution and the cracks between meshes were filled by adding skirts around each block.The results show that the rendering and updating of data is easier to be controlled,the geographical range of terrain and image data doesn't need matching exactly as before and massive data can be loaded and rendered quickly.
  • ARTICLES
    ZHU Jiangang, YU Xinxiao, LI Jing, ZHANG Zhenming
    2009, 11(5): 610-616.
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    Computation and analysis of fractal dimension of river networks would help to better understand its relationship with the processes of geomorphologic development,runoff,sediment yield,etc.Based on fundamental theory of fractal dimension calculation,we present an improved method for simultaneous computation of box-counting dimension and information dimension of river networks according to the image analysis.This method was validated by regular fractals with known fractal dimension,such as Koch curve and Sierpinski gasket,and the results showed its high precision which due to(1) it distilled the information what we cared about,i.e.,the target graphics,out from the carrier,i.e.,the image,and dealt with target graphics independently.So it was no longer restricted to the proportion of target graphical area to entire image size and just related to the size of target graphics as well as the relative position between the initial cower box and the target graphics.And(2) it ascertained the optimal descending equal-partition-condition consisting of the way of equal-partition,the size of initial cover box as well as the relative position between the initial cower box and the target graphics automatically rather than artificially.In addition,cell array technique was used in the computation,with its good fitness in generating descending sub-matrixes in iteration process,to implement the equal-partition of grids continually,which enhanced the readability of the computer code.Finally,an example of Jinghe and North Luohe demonstrated the application of this method.We suggested that the computation of fractal dimension of river networks in the real three dimensional space rather than two dimensional images may be a crucial research challenge in future.
  • ARTICLES
    LU Feng, DUAN Yingying, ZANG Zhigang
    2009, 11(5): 617-622.
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    Implementing convenient traveling information service is a crucial task for carrying out the strategy of intelligent transportation system and developing location-based services.At present,most of the domestic traveling information service systems only provide relatively static information which can't reflect the possible short-term changes of traffic,and result in very limited practical use.Although there have emerged some car navigation products and other applications involving real-time traffic information,considering the rapid change of city traffic situation,these products and applications still face practical difficulties for all the information received real-timely will get outdated within a few minutes,which makes the so called dynamic applications basically time-slice limited static ones.This paper presents a practical short-term traffic prediction approach in real-time conditions by integrating historical traffic based statistical reasoning with back propagation neural network based analytical model,and commercial microscopic traffic simulation software.The historical traffic based statistical reasoning utilizes the inherent traffic rules by identifying the general spatial-temporal distribution pattern,and ignores any inputs that don't contribute to the output during the training process,including the gross error in the collected traffic data.The commercial microscopic traffic simulation software process the traffic abnormities that always exist in big cities,and has no requirement for the collected real-time traffic information to cover the whole road network,hence provides an effective supplement for short-term traffic forecast.Then an approach is developed combining GIS server,traffic prediction server and database management system to implement dynamic route guidance.The traffic prediction server receives real-time traffic information obtained from floating vehicles and achieves short-term forecasting results for the whole road networks,then fed the results back into the database management system and GIS server,so that a time-dependant optimal routing can be conducted through a dynamic least traveling time algorithm developed in this study.A prototype fulfilling the above aspects has been developed and validated with a city road network and real-timely collected traffic information.The approach presented in this paper is argued to provide a practical solution for real-time public traveling information service and dynamic web maps.
  • ARTICLES
    LV Ning, LIU Ronggao, LIU Jiyuan
    2009, 11(5): 623-630.
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    Downward shortwave radiation(DSR) is an important physical and ecological parameter under the total energy exchange process between atmosphere and land surface.DSR retrieval from satellite data is of significance to be fully aware of the spatial variability and interannual variation features of this parameter.Based on DSR at surface retrieved from Geostationary Meteorological Satellite(GMS) 5 data over China from 1998 to 2002,the features of DSR spatio-temporal variation over China are comprehensive analyzed.The results show:(1) on the Nationwide,the maximum DSR is on Tibetan Plateau and the minimum value is over the Sichuan Basin and Guizhou,both the extreme values are located on the belt between 22°N to 35°Napart from Sichuan Basin and Guizhou,DSR usually increases from East to WestDSR in West region decreases with the increase of latitude,while Yangtze River basin in East part has the lowest DSRDSR increases from South to North,the maximum DSR is in North China,the second largest place is in South China,DSR decreases with latitude in Northeast China(2) the distribution of monthly DSR is complicatedthe minimum DSR happens in December,however the maximum DSR,controlled by the rainy season,is in July after the rainy season in Pearl and Yangtze River,May and June before the rainy season in South and Northeast China and Qinghai Tibetan Plateau,while April and May before the rainy season in Southwest China(3)DSR over Southeastern coastal regions has increased by 13.71%(+4.37W/m2·a)for those 5 years,while DSR over Southwestern Plateau has decreased by 9.31%(-3.47W/m2·a)the overall average DSR over China has decreased by 0.84%(-0.27W/m2·a).
