最新刊期
卷 15 ， 期 6 ， 2011
- 摘要：A definition of earth surface modeling is proposed on the basis of discussing the concept of earth surface.Studies on earth’s surface topography modeling and climate system modeling are reviewed,which indicates that it is eagerly necessary to develop simulation methods with high speed,high accuracy and low memory requirement.Introduction of methods for high accuracy and high speed surface modeling（HASM）,developed by means of the fundamental theorem of surfaces,might be an efficient way to characterize the states of earth-surface and changes in those states.
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发布时间：2021-06-10 - 摘要：Take octahedron as an example,the aperture 4 hexagonal discrete global grids（A4HDGGs） is analyzed in this paper.The two adjacent triangle patches（up and down） in the platonic polyhedron are merged into one quadrilateral to create a twodimensional coordinate system,and the hierarchical location coding on A4HDGGs is therefore put forward.Firstly,the coding characteristics of A4HDGGs in different positions are analyzed.Secondly,a searching algorithm for A4HDGG,called A4-2D-coordinates,is given in details.Finally,the experimental analysis is developed.The efficiency of neighbor-finding,children-finding,and parent-finding in this algorithm have been validated by the experimental results to improve respectively by 900 times,120 times and 120 times compared with traditional Vince algorithm.关键词：octahedron;aperture;hexagonal discrete global grid;location coding;indexing
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发布时间：2021-06-10 - 摘要：Forest above ground biomass（AGB） estimation using microwave backscattering coefficient is normally limited to low level AGB because of the "saturation" problem in backscattering coefficient.In addition,forest height may be used to estimate AGB by allometric equation,but the changing conditions of the forest in terms of density,tree species composition etc.limit the accuracy and performance of the method.In order to overcome the above disadvantages and improve the estimation accuracy,a method for AGB estimation is proposed in this paper,which is based on polarization coherence tomography（PCT） technology.Using repeat pass ESAR L-band PolInSAR data collected by DLR at the Traunstein test site,the radar relative refiectivity function of each pixel is reconstructed using PCT,from which the average relative refiectivity profiles for the 20 validation stands are computed.Then 9 profile characteristic parameters closely related to biomass are defined and extracted for each forest stand.The natural logarithms of these 9 profile parameters are taken as independent variables for multivariate linear regression analysis with the natural logarithm of the field-measured AGB as dependent variable using stepwise regression method.Forest AGB estimation model is established and evaluated,and the factors possibly affecting the performance of the AGB estimation model are also analyzed.The results show that these parameters,which are extracted from the average relative refiectivity function inversed with PCT,are sensitive to forest AGB.The accuracy of AGB estimation can be improved if we make full use of the information contained in the relative refiectivity function.关键词：polorimetric interferometric SAR;polarization coherence tomography;stepwise regression analysis method;forest above ground biomass
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发布时间：2021-06-10 - 摘要：we presented a newly regional three-band model to estimate Chla（Chlorophyll-a） directly by a case study in Taihu Lake and Shitoukoumen Reservoir.Inherent optical properties of the target waters were investigated to determine the model coefficients describing the relationship between three-band combination and Chla concentration.Results show that the proposed model is intended to both provide high accuracy and greatly reduce the uncertainty caused by regression algorithms.Based on the accurate and long-term water optical observations,the regional three-band models designed for different water areas would promote the operational monitoring of Chla in inland waters.关键词：inland waters;three-band model;chlorophyll-a;chlorophyll-a specific absorption
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发布时间：2021-06-10 - 摘要：A route representation framework and its main implementation procedures are proposed for generating contextadaptive route directions,which could meet human cognitive habits,reflect user’s spatial knowledge,and is apt to be expressed in natural language.In the framework,a route is represented as a sequence of uniform temporal and various granular instruction units,which can be processed into route instruction phrases or sentences.For the implementation of context-adaptive route directions,landmark extraction,various granular instruction unit generation and most appropriate instruction unit sequence selection are introduced,while some contextual factors such as environmental structures,route characteristics and prior knowledge are also considered in these procedures.After compared with traditional route directions predominantly using distance-to-turn information,it can be found that the context-adaptive route directions based on spatial cognition is more conformable to the way people describe routes,and thus could decrease user’s cognitive workload and promote the efficiency of navigation systems.关键词：route directions;spatial cognition;landmark;spatial knowledge
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发布时间：2021-06-10 - 摘要：A 3D digital image model is proposed to represent the LIDAR data.The mathematical morphology is extended to 3D and then,dilation and erosion operators are re-defined.A method combining 3D mathematical morphology with clustering analysis is developed.Sequential dilation operations and clustering analysis are introduced into the 3D point cloud to achieve the pixel-level results of point cloud.The relationships between the two parameters and data property,resolution of point cloud and the minimum distance between objects,is discussed.Two case data are used to demonstrate the feasibility of the proposed method.The result for the first dataset is compared with those from the two other methods,Mean Shift algorithm and adaptive TIN filter method.The advantages and disadvantages are summarized using segmentation evaluation factors,segmentation accuracy,and computation efficiency.Meanwhile the stabilization of proposed method is also analyzed.关键词：LIDAR;point cloud;3D digital Image;3D morphology;segmentation
