最新刊期
卷 ， 期 2 ， 2008
- 摘要：Analytical algorithm,which is based on bio-optical model,represents the trends of algorithms in retrieving water quality parameters from remote sensing data.In analytical algorithm,inherent optical properties,including absorption coefficients and back-scattering coefficients of each component of water,are important input parameters.The absorption coefficients of each component of water can be measured easily in laboratory.On the other hand,the measuring of back-scattering coefficients of suspended matter in water is always difficult,especially for inland waters.There are mainly three kinds of methods in measuring back-scattering coefficients of suspended matter:（1） measuring in field with specific instruments;（2） collecting water samples in field,measuring the scattering phase functions of the water samples in laboratory,and then calculating the back-scattering coefficients based on the scattering phase functions;（3） collecting water samples in field,measuring the total absorption coefficients and beam attenuation coefficients of the water samples,and then calculating the back-scattering coefficients by substracting the total absorption coefficients from beam attenuation coefficients,and then multiplying ratio of back-scattering coefficients of suspended matter.However,all these three methods have some drawbacks:（1） these methods are mainly designed for ocean waters,and may not be suitable for inland waters due to the great differences in optical properties between them;（2） the scattering phase function measuring instrument is hard to be designed and installed,and there are few such instruments in China;（3） the ratio of back-scattering coefficients of suspended matter,which is difficult to measure,has to be estimated in calculating back-scattering coefficients of suspended matter,and the estimation will lead to some errors.In this paper,a new method of calculating back-scattering coefficients of suspended matter is put forward.Based on bio-optical model,this method uses the water surface reflectance spectra data and absorption coefficients of water components to retrieve back-scattering coefficients of suspended matter.Validated by data acquired from Meiliang Bay,Taihu Lake,this method shows advantages as follows:（1） based on bio-optical model,it has sound theoretical basis;（2） it is easy to be carried out because the data used in this method are easy to obtain.Provided the above advantages,data of back-scattering coefficients of suspended matter can be acquired for the application in the future.关键词：bio-optical model;analytical algorithm;back-scaterring coefficient;suspended matter
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发布时间：2021-06-10 - 摘要：FY-3 meteorological satellite is the 2nd generation of China’s polar-orbit meteorological satellite,and the Microwave Humidity Sounder（MWHS） is one of its main payloads.The basic principle of atmospheric humidity sounding by microwave radiometer and the technical specifications of MWHS onboard FY-3 satellite are briefly introduced in this paper.The block diagram and operating modes of MWHS are presented.MWHS is a dual-frequency,five-channel millimeter wave radiometer which is a total power type microwave radiometer based on a heterodyne receiver,and performs cross-track scanning.The frequencies of MWHS include both the atmospheric transparent windows of 150GHz and water vapour absorption lines around 183.31GHz.The 150GHz radiometer has two polarizations of V and H,and the 183.31GHz radiometer has three channels of 183.31±1GHz,183.31±3GHz and 183.31±7GHz,respectively.The swath width of about 2700km is implemented by cross-track scanning of the antenna beams.Final testing verifies that the performance of MWHS satisfies technical requirements of specifications.MWHS consists of three units: antenna and receiver unit,electronic unit and power supply unit.Antenna and receiver unit collcets emission from the atmosphere. The received signal is focused to the horn-feed and the first element of the high frequency front end,and then down-converted by a double side band mixer to Intermediate Frequency;IF signal is been down-converted to Low Frequency（LF） by a detector,and then integrated.The electronic unit digitizes the LF signal, controls the scanning mechanism and measures physical temperature of the on-board hot target for calibration,and communicates with satellite through a 1553B data bus.The power supply unit performs DC/DC conversion,distributies the DC lines to the various sub assemblies and switches between the nominal and the redundant unit.One motor drives two separated reflectors for the 150GHz and the 183.31GHz channels,the scanning period is 2.667s.Main beams of the antenna scan over the observing swath（±53.35° from nadir） in the cross-track direction at a constant periodicity of 1.71s.During each period,two-point calibration are performed to calibrate the receiver gain and noise.The calibration is implemented by observing an onboard hot target and the background emission of the cold sky.关键词：FY-3 meteorological satellite;payload;microwave humidity sounder;atmospheric humidity sounding
