Theory of synthetic aperture radar altimeter and the delay/compensation technology are introduced first from view of Doppler beam sharpen and echo phase analysis, and the point target response is presented. Based on that, requirement of Doppler error for delay/compensation is presented.
Correct segmentation and effective feature extraction is a critical problem in target recognition of synthetic aperture radar images. In this paper, level-set method was applied in target recognition of synthetic aperture radar images. Target and shadow regions of each image were segmented from background clutter regions using level-set method. The shape of target region was used as significant feature in target recognition based on template matching. Image samples of three targets in MSTAR database are used to verify the method. The results show that using level-set segmentation and template matching can extract effective feature of target and achieve correct recognition of targets.
Remote sensing technique is playing an important role in flood monitoring and assessing system. This paper takes Dongting Lake district as the studying area and utilizes multi-temporal MOS-1b/MESSR data as remote sensing info source. By the combination operation and ratio transform processing and the image, spectrum and histogram comparison of the MESSR image data of all bands for the flooding season and dry season with the ERDAS IMAGINE system, a classification model (B1+B2)/(B3+B4)>t is established, in which model can be used to acquire the spatial distributing information of water bodies.Meanwhile a water depth index (WDI ) model WDI=B1/B2 is derived and built and then a model for detecting the depth of waterbody based on the non-linear recursive analysis. By the overlay analysis of the classification thematic images based on themodel for extracting flood information, the flooding area and distributing information is acquired, which can offer an important scientific basis for flood fighting and prevention in time.
The aim of this study was to test a method for small-scale soil classification using MODIS and digital elevation data in Xinjiang province, northwest of China, where the soil survey is restrained commonly.A series of MODIS data products including surface reflectance, vegetation indices, land surface temperature of daytime and nighttime, etc., were processed to extract features of images, while several terrain descriptors were achieved with DEM, such as elevation, slope, curvature, aspect, and so on.These layers of data were integrated to a dataset for classification.Considering the complexity of classification, we adopt the soil class of soil genesis taxonomy as unit of classification.With the data of soil genesis taxonomy achieved in the second soil survey in China, training points were collected and used to analyze separability of soil units.According to the J-M distances, some pairs of soil classes with same landscapes have been merged.At last, there are 26 units confirmed.Using the maximum likelihood classifier, the dataset was classified.A performance of about 70% was achieved, assessed with confusion matrixes.
For many kinds of distances, remote sensing anomalies usually exist in some weak information. The various changes of the spectrum curve and the multi-value and uncertainty of the image characters of the geologic bodies increase the difficulty in extracting the weak information, however, there must be some differences between the information and other things around it in spectrum. Meanwhile, with the increasing of the remote sensing resolution as well as the development of the technology in image progress, it is possible to extract the anomaly information. The paper introduces the method and process using the functions of image management and spatial modeling in ERDAS IMAGINE based on the mature methods for the extraction of geological information and has been applied in Xinjiang.This approach afforded a simple and convenient way for the extraction of alteration anomalies.
Temperature Vegetation Drought Index (TVDI) is a valid indicator of drought and also an important parameter for retrieval of soil moisture. Vegetation cover type is an important factor affects the retrieval of TVDI with remotely sensed data.To reduce the impact of soil back ground on the accurate retrieval of TDVI and enhance the sensitivity of densely populated vegetation,this paper utilizes modified soil-adjusted vegetation index (MSAVI) to replace NDVI.After the vegetation cover was classified,TVDI retrieved after classification was compared to that derived with traditional method that employ all the pixels of remotely sensed data of region to examine the effects induced by the introduction of vegetation classification. The results show that the average TVDI of broad-leaf forest,scrub and close grassland is evidently different from those obtained with traditional method,the differences between the retrieved TDVI with these two different procedures reach to about +7.2%,-6.6% and -5.5% respectively.This was mainly attributed to the difference of canopy structure and optical properties of vegetation types,which causes the shifting of “wet” and “dry” lines in the LST-MSAVI space characteristics.Therefore,for the large-scale drought evaluating research and soil moisture retrieval by means of TDVI, different vegetation types should be taken into account for modeling LST-MSAVI space to achieve the goal for improving soil moisture retrieval accuracies.
