BJ-1 Microsatellite is the advanced member of the Disaster Monitoring Constellation (DMC) with two powerful cameras.One camera can monitor coverage of 600km by 600km , while the other developed by Sira, can capture images of a 24km wide strip of ground with a resolution of four metres.Vegetation fraction coverage is an important parameter for describing vegetation quality and indicating ecosystem change.Inthis study, BJ-1 images were used to detect and analyze the vegetation fractional coverage in the basin of Miyunreservoir.Based on the analysis of the current methods, this paper uses three kinds of methods, including Dimidiate PixelModel from Normalized Difference Vegetation Index (NDVI),3-bands Grads Difference Method and a new method based on Renormalized Difference Vegetation index (RDVI).According to the experimentation, the estimating values by RDVI method has abetter relationship with the verification values, while the other two methods appeared a bigger difference with the groundtrue values.On the whole, RDVI method shows good characteristics and can be used in estimating of vegetation fraction in conjunction with BJ-1 satellite image data.
An experiment was carried out to evaluate the precision of hyperspectral reflectance model to monitor corn leaf area index (LAI).Corn were cultivated under water-fertilizer coupled control condition,and corn LAI was collected simultaneouslywith LI-COR LAI-2000,and Corn canopy reflectance data were collected with ASD spectroradiometer (350~1 074nm). Firstly,eachband of NIR and red were applied to establish five Vegetation Indices; secondly,find out the best band for each kind ofVegetation Index respectively; finally,five Vegetation Indices with the best reflectance band were applied to regressagainst corn LAI.The result shows that the best Vegetation Indices with reflectance which could be applied to regressagainst corn LAI were DVI and PVI,however,TSAVI was not as well as DVI and PVI,but better than NDVI and RVI.
On-board Autonomy (PROBA) satellite, which was developed by the European Space Agency, was launched on October 22, 2001.PROBA satellite carries the Compact High Resolution Imaging Spectrometer (CHRIS) with high spatial resolution,hyperspectral resolution and multi-angular image data. CHRIS has five operating modes, among which mode 2 is optimized for water quality research, and has 18 bands in the visible/near-infrared wavelength from 400~1050 nm at a spatial resolution of 17 meters. All the characteristics of CHRIS make CHRIS well suited for inland water quality monitoring. To validate this, a campaign was carried out at Taihu Lake in East China to measure optical parameters of the water and the oncentrations of water constituents on October 10, 2005. Then, using these data, chlorophyll retrieval algorithm is eveloped and optimized to the spectral characteristics of the CHRIS sensor. The results of retrieved chlorophyll oncentrations from CHRIS images are encouraging.
Integrating Geographic Information System combined with an improved artificial neural network create a visually uncertain river water quality model to complement the limitations of deterministic models used commonly. The coupled model was tested by using the observed data of Baiyin section of Yellow River. The results indicate the proposed model can well simulate the water quality and easy to operate.
Tongyu county,an important part of Songnen desert, is the typically frail zone of land eco-environment in semi-arid region.The objective of this study is to analyze the temporal characteristic and spatial landscape characteristic of land use/cover of Tongyu county from 1979 to 2001. Firstly, various land use types were derived from multi-temporal landsat images (MSS, TM, ETM+) from 1979 to 2001. Then the area and the landscape characteristic of various land use types were calculated by using GIS and land metrics. The results revealed that: (1) the dominant land use types in Tongyu were cultivated land, grass land, forest and severely Saline-alkali land. (2)The primarily dynamic change of land uses in Tongyu were the decreasing grassland and the increasing severely Saline-alkali land. (3)The fragmention of cultivated land, grass land and forest increased instantly while it is opposite to the severely saline-alkali land. (4)Tongyu county is in the transition phase from wane to stabilization.
when retrieving leaf water content Normalized Difference Water Index(NDWI), based on SWIR and NIR, is better than NDVI hich employs VIR and NIR. NDWI responds efficiently in the situation of vegetation water stress. Based on MODIS images nd ground meteorological data of summer of 2003, this investigation studied two areas(one woods and one farmland) in iangxi Province, and compared the effects of normalized difference data of averaged NDVI and NDWI indices in short-term rought monitoring. The result shows that NDWI is more sensitive to canopy water content and exactly reflected the temporal and spatial status of short-tem drought.
It has being more and more noticed that vegetation coverage change impact on ecological environment protection. The vegetation index which can quantificationally indicate vegetation coverage change are researched. Taking Fujian province as demonstration, the vegetation coverage index which based on model of enhance vegetation index are calculated every year by using EOS/MODIS data during 2001～2005, and the interannual dynamic change of vegetation coverage index in Fujian province are analysed. The results show that there are different degradation phenomena of vegetation coverage in different regions,and that the vegetation coverage degradation in residential area, sides of river, coastal region and island are most apparent. The change of vegetation coverage away from ocean is less apparent than that near ocean, especially in mountainous area. This shows the fact that the changes of vegetation coverage in Fujian province are mainly affected by human activities.
Taking the Urumqi urban district as a study area, this paper uses Landsat the TM/ETM thermal band data inversion ground temperature to calculate its relative temperature index (RTI) and analyses its distribution pattern of changes from the temperature relativity and dynamic angle, and then obtains the changing characteristics and the spatial distribution ruleof the urban heat island effect. This method avoided some negative factors on research and analysis of urban heat island effect, such as the complexity of underlaying surfaces and difficulties to build the Ground Temperature-atmosphereTemperature model.