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发布时间：2021-06-10 - 摘要：A novel segmentation method based on Markov Random Field（MRF） and Support Vector Machine（SVM） posteriori probability is proposed in the paper.As a rule,image segmentation using MRF model has two steps.Firstly,distribution of conditional probability of pixel characteristic is obtained by the parameter estimate for probability density and then maximum a posteriori（MAP） principle is always used to gain the optimum estimate of class label.In practice,the hypothesis of Gauss distribution model is always adopted,but it is not the model fit for any images,for example,SAR images often fit to a model of Rayleigh distribution and especially some texture images,it is very difficult to deduce an accurate distribution model.In order to solve the two major problems which are the complexity of parameter estimate in using the distribution of conditional probability and the difficulty of deducing an accurate distribution in theoretical way,the new segmentation approach based on MRF and SVM posteriori probability is proposed.Support Vector Machine is a set of related supervised learning method,it is a classification technique based on the structural risk minimization principle and it maps input vectors to a higher dimensional space where maximal separating two parallel hyperplanes are constructed.An assumption is made that the larger the margin or distance between these parallel hyperplanes the better the generalisation error of the classifier will be.However,in the pattern recognition practice,people need soft decision,that is to say,not only gain class label which the sample belongs to,but also obtain the membership degree of sample in each class label,that is posteriori probability of sample.The new segmentation algorithm proposed by the paper follows three steps.Firstly,the paper adopts the Platt’s method to obtain the posteriori probability by mapping the output of SVM decision-function after training.Secondly,it converts the conditional probability estimate into posteriori probability estimate in terms of Bayes formula,and then proposes a new segmentation method which depends on MRF model based on posteriori probability.Finally,it brings the information of posteriori estimate into MRF model,thus the posteriori probability based on SVM is combined with MRF in the application of image segmentation.Two experiments has been conducted,one is that the paper selects twelve texture images from Brodatz standard texture database to make up some merged texture images.The number of training samples in each texture class is 30 and eight features are used to characterize each texture sample.The results of three group segmentation experiments all show that the new method appears preferable to Gaussian MRF method.The other experiment is that the synthesis texture image is composed by SAR texture images,SAR images do not fit for Gauss distribution,as a result,Gaussian MRF method results in high misclassification rate and low robustness.On the contrary,the proposed algorithm depends on the information of posteriori probability estimate based on SVM without the hypothesis of sample conditional probability,so it achieves a higher level of robustness and segmentation results demonstrating its efficiency.关键词：Markov random field;SVM;posteriori probability;texture image segmentation
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发布时间：2021-06-10 - 摘要：Since primitive line segments extraction is an important procedure,how to select the proper line segments extraction approach is the key to the extraction of linear object of SAR images.This paper first briefly reviews three existing methods: Radon technique,the Burns line detector,the line detector based on template matching.In the Radon Transform methods the transform is applied to each sets of the connected pixels,the relative maximum in the transform corresponds to possible lines in the binary image.In order to reduce inter-edge influence,after extracting the possible primitive line segment,only the line associated with the maximum Radon coefficient is inspected at each iteration instead of continuing and proceeding with the next relative maximum.This process is recursively repeated until the maximum Radon coefficient reaches a minimum value.In Burns line detection method,edge pixels are first determined by convolution with two simple 2×2 masks.The pixels are grouped into line-support regions of similar gradient orientation.The intensity surface associated with each line-support region is approximated by a planar surface.Straight lines are extracted by intersecting this fitted plane with a horizontal plane representing the average intensity of the region weighted by a local gradient magnitude.In the method based on template matching,each edge pixel is given a line label based on certain templates in the first step.The result of this step is that edge pixels that lie on the same line get the same line label.Furthermore,corresponding to each line label,a complete description of the line is obtained.In the second step,these lines are further linked based on certain criteria.While an