  • ARTICLES
    REN Na, LIU Xuejun, ZHU Changqing
    2009, 11(5): 631-637.
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    Close-range photogrammetry is one of the main methods to achieve high-precision three-dimensional modeling of ground objects.In the actual photogrammetry process,the ordinary digital cameras can not focus all the targets then can not make sure that all close-range images are clear at the same time.We can use image fusion techniques to get the whole clear image and increase the application of these data.Image fusion is a technique that integrates and processes several images from different sensors by some algorithm to obtain a new image which meets the requirements of some demand.The result of image fusion is a new image which is more suitable for human and machine perception or further image-processing tasks such as segmentation,feature extraction and object recognition.The different focal close-range image fusion is explored,and the measure index of sharpness of the image of wavelet image energy is given.Curvelet is more appropriate for analysis of image edges such as curve and line characteristics than wavelet,and it has better approximation precision and sparsity description.We introduce the second generation curvelet transform to image fusion,and a new method to solve the close-range image with different focus fusion is proposed.Firstly,using the second generation curvelet transform method,two source images are fused to get the primary fusion image.Then,according to the wavelet image energy,the whole image is divided into three parts,namely,clear part,blurring part and the part between them.As to the clear and blurring part,the former is selected as the corresponding block of the fusion image,while the part between clear and blurring one is fused by the choice of the image using the second generation curvelet transform.At last,to demonstrate the performance of the new algorithm,new approach is applied on two sets of experiments,and image entropy,mean square error and peak signal to noise ratio are used to evaluate the results.The results show that the proposed algorithm improves the quality of the fused image effectively,and performs better in preserving edge information for the test images than other image fusion methods.
  • ARTICLES
    LIU Xuejun, WANG Yanfang, JIN Bei, YANG Jie
    2009, 11(5): 638-644.
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    Raster structure is widely used in GIS with its merits that simple structure,easy spatial analysis and perfect match with remote sensing data.The popular use demands higher accuracy when converting vector data into raster one.The grid resolution,which directly determines the closeness to spatial object,is the first and critical issue for rasterizing of spatial data.Low resolution will cause mixed pixel that can't express the object clearly,while higher one will induce geometric growth of the data quantity with a result of data redundancy.Choosing a suitable grid resolution for output maps is not an easy thing since many facts must be considered,such as the scope of the study areas,research purposes and distribution of the original data.In fact,in most GIS projects,grid resolution is selected arbitrarily and blindly,without specific and scientific justification.Efforts were made to determine the raster resolution considering the inherent properties of input data,the rules of cartographic,computer processing power and other statistical concepts concerned with the various sources.Nyquist sampling theorem and the Smallest Visible Object(SVO) theory,the main basic theories in communications and map generalization,were used to demonstrate the suitable resolution.They are helpful in determining the appropriate grid resolution for the vector-grid conversion,terrain data,remote sensing image and scattered points with the restriction of computer processing power.According to the methods for different sources,a raster resolution calculator was developed under ArcGIS environment.The category of the source data and necessary parameters were inputted in the raster resolution calculator.Three standard grid resolutions for output maps are recommended: the coarsest legible grid resolution,the finest legible grid resolution and the recommended one.Finally,three kinds of input data,polygon in vector,contour lines for terrain and sampled point data for pH,were verified in the raster resolution calculator.The results of experiments showed that the recommended resolution which avoids the blindness is superior to the resolution defaulted by the system.
  • ARTICLES
    LI Aiqin, LI Deren, GONG Jianya, DENG Yi
    2009, 11(5): 645-651.
