EN中文

Archive

  • 2012 Volume 14 Issue 2
    Published: 25 April 2012
      
    ARTICLES
  • Select all
    |
    ARTICLES
  • ARTICLES
    Problems and Countermeasures of Standardization of Geographic Information Industry in China
    ZHANG Qiuyi, WANG Chunqing, GUO Jiankun
    2012, 14(2): 143-148. https://doi.org/10.3724/SP.J.1047.2012.00143
    Download PDF ( )   Knowledge map   Save
    Geographic information standardization is confronted with the new and higher challenges of the rapid development of geographic information industry in China. In this paper we reviewed the progress in geographic information standardization in China during the period of "11th Five-Year Plan", and elaborated the importance of standardization for geographic information industry. Based on the statistics of national geographic information standards and the working items, we analyzed the composition and the change of the national geographic information standards and the standard-makers. The result showed that the standards for geographic information application and services were deficient and the standards makers were mainly the government-related organizations. Then the typical standardization problems for geographic information industry were discussed. The conclusion was that the improper working mechanism of standardization is the root of all sorts of standardization problems for geographic information industry. The recommended standardization working mechanism was designed for geographic information industry and the countermeasures were put forward.
  • ARTICLES
    A Novel Method for Dynamic Modelling and Real-time Rendering Based on GPU
    YAN Changqing , YUE Tianxiang
    2012, 14(2): 149-157. https://doi.org/10.3724/SP.J.1047.2012.00149
    Download PDF ( )   Knowledge map   Save
    High accuracy surface modeling (HASM) is a method for building surface with high accuracy in terms of sampled points, which is based on the fundamental theorem of surfaces and gives a solution to error problem in geographic information system (GIS). Previous studies show this method can model surface with much higher accuracy than other classical methods widely used in GIS, while its speed is limited because of its huge computational cost. In order to accelerate its computational speed, a novel parallel and interactive method of HASM for real-time rendering on GPU using compute unified development architecture (CUDA) is presented, which allows for efficient and high quality visualization. The computational task of HASM is parallelized and run simultaneously on many cores of modern GPUs which have multiprocessors and many stream processors, which can improve the performance significantly. Coupled with an efficient rendering method, dynamic surface simulation and real-time rendering is done concurrently on GPU. Preconditioned conjugate gradients methods are used to solve the huge linear systems arising from HASM. Fully harnessing the processing power of modern GPUs with a highly parallel architecture and multiprocessors and many stream processors, we can simulate the surface dynamically and post it to rendering pipeline simultaneously. Making use of state-of-the-art GPU techniques such as vertex buffer object, texture buffer, the rendering can be carried out with a very high efficiency. A few experiments were carried out including some digital elevation model constructions and the tests results showed that our method can construct surface dynamically and visualize it at very high frame rates.
  • ARTICLES
    The Application of Modified Three-Tuple Sparse Matrix Technology in HASM: A Case Study in the Simulation of Global Temperature
    ZHANG Hao, YUE Tianxiang, LI Changhua, DU Zhengping, FAN Zemeng, SUN Xiaofang, ZHAO Na
    2012, 14(2): 158-164. https://doi.org/10.3724/SP.J.1047.2012.00158
    Download PDF ( )   Knowledge map   Save
    In terms of the fundamental theorem of surfaces, High Accuracy Surface Modeling (HASM) method, which is based on the differential geometry theory, transforms the surface modeling to a linear system by using the principle of least square method and describes the properties of the surface. Comparing with the classical surface methods in GIS application, such as inverse distance weight (IDW), triangulated irregular network (TIN), KRIGING and SPLINE, HASM has a much higher accuracy and the error problem of the surface modeling is solved in theory by HASM. However, the computational cost of HASM is high. The cost of HASM algorithm is expensive when it applies preconditioned conjugate gradient method (PCG). Using compressed storage formats can effectively save memory. Among these formats, the three-tuple storage format of the sparse matrix is widely used in the past. In this paper, based on the characteristic of HASM-PCG, we modify a large part of the sparse matrix-vector multiplication by using three-tuple technology. The computational efficiency is enhanced though adjusting the calculation order of HASM-PCG and abandoning some nonzero elements that are not need to store. Long term (1998-2008) averaged monthly data were obtained from site measuring temperature (3000 sites). Combining with the digital elevation model of the globe, the data are used to simulate the global mean temperature in May, June, July, and August of the eleven years from 1998 to 2008. Numerical results show that with this three-tuple technique, the computing efficiency of HASM is great improved.
