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  • 2008 Volume 10 Issue 5
    Published: 25 October 2008
      
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  • ARTICLES
    Estimation of Grid Based Spatial Distribution of Wind Energy Resource in China
    LIAO Shunbao, LIU Kai, LI Zehui
    2008, 10(5): 551-556.
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    Wind energy is one of the clean and renewable energy resources.It is transformed from solar energy,but cost of development of wind energy is lower than that of solar energy.Therefore,wind energy is one of renewable energy resources with bright prospect in the future.Estimation of potential of wind energy and its spatial distribution nationwide is a fundamental work for development of wind energy.In this study,meteorological data from 395 stations with the duration of 10 years and frequency of 4 times per day,including temperature,atmospheric pressure,relative humidity and wind speed,were used to calculate density of wind energy and number of hours of effective wind speed.And IDW（Inverse Distance Weighted） spatial interpolation method in ARC-GIS was employed to generate grid of distribution of density of wind energy and number of hours of effective wind speed nationwide.Analysis showed that areas of wind energy density > 150w/m2,100-150 w/m2,50～100 w/m2 and <50w/m2 occupied 2.51%,16.45%,53.39% and 27.65% of national total area respectively,and areas of number of hours of effective wind speed >5 000h,4 000h-5 000h,2 000h-4 000h and <2 000h occupied 5.28%,22.19%,53.54% and 18.98% of national total area respectively.Both wind energy density and number of hours of effective wind speed can be used to express potential of wind energy resource in general though there is a little bit difference between them.In fact,the relation ratio reaches to 0.78.It should be pointed out that there is different precision and uncertainty of estimated wind energy resource in different regions.In northwest China,there is lower precision and higher uncertainty for lower density of meteorological stations while there is higher precision and lower uncertainty for higher density of meteorological stations in Southeast China.Increasing quantity of meteorological stations is the most effective way to enhance precision of estimated results.
  • ARTICLES
    The Design and Application of CO2 Flux Data Processing System at ChinaFLUX
    LI Chun, HE Honglin, LIU Min, SU Wen, FU Yuling, ZHANG Leiming, WEN Xuefa, YU Guirui
    2008, 10(5): 557-565.
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    The standardized processing of observed CO2 flux data and issue of high grade data product are the precondition and foundation of researches at CO2 Flux and its related field.However,there are a system of problems when we process these observed flux data,such as tedious processing,unified methods and lag of processing.In order to solve these problems,we choose MATLAB as development toolkit.Through making a use of its powerful mathematical computation functions and visible GUI technology,and through making an integration of current flux data processing methods,we developed the processing system of observed flux data at ChinaFLUX with independent intellectual property rights.The processing object is to observe CO2 flux data with half-hour interval.The main processing steps included turbulent flux computation,quality control/quality assurance of observed data,gap filling of missing data,separation and computation of carbon flux exchange at different time scales and so on.On the basis of current researches at ChinaFLUX,we improved the algorithms of abnormal data rejection,u* threshold determination and nonlinear gap-filling method,which we considered to be optimal.The outputs of NEE,GEE and Re at Qianyanzhou Flux Tower at ChinaFlux are-352.19 gC m-2 y-1,1 284.88 gC m-2 y-1 and-1 637.07 gC m-2 y-1,which are similar to other research results.This system,with high automaticity and visualization,can provide a valid platform for processing observed CO2 flux data.
  • ARTICLES
    On Comparison of Spatial Interpolation Methods of Daily Rainfall Data:A Case Study of Shenzhen
    SONG Liqiong, TIAN Yuan, WU Lun, ZHANG Hui
    2008, 10(5): 566-572.