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    Conceptual framework is one of the most important research topics of map generalization,but at the same time it has been too much ignored.There are both relationship and difference between spatial data multi-scaling representation and processing in GIS and map generalization.The multi-scale representation and processing is mainly driven by the objectives of geographic information analysis and querying,while map generalization emphasizes more on the cartographic representation,driven by the objective of information transmission and communication.This paper makes an attempt to study and look for a simple knowledge representation method and processing framework,so as to set up a scale-independent spatial database,or so called multi-scaling GIS,which has provided the theoretical foundation and practical experience for the efficient organization and management of spatial database as well as the research and development for multi-scale representation and processing.It proposes that "information selection" is the core not only for spatial data representation,processing and organization but also for map generalizationmakes analysis on the difference and relationship between geographic spatial databases and map databasesemphasizes that geographic spatial databases are the abstract representation of features in the digital landscape model,but not just the display of graphicsmakes analysis on the requirements of multi-scale representation and processing to spatial databaseemphasizes that feature elements should be represented integrally and seamlesslymeanwhile,proposes that attention should be paid to the significance of various thematic spatial partitions and logically thematic spatial information in multi-scale representation and processingand proposes multi-grade modeling representation rules based on thematic models in different subject realm as well as knowledge representation framework of multi-scale representation and processing based on spatial feature classification structure and parameter table.This paper aims at GIS analysis purpose.Based on analysis of lots of literature,a number of issues about spatial scale,multi-scaling,manual map generalization,digital map generalization,geographic database,cartographic database and conceptual frameworks are discussed.This paper proposes and tests a simple conceptual framework for spatial data multi-scaling representation and processing in GIS.
  • ARTICLES
    YANG Lin, SHENG Yehua, WANG Jing
    2009, 11(5): 652-656.
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    This paper analyzes the difficulties and characters of informationization in small & medium logistics enterprises,emphasizing on designing of the general framework,which involves four parts,i.e the management information sub-system,the monitoring sub-system,web site sub-system and data exchange platform.It also discusses the general framework and functions of the logistics information system based on GIS(Geological Information System) for minimizing the informationization cost,in which the key problem and choke point of huge data accessing and the priority of multi-user based on web data exchange platform are also discussed.Furthermore,it introduces the implement of the management system,involving the visual models of operation process based on UML(Unified Modeling Language),the key technologies and arithmetic based on GIS(for example the optimal distribution scheme based on real-time vehicles dispatching and the location model of logistics units based on ArcGIS),and necessary and optimal equipment of hardware and software.The research and development of the logistics information system aided reconstructing and optimizing the operation flowing and supply chain,improving working efficiency and level of management,which had been applied to some medium logistics enterprise in Nanjing successfully,and set a good example and reference of operation informationization for other small &medium logistics enterprises.
  • ARTICLES
    XU Feng, DENG Min, ZHAO Binbin, CHEN Jianjun
    2009, 11(5): 657-663.
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    To improve both the reuse and the quality of existing spatial data,it is urged to develop approaches for integrating and updating spatial data,which possibly are collected from multiple sources,at different time,and/or multiple representations for the same spatial region.For this purpose,object matching has become one of the crucial technologies,and it is conducive to detect change and/or difference between different spatial datasets(e.g.two different scales of maps)by comparison of corresponding objects.Currently many matching methods have been developed for different types of objects in practical applications.These methods can be classified by two modes,i.e.matching criterion and object type.Methods based on matching criterion can be classified into three categories,i.e.geometric,topological and semantic matching,which are respectively implemented by geometric constraints(e.g.distance,shape similarity,direction),topological constraints(e.g.connectivity,node degree) and semantic constraints(e.g.semantic similarity),whereas the matching methods based on object type can be further referred as point-to-point,point-to-region,line-to-line,line-to-region,and region-to-region matching.In the process of object matching,there are possibly six matching mapping relations,i.e.1∶0,0∶1,1∶1,1∶N,N∶1,N∶M.As for the latter three matching mapping,an iterative searching process is needed to build the mapping relations between the correspondences in two different spatial datasets.Through analysis of literatures,one can find that each of the matching methods to some extent has its advantages for some particular types of objects(e.g.line or area) and/or applications.That is to say,they are lack of generality.Based upon this situation,this paper makes a systematical investigation on existing matching methods,including their classifications,basic principles and procedures,and the applications in geo-spatial information science(e.g.map updting,spatial data integration,etc).A detailed comparison is made for these matching methods from aspects of matching criterion,object type and scale.In particular,it is pointed out the characteristics of object matching with different scales of map updating,which is distinctly different from the object matching with same or similar scales.This work is very helpful for further development of general matching methods.
  • ARTICLES
    LUO Jiancheng, ZHOU Chenghu, SEHN Zhanfeng, YANG Xiaomei, QIAO Cheng, CHEN Qiuxiao, MING Dongping
    2009, 11(5): 664-669.