  • ARTICLES
    Geometrical Characteristics Extraction and Accuracy Analysis of Road Network Based on Vehicle Trajectory Data
    JIANG Yijuan, LI Xiang, LI Xiaojie, SUN Jing
    2012, 14(2): 165-170. https://doi.org/10.3724/SP.J.1047.2012.00165
    Download PDF ( )   Knowledge map   Save
    Electronic map data is of enormous importance for analyses of travel, urban congestion, etc. It is growing an important basic data of transportation research and widely employed in vehicle navigation system and intelligent transportation system. Of electronic map data, road network data is a fundamental part and often updated. As a result of a lot of expense of manpower and resources of traditional method, more and more research efforts have been made on extracting geometrical characteristics of road network from other data resources like LIDAR data. The wide use of mobile positioning devices makes it possible to obtain a large volume of vehicle trajectory data within a short period. These data are complete records of vehicles' movement and able to reflect geometrical characteristics of road network as well. By this means, vehicle trajectory data can be employed to figure out changes happening to the spatial extent of road networks as long as enough data are available, and then we can update the road network database. Since trajectory data integrate both spatial and temporal information and their volume is often huge, it is not straightforward to realize the aforementioned target. In view of this, the paper proposes a thinning-algorithm-based method to construct road network. Vehicle trajectory data are vector data, are first converted to raster data, then thinning method can be used to extract geometrical characteristics of road network. With this method, center lines of road networks can be extracted, network topology be maintained, and meanwhile redundant information be removed. A case study in Lujiazui, Shanghai with taxi trajectory data is conducted and the results are evaluated.
  • ARTICLES
    Extraction of Digital Drainage Network with "Stream Burning" and "Surface Reconditioning" Methods in the Bohai Sea Bay Region
    HUANG Ling , HUANG Jinliang
    2012, 14(2): 171-178. https://doi.org/10.3724/SP.J.1047.2012.00171
    Download PDF ( )   Knowledge map   Save
    When extracting digital stream network based on digital elevation models (DEMs), wrong information such as parallel river channels is often generated due to the topographic effects like plains and sinks. In view of this, two algorithms including "Stream burning" and "Surface reconditioning"(Agree algorithm ) using Arc Hydro tools in ArcGIS environment were employed in this study based on Shuttle Radar Topography Mission (SRTM) DEMs, released by NASA and NIMA, to extract digital drainage networks in the Bohai Sea Region. Actual three-level stream network data in China in both vector and raster formats were available from National Geometrics Center of China (NGCC) and then were used to compare with the stream network extracted based on SRTM DEMs. The results showed that the known stream network information is helpful to extract the stream network. Without aid of the known stream network, there were only two streams consistent with the known stream network based on traditional method and the extraction precision was at low level. Comparatively, using "Agree algorithm", several digital streams tallied with typical known stream network, indicating that "Agree algorithm" can produce more precise results than by traditional method. To improve the extraction precision of digital stream network, "Stream burning" was further employed. This algorithm generated more detail of digital stream network and less parallel river channels. The overall results illustrated that "Agree algorithm" and "Stream burning" were more sophisticated than traditional method in terms of digital stream network extraction. It should be noted that the results of extraction of digital stream network in this study were not perfect due to the extensive existence of plains in the study region. Therefore, the characteristics of two algorithms, namely "Agree algorithm" and "Stream burning" were synthesized into a new method to extract the drainage network. Luanhe River Basin was finally chosen to validate the result derived from such a new method.
