应用FY-1D气象卫星监测雾(英文)

FY-1D is the second national operation meteorological satellite of China, and is much better compared to monitoring fog. However, research on monitoring fog using FY-1D is very few. In this paper, based on the typical FY-1D data, a fog＇s spectral characteristics in the different channels are analyzed using the histogram analysis method, and a method of monitoring fog using FY-1D is suggested. The results indicate that the 1st and 4th channels are the representative channels of FY-1D for the identification of fog. In the 1st channel, the fog is with uniform veins, smooth top, and clear-cut boundary, and its albedo is 20%-48%. In the 4th channel, the fog＇s brightness and temperature is 272-289K, and the difference value between the fog＇s and the ground surface＇s is not more than 6K.     

A new vector data compression approach for WebGIS

High compression ratio,high decoding performance,and progressive data transmission are the most important require-ments of vector data compression algorithms for WebGIS.To meet these requirements,we present a new compression approach.This paper begins with the generation of multiscale data by converting float coordinates to integer coordinates.It is proved that the distance between the converted point and the original point on screen is within 2 pixels,and therefore,our approach is suitable for the visualization of vector data on the client side.Integer coordinates are passed to an Integer Wavelet Transformer,and the high-frequency coefficients produced by the transformer are encoded by Canonical Huffman codes.The experimental results on river data and road data demonstrate the effectiveness of the proposed approach:compression ratio can reach 10% for river data and 20% for road data,respectively.We conclude that more attention needs be paid to correlation between curves that contain a few points.     

Comparative assessment of the relationship of satellite data with the above ground biomass of Sal trees (<Emphasis Type="Italic">Shorea robusta</Emphasis>) determined from phenologically different time periods

The Above Ground Biomass(AGB) estimates of vegetation comprise both the bole biomass determined through a volumetric equation and litter biomass collected from the ground.For mature trees,the AGB estimated in phenologically different time periods is directly affected by the litter biomass since the Diameter at Breast Height(DBH) and height(H) of such trees that are used in the estimation of bole biomass would remain unchanged over a reasonable time period.In the present study,we have determined the AGB of Sal trees(Shorea robusta) in two contrasting seasons:the peak green period in October being devoid of lit-ter on the ground and the leaf shedding period in February with abundant amount of litter present on the ground.Estimation of AGB for the month of February included the litter biomass.In contrast,the AGB for October represented only the bole biomass.AGB was estimated for ten different plots selected in the study area.The AGB estimated from ten sampling plots for each time period was re-gressed with the individual tree parameters such as the average DBH and height of trees measured from the corresponding plots.The regression analysis exhibited a significantly stronger relationship between the AGB and DBH for the month of October as compared to February.Furthermore,the correlation between the remotely sensed derived data and AGB was also found to be significantly higher for the month of October than February.This observation indicates that inclusion of the litter biomass in AGB will tend to decrease the re-gression relationship between AGB and DBH and also between the remotely sensed data and AGB.Therefore,these conclusions invite careful consideration while estimating AGB from satellite data in phenologically different time periods.     

Research on the deformations in Qinghai-Tibet plateau and its margins by inverting seismic moment tensors and GPS velocities

We have determined approximate average rates of deformation in the Qinghai-Tibet plateau and its margins from the GPS data for last 10 years and the moment tensors from earthquakes between 1900 and 1999.We also determined the strain rate (seismic strain rate) associated with the seismic deformation using 254 Mw≥5.0 earthquakes,and estimated the shortening and extension rates for every block in the area as well.We also estimated the strain rate (geodetic strain rate)by 80 GPS sites' velocity vectors and analyzed characteristic of kinematics by two kinds of strain rates and discussed earthquake potential in the area.As a result,the deformation rates from seismic moment tensors and from GPS velocities are basically agreed with each other.It is feasible to analyze seismic risk by comparing geodetic strain rate with seismic strain rate based on the opinion that strain energy will be released through earthquake.It is concluded that there is no strong earthquake potential (＞M7) in the Qinghai-Tibet plateau and its margins,but there is earthquake potential (＞M5) in middle Tibet in a few years.     