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    Discrete or continuous rainfall data are required to run many GIS models for environment and planning.The paper attempts to make a general comparison on different spatial interpolation methods.It carried out a study on four spatial interpolation methods: Inverse Distance Weighing(IDW),Local Polynomial,Ordinary Kriging and co-Kriging with respect to elevation.Daily rainfall data obtained from 36 rainfall stations during 27 inconsecutive days in the rainy season of 2006 in Shenzhen was employed in this study.Cross validation of the results shows that the four methods could to some extent reflect the rainfall situation of the region,yet the four interpolated surfaces are more smoothing than the practical circumstance.Particularly,IDW is the most smoothing one of the four.Besides,all the criteria(Mean Error,Mean Absolute Error,Root Mean Square Error and Percentage Error)that brought up in our study to measure accuracy of the four methods demonstrated that Ordinary Kriging and co-Kriging methods are superior to Local Polynomial and IDW.Inclusion of elevation in the co-Kriging method does not lead to improvement of result compared with Ordinary Kriging method.Furthermore,the interpolation data was grouped according to elevation and average daily rainfall and the same criteria above was bought to the statistics of those groups.Comparison on the criteria reveals that,the interpolated result on rain gauge stations with high elevation tend to larger than the observed data,and those rain gauge stations with low elevation are on the contrary.The interpolation error increases sharply while the average daily rainfall is bigger than 50mm.
  • ARTICLES
    Simulating Changes of Methane emission from Rice Paddies of China,1990～2000
    2008, 10(5): 573-577.
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    Methane is the secondary important greenhouse gas in the atmosphere.Among terrestrial sources of methane,rice paddies account for 20% of the annual emission on global scale.China has about 30×106hm2 of rice cultivation area,knowledge of the historical change of methane emission from the rice paddies is therefore helpful to th understanding of the future climate change.By applying a semi-process model（CH4MOD） that simulates methane emission from rice paddies with various agricultural practices,this paper made an estimation of the methane emission on national scale from 1990 to 2000.The whole country was divided into grids of 10×10km2 and each grid was assigned a set of the model input parameter values.By running the model for each grid and summarizing the model outputs,the temporal changes of methane emission of China were then calculated.The results showed significant inter-annual variation during the 10 years.Due to less rice cultivation of about 29.3×106hm2 in 1993-1995,the methane emission of around 5.37Tg a-1 was also lower than the other times which was 5.93 Tg a-1～6.22 Tg a-1.Besides the rice cultivation acreage,changes of methane emission from a unit rice area was also a significant factor to the changes of the national emission.Due to this reason,the national methane emission in 1997 was comparable to that in 1993 even through the latter has 1.84×106hm2 more rice cultivation acreage.In respecting to the spatial distribution of the methane emission,Hunan,Hubei,Jiangxi,Guangdong,Guangxi,Sichuan,Jiangsu and Anhui provinces are always the primary rice cultivation regions and therefore the main contributors of the national methane emissions.And more than that,the North-east China has emitted more and more methane in recent years.
  • ARTICLES
    An Analysis of Fire Danger Rating Assessment Method and Application
    WANG Litao, WANG Shixin, QIAO Dejun, ZHAO Qing
    2008, 10(5): 578-585.
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    The resource of forest and grassland is abundant in China.Furthermore,forest and grassland are important to socio-economic development and environmental protection in China.But frequent fire occurrence in forest and grassland has become a great threat to economy and environment,especially in border area.Assessment study on fire danger rating is a meaningful way in forest and grassland management and can provide useful information to support fire management decisions.This paper firstly defined some concepts on fire danger,fire danger rating,fire danger index,and so on.Then the fire danger indicators were summarized and classified into fire categories.Their application in fire danger rating assessment was analyzed,too.The second key to fire danger rating assessment is how to construct the fire danger index algorithm.In the paper,we reviewed the evaluation methods in fire danger rating assessment study,including both qualitative and quantitative.And then,an application example on the fire danger rating assessment based on remote sensing was given.Four provinces in Northern China(Helongjiang,Jilin,Liaoning and Inner Mongolia) were selected as the study area.Five fire danger indicators retrieved from remotely-sensed data were integrated to calculate the fire danger index by the method of Analytical Hierarchy Process.According to the value of fire danger index,fire danger was classified into five ratings.Using the constituted criterion,fire danger rating distribution can be mapped and used to provide useful information for supporting fire management decisions in forest and grassland.
  • ARTICLES
    Algorithm of spatial outlier mining based on MST clustering
    LIN Jiaxiang, CHEN Chongcheng, FAN Minghui, ZHENG Minqi
    2008, 10(5): 586-592.