Yangtzi River is the largest river in China. It brings 4.245×108 ton soil and sands into the ocean each year, which greatly influences the suspended sediment concentration (SSC) in the area of Yangtzi River estuary and continental shelf area of East Chinese Sea. Remote sensing technology is one of useful methods to monitor the SSC in the surface water. In this sea area, there is a good relativity between surface water SSC and vertical average SSC. In this article, the author uses MODIS data to reverse the SSC in the area around the Yangtzi River estuary and analyzes the characteristic of its distribution and movement as well as the influence to peripheral sea.
Forest disease and insects are one of the main factors of influencing the forest health, advanced technology was applied to monitor the damage overally, accurately and rapidly. This paper utilizes the spectral characteristic and leaf chlorophyll concentrations to study the damaged larch, we divided the larch into four grades based on their damaged level, analyzed the chlorophyll concentrations, carotenoid and spectral reflectance of 11 groups of different damaged leaves. The result indicates that four obvious differences are in the spectrum reflectance which are in “green peak”,“the absorbed valley”, “ red edge” and moisture absorbed position respectively, furthermore, with the damage becoming more serious，blue shift of the red edge spectra and red shift of the chlorophyll reflectance peak are obvious．Stronger relationship between the band of “red edge”,“absorbed valley” and the chlorophyll concentrations offered the approaches to study the forest disease and insects using hyperspectral data.
This paper takes Luxiang town of Shuangyang district in Changchun city as study area. Based on SPOT5 remote sensing images and DWG full-factor relief map, NDVI was extracted and density was segmentated to indentify the vegetation-covered rate by remote sensing software. Meanwhile, the slope information was extracted from the DWG file by GIS software and degree the topography slope. According to the vegetation overlap degree, the topographic map and land use map, we identified the degree index of the soil erosion intensity,as a result, soil erosion map was gained.
Based on the Geoway software system of the vector data collecting of the forest resources, this paper discussed the principles of classifying and coding of forest resources geographical information according to the need of forest resources geographical information management system in Hefei.It established a scheme of sorting and coding of the forest resources information in Hefei using graphic classification.The data collected meet with need of various GIS softwares.This scheme has been used in forest resources spatial database in Hefei and received a good results.
For remote sensing image de-noising , the threshold of Wavelet domain can effectively remove image noise , however,the value of threshold is fixed.For example, Donoho brings forward the general threshold value reducing noises formulary based on wavelet transform, for the absent of self-adaptability between scales ,the images lose many details.The paper improves Donoho threshold and threshold function, and puts forward the method to establish the coefficient of the threshold adaptation.
During the digital processing of remote sensed image, a high resolution city mosaic image posses a big data volume,sometimes, which is tens of Gigabytes.It is a waste of time and web resource for such a huge volume,ECW compression technique as a wavelet-based and open technology provides the most advanced technique for huge volume image data. A new framework for the image distribution has been put forward using SDK DEVELOP KIT provided by Ermapper Co. and combined with the Image Web Server.
In this paper, five image fusion algorithms including HIS transformation，Brovey transformation，Weighting fusion, SFIM ransformation and ISVR ransformation are experimented between Landsat-7 ETMPAN band and multi-spectral bands. The result f different fusion methods is evaluated qualitatively and quantitatively by comparing the spectral fidelity and the patial resolution．The study indicates that HIS transformation distorts the spectral quality most seriously. Brovey ransformation is not very nice both in retaining the spectral quality and improving the spatial resolution. The result of eighting fusion depends on the weighting seriously. Smoothing Filter-Based Intensity Modulation(SFIM) distorts the pectral quality greatly, however,it can not improve the spatial resolution. Improved Synthetic Variable Ratio(ISVR) is very fit for fusion with ETM images on the who1e．ISVR technique distorts the spectral quality slightly，as well as improves the spatial resolution obviously. The advantage is that it considers the relation of panchromatic band and ultispectral bands, which is ignored by other methods in this paper.