  • ARTICLES
    On Interactive Digital Terrain Editing for Landscape Planning & Design and Its Implementation
    LI Jieguang, TANG Liyu, CHEN Chongcheng, ZOU Jie, LIN Ding
    2012, 14(2): 179-186. https://doi.org/10.3724/SP.J.1047.2012.00179
    Download PDF ( )   Knowledge map   Save
    Digital terrain editing is one of important research contents in virtual geographical environment and 3D landscape simulation system, which has significant value in digital design practices of city and country, road network, landscape planning, etc. In this article we took the digital terrain based on regular grid as research objectives, oriented to practical application of the city and landscape planning & design, and proposed an interactive digital terrain editing scheme. OpenSceneGraph uses the directed acyclic graph for managing the scene graph, level of detail (LOD) and pagination technique for real-time rendering. Specific processes and related major implementation technology of the terrain interactive editing based on pagination technology was described. Firstly, the target region was selected through the mouse interactive operation combined with ray intersection algorithms. Secondly, the grid data under the region was gotten in the basis of polygon angle sum algorithm. Lastly, the grid elevation of region was assigned a new elevation value by dragging of mouse in the vertical direction. Under the edited region, by the grid method that is used to calculate earthwork volume, it is calculated that the volume of the fills and the excavations. In addition, the trees models were loaded by modeling software of ParaTree, which is researched and developed by our group, and the three-dimensional architectural models were built by the 3DMAX. All the models were loaded into the virtual forest visualization system (VisForest). The virtual town/village landscape in the flattened region was constructed according to user's design idea. The editing function was preliminarily realized, which showed the results of application in urban residential landscape design. This study showed that the digital terrain editing based on regular grid and pagination technology has advantages of simple algorithm, small amount of calculation and easy to realize. What is more, mouse interactive operation can show the editing result in a real-time and intuitional way, and achieve the effect of "what you see is what you get".
  • ARTICLES
    Research on the Distributed Real-time Collaborative Plotting System Based on Grid
    ZHANG Jianbing, REN Yingchao, XU Yunbo, ZHAO Yanqing
    2012, 14(2): 187-191. https://doi.org/10.3724/SP.J.1047.2012.00187
    Download PDF ( )   Knowledge map   Save
    With the rapid development of computer network technologies and distributed computing technologies, common collaboration and cooperation based on geospatial information for team users are increasingly popular. Since the traditional plotting system is single-user mode that is not able to meet the requirement of collaborative plotting of group users in modern society in a distributed environment, in this paper we focused on establishing a distributed real-time collaborative plotting system with grid technology, and the structure of the system based on grid was designed. The system structure is introduced and the key technologies such as collaborative management, collaborative information and grid dispatcher were also presented. The prototype of the distributed real-time collaborative plotting system was implemented based on the combination of gird and GIS technologies, and common collaboration and cooperation based on geospatial information for team users was achieved. The network symbol library and WebGIS software are used in the system. The research showed that the distributed real-time collaborative plotting system we built with gird technology can satisfy the requirement of collaboration on the condition of Wide Area Network, and the experiment of collaborative plotting of users showed that the distributed real-time collaborative plotting system achieved fast response and high stability.
  • ARTICLES
    Design and Implementation of Rich WebGIS Application Framework Based on SilverLight and REST Services
    LU Yagang, QIU Zhi, YOU Xianxiang, ZHANG Hongmei, CHEN Li
    2012, 14(2): 192-198. https://doi.org/10.3724/SP.J.1047.2012.00192
    Download PDF ( )   Knowledge map   Save
    The architecture and implementation technique of WebGIS are always the focus of scholars in its rapid developing process. Aiming at disadvantages of high complexity,poor interactive experience,and low response efficiency in "traditional" WebGIS application,this paper proposes a rich WebGIS application framework based on RIA/SilverLight and REST technologies which was divided into data access layer(DAL),business logic layer(BLL) and user interface layer(UI). Silverlight is an application framework for creating and delivering rich internet applications (RIA) and media experiences on the Web,which combining with the representational state transfer (REST) software architecture style can significantly remedy these shortages of "traditional" WebGIS application mentioned above. Firstly,in this paper the detailed description on designing and building steps of spatial databases were given,and the optimization experiences on spatial database were shared. Then the composition of business logic layer and its operating mechanism had been analyzed. To improve the efficiency of the user interface layer,the Model-View-ViewModel (MVVM) architectural pattern had been adopted. And to follow the user's habit,the office ribbon style had been used visually. The code-behind was programmed with.NET C#,and according to different function types,it was designed into event center component,configuration management component,UI interactive component,map container component,control management component,auxiliary function component,and the event center component is the communication hub. Finally,based on this framework,a rich WebGIS application which named LightGIS had been developed. It showed that the applied framework can effectively improve the efficiency,enrich user’s experience and enhance the system capability.