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发布时间：2021-06-10 - 摘要：This paper analyzes parallel ICA algorithm in symmetrical multi-processing（SMP） cluster architecture.Based on our proposed single-level share memory model parallel ICA algorithm,two-level synchronous and asynchronous parallel ICA algorithms are presented,respectively,in the manner of synchronous and asynchronous parallel iteration for computing fixed-point function.By the use of these algorithms,two-level grouping parallel ICA algorithm is also proposed.In experiment with real hyperspectral remote sensing image,synchronous and grouping parallel ICA algorithms maintenance the endmember extraction accuracy with respect to the original algorithm.Meanwhile,they also demonstrate high parallel performance and greatly improve the performance of ICA endmember extraction.Asynchronous parallel ICA algorithm is suitable for the case of small number of nodes in cluster.关键词：hyperspectral remote sensing;independent component analysis;endmember extraction;symmetrical multi-processing;Cluster;parallel computing
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发布时间：2021-06-10 - 摘要：Fine beam dual polarization data onboard Advanced Land Observing Satellite-Phased Array type L-band Synthetic Aperture Radar（ALOS PALSAR） for Hai’an,Jiangsu,China acquired in 2008 were used to analyze rice backscatter features at L-band SAR for the development of rice mapping method.Similar temporal change trend of backscatter was observed at L-band SAR to that of C-band.With the dependence of HH backscatter on the spatial distribution structure of the rice canopy,Bragg resonance scattering has been observed in some mechanically planted fields due to extremely enhanced backscatter,making it difficult to map rice using L-band SAR.However,the HV polarization is not subject to Bragg resonance.Considering the Bragg resonance effect in HH polarization,a rice mapping method was proposed based on the temporal change characteristics of backscattering coefficient by the synergistic use of HH and HV polarization images of ALOS PALSAR.A mapping accuracy of about 88.4% was achieved.关键词：ALOS;PALSAR;L-band;rice mapping;Bragg resonance
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发布时间：2021-06-10 - 摘要：Impervious surface percentage（ISP） is the key parameter for urban regional environment research.This paper compares the ISP estimate-performance of spectral mixture analysis（SMA） and support vector machine（SVM） on TM image.The SVM model establish the non-linear relationship between spectral feature of TM pixels and corresponding ground sample ISP values and then be implied on without-sample TM pixels for ISP estimation.On the TM image of Tianjin urban area,we first select high resolution image from Quickbird classification results,including college,industrial and residential districts as training sample（7020 items） and then test sample（1500 items）.The toot mean square error（RMSE） of SVM model is 15.4%,which is better than SMA with 19.4%.Additionally,after adding "greenness" of tasseled cap transform and "high-albedo" of SMA,the RMSE decreases to 12%.The results of the study indicate that SVM model is suitable for large area ISP mapping without insufficient samples because of the non-linear characteristic and good performance of small-sample generalization.By adding spectral feature vector having significant relation with ISP,it can adjust the value of ISP estimation where the land cover types is lack of training samples and improve the overall accuracy of regional ISP estimation.关键词：impervious surface;impervious surface percentage;spectral mixture analysis;support vector machine;estimation
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发布时间：2021-06-10 - 摘要：The retrieval and application of emissivity spectrum and temperature are key issues in thermal infrared remote sensing.Thermal airborne hyperspectral imager has 32 bands from 8 μm to 11.5 μm,which can provide abundant useful information for the retrieval of emissivity spectrum and temperature.This paper establishes regression between MMD and β min using 274 laboratory reflectance and field emissivity spectra,analyzes its accuracy using the data field measuring,and evaluates urban surface diurnal temperature range.The result shows that:（1） the average absolute difference between the temperature of retrieval and the measurement is 1.8 K,and the relative difference is 0.59%;（2） the mean difference between the broadband emissivity and the mean emissivity from TASI is 0.036,and the standard error of difference is 0.032.Because of the effects of scale and atmosphere,the predicted value does not equal to the laboratory measurement,but the pattern of predicts is similar to the laboratory measurement;（3） the result of diurnal temperature range is reasonable.Therefore,the accuracy of this method can satisfy operational application and it is feasible to retrieve the emissivity spectrum and temperature for TASI data.关键词：thermal infrared airborne hyperspectral data;temperature;emissivity spectrum;diurnal temperature range;TES