Hyperspectral images are hard to compress because of their abundant details,complicated texture and insignificant special correlation.Making use of the significant spectral correlation within the hyperspectral images,We use pixels of several bands to adaptively predict the pixels of the current band.We can know the optimal prediction of the current pixels is its conditional expectation,which can be translated into computational expression by using subsection ingtegral ,and associate with pixels of other bands.We choose neighboring pixels to adaptive estimate every parameter in order to get residual image,which remove most spatial and spectral redundancy,and then we use JPEG-LS to remove the spectral redundancy. Experiments show that the algorithm can compress the data efficiently and works better than other algorithms.
There are kinds of methods for ortho-rectification in application of remote sensing images，including Collinearity Equation Model，Strict Geometric Model based on Affine Transformation，Improved Polynomial Model，Rational Function Model，Method based on Neural Network，and so on.But there is lack of system comparison among these methods.On the basis of introducing the principle of the methods above，advatanges and drawbacks about these algorithms are summarized in this paper.Specific emphasis is the mathematical derivation and algorithm design of FM.Tikhonov method is taken to the progress of computation of RFM.Two kinds of algorithm based on neural network was taken in application of ortho-rectification.To compare accuracy and effectiveness between the above methods，we make some experiments.The result shows that: on the condition of the same GCPs distribution，Rational Function Model that can reach sub pixel accuracy is the best of all from the viewpoint of precision and can be used in practice in spite of its relatively slower speed.
This paper elaborates the methods on how to process the scanning relief maps and describes technological process. It resolves the problems about how to deal with the correction, polygon subset, mosaic image etc., when the single relief maps are putted together into the whole on the condition of controlling the precision of the error. It also summarizes and probes the methods of the geometry correction and image mosaicing based on the ground control points in the ERDAS IMAGINE8.6, and takes precision analysis of the result.
Although the theory and method of 3D GIS interactive editing is scarce and primitive,the need to develop it has become gradually urgent. Editing in 3D environment by a digital control plane,the method can deal with some geometry efficiently,such as point,line,and polygon,etc. Moreover,based on OpenGL,a 3D GIS editor system in the form of COM plug-in embedded in ArcGIS 3D environment is developed. The result indicates that the method is easy and feasible,and can supportmuch work greatly in geographical field.
The data of GIS are divided into vector data and grid data for its structure. The spatial model of GIS is mainly based on grid data. Therefore, some vector data with special properties should be transformed to grid data and area occupied superiorly method is widely used. However, this method did not fully consider the fuzzy attribute of spatial data. Rough set theory is used to discuss the potential approach to convert polygon data to grid data, meanwhile, using the membership function and fuzzy rough set to determine the uncertainty for the boundary of polygon and to transform the polygon to grid.
Earth observation system and technology realized the global real-time observation and played an increasingly important role in acquiring space-time information of global surface and deep earth which provides condition for environment monitoring and earth system research. Development trend of earth observation system was discussed based on three aspects as high resolution development direction of earth observation satellites and sensors, networking earth observation satellites as well as integrated and coordinative development of earth observing system. At the same time, technology scopes and requirements were analyzed from the aspect of country investment, capabilities of equipments development and their potential application value in other fields, cost of development and operational needs of the time and so on.
Detecting red tides using remote sensing techniques is one of the most important applications of satellite data. Compared with other sensors MODIS has advantages on spectrum and spatial resolutions. Therefore, MODIS will be great useful on red tide detecting. In this paper main methods of red tides detecting using MODIS have been listed and reviewed. Furtermore,the advantages and disadvantages of MODIS in red tides detecting were analyzed.