  • ARTICLES
    Design and Implementation of the Landslide Hazards Weather Forecast Information Sharing Platform Based on ArcGIS Server
    GUO Chengyan, JIA Jianhua, MA Ronghua, XU Jinduo, XING Yongchao, LV Chunguang
    2012, 14(2): 199-208. https://doi.org/10.3724/SP.J.1047.2012.00199
    Download PDF ( )   Knowledge map   Save
    Landslide is the most common form of geological disasters. Its main incentive is rainfall, so landslide often occurs in areas with abundant rainfall or occurs in flood season. Due to natural environmental and geological characteristics of Nanjing City, landslide is a major geological disaster there. In order to forecast landslide hazards effectively and minimize the loss caused by the unexpected landslide hazards, this paper established the landslide hazards weather forecast information sharing platform. On the basis of the existing data of geological hazards-prone areas, we use historic landslide data of Nanjing, meteorological data (rainfall) and the model of geological hazard forecast to establish the method of landslide hazards weather forecast and determine the landslide hazards weather forecast technique in Nanjing City. Then a forecasting information sharing platform is developed. Based on the method and the technology process of landslide hazards forecast, this platform uses C# as the development language and applies the following techniques: the database technology, the ArcGIS Server technology, the.NET technology, the remote call technology, the partial refresh technology of AJAX and the map cache technology. It also merges the geographic information system functions and landslide hazards forecast business functions together. This platform can achieve a dynamic and scientific management of the basic data of landslide hazards and the real-time meteorological data. It also can combine the real-time rainfall data to achieve the prediction of landslide hazard in Nanjing, and then it publishes the landslide hazards information on line in real time. At the same time, it provides the functions of landslide hazards information retrieval and statistical analysis and so on. Ultimately we hope this platform can provide a decision support for the landslide hazards prevention and mitigation and references for other cities which need to build a landslide hazards prediction platform.
  • ARTICLES
    A Tax Administration WebGIS System Based on Service-Oriented Architecture
    HUANG Fenghua , YAN Luming
    2012, 14(2): 209-216. https://doi.org/10.3724/SP.J.1047.2012.00209
    Download PDF ( )   Knowledge map   Save
    In order to reflect the spatial distribution rules and trends of the taxation status in different regions intuitively, iconically and dynamically, improve the capability of data sharing and interoperability of the heterogeneous tax administration GIS systems, a tax administration WebGIS system based on Service Oriented Architecture (SOA) is constructed by the integration of the GIS enterprise-level middleware and GIS Web services (GIServices) on account of the specifications of Open Geospatial Consortium (OGC). STAXGIS is based on the consistent business model and information model. The GIS enterprise-level middleware can provide spatial data conversion, taxation business processing, taxation spatial analysis and other advanced service functions, meanwhile the GISservices can provide information services (such as query and location of tax sources, tax thematic analysis, taxation queries and declaring and so on). The four-layer framework of J2EE which contains the data layer, application service layer, Web service layer and client layer is used for the hierarchical management and deployment of the STAXGIS. Compared with the traditional tax administration GIS systems, the administration efficiency and scalability of the STAXGIS is greatly improved. The research which takes Fuzhou City in Fujian Province as an example has shown that STAXGIS could strengthen the capabilities of information sharing and interoperability of the decentralized heterogeneous tax administration GIS platform in the distributed environment currently, and improve the overall efficiency of spatial analysis for tax administration in heterogeneous environment. It can also provide the tax administration departments at different levels with decision support directly or indirectly.
  • ARTICLES
    The Global Oil and Gas Geology Database Information Sharing System Based on ArcGIS Server
    SU Guohui , SHEN Yanping, SUN Jihong , HE Shufeng , WEI Helong
    2012, 14(2): 217-222. https://doi.org/10.3724/SP.J.1047.2012.00217
    Download PDF ( )   Knowledge map   Save
    It is an important research subject to build hydrocarbon resources information database and provide decision support service by information technology. Strategic Research Center of Oil and Gas Resources organizes a global hydrocarbon geology research project, collects the global latest hydrocarbon resources information, and establishes global hydrocarbon geology database, which has the following characters: wide scope, perfect content and strong timeliness. In order to provide the database information service, the Global Hydrocarbon Geology Database Information Sharing System is established based on ArcGIS Server, Visual studio.NET development platform and the Oracle database management system. It fills in the domestic gap of hydrocarbon geology information management and sharing system, provides a way to reach sharing and interoperability. The information sharing system is a WebGIS application platform, providing information release, map browsing, graphics search, spatial analysis, thematic mapping and other functions. By the graphics, text and charts, it presents the latest research results of basic geography, basic geology, hydrocarbon geology, potential resources, investment environment, etc. It provides efficient information access for the public and researchers, provides reliable information support for national oil and gas resources management and energy policy, realizes information sharing and service. In this article we briefly introduced ArcGIS Server and why we chose ArcGIS Server, mainly specified the system framework, including logical framework and physical framework, data entity classification, system environment and function modules, such as information retrieval module, navigation module, metadata service module, spatial data service module, data download module and system management module, for the purpose of discussing the design and realization of information sharing system based on ArcGIS Server.