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    A spatial outlier is a spatial object whose non-spatial attribute values are significantly deviated from the other data's in the dataset.How to detect spatial outliers from spatial dataset and to explain the reason causes the anomaly in practical application have become more and more interesting to many researchers.Spatial outliers mining can bring us a lot of interesting information,but for the complicated characteristic of spatial data,such as topological relation,orientation relation,measurement relation,and so on,traditional algorithms for outlier mining in business database seem to deficient in spatial dataset,the main problem lies in the difficulty to maintain spatial structure characteristics for most existing algorithms during the process of outlier mining.Thanks to the similarities between clustering and outlier mining,clustering based outlier mining is an important way to detect anomalies from dataset.However,due to the diversity of clustering algorithms,it is difficult to choose a proper one for outlier mining,and the main purpose of clustering is to find out the principal features of the dataset,outliers are the by-products of clustering.Based on minimum spanning tree clustering,a new algorithm for spatial outlier mining called SOM is proposed.The algorithm keeps basic spatial structure characteristics of spatial objects through the use of geometric structure: Delaunay triangulated irregular network and minimum spanning tree(MST),and it gains MST clustering by cutting off several most inconsistent edges of MST,so that it not only owns the function that it can acquire clusters from non-spherical and unbalanced datasets as the density-based cluster algorithms does,but also has the advantage that it doesn't depend on user's pre-set parameters,so the clustering result is usually more reasonable.Finally,the validity of SOM algorithm is validated by real application of geochemical soil elements dataset inspected to coastal areas of Fujian province,through analysis it is found that the algorithm is also applicable for spatial outlier mining in massive spatial dataset.
  • ARTICLES
    Data Model for the Realization of Long-Distance Pipeline Integrity Management and Its Application
    2008, 10(5): 593-598.
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    Along with the constant development and expansion of the industry of long-distance pipeline construction in China,pipeline security has gradually become a focus of the country and the whole society.In view of this,some experts proposed pipeline integrity management combined with techniques of GIS,which has been considered as a well-adapted solution.In this approach firstly it needs data modeling and then all data such as pipeline design,as-constructed,inspection data,et al.are altogether and efficiently managed within defined spatial database.In this paper,the author first compares several worldwide currently existing pipeline data models,and then explains in detail the designing process of the long-distance pipeline data model that suits our pipeline industry,referring to the international pipeline integrity management theories and methods as well as domestic practical experience.Finally,the author elaborates the whole process of establishing the pipeline integrity management information system by dint of techniques of geographic information system and spatial database.In the latter process of model application,the pipeline integrity management information system is established then,which makes full use of all types of information provided by the data model and successfully develops the LineLoop management module,risk / integrity evaluation module and site management module.Practice has proved a high potential for applications of this proposed pipeline data model in China pipeline integrity management.
  • ARTICLES
    Study on Spatial Information Service Model in PPGIS
    TAN Yumin, LIU Sainan, JIANG Jianjin
    2008, 10(5): 599-603.
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    Today's researches on PPGIS have been more about the effect of GIS technology on society or culture.Based on the requirement of public participation in civil informationization and sustainable development,together with the importance of spatial information technology in solving problems with geo-spatial reference,the authors present the necessity of studying spatial information service in PPGIS.In this paper,the authors mainly study spatial information service model of PPGIS from the view of Abstraction by building several models,including semantic model which includes organization model and process model,evaluation model,and so on.By doing so,the essence of service model in PPGIS is made clear.The purpose of spatial information service in PPGIS is to solve the problem by connecting information given by participants,that is to say,its information flow is two-way,and its aim is to solve those spatial problems by geo-spatial technologies which closely connect with people's daily life.The organization model mainly describes participants and their relation,and participants play two roles in this model: system users and information provider;the process model is built based on such knowledge: every difficult duty can be divided into several small easy sub-operations,including pre-evaluation,problem definition,spatial decision and decision evolution;the evaluation model is composed of data quality control and decision transparency evaluation,and service mode.The authors also discuss the system architecture for providing PPGIS-aimed spatial information service,and give an ArcIMS based example.Another part of the work of this paper is the design and development of extended spatial data engine for managing spatial data produced during participation in a PPGIS based on ArcIMS and ArcSDE.