extensive literature exists on the problem of PL extraction,most of the researches only give qualitative analysis of the behavior of PL extraction,made by a visual comparison of different results.To provide a solution,in this paper we propose a set of quantitative evaluation metrics to determine how many lines are correctly extracted.The basic idea is to compare the extracted PLs with the lines in the ground truth data,thus the performance of the PL extraction can be showed through a series of performance metrics.We consider in this paper three categories of performance metrics,namely,a) pixel-based metrics,which are composed of completeness,correctness,quality,and ROC curve;b) line-based metrics,which are composed of the percentage of the extracted lines and mean number of PLs per line,c) computational complexity.To correctly compute these quantities,we first need to define when a line may be considered as extracted,and then manually extract the start and end points of the center line of each line in the test image as a reference.In summary,the paper studies approaches of primitive line segments extraction,presents a series of quantitative performance evaluation measures and evaluates these three methods.The proper line segments extraction approach for linear object extraction can be selected based on the evaluation results.关键词：SAR image;primitive line segments extraction;linear object extraction;quantitative performance evaluation
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发布时间：2021-06-10 - 摘要：In this paper,we propose a novel semi-automatic ribbon road extraction scheme which combines angular texture signature and profile matching.The angular texture signature was proposed by Haverkamp in 2002 for extracting straight road structure from IKONOS satellite imagery.In this method,a rectangular template region rotates around a specific point with certain angle intervals,and computes texture signature of all points in this template region at each position of rotation.The basic texture signature is variance and the entropy also to be tested in this paper.A profile means that in the centerline points,perpendicular to the direction of the road,we paint a straight line segment,and extract gray values of various points along the line segment.And the straight line segment should be longer than the road width. Profile matching calculates the least square values between profile line model and the profile in the predicted points.To a certain extent,we offset the profile in the predicted point of and calculate values of at the least square each offset position,we believe the corresponding offset with the minimum value should be possible point of road centerline,therefore,the final road centerline can be determined through predicted points and the offset least square values.In the scheme,user inputs the initial position,direction,and width of the road firstly.The initial road centerline points are predicted based on angular texture signature,and road center trajectory model is created using parameters of parabola.The multiple linear regression method is used for acquiring the road trajectory parameters,and we utilize these parameters and the initial centerline points coordinates to compute the initial mean of the curvature.Then we make use of the method of curvature change to verify the points in trajectory.By comparing the value and the given threshold,we’re got following conclusion: if it exceeds the limit,the verification fails,a profile matching algorithm will be used to re-predict and decide the position of center points again;if the value doesn’t exceed the limit,the verification succeeds,we believe the centerline points predicted in angular texture signature is the final position.In the algorithm,the manual intervention is necessary especially for complex situation.After the verification,we can achieve the final centerline points and add them to the trajectory.If these two algorithms both fail,we could decide the final centerline point completely manually.In this paper,we implement the above mentioned scheme and build a prototype system using Visual C++,and verify the extraction result of ribbon roads with appropriate width in QuickBird and IKONOS imagery.In the experiment 1,the road has uniform texture,and the contrast to background is obvious,but no obvious obstructions on the road.In this situation,the scheme extracts the whole road automatically without any manual intervention.In the experiment 2,the ribbon road extraction from IKONOS is generally successful and need a few manual intervention.In the experiment 3,a rather complex situation with several roads in an digital aerial image,we extract the main roads automatically and some junctions of the roads needs semi-automatic extraction,but the final result is satisfactory.We also utilize experiments to compare our scheme with traditional profile matching semi-automatic extraction algorithm and Snakes algorithm.After these experimental verification,it proves this semi-automatic ribbon road extraction scheme can achieve good results.关键词：semi-automatic road extraction;angular texture signature;profile matching;combined model