  • ARTICLES
    Construction of the GeoData Service-oriented Mineral Resources Planning Information Service System
    YUAN Lei, ZHAO Junsan , ZHANG Wanqiang, ZU Qi
    2012, 14(2): 223-231. https://doi.org/10.3724/SP.J.1047.2012.00223
    Download PDF ( )   Knowledge map   Save
    Up to now, China has implemented two rounds of national mineral resources planning and accumulated a large number of mineral resources planning data. However, current situation of informatization construction of mineral resources planning is backward relatively. There are still some problems, especially how to research and implement a set of efficient information service system which conforms to the development requirements of mineral resource planning information construction, and making all kinds of users acquire information or services of mineral resources planning by a network on-demand is a problem that deserves thorough research. Through the study on current situation of informatization construction of mineral resources planning, and on the basis of analysis of the GeoData Service's technical features and advantages, this paper proposes to build the Mineral Resources Planning Information Service System (MRPISS) which adopts three-tier B/S model with the service-oriented concept in order to solve those problems above. Firstly, the paper focuses on the detailed design of the system's logical structure, spatial database and functions. Secondly, it describes the key points in the system building, the processing method and the method's technical advantages of the GeoData Service, which the results of the mineral resource planning data is packaged into. Besides, the practical running effect of the system which is developed with the technology of ArcGIS Server.NET ADF under the Dotnet framework is demonstrated. Finally, the paper analyzes how to implement some key technologies in the system, such as the asynchronous callback technology of Web ADF, the dynamic navigation of Web based on JavaScript, the data access technologies of ADO.NET, the optimization of the system performance and so on. The running results of the Mineral Resources Planning Information Service System built in this paper shows that it brings a change which from Web GISystem to Web GIServices on the approach of the system architecture in the fields of informatization construction of mineral resources planning, and provides a new application model for synchronous update, remote extraction, sharing and management of the mineral resources planning data under a distributed network.
  • ARTICLES
    Review of Drought Monitoring by Remote Sensing
    LIU Huan , LIU Ronggao, LIU Shiyang
    2012, 14(2): 232-239. https://doi.org/10.3724/SP.J.1047.2012.00232
    Download PDF ( )   Knowledge map   Save
    Drought is one of the most extensive natural disasters in the world which could cause serious economic losses. It is important to monitor large area drought events. Remote sensing technology has a great advantage in large-area monitoring of drought. In this paper, methods for drought monitoring by remote sensing are reviewed, including their advantages and disadvantages and their applications. These methods includes thermal inertia and microwave methods for bare surface, Normalized Difference Vegetation Index, Anomaly Vegetation Index, Vegetation Condition Index, Normalized Difference Water Index, Normalized Difference Drought Index and Vegetation Supplication Water Index based on visible, near infrared, shortwave reflectance data for partly and fully covered surface. Temperature Vegetation Dryness Index, Temperature Condition Index, Crop Water Stress Index, and Water Deficit Index based on thermal infrared remote sensing data for partly and fully covered surface are introduced too. Finally, the trend of remote sensing for drought monitoring is discussed.