  • ARTICLES
    An Arc-labeling Shortest Time Path Algorithm
    GAO Song, LU Feng
    2008, 10(5): 604-610.
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    Label-setting algorithm is one of the most classic shortest path algorithm,and widely used in the field of transportation.In the field of transportation,the shortest time path is more significant than the shortest length path.And the shortest time path is related with many factors such as the hierarchy of the roadway,the average speed and the delay from one roadway to another.In general,a logic road network is produced from a real one in this way: the real roadway is Abstracted as an arc in the logic network and the node is the crossing.After a brief description of some typical kinds of transportation network data model,an arc-labeling time shortest path algorithm is discussed here,which is more suitable than the node-labeling shortest path algorithm.The principle and theory analysis are presented in this article as well as the base data and running structure.In the following the characteristics and advantages of the arc-labeling algorithm,compared to node-labeling algorithm,are given.That it is more easily to calculate the delay and trace the time shortest path in arc-labeling algorithm.By the theory analysis and experiment test,it is proved that the arc-labeling algorithm can take the traffic informat affect and turning delay into account easily.So it is a practical shortest time path algorithm.
  • ARTICLES
    About Innovation Stratagem of GIS Technology
    PAN Mao, JIN Jiangjun, LI Jun, WANG Zhangang, QU Honggang
    2008, 10(5): 611-614.
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    To put Geographic Information System(GIS) technology innovation stratagem in practice,can not only satisfy the requirement of geographic information better,but also promote the development of geographic information industry.In this paper,three modes of GIS technology innovation were analysed firstly,that is technology push mode,requirement pull mode and mixed mode.Introducing the other technology and the deepening of application were the main causes of GIS technology innovation.Then,the methods of how GIS company actualizes technology innovation were presented,such as to absorb new science and technology in the process of GIS research;put oneself in right place according to GIS market situation and real requirement of users;cooperate with users and scientific research institutions,the other GIS companies,and related sector of society;and perfect the mechanism of GIS technology innovation.Finally,the function of government in carrying out GIS technology innovation stratagem was expatiated,such as to support baisc research in GIS domain,cultivate new type of technical personnel in GIS technology innovation,build up technology innovation platform for middle and small GIS companies,and create good environment for GIS technology innovation activities.
  • ARTICLES
    Construction and Application of GIS Based Greenstuff Traceability Logistics System
    QU Xiaohui, ZHUANG Dafang, QIU Dongsheng
    2008, 10(5): 615-622.
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    Vegetable and fruit are necessaries of people in daily life,whose safety problems are beneficial not only to the people's livelihood,but also to the competition capability of Chinese agricultural products in the international market.The safety problems of agricultural products for the 2008 Olympic Games in Beijing,have already been intensively regarded by the authorities.In this article,the concept of traceability logistics of agricultural products is brought forward by relating the traceability with the process of agricultural product logistics,and the solutions of it are put in practice to use IC card to record and store the traceability information of agricultural products logistics.On this basis,a prototype of traceability logistics system is constructed by using COM pattern and described in detail from database construction,system framework,structure of function,and structure of component.Finally,the system is put into effect with the data of the study areas in Beijing.It is proved that the solution of traceability logistics in agricultural products with the support of GIS is feasible and efficient,which provides an innovative idea for how to establish an efficient,credible and banausic traceability system of agricultural products in China.
  • ARTICLES
    Research on the Content and Framework of Enterprise Geographical Information Service——Taking Digital Tobacco as an Example
    MEI Xin, CUI Weihong, WU Mengquan
    2008, 10(5): 623-628.