Inshore ship detection has significant practical meaning, especially for the target change detection. However, it is difficult to realize the inshore ship detection utilizing the traditional area-based method because of the complex background. A partial Hausdorff distance measurement based on image contour matching method is proposed, which is fit for the inshore ship search and location. The main characteristics of the proposed method are, 1) a fast distance transform and pyramid decomposition are used to speedup the Hausdorff distance matching; 2) a pyramid is constructed from the original image to avoid the over-sample of contour. Experiments with images of satellite are carried out to validate and analyze the proposed method.
Taking advantage of Laplacian pyramid transformation and statistical characteristic of fully developed speckle in SAR images, a Laplacian pyramid transformation fusion algorithm based on local conditional information of SAR image is proposed. When applied to the fusion of alternating polarization SAR images of urban terrain, it provides higher quality fusion results than fusion algorithms based on data variation, entropy or edge features, with lower mean absolute error and cross entropy as well as higher peak to peak signal to noise ratio and correlation coefficient.
A method for POL-SAR image classification is presented,with which combines physical scattering mechanism, textureinformation and SVM. The test data is DLR ESAR L-band full polarized data of the area of Oberpfaffenhofen Test Site Area(DE), Germany. This area contains natural target, such as forest, field and manmade target, such as building, runway etc.Firstly, OEC decomposition is used to get the scattering features. The texture features of HH and HV channels are alsoobtained. SVM is used for feature selection and classification. Then Freeman decomposition is used to get other features.Repeating the test by adding the new features, good result is achieved. The different targets can be well classified. Thetest proves the efficiency of classification by combining scattering features and texture features. It also proves thevalidity by using SVM for feature selection.
The technology to register the multi-temporal spaceborne SAR image is presented. Manual coarse registration is executed to solve the rotation and scale problem first, and then homologous feature points in the images are detected by feature point detector and image matching. The irregular triangle network is constructed based on homologous points and fine registration is realized. Several couples of spaceborne SAR images are fine registered by the technology and accurate checking shows that the registration achieves good effect and the accuracy reaches less than one pixel.
Airborne SAR/GMTI system based on DPCA technique has tight limitations on the velocity of platform,PRF,and the phase and amplitude characteristics of two apertures and receive channels.Any error induces the dissatisfaction of DPCA conditions and the decline of system performance.This paper analyzes the signal model,proposes an adaptive channel balancing method,gives the channel balancing flow and analyzes the performance of this channel balancing method.This method makes the phase and amplitude characteristics precisely matched in the sense of Least Square,then reduces the requirement for DPCA conditions.This technique is based on a two\|dimensional frequency domain approach which implies that the data sequences received by radar are sufficiently long.The performance of this technique depends on the Signal Clutter Ratio(SCR).
Ground Moving Target Indication (GMTI) using Spaceborne Radar (SBR) gives the opportunity for large scale surveillance,such as spying,target tracking,and positioning.It is specially valuable for military application.Utilizing the space domain sampling character of distributed spaceborne SAR for GMTI is attractive to researchers.Simulation is an important way to carry out the study of distributed spaceborne SAR-GMTI system.The simulation method and flow are discussed comprehensively in this paper,including ground clutter model,ground moving target model,return signal simulation method and signal processing flow and method.Based on the small facet model and the scatter characteristic of the rough terrain,3D ground scene clutter model is established.The received signal expression is formulated.An integrative distributed spaceborne SAR-GMTI simulation system is established,and the simulation results proved its reliability.
This paper investigates the mobile phone’s interference to the 183.31 GHz receivers of the MWHS (Microwave Humidity Sounder) in the FY-3 Meteorologic Satellite by a set of related experiments, by which way find the interfering path. Andit analyses the influence of the mobile station’s interference to the orbiting Spaceborne Microwave Radiometer in theory.The factors related to the jamming distance and their forces are analyzed. The way to prevent and resolve the interference is proposed and proved highly effective.
The methods used to in situ measure permittivity have been summarized.The techniques using a monopole antenna as aprobe are especially analyzed and compared.Their advantages,shortages and development are illuminated.A simple in situmeasurement system is developed,which is designed for the in-the-field measurement and the future deep space exploration.The theory and the experiments of the system are introduced in detail.The measured results are given.Comparisons between the complex permittivity obtained with this simple system and those measured with the Net-Analyzer show good agreement.The great advantages of this system are small,light,simple and its relative high accuracy.
Using modern information technology,network technology,GIS,RS,GPS and traditional ground investigation technique to monitor the grassland is the inevitable trend.Construction target,system structure,system data base,system function,technology train of thought and key technology have been designed all-round.The technology basis for the construction of Sichuan Province grassland monitoring information system established.
In order to reuse the existing code resources based on MapObjects component in Web environment,herein a kind of solution for WebGIS is proposed,which was implemented by using Internet Information Services to manage MapObjects application.The system based on MapObjects2.2 GIS component was built by using C＃ in .NET environment.The server managed by IIS and embedded with Mapobjects component can supply GIS function;Meanwhile,ASP .NET was used to build web pages responding to clients,for it allows us to separate user interface from code files.Besides,web pages being built by ASP .NET have pellucid architecture and better security.In addition,users don’t have to download as well as install plug-ins,they can enjoy WebGIS services by using general browser,which increased the using frequency.As a validation for feasibility and high efficiency,a web version of Lanzhou city’s traffic digital map was implemented by using the solution as the frame.
Oil which naturally leaks to the sea-surface from seabed is called oil seep. Oil-seep information is very important to detecting and exploiting seabed oil resource. At present, SAR has become a new supplementary method for seabed oil detection. In the paper,the detection mechanisms of oil seep were summarized, including the formation mechanism, SAR imaging principle and the SAR image features. Then, the detection method and the application were introduced. At last, the existing problems and the development direction were put forward.