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发布时间：2021-06-10 - 摘要：Advanced sound-based remote sensing technology for terrestrial animals could greatly enhance our ability of animals monitoring,research and protection.In this research,we designed an inexpensive bioacoustic localization system for terrestrial animals,which integrates commercial off-the-shelf recorders and wireless controllers and is much cheaper than most animal localization systems.Combined with the bioacoustic localization software we developed,the system is veri? ed to have the ability to ful? ll our requirements because its localization errors along the X and Y directions are both less than 1.69 m,although the error along the Z direction is a little bit larger.In order to assess the factors influencing the localization accuracy,we applied Monte Carlo simulation method to conduct error analysis.We found that errors,including in surveying recording stations,estimating Time Difference of Arrival（TDOA）,and estimating sound velocity,will all influence the final localization accuracy.Besides,the Monte Carlo method could also be used for choosing the values of system parameters when implementing a bioacoustic localization system of terrestrial animals,such as the total number of recording stations and spatial ranges of the system.关键词：sound-based remote sensing;bioacoustic localization;biological monitoring;error analysis;Monte Carlo
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发布时间：2021-06-10 - 摘要：Light detection and ranging（Lidar） point cloud data contains the information of the 3D coordinate and intensity,which can be applied to acquire the height of crown,fractional cover etc.in high-statue vegetation,such as the forest.Meanwhile,with the improvement of data storage capacity and processing speed,small footprint airborne Lidar is able to store the entire reflected waveform through digitally sampling,which expands the application of Lidar.However,the methods used in forest are not suitable for shrubs,crops and other low canopies.In this paper,we choose the cron as the study object,and propose a crop fractional cover and leaf area index（LAI） retrieval method using airborne Lidar intensity of ground hits and the distance and zenith angle information contained in waveforms data.Relevant fight experiment and ground measurements in Heihe indicate that the method is reliable,and the experiment also validates the great potential for Lidar to be applied to monitor low natural vegetation in agriculture.关键词：LiDAR;point cloud;full waveform;crop;fractional cover;LAI
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发布时间：2021-06-10 - 摘要：With a convolution algorithm,urban land use proportions were calculated based on remote sensing classification data,which were used as thresholds to distinguish between urban and non-urban area,and then urban extent was extracted.Indexes system was proposed to determine the size of the convolution template and the threshold by evaluating extraction results.We took Beijing as a study area and validated the feasibility of the method by using classification data of SPOT 5 multi-spectral images.Combining with the built-up area of statistical data,504 combinations of template and threshold were used to do the extraction test and the effects of templates and thresholds on the extraction results were discussed.Finally,combination of（205,51） was selected to extract the urban extent.The result showed that:（1） this method solved the problem that urban land acquired from remote sensing monitoring differed from urban extent that geographical studies cared about and provided a new way to prepare the basic data for urban study.（2） Test result indicated that both the lower or higher threshold will exaggerate or understate the extracted result,and that a small size of template cannot eliminate the random error meanwhile a large size would lead the result being too smooth.（3） For the classification data of SPOT 5 multi-spectral image,the extraction results were the best while the size of the template ranges from 193 to 205（around 4 km2） and the threshold is around 50.关键词：urban extent extraction;remote sensing monitoring;convolution algorithm;urban land use proportion;Beijing
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发布时间：2021-06-10 - 摘要：For inversion of forest canopy height in large scale,it is of great signi? cance to integrate space-borne Lidar and optical remote sensing data effectively.The homemade satellite will provide a plentiful datum for forest ecological researches.In this paper,the processing of GLAS waveform data and the algorithm of forest canopy height in different terrain were implemented.The GLAS + MERSI joint inversion model of canopy height of different forest types in regional scale was established and used to map the forest canopy height of Jiangxi province.Overall,high accuracy was observed for the canopy height estimated by GLAS + MERSI joint inversion model with R2=0.733 for the needle-leaf forest,following by the broadleaf forest（R2=0.610）.The results showed that the established model was workable.It was found that the GLAS + MERSI joint inversion model which considers the optical remote sensing of biophysical parameters can provide good estimates of forest canopy height at regional scale.The space distribution characteristic was found consistent with the data of land cover.关键词：forest canopy height;Lidar;GLAS;FY3A-MERSI
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发布时间：2021-06-10 - 摘要：Remote sensing technology with the characteristics of rapid,economical and macroscopic provides an important real-time dynamic data source for drought monitoring and decision making.In this paper,monitoring methods based on remote sensing data are overviewed and classified into four kinds:soil thermal inertia methods,soil spectrum characteristic methods,evapotranspiration model methods and vegetation index methods.The monitoring principle,applicability and advances for each method are presented.Combination with the drought of Southwest China occurred in the spring of 2010,a drought remote sensing method using vegetation water indices is introduced including monitoring model,data processing and application analysis.And the monitoring results are statistical analyzed and evaluated.关键词：drought monitoring;remote sensing;advances;application analysis
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发布时间：2021-06-10
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