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    Tobacco enterprise is a special enterprise,which has strong correlation to regional geography.But in the past research and application,the combination between tobacco and GIS is limited to the use of digital maps to assist cigarette distribution.How to comprehensively import GIS to construct digital tobacco is the main research aspect in this paper.Geographical information service is the new stage of geographical information development.The current research work emphasizes particularly on the study of pattern.However,the concrete application research for geographical information service with enterprise and commerce is seldom reported.Tobacco industry is the important source of finance and revenue in China.Digital tobacco is the new stratagem stage for tobacco industry informatization.Geographical information service entering the digital tobacco will bring about revolutionary changes for tobacco industry and correlative related commerce.The paper discusses concrete application content of enterprise geographical information service combining with digital tobacco.And then it gives corresponding framework design.The practice in this paper proved that this research may bring great benefits for tobacco company and government departments,including national revenue.
  • ARTICLES
    The Design and Technology Realization Method of Embedded GIS Data Collection and Navigation System
    CHEN Yingbiao, QIAN Qinglan, CHEN Jianfei
    2008, 10(5): 629-637.
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    Embedded GIS software is the latest GIS development technology,and also is the main technical direction of GIS application.Recently GIS technology has been widely used by users at home and abroad.The paper makes demo program with eSuperMap GIS+ Embedded Visual C++ and realized the design of embedded-GIS data collection and navigation system.The paper firstly analysed key technology of embedded-GIS data collection and navigation system,and thinks that mobile computation,embedded technology,mobile wireless techniques and mobile access technology are the core technologies.In the system design the paper mainly analysed the EVC and eSuperMap GIS technology architecture and description vector data layer and organized method,spatial data display scale technology,data model and SIT image compressed technology.And based on the detail description the paper discussed the main development interface of EVC,and attribute and method setting by combining the eSuperMap GIS+Embedded Visual C++ technology design with the original system,and realized some functions like map display and browse,map data management and map measurement,attribution management and query,object editor and mobile object compution,best route analysis and GPS data collection and terminal operation etc.In the embedded-GIS data collection and navigation system,the author thinks that mobile computation,embedded technology,mobile wireless techniques and mobile access technology are the key technologies.In the system design the author thinks that vector data layer display technology and organized layer and scale display method,spatial data display scale technology,data model and SIT image compression are the key technologies.By combining eSuperMap GIS+Embedded Visual C++ technology the paper presented the efficiency solution method.By using the demo practice we think that practicality,conveniency and pertinency tool software is very important and can make development easily and operation effectively.The software has important practical meaning and theoretical reference merit for many application fields.
  • ARTICLES
    Simplified Computation of Atmosphere Downward Radiance and Impact of Surface Reflectance Characteristic on Atmospheric Downward Radiance Effect
    ZHU Li, GU Xingfa, WANG Qiao, CHEN Liangfu, YU Tao
    2008, 10(5): 638-644.
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    Atmospheric downward radiance effect should be considered in the retrieving surface temperature and validation of thermal infrared bands data.In the field of thermal infrared remote sensing the computation of the effect is often simplified under two assumptions: one is the Lambertian reflection of the surface;another is the isotropic downward thermal radiance of atmosphere.The simplified computation method of atmosphere downward radiance has been researched,and the effect of Lambertian reflection assumption on the atmosphere downward radiance effect and at-pupil radiance of remote sensing sensors has been analyzed in the theory.Then atmosphere profiles and land surface temperature of a year were input to MODTRAN4 to calculate the atmospheric downward radiance effect and analyze the utmost error caused by two assumptions in erlianhaote region of Inner Mongolia of China.The result showed:(1) the error was up to 4 degree if the atmospheric downward radiance effect was ignored for such an inner land region as erlianhaote and the proportion of the effect would increase with the increase of satellite view angle.(2)The assumption of the isotropic downward thermal radiance of atmosphere was not appropriate and we can choose the downward radiance in an optimal angle to be equal to the average of hemispheroidal downward radiance.And the optimal angle was 57° for erlianhaote.(3)The assumption of Lambertian reflection of the surface was appropriate for calculating downward radiance effect.
  • ARTICLES
    Spatial-Temporal Patterns of Grassland Gradation in Southern part of the Headwaters of the Three Rivers,Qinghai in China
    ZHANG Xiaoyong, SHAO Jingan, HUANG Lin
    2008, 10(5): 645-650.