Approximate approaches to geometric corrections of high resolution satellite imagery

The exploitation of different non-rigorous mathematical models as opposed to the satellite rigorous models is discussed for geometric corrections and topographic/thematic maps production of high-resolution satellite imagery (HRSI). Furthermore, this paper focuses on the effects of the number of GCPs and the terrain elevation difference within the area covered by the images on the obtained ground points accuracy. From the research, it is obviously found that non-rigorous orientation and triangulation models can be used successfully in most cases for 2D rectification and 3D ground points determination without a camera model or the satellite ephemeris data. In addition, the accuracy up to the sub-pixel level in plane and about one pixel in elevation can be achieved with a modest number of GCPs.     

A shoreline change analysis along the coast between Kanyakumari and Tuticorin,India, using digital shoreline analysis system

The shoreline is one of the rapidly changing landforms in coastal areas.They are the key element in coastal GIS and provide the most information on coastal land form dynamics.Therefore,accurate detection and frequent monitoring of shorelines is very essential to understand the coastal processes and dynamics of various coastal features.The present study is to investigate the shoreline changes along the coast between Kanyakumari and Tuticorin of south India(where hydrodynamic and morphologic changes occur continuously after the December 2004 tsunami)by using Digital Shoreline Analysis System(DSAS),an extension of ArcGIS.Multidate IRS and Landsat Satellite data(1999,2001,2003,2005,2007,and 2009)are used to extract the shorelines.The data is processed by using the ERDAS IMAGINE 9.1 software and analyzed by ArcGIS 9.2 workstation.The rates of shoreline changes are estimated by three statistical methods,namely,End Point Rate(EPR),Linear Regression Rate(LRR),and Least Me-dian of Squares(LMS)by using DSAS.The study reveals that most of the study area has undergoing erosion.Both natural and an-thropogenic processes along the coast modify the shoreline configuration and control the erosion and accretion of the coastal zones.The coastal zones along the estuary have experienced accretion due to the littoral processes.The zones with headlands have more eroded than other zones along the study area.The study also shows that the coastal zones where sand is mined have relatively more rate of erosion than that of the other zones.Improper and unsustainable sand mining may also lead to severe erosion problem along this area.The shoreline change rates are altered by various geological processes along the coast.Thus,the present study implies that proper beach filling and nourishment projects should be made in the study area to save from hazards.It also indicates the advantage and suitability of DSAS to assess the shoreline changes compared with the traditional manual shoreline change analysis and prom-ising its applications for coastal zone management in other regions.     

大型土木工程结构的动态位移远距离实时监测系统(英文)

Based on digital image processing technique, a real-time system is developed to monitor and detect the dynamic displacement of engineering structures. By processing pictures with a self-programmed software, the real-time coordinate of an object in a certain coordinate system can be obtained, and further dynamic displacement data and curve of the object can also be achieved. That is, automatic gathering and real-time processing of data can be carried out by this system simultaneously. For this system, first, an untouched monitoring technique is adopted, which can monitor or detect objects several to hundreds of meters apart; second, it has flexible installation condition and good monitoring precision of sub-millimeter degree; third, it is fit for dynamic, quasi-dynamic and static monitoring of large engineering structures. Through several tests and applications in large bridges, good reliability and dominance of the system is proved.     

南极国际GPS跟踪站的海潮位移改正 (英文)

This paper describes the ocean loading tides corrections of GPS stations in Antarctica, such as the Great Wall station and Zhongshan station. Based on the theory of ocean loading tides, the displacement corrections of ocean loading tides on GPS stations in Antarctica are calculated by using the CRS4.0 ocean loading tides model. These corrections are also applied to GPS data processing. The GPS data are analyzed by the GAMIT software with and without these corrections. We compared and analyzed the GPS baseline components to get the differences. The results show that the ocean tidal displacement corrections have obvious effects upon GPS baseline components. Therefore, we should not ignore the ocean loading tides corrections of GPS stations in Antarctica to obtain precise and reliable results.     

A design of three-dimensional spatial data model and its data structure in geological exploration engineering

The key to develop 3-D GISs is the study on 3-D data model and data structure. Some of the data models and data structures have been presented by scholars. Because of the complexity of 3-D spatial phenomenon, there are no perfect data structures that can describe all spatial entities. Every data structure has its own advantages and disadvantages. It is difficult to design a single data structure to meet different needs. The important subject in the3-D data models is developing a data model that has integrated vector and raster data structures. A special 3-D spatial data model based on distributing features of spatial entities should be designed. We took the geological exploration engineering as the research background and designed an integrated data model whose data structures integrats vector and raster data byadopting object-oriented technique. Research achievements are presented in this paper.     