  • ARTICLES
    A Comparative Analysis of the MODIS Land Cover Data Sets and Globcover Land Cover Data Sets in Heilongjiang Basin
    NING Jia , ZHANG Shuwen, CAI Hongyan, BU Kun
    2012, 14(2): 240-249. https://doi.org/10.3724/SP.J.1047.2012.00240
    Download PDF ( )   Knowledge map   Save
    As global change is becoming serious, the global land cover data sets which the global change research needs have become more and more important. The current global land cover data products mainly include five products which are produced by European and U.S. The global land cover data sets produced by Boston University (i.e. MODIS data sets) and by European Space Agency with global cooperation (i.e. Globcover data sets), which are somehow better and more effective than the others, are used more and more widely. Because of the difference of data sources, classification systems and classification methods, there are significant differences between two land cover data sets both in quantity and spatial distribution. In this study, as a products' user, we compared the MODIS and Globcover data sets in Heilongjiang Basin on the quantity and spatial distribution, using LANDSAT TM / ETM + images and field photos to verify the accuracy of the classification of two data sets. The results show that, in Heilongjiang Basin, there are great differences in the quantity and spatial distribution between the two data sets. As to the quantity, the main land cover types (forest and cropland, followed by grassland) in both data sets are similar. When it comes to the spatial distribution, they are of great difference. The two data sets are both of low precision, with a precision of only 60%. The Globcover data sets is more clustering than MODIS data sets, and the overall accuracy is slightly lower than MODIS data sets, while the accuracy of different land cover types is different. Taking into account the representation of Heilongjiang Basin, we believe that Globcover data sets and MODIS data sets are able to meet lower demand for land cover information. This study provides a basis for global change research in selecting the appropriate data sets.
  • ARTICLES
    Atmospheric Carbon Dioxide Satellite Remote Sensing Retrieval Accuracy Inspection and Spatio-temporal Characteristics Analysis
    HE Qian, YU Tao, CHENG Tianhai, GU Xingfa, XIE Donghai, WU Yu
    2012, 14(2): 250-257. https://doi.org/10.3724/SP.J.1047.2012.00250
    Download PDF ( )   Knowledge map   Save
    Atmospheric concentration of carbon dioxide (CO2), which is one of the most important anthropogenic greenhouse gases, has increased significantly since the beginning of the industrial revolution. It is expected that further increase of CO2 will definitely result in a warmer climate with adverse consequences including rising sea levels and increasing extreme weather conditions. A reliable prediction requires an accurate understanding of the sources and sinks of the greenhouse gases. Compared to traditional methods based on ground-based observations, an approach that uses satellite remote sensing to detect atmospheric CO2 concentration has many other advantages such as stability, continuity, large-scale, as well as easily getting global spatial and temporal distribution of CO2. As the technology of satellite remote sensing is growing rapidly, a series of satellites, launched for detecting atmospheric CO2 concentration, including SCIAMACHY, GOSAT and AIRS, have been collecting a large amount of global CO2 concentration distribution data for many years. This paper gives analyses by comparing those satellite data among themselves in some parameter indexes and conducts validation by comparing those remote sensing data to the long-term global ground-based observation records. The results indicate that, among those three CO2 satellite remote sensing products, the SCIAMACHY data is systemically slightly higher than ground-based observations and limited in coverage, the GOSAT data is predominant in stability but inferior in systematic errors which is nearly 9ppmv on average lower than ground-based data, and the AIRS data, which is better than the aforementioned two satellites in both coverage and accuracy, whose monthly global coverage is up to 90%, the average error is less than 2ppmv(0.5%) from the ground-based observations and the correlation coefficient is greater than 0.9, can be able to better reflect the global distributions of atmospheric CO2 concentration. An investigation from satellite and ground-based observations shows that the global spatial distribution of CO2 concentration represent significant latitude distribution and land-sea distribution, and there is a significant seasonal variation in CO2 concentration that illustrates a peak most likely in April and a valley in August.
  • ARTICLES
    Effects on Application of Spectroscopy in Estimating of Soil Organic Matter Content
    HU Wensheng, REN Hongyan , ZHUANG Dafang, SHI Xuezheng, LIU Shaogui, HUANG Yaohuan, YU Xinfang
    2012, 14(2): 258-264. https://doi.org/10.3724/SP.J.1047.2012.00258
    Download PDF ( )   Knowledge map   Save
    Reflectance spectra of soil responds to the differences of soil particle sizes, which affects directly the capability of predicting soil organic matter (SOM) content by spectral reflectance. With soil samples of different particle sizes at 2mm, 0.25mm and 0.15mm, reflectance spectra was collected under the condition of simulated sunshine in the laboratory and SOM contents were acquired. Multiple scattering correction (Msc), first derivative (Fd) and continuum removal (Cr) were used as data pretreatment methods to raise the Signal-to-Noise of raw spectra (Raw) before analyzing the correlation between spectral reflectance and SOM contents. Single waveband at 2250nm is selected from Fd-treated reflectance spectra because of its maximal linear correlation coefficient (r=0.82, P<0.01) responding to SOM contents, and then a linear regression is built with a moderate precision (R2=0.69). Furthermore, partial least square (PLS) was adopted to extract several principal components (PC) of full wavelength from 350 to 2500nm and to build prediction models. Only PLSR model of Msc-treated reflectance spectra of soil samples at 2mm particle size yielded better prediction for SOM content (RPD=3.56, R2=0.90, RMSEP=1.96g/kg). It indicates that particle size of soil sample poses obvious effects on soil reflectance spectra. There is a conceivable turning point of particle size because the correlation between particle size and reflectance is not simple linear relation. Capability of predicting SOM content by univariate linear regression model is markedly lower than that of PLSR model. In addition, prediction precision is significantly affected by capacity of soil samples. Hence, satisfying prediction precision of SOM content can be acquired by effective combination of moderate particle size (2mm) and proper spectral pretreatment (Msc).