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    Grassland is a main land type in the study area,the status and trends of its degradation become a major issue of the ecological construction in China,and have been raised to the level of the needs for national ecological economic strategy.Many studies showed that grassland ecosystem degradation is,in the succession process of the climate-land cover-human activities,an indication of out of balance.Grassland degradation will lead to a series of environmental problems such as lower grassland production,land desertification,loss of biodiversity,soil degradation,loss of carbon sinks.Study areas located in the south of the head of Yangtze river.The total area is about 34 069.31km2,mainly covered by grassland(71.49%) and swamp(10.11%).The low and moderate covered grassland is 71.16% of the total grassland area.The increasing destruction of the land in this area have been kept increasing the risk of environmental degradation.Based on the TM/ETM in 1977,1990 and 2004,geographical map(1∶100 000),grassland map(1∶1000 000),and field data,the authors extract grassland degradation distribution characteristics.The Arcgis 9.1 software was used to convert data types and do the overlay.reclassification,and zonal statistic analysis.Results show that grassland degradation is the most important land cover change in the study area,which occupied 11.84% of the whole region in the former phase and 21.54% in the later phase.The areas of degraded grassland are more in the later phase than in the former phase.Grassland in the former phase became better in some regions because of the climate and glacier ablation.The degraded grassland mainly occurs in the low altitude with relatively higher population density.
  • ARTICLES
    Measuring Mining Induced Subsidence by Using InSAR Technique——Taking Wuan Mining Area in Hebei as An Example
    ZHANG Jingfa, GUO Qinshi, GONG Lixia
    2008, 10(5): 651-657.
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    The InSAR technique has become one of the important tools to measure small surface deformation.In Wuan region of Hebei province,surface deformation occurs to different degrees due to mining activity,causing more geologic disasters.It is necessary to determine the scope and extent of surface subsidence and analyze the changing trend for working out actual resolved plan.In this paper,many pairs SAR data,Jers-1 and ENVISAT SAR data from 1992,were used in InSAR processing.The best SAR pairs were selected and feasible technique plan was determined and the different D-InSAR images were obtained according to the time and baseline of SAR pairs.Finally,the scope and extent information at different periods were acquired.Besides,taking Huilan village as a example shows the mineral area subsidence evolvement procedure.The process flow and key step of InSAR technique are summarized by the application of Wuan subsidence measurement.In the end,the result of InSAR application is evaluated.
  • ARTICLES
    Design of Metadata System for Exchange and Sharing of Remote Sensing Information and Knowledge
    ZHANG Huifang, SHI Runhe, LI Lin, HU Yong
    2008, 10(5): 658-662.
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    With the rapid development of remote sensing technology,remotely sensed data are playing more and more significant role in many fields,such as urban planning,geoscience,digital earth etc.However,facing the expansion of data amount and enlargement of application fields,many scientists began to research on spatial metadata so as to manage,store,update and reuse the obtained data efficiently.Therefore,it is necessary to design a metadata system for the description of remotely sensed data and related resources including ground measurements,application models,and related knowledge about sensors and platforms,which can meet the needs of users to understand and use the data correctly and conveniently.In this paper,we designed a metadata system for exchange and sharing of remote sensing information and knowledge based on related international and domestic metadata standards.The system integrates the remotely sensed data,ground measurements,application models,and related knowledge about sensors and platforms into a unified and standard form which promotes the exchange and sharing of remotely sensed information and knowledge at metadata level.
  • ARTICLES
    Study on Terrestrial Water Information Identified Based on the Analysis of Spectral Signature and Ratio Index
    ZHONG Chunqi, ZENG Congsheng, LIU Zhengzheng
    2008, 10(5): 663-669.