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    The essential issue of remote sensing application is to extract thematic information and domain knowledge from earth observation images,and thereby these information to be used in various processes of analysis and decision-making.However,information computation is the basement of the entire remote sensing application service technology system.Based on the theory of geo-informatic Tupu,we proposed the spatial cognition theory coupled with remote sensing information Tupu,constructed the theoretical and methodological system of remote sensing information Tupu in the way of "pixel-object-target-pattern",which can be divided into two levels of "pixel-level" and "object-level".This paper also discussed the idea of the designing and developing the remote sensing Tupu computation platform based on the high performance computation environment,and summarized the developing trend and important research issues of remote sensing information Tupu computation.
  • ARTICLES
    WU Qiumin, LV Heng
    2009, 11(5): 670-676.
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    In this paper,we took Jiangsu Province,which consists of northern,central and southern parts,as the study area,and extracted land use conversion matrix tables of the three parts based on land use data of Jiangsu Province during four different periods(1985,1995,2000 and 2005).Accordingly,we analyzed the regional differences of land use and the driving mechanism of land use change in light of data on population,urbanization,adjustment of agricultural structure and policy.Land use conversion matrix tables show that cultivated land declined and rural and urban land use degrees expanded from the southern part to the northern part of Jiangsu Province,and regional differences become greater over time.Moreover,driving mechanism analysis shows that the use of cultivated land is extensive and the problem of advanced non-agricultural use is very serious in southern part of Jiangsu Province.In a time before a rapid development,the more developed the social is,the more the population growth will lag behind the reduction of cultivated land.During a process of urbanization,the more developed a city is,the less the increase of the urban population density will impel cultivated land to be converted into urban land."South Jiangsu Model" is an important factor to result in regional differences.
  • ARTICLES
    XIA Rui, LI Yunmei, WANG Qiao, WANG Yanfei, JIN Xin, XU Enhui
    2009, 11(5): 677-683.
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    Taking the Landsat TM / ETM + images of Wuxi City in 2001and 2008 as the data source,this paper uses the DBI-SAVI index to extract the information of town in Wuxi City,and achieves the urban expansion map of Wuxi City from 2001 to 2008.At the same time it uses thermal infrared band to invert the urban surface temperature,and respectively achieves the surface temperature map of Wuxi City in 2001 and 2008.At last,combining with urban thermal field variance index and the data of socio-economic and humanities,the relationship between urban expansion and heat island response is analyzed.The results show that urbanization of Wuxi City presents a growing trend from 2001 to 2008,with an uneven development of spatial expansion which mainly includes centralized development and ribbon-shaped development.The mostly direction is along the centerline of Changzhou-Wuxi-Suzhou Cities and encircles the Taihu Lake.The expansion speed in south-east is the fastest.In the process of urban expansion,surface temperature of Wuxi City has increased,area of urban heat island has been growing,and from ribbon-shaped to dumbbell-shaped distribution,urban expansion and heat island distribution have shown consistency in space,so urban heat island is a direct reflection of the urban expansion.
  • ARTICLES
    YANG Baolong, FANG Yuan, FENG Huihui, CHEN Hongshun
    2009, 11(5): 684-690.
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    This paper takes Dongguan City which is in the Area of Pearl River Estuary as an example.Under the strong trend of urbanization and industrialization,affected by both natural and artificial factors,the urban land expansion and the changes of landscape pattern continued year by year.Applying satellite images of Landsat-TM and integrating techniques of remote sensing imagery processing and GIS,the present study analyzed temporal and spatial process and driving factors of urban land expansion in Dongguan City from 1988 to 2002.The characteristics of urban land expansion are identified by several methods in analyzing the spatial-temporal features of Dongguan City from 1988 to 2002,which include expansion area,expansion speed,expansion intensity index and transformation matrix index.The main results are as follows:(1) during the last 15 years,area of construction land has been almost sevenfold which is more obvious during the 1988-2002 period.(2)The urban land expansion in different districts was obviously diversified and the main directions of urban land expansion are northeast and southwest.(3) The main types occupied by urban land expansion are arable land and developing land,the changes in the main occupation before and after 1995 as the result of the differences of the factors such as policies and economy,but in general the occupation of arable land is still the largest number in all landscape types.(4) The driving force of urban land expansion and its comprehensive evaluation are given in this paper using social economical data and correlation analysis.The economic growth is the decisive factor influencing the urban land expansion,and the correlative policies direction the economic growth run through the urban growth from beginning to end.