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发布时间：2021-06-10 - 摘要：Recent progresses in airborne light detection and ranging（LIDAR） technology allow rapid and inexpensive measurements of topography over large areas.This technology becomes a primary method for generating high-resolution digital terrain model（DTM） that is essential to numerous applications.LIDAR techniques represent a new and fruitful approach in the determination of digital surface model.LIDAR systems usually return a three-dimensional cloud of point measurements from reflective objects scanned by the laser beneath the flight path.One of the goals in processing LiDAR point cloud is to set up filtering methods in order to extract the digital terrain model automatically.There are a lot of methods of extracting DTM from LiDAR point cloud,but removing nonground points is still a challenging task.In order to generate a DTM,measurements from nonground features（buildings,vehicles and vegetation etc.） have to be removed.Mathematical morphology is based on set theory to extract features from an image and fits for signal analysis.It has been demonstrated that operation opening can remove objects on ground（vegetations,buildings,etc.） from LiDAR point cloud and reserve objects larger than structuring element.To find out a proper structuring element is very difficult.The larger window size of structuring element would over filter DTM and the smaller window would not filter all nonground objects.All nonground objects could be removed by one time opening operation theoretically if the structuring element is appropriate.Unfortunately there is no such structuring element in reality because of the complexity of terrain surface.This can be resolved by gradually increasing structuring element,which can filter objects on ground,but some terrain measurements also have been filtered at the same time.This results in too flat on terrain surface and the extracted DTM is lower than the real.In this paper,a restricted filter method is developed to solve the terrain details loss caused by over filtered.The overall process starts from an initial set of points,then gradually increases the structuring element which is restricted with elevation difference thresholds at the same time.Elevation difference threshold is set by undulation of terrain,and it can control result.The ratio of elevation difference of before and after opening to structuring element window size is k,which represents undulating grade.The larger the value of k is,the steeper the area is,and vice versa in order to reserve the terrain details,the threshold of k is set k0.Result value of filtered remains invariable when k<k0 otherwise equals result value of opening.This procedure iterates while the window size of structuring element gradually increases.The times of iteration are determined by window size of and increasing style.The different size of nonground objects（vegetation,building etc.） are filtered by iteration and the details could be reserved.The feasibility and validity of the method is demonstrated with an example data of airborne laser scanning system developed by China.The results show that the filter can remove most of the nonground points effectively.关键词：DSM;DTM;mathematical morphology;airborne laser scanning
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发布时间：2021-06-10 - 摘要：There are many features used to distinguish target from clutter in Synthetic Aperture Radar（SAR） target detection,such as amplitude feature,polarimetric feature,azimuthal feature,multi-resolution feature.There are many reports about the first three features,but there are very few reports about the development of multi-resolution feature.The approaches proposed in concerned references are effective to improve the performance of SAR target detection.But most of them discuss the multi-resolution feature for target detection of high-frequency SAR,so the proposed approaches are commonly suitable for the target detection of high-frequency SAR.Ultra-Wide Band Synthetic Aperture Radar（UWB SAR） can be used to detect the concealed targets because it works at low-frequency,and the corresponding detection background is the strong clutter produced by trunks.The application of multiresolution feature in UWB SAR target detection are analyzed,and the approaches suitable for UWB SAR target detection are proposed.In this paper,we establish the equivalent models of target and trunk clutter in UWB SAR images according to electromagnetic scattering theory based on the particularity of UWB SAR operation system.The differences between target and trunk clutter under different multiresolution are analyzed from UWB SAR image.The analysis supplies a key basis for the extraction of multiresolution feature in UWB SAR images.Two forms of first-order Auto-Regression（AR） model are used to deal with the multiresolution sequences.In the first AR model,we discuss its statistic distribution of residual to represent the differences between target and trunk clutter.In the second AR model,we discuss its statistic distribution of coefficient to represent the differences between target and trunk