Monitoring the dynamic characteristics of tall buildings by GPS technique

Dynamic characteristics of large structures,such as tall buildings,long-span suspension,cable-stayed bridges and tall chimneys,are key to assess their drift and stress conditions.The dynamic characteristics of large structures are difficult to measure directly under the condition of earthquakes or strong winds using traditional techniques such as laser collimator,total station and accelerometers.Therefore there is a great need for developing new method or technique for this purpose.Recent advances in Global Positioning System (GPS) technology provide a great opportunity to monitor long-period changes of structures reliably.GPS receivers capable to gauge the motion at the centimeter or sub-centimeter level with sampling frequency 10Hz or even 20 Hz are now available from several manufacturers.To the authors' knowledge,the capability of identifying dynamic characteristics from GPS observations has not been widely verified.For the feasibility study on using kinematic GPS technology to identify the dynamic characteristics of tall buildings,some experiments were conducted in a simulative environment.This paper discusses in detail the experiment device,and the ways through them GPS data are recorded,processed and analyzed.With post-processing version of NovAtel's Softsurv software and auto-regressive (AR) spectral analysis method,relative displacements and corresponding vibrating frequencies have been derived from GPS observations.The results indicate that the dynamic characteristics can be identified accurately by kinematic GPS technology.     

Analysis on public transportation influences on real estate development in East Lansing

The purpose for this article is to research the relationship between public transportation and real estate based on the area of East Lansing.Two methods are mainly used to analyze the data:correlation analysis and means analysis with the help of Statistical Package for the Social Sciences(SPSS) data analyzing software.There are two analysis results:(1) the real estate,which is closer to public transportation,will have higher value than that is far from public transportation,and(2) the number of bus in one bus stop has no obvious relation with the value of real estate.Based on these results,real estate developers could build residential real estate close to public transportation or bring public transportation in their real estate community by contract with transportation corporations.In sum,they should reasonably use public transportation as attractive features to convince people to prefer to their houses.     

Verification of Net Primary Production Estimation Method in the Mongolian Plateau Using Landsat ETM＋ Data

We plan to estimate global net primary production (NPP) of vegetation using the Advanced Earth Observing Satellite-Ⅱ (ADEOS-Ⅱ) Global Imager (GLI) multi-spectral data. We derive an NPP estimation algorithm from ground measurement data on temperate plants in Japan. By the algorithm, we estimate NPP using a vegetation index based on pattern decomposition (VIPD) for the Mongolian Plateau. The VIPD is derived from Landsat ETM multi-spectral data, and the resulting NPP estimation is compared with ground data measured in a semi-arid area of Mongolia. The NPP estimation derived from satellite remote sensing data agrees with the ground measurement data within the error range of 15% when all above-ground vegetation NPP is calculated for different vegetation classifications.     

Network analysis modeling towards GIS based on object-relation database

This paper compares the differences between the mathematical model in graph theory and GIS network analysis model. Thus it claims that the GIS network analysis model needs to solve. Then this paper introduces the spatial data management methods in object-relation database for GIS and discusses its effects on the network analysis model. Finally it puts forward the GIS network analysis model based on the object-rela-tion database. The structure of the model is introduced in detail and research is done to the internal and external memory data structure of the model. The results show that it performs well in practice.     

根据多卫星高度计海面高数据推算南中国海及菲律宾海域重力异常(英文)

t Gravity anomalies on a2.5 ×2.5 arc-minute grid in a non-tidal system were derived over the South China and Philippine Seas from multi-satellite altimetry data. North and east components of deflections of the vertical were computed from altimeter-derived sea surface heights at crossover locations, and gridded onto a 2.5 × 2.5 arc-minute resolution grid. EGM96-derived components of deflections of the vertical and gravity anomalies gridded into 2.5 × 2.5 arc-minute resolutions were then used as reference global geopotential model quantities in a remove-restore procedure to implement the Inverse Vening Meinesz formula via the 1D-FFT technique to predict the gravity anomalies over the South China and Philippine Seas from the gridded altimeter-derived components of deflections of the vertical. Statistical comparisons between the altimeter-derived and the shipboard gravity anomalies showed that there is a root-mean-square agreement of 5.7 mgals between them.     