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    With the fast development of aviation and space technology,remote sensing technology became irreplaceable and advanced means in the fields of global changing and population-resources-environment.Utilizing the satellites data,it is possible to draw water information and macroscopic monitored water resource,assess the range of flood,monitor dynamic change of wetland resource and monitor the changes of coastline,which got extensive studies and applications during the last decades.The macroscopic studies of water are closely related to the accurately drawn range and boundary line of water information,which are especially important in the research of monitoring coastline change and flood.The study of the extraction of water information from satellite data has been further investigated by many scholars in the past.The most common methods are spectrum classifier(maximum likelihood classifier is most extensive),normalized difference water index(NDWI),ratio classifier and so on.However,how to overcome the interference of the shade has always been a difficult problem in the terrestrial water body information extraction.Such as maximum likelihood classifier,which was a traditional statistics categorised method,took all massif shade as lake information.Through experiment,Professor Xu found that the result,using NDWI index to extract water information,contained a lot of city building information,so he believed that the NDWI index was not suitable for extracting water information in the range of the constructed urban areas.The paper analyzed the spectrum characteristic of the water body and several other main surface features based on Yang Cunjian's viewpoint of water having characteristics of TM2 +TM3>TM4+TM5 in TM imagery.It found that water body,residential area and the shadow of mountains all have the characteristic of TM2+TM3>TM4+TM5,but the ratio of(TM2 +TM3)/(TM4+TM5) differs greatly between them,so it was easy to separate water body from all other surface complement only by assisting suitable threshold value(for example,the suitable threshold value of water body is(TM2+TM3)/(TM4+TM5)>2.0).And the experiment on TM imagery of Fuzhou city which including different types of water bodies was carried out and the result indicated that it can effectively distinguish water information from residents's shade or Massif shade.This method emphasized the spectrum difference law among all parts of the background features,it simplified the analytic process among the complicated tables and had reduced analytic difficulty among the tables,so it was a fast,simple and accurate water information extraction technology.It can be used to extract water information from landsate TM not only in the region containing Massif shade but also in the urban built-up land.
  • ARTICLES
    Method of Fused Image Based on IHS and Wavelet Transform and Realization in MATLAB
    LIU Lijuan, FAN Wenyi
    2008, 10(5): 670-677.
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    In order to improve eye-interpretation effect of multi-spectral images of Landsat series,an integrated technique based on IHS and wavelet transformation is proposed in this paper.For increasing relativity and decreasing spectral deviation,firstly,under the developing environment of Matlab,the intensity component of multi-spectral image and the panchromatic image histogram match each other,and then decompose respectively using wavelet,finally fuse images by special rules.Among the rules,the most important thing is the choice of wavelet bases,wavelet decomposed layers and wavelet coefficients.In order to choose the best parameters,the author carries out repeated experiments using assessment parameters: mean value,standard deviation,average gradient,correlation coefficient and spectral distortion.Compared with other parameters,wavelet base of coif5 made better fusing result in this paper.Therefore,parameters are fixed on coif5 and decomposed of three layers,and reconstructed coefficients based on regional standard difference.The experiment indicates that the proposed method is much better than single transform of IHS or wavelet.Observed from the fused image,the lines and details of road,river,farm and forest are improved obviously.At the same time,the higher correlation coefficient and the lower spectral distortion show that spectral information is kept down well.The experiment through fused ETM+ multi-spectral and panchromatic images verified the method of the author proposed is feasible,the result is not only improved obviously in spatial resolution,but also preserves multi-spectral information effectively.
  • ARTICLES
    Image Quality Evaluation of EO-1 Hyperion Sensor
    ZHOU Yuji, TIAN Qingjiu
    2008, 10(5): 678-683.
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    This paper conducts the quality evaluation of a Hyperion L1R image of Yangzhou area by the objective image evaluation methods.The main indexes chosen for observation are radiation precision,the amount of information,sharpness,signal to noise ratio(SNR) and so on.It turns out that there are 44 zero bands and 25 water vapor affected bands among the 242 bands of the Hyperion data.The indicators of the remaining 173 bands are relatively moderate,except for those located near the water vapor affected bands,whose SNR are relatively lower.For this reason,it is considered that the environment and atmosphere conditions while acquiring images would affect the exact number of the available bands.As the conclusion,the image quality of the VNIR bands is obviously higher than that of the SWIR bands,and the image quality descends as the wavelength increases generally.The VNIR and SWIR bands before Band 120 possess the optimal image quality while bands after the 130th are of less sense for applications.Real spectral information could be extracted from these bands.After removing the striping noise and the smile effect,Hyperion image data could be used in the fields of agriculture,forestry,geological investigation,petroleum finding,ocean water color research and so on.