clutter.In two forms of first-order AR model,the corresponding definitions of Generalized Likelihood Ratios（GLR） are given.The definition of 2-D GLR is proposed based on two forms of AR model.The performance of the 2-D GLR is more robust in the multiresolution feature extraction because it integrates two forms of first-order AR model.The three steps of 2-D GLR calculation based on UWB SAR image are given: 1) generating multiresolution image sequences,2) training statistic model,3) calculating 2-D GLR.The multiresolution feature extraction experiment is accomplished in an actual UWB SAR image for the two 1-D GLRs and the 2-D GLR proposed in this paper.The results of the experiment show that the multiresolution features corresponding to the proposed three GLRs can all be used to improve the signal-clutter ratio（SCR） of the original image effectively,and the performance of the 2-D GLR is better than the two 1-D GLRs.关键词：UWB SAR;target detection;multiresolution;Auto-Regression（AR）;generalized likelihood ratio（GLR）
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发布时间：2021-06-10 - 摘要：Remotesensing image segmentation is the process to divide the image into regions with different features and extract the object through segmentation,which will probably be used into the next processing step.Remotesensing image segmentatian is an important step from image processing to image analysis.In recent years,segmentation of remote sensing images plays the most important role in the interpretation of remote sensing images,but there is no reliable model to guide the remotesensing image segmentation.Markov Random Field（MRF） has been extensively applied in segmentation of images as priori probability model,and in fact,this method can be applied to improve the result of segmentation of images.Influenced by environment and the sensor,remote sensing images with complex texture,large brightness range and vague bridge boundary,can not be apt to use the standard MRF,and the result of segmentation of remote sensing images using standard MRF is not satisfactory.Therefore in remote sensing image segmentation,the algorithm using classic MRF is often inefficient.Aiming at ambiguity in the segmentation of remote sensing images,the Fuzzy Markow Random Field（FMRF） is put forward in this paper.Framework in segmentation algorithm based on FMRF is proposed.The method solves problems resulting from randomicity and fuzzability and gets the priori probability model reasonably,simultaneously,adds the gray feature and the texture feature into the segmentation model in order to get more accurate result.In the past,the techniques in fuzzy segmentation focused on the gray feature of image,so there are obvious defects with these techniques in multi-level classification.Under the Maximum a Posteriori Principle（MAP）MRF framework,we extract gray and texture features.We develope models respectively with their features.The experiments show that it is efficient to multi-level images.Finally,there are less parameters used in this method,however,segmentation needs ability to learn parameters and to realize unsupervised image segmentation. We apply the simulated annealing（SA） and expectation-maximization（EM） algorithm to estimate unknown parameters and get the global optimal solution.The segmentation experiments of SAR images demonstrate that the proposed algorithm is more efficient to distinguish interlaced edges and restrain the speckle noise than the algorithm of the Fuzzy C-Mean FCM and standard MRF.We apply algorithms that are mentioned in this paper to SAR images segmentation with VC++ 6.0,and compare indicators of segmentation by different algorithms.关键词：fuzzy markov random field model;gibbs distribution;image segmentation;EM
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发布时间：2021-06-10 - 摘要：This paper presents a bottom-up approach to improve the classification performance for remote sensing applications.Top-down approaches,such as statistical classifiers,have inherited limitations in dealing with complicated relationships in classification.For example,data correlation between bands of remote sensing imagery has caused problems in generating satisfactory classification with statistical methods.In this paper,ant colony optimization（ACO） based on swarm intelligence is used to improve classification performance.Actually,ACO is a complex multi-agent system,in which agents with simple intelligence can complete complex tasks through cooperation such as classification problems.Ants guide their route selection based on pheromone,which is accumulated from the collective movements of individual ants.In this way,an ant learns from the past experience of others.Ant-Miner is different from decision tree approaches.The entropy measure is a local heuristic measure,which considers only one attribute at a time,and so it is sensitive to attribute correlation problems.Whereas in Ant-Miner,pheromone updating tends to cope better with attribute correlation,since pheromone updating is directly based on the performance of the rule as a whole.Thus,Ant-Miner should have great potential in improving remote sensing classification.In this study,an Ant-Miner program for discovering classification rules is developed for the classification of remote sensing images.In the Ant-Miner program,the route search by an ant colony is to find the best links between attribute nodes and class nodes.An attribute node corresponds to a band value of remote sensing images.An attribute node can only be selected once and must be associated with a class node.Each route corresponds to a classification rule,and discovering a classification rule can be regarded as searching for an optimal route.To enable ACO to effectively classify remote sensing imagery of very large data sets,original band values are sliced into a number of intervals by using a discretization technique.The ACO method is more explicit and comprehensible than mathematical equations.Our study in Guangzhou city indicates that the ant colony-based classifier yields better accuracy than conventional maximum likelihood classifiers and decision tree classifiers.The overall accuracy of the ACO method is 88.6%,with a Kappa coefficient of 0.861.The decision tree method has an accuracy of 85.4% and a Kappa coefficient of 0.822.The maximum likelihood method has an accuracy of 83.3% and a Kappa coefficient of 0.796.The results clearly support the conclusion that the method explored in this paper can be more effective than conventional classification methods.关键词：ant colony optimization;remote sensing data;classification;artificial intelligence
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发布时间：2021-06-10 - 摘要：The GVG crop sampling instrument is an integration system based on GIS,and is made up of GPS receiver,Video capturing.It has been applied in the field of the crop yield estimation widely.The authors verified accuracy of the representative of the GVG sampling lines in a test ground with an area of 5km×5km in Gong’an County,Hubei Province.The map of land plot in the experiment area was drawn out based on land use map and high resolution satellite image-SPOT5.The crop area proportion of each land plot was investigated and marked on the map of the land plot,and then the true proportions of the crop in the experiment area were worked out.Four types of the sampling lines were set up in the experiment area.They were freeway,national road,provincial road and countryside road.The GVG instrument was used to sample the crops based on the sampling lines,and then the crop proportion of GVG were obtained.The buffers of 200m,500m,800m,and 1000m of each sampling line were set up and the true crop proportion of the buffers were obtained based on GIS.The representative of the sampling lines was verified by comparing the true values with the experimental values.The results showed that the sampling lines of freeway and countryside road had the best accuracy greater than 95%,the national road took the second place with an accuracy of 86.726%,and the provincial road was the worst with an accuracy of 65.447%.Among all the buffers,the 200m-buffers of the freeway,provincial road and countryside road had the best representative,and it matched the buffer of 100—200m as we designed the GVG system.But the best of the national road is the 800mbuffer.As for different crops,no matter what type the sampling line or buffer is,the accuracy of the cotton was the best,the lowest was the 1000m-buffer at the type of the provincial road sampling line with the accuracy of 78.146%,and the best was the 800m-buffer of national road with the accuracy of 99.974%.All the accuracies of the sampling lines were over 94.8%,except the provincial road.It showed that the GVG instrument has a very good representative for the dominant crop-cotton which had the highest accuracy to each buffer in every sampling line.关键词：GVG sampling line;buffers;representation;verification
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发布时间：2021-06-10 - 摘要：This paper proposes an approach of modeling with a permanent-scatterer（PS） network（MPSN） based on the neighborhood differential idea,aiming at effectively and reliably detecting both linear and nonlinear ground deformations and estimating atmospheric effects by differential synthetic aperture radar interferometry with permanent scatterers（PS-DInSAR）.Firstly,the triangular irregular network（TIN） of PSs is generated based on the PSs’ image coordinates.Deformations are correlative both temporally and spatially,but atmospheric delays are only correlative spatially.Furthermore,the shorter the intervals of space and time series are,the more the correlations of deformations and atmospheric delays will strengthen.So the phase difference of neighboring PSs can depress the atmospheric influence.Then the neighboring differential phase model（NDPM） is constructed based on the neighborhood of PSs among the TIN,and the corresponding set of neighboring differential phases is generated.What are unknown in NDPM are residual elevation difference Δhij and mean velocity difference Δvij between two neighboring PSs i and j.Secondly,the TIN is twice optimized according to distance（<1km） and multi-image phase coherence（γ） between two neighboring PSs,and the neighboring differential phases hardly influenced by atmosphere delays are selected to resolve the NDPM by using a simple periodogram,i.e.to estimate the residual elevation difference Δhij and the mean velocity difference Δvij between two neighboring PSs i and j.After the estimation of Δhij and Δvij,the elevation Δh and the mean velocity v of every PS are respectively calculated through network adjustment based on the optimized TIN.Finally,the PS’s phase residue Δres can be calculated.Then the temporal and spatial correlations of deformations and atmospheric delays are taken into account again,and the appropriate filters are selected to discriminate the following phases from phase residue Δres,（1）PS’s atmospheric phases in differential interferograms,（2）PS’s atmospheric phases in SAR images,（3）PS’s no-linear deformation phases.A set of computer programs are developed in Matlab environment to implement the above approach.Lujazui in Shanghai is selected as the study site,and the experiments are performed using 26 SAR images taken by ERS-1/2 from 1992 to 2002 to estimate linear motion rate,nonlinear motion magnitude,total deformation distribution,and atmospheric delay for each SAR image.The obtained measurements are very consistent with the ground-based measurements.Based on modeling with PSs’ TIN,the neighboring differential phases hardly influenced by atmosphere delays are selected to resolve the NDPM.The results are more reliable and precise.The experiment results show that the proposed modeling and methods are viable,and the computation software is reliable.关键词：DInSAR;permanent scatterer;Modeling;deformation;atmospheric influence
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发布时间：2021-06-10 - 摘要：Sea surface salinity（SSS） is a very important parameter of ocean’s circulation and global meteorological and climatic predictions.Salinity data will permit estimates of sea surface density,or buoyancy,which drives the ocean’s three-dimensional circulation.L-band（1400—1427MHz） microwave radiometer is the most effective remote sensing tool of SSS measurement.In L-band,the sensitivity of radiometer brightness temperature variations associated with salinity is 0.5K/psu.Since a salinity change of 0.2psu results in a brightness temperature change of 0.1K,it is necessary to have a microwave radiometer with sensitivity of better than 0.1K.Highsensitivity airborne L-band microwave radiometer uses digital auto-compensation methods for gain-fluctuations and environment temperature variations,and 6-th Chebyshev high effect filter to reduce GPS interference which helps its sensitivity surpass 0.08K.The antenna with dimensions of 1m×1m belongs to microstrip type,antenna 3dB beamwidth is 15°,nadir incidence angle is 35°,and its weight is about 15kg.The antenna gain is 20 dB and side lobe level is lower then-17dB.In September 2005,the aircraft remote sensing measurements were carried out.The L-band horizontl and vertical polarization signals were recived simultaneously.The cross-polarization isolation is ≥30 dB.The microwave radiometer was fixed on CMS3807（Y12 mode） aircraft over flat sea surface conditions at 122°50′E,39°30′N—39°6′N.During the experiment,sea surface salinity were detected on a ship when aircraft was flying in same area of the sea at the same time.The experiments were compared with site test on the sea.The results of these measurements are presented in this paper,with the resolution of better than 0.2psu and the accuracy of 0.42psu.关键词：high sensitivity;Microwave radiometer;sea surface salinity remote sensing;gain-fluctuation compensation;temperature compensation
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发布时间：2021-06-10 - 摘要：The activities of mining produce great heavy metal pollution which threatens the surrounding ecosystem and human’s health,the heavy metals can be transported to the surrounding soil,river and underground water.The heavy metal’s stress to the biology can cause the variation of plants and community,which is called biogeochemistry effects.The excessive copper impedes the growth and development of vegetation,such as greenness decreasing,photosynthesis weakening,and the absorption capacity of other elements decreasing.The leaves of the vegetation lack water and get withered,so the spectral characteristics change with the influence of the stress.Dexing copper mine is an oversize multi-metal mine bed in our country.The development of mining has caused the pollution of mine environment,such as the ecologic problem in mine vegetation,land,water and the heavy pollution of solid waste and tailing water,particularly,the pollution of heavy metals such as copper.These problems have influenced the growth of vegetation greatly.This paper studies the heavy metal contamination and the biogeochemistry responses of vegetation Rhus chinensis Mill in Dexing copper mine area.The spectral characteristics of the responses are systematically extracted and analyzed with the principles and methods of remote sensing biogeochemistry.Acid,Cu,Cd are the main environmental pollution factors,the copper content in the soil is much more than the national environment standard and the pH value of the water in the lower reaches of the river is about three over the year.The plant Rhus chinensis Mill has enriched and translocated responses to copper,this plant is suitable for the environmental recovery which is one of the main vegetation and grows well in the area.From spectral processing such as derivative technology,continuum-removed spectra,red edge,vegetation index,we can get that the spectral position effects are notable to the influence of heavy metals.With the increasing of the influence of heavy metal stress: （1） the spectral reflectance of Rhus chinensis Mill increases obviously,about 5%—30%,（2） spectral shape blue-shift occurs,about 5—15nm,（3） the red edge slope increases,from 4.5534 to 8.9475,the variation is up to five,（4） the chlorophyll absorption depth decreases,the absorption center is near 680 nm and blue-shift,（5） the water absorption depth becomes lower and red-shift occurs about 10—20nm,（6） vegetation indices alter obviously,the ratio B4/B3 is from 18.763 to 13.1839,indicating the decrease of chlorophyll content in leaves,the WEI（water effect index） changes from 0.098014 to 0.226503,indicating the increase of intensity of water stress effect.Then some predominant characteristics are selected which are suitable for the evaluation of heavy metal pollution with the comprehensive analysis of spectral characteristics and the correlation between them and the contents of heavy metals.关键词：heavy metal contamination;biogeochemistry responses;spectral characteristics;Rhus chinensis Mill
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发布时间：2021-06-10 - 摘要：Pattern directionality is a key characteristic of landscape pattern,it both reflects and affects ecological flow within the landscape,and it is very important to realize fast and accurate auto-extraction of the pattern directionality information,especially for landscape heterogeneity analysis and driving forces analysis.Qian-an county lies in the northwest of Jilin Province in China,where the climate is characterized as temperate semiarid continental monsoon,the evaporation greatly exceeds the precipitation.Wind,especially the strongly prevailing wind in winter from northwest to southeast plays an important role in shaping some local landscapes.For most time of the year,the weather is extremely dry and the soil is sandy and uncovered.There are many lakes,known as Qian-an Group Lakes in Qian-an county.The lakes are typically small,and the water in the lakes is salty,seasonal and shallow,commonly about 1—2m deep.The lakes are mostly in the shape of a raindrop,with gently sloping lake beds in each lake’s northwest（the windward side）,and a steeply sloping lake beds in the southeast（the down wind side） with dune or loess piling up on this side.Wind is considered to be one of the most important forces driving the pattern formation of the lakes,i.e.,the current shape of the lakes is the result of windy erosion upon the tectonic basins.In order to provide a quantitative and visual basis for the above mentioned conclusion conveniently and objectively,based on object-oriented method Qian-an Group Lakes are extracted by multi-resolution image segmentation from Qian-an TM image.To achieve the high classification accuracy,a perimeter-area shape complexity metric called the Square Pixel Metric（SqP） is used,then vector analysis theory on landscape pattern（VATLP） is applied to the homogeneous objects to extract vector information of group lakes.Where,vector analysis theory on landscape pattern（VATLP） is developed by Shuqing Zhang et al.（2006） based on planar characteristics defined in mechanics such as centroid,moment of inertia,product of inertia and principal axes,and its application helps us better understand the pattern formation of the lakes and the related ecological processes that occur on both ends of the major principal axis,e.g.,the transportation of energy and materials flow,and the ecological gradients.The experimental results show that our method achieves the high segmentation accuracy（producer’s accuracy: 97.8%,user’s accuracy: 97.5%）,and extraction of directionality information is accurate and convenient.This can establish the groundwork for the further geographic analysis.This paper offered two-aspect idea: one is the use of landscape pattern metrics in image classification,the other is the further application of vector analysis theory on landscape pattern （VATLP）.关键词：multi-resolution segmentation;vector analysis theory on landscape pattern（VATLP）;vector index on landscape pattern;landscape orientation
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发布时间：2021-06-10 - 摘要：Sea surface temperature derived from NOAA/AVHRR and chlorophyll-a derived from MODIS and SeaWiFS as well as QuikSCAT wind vectors data during summer（from May to October） in 2004 have been used to investigate the short-term variability of upwelling events in Zhejiang coastal areas.Short-term observations of satellite images during summer of 2004 have revealed two upwelling zones in the study area.The upwelling near Zhejiang coastal areas is located at 29°—31°N,121.5°—123°E,with the upwelling core near 30°N,and the upwelling near Yangtze River estuary