内核超速旋转引起的重力场变化(英文)

Due to the super rotation of the Earth＇s inner core, the tilted figure axis of the inner core would progress with respect to the mantle and thus cause the variation of the Earth＇s external gravity field. This paper improves the present model of the gravity field variation caused by the inner core super rotation. Under the assumption that the inner core is a stratifying ellipsoid whose density function is fitted out from PREM and the super rotation rate is 0.27-0.53°/yr, calculations show that the global temporal variations on the Earth＇s surface have a maximum value of about 0.79-1.54×10^3 pGal and a global average intensity of about 0.45-0.89×10^ 3 μGal in the whole year of 2007, which is beyond the accuracy of the present gravimetry and even the super conducting gravimeter data. However, both the gravity variations at Beijing and Wuhan vary like sine variables with maximal variations around 0.33 pGal and 0.29 pGal, respectively, in one cycle. Thus, continuous gravity measurements for one or two decades might be able to detect the differential motion of the inner core.     

Spectral Representation Precision Based on the and Analysis of the KBR Earth Gravity Spectrum

Satellite-to-Satellite Tracking in low-low model （SST-Ⅱ） is a new technique to resolve the series of problems met in the determination of the earth＇s gravity field. As the key technique of SST-Ⅱ, KBR can get SST-Ⅱ measurements directly. So the KBR performance analysis is the first step in SST-Ⅱ design. In this paper, assuming that the satellite pairs of SST-Ⅱ are in near circle polar orbits, the spectrum relationship between the earth gravity field and KBR is established using analytic method. And then some examples are analyzed, the suggestions and conclusions are drawn from these examples. The research results could be taken as a reference for future satellite gravity project of China.     

Solving Three Types of Satellite Gravity Gradient Boundary Value Problems by Least-Squares

The principle and method for solving three types of satellite gravity gradient boundary value problems by least-squares are discussed in detail. Also, kernel function expressions of the least-squares solution of three geodetic boundary value problems with the observations {Γ zz },{Γ xz , Γ yz} and {Γ xx -Γ yy ,2 Γxy}are presented. From the results of recovering gravity field using simulated gravity gradient tensor data, we can draw a conclusion that satellite gravity gradient integral formulas derived from least-squares are valid and rigorous for recovering the gravity field.     

基于改进的模糊c-均值聚类方法遥感影像分类研究(英文)

Classification is always the key point in the field of remote sensing. Fuzzy c-Means is a traditional clustering algorithm that has been widely used in fuzzy clustering. However, this algorithm usually has some weaknesses, such as the problems of falling into a local minimum, and it needs much time to accomplish the classification for a large number of data. In order to overcome these shortcomings and increase the classification accuracy, Gustafson-Kessel （GK） and Gath-Geva （GG） algorithms are proposed to improve the traditional FCM algorithm which adopts Euclidean distance norm in this paper. The experimental result shows that these two methods are able to detect clusters of varying shapes, sizes and densities which FCM cannot do. Moreover, they can improve the classification accuracy of remote sensing images.     

粗糙集理论进行遥感图像监督分类的样本质量评价的研究(英文)

In the supervised classification process of remotely sensed imagery, the quantity of samples is one of the important factors affecting the accuracy of the image classification as well as the keys used to evaluate the image classification. In general, the samples are acquired on the basis of prior knowledge, experience and higher resolution images. With the same size of samples and the same sampling model, several sets of training sample data can be obtained. In such sets, which set reflects perfect spectral characteristics and ensure the accuracy of the classification can be known only after the accuracy of the classification has been assessed. So, before classification, it would be a meaningful research to measure and assess the quality of samples for guiding and optimizing the consequent classification process. Then, based on the rough set, a new measuring index for the sample quality is proposed. The experiment data is the Landsat TM imagery of the Chinese Yellow River Delta on August 8th, 1999. The experiment compares the Bhattacharrya distance matrices and purity index zl and △x based on rough set theory of 5 sample data and also analyzes its effect on sample quality.     

Study on gis data directly integrated into image processing

The basic properties to be dealt with ,when considering initially the research needs related to the integration of remote sensing (RS) information into a geographic information system (GIS),are many-sided.The primary combination of remote sensing and GIS is mainly realized by the transforms of data structure .Because of its own limitations,there is an urgent need to investigate the integration of RS and GIS in higher levels.In this paper,we discuss the different types of combinations of RS with GIS,and propose that GIS data should be directly brought into image processing from the beginning.A tentative idea of how to use the method of granularity to study the common processing unit of RS and GIS is described.The example for the determination of granularity of spatial data processing related to run-length-code line is also given.