  • ARTICLES
    Multiple Index Information Extraction of Marine Oil Spills
    ZOU Yarong, ZOU Bin, LIANG Chao, CUI Songxue, ZENG Tao
    2012, 14(2): 265-269. https://doi.org/10.3724/SP.J.1047.2012.00265
    Download PDF ( )   Knowledge map   Save
    The oil spills bring great damage to the marine ecological environment even taking decades to repair. Using remote sensing technologies for marine oil spill detection has become a major direction. In this paper, through analyzing the marine oil spill remote sensing detection methods, a new one based on the multivariate index of oil spill information extraction with the SAR data is proposed. First, segmenting the images, and then establishing the shape parameters, the texture feature indexes, and the physical indexes of the spots, the indexes weights were given based on the hierarchical analysis method. For each category index, on the image processing with the on-site validation information, select shape parameters, e.g. the perimeter-to-area ratio, complexity, to establish oil spill shape interpretive level. Choose the texture characteristics parameters from the gray level co-occurrence matrix, e.g. relevance, entropy and change, to establish the oil spill texture feature judgment level. Choose the physical characteristics, e.g. the standard deviation, RMS and contrast, to establish the oil spill physical parameters judgment level. Finally, by calculating the remote sensing information extraction index of the segmentations image dark spots, we can evaluate the credibility of the oil spill remote sensing information extraction, even get a significant basis for the oil spill identification. From the paper, oil spill in the SAR image performance mechanism, the image characteristics and the shape aspects can comprehensively reflect oil spill remote sensing detection characteristics, and the three combination confidence in the remote sensing monitoring has certain practical value.
  • ARTICLES
    Analysis on Spatio-temporal Change and Driving Forces of Land Use in Tianjin Harbor
    LIU Baoxiao, HUANG Yaohuan, FU Jingying, JIANG Dong
    2012, 14(2): 270-278. https://doi.org/10.3724/SP.J.1047.2012.00270
    Download PDF ( )   Knowledge map   Save
    In this paper, land use data of Tianjin harbor of four periods from 1987 to 2010 was obtained based on Landsat multispectral TM images. With the introduction of dynamic index of each land use type, dynamic index of land use change, conversion matrix and spatial pattern center of land use type, land use conversion in Tianjin harbor was analyzed quantitatively from the aspects of direction, extent, spatio-temporal differences and expansion pattern by support of GIS software. The results indicated that: from 1987 to 1995, Tianjin harbor was in the exploration stage after reform and opening-up with a low level of land use change; from 1995 to 2003, Tianjin harbor developed steadily while the construction land of port area expanded rapidly to the north; from 2003 to 2010, Tianjin harbor stepped into the specialization stage characterized by migration outside and land use type changed drastically during this period. For more than 20 years, Tianjin harbor presented an expansion pattern of along the coastline first to the north and land, then to the south and sea. Occupying of paddy fields and beaches, and sea reclamation are the main approaches of construction land expansion in Tianjin harbor. Meanwhile, extensive and irrational sea reclamation for land and aquaculture is prevalent in the study area. Research considered that port specialization development, national and regional policies and individual driving force were the principal factors that caused land use change of Tianjin harbor from the perspective of time and space. Harmonizing relationship between ecology, economy and regional development, optimizing port layout and promoting land use structure adjustment with the aim of ecological safety are the inevitable way to sustainable development. This article is of important significance in the full realization of port development pattern, the protection of precious port coastal resources, and the reasonable planning of land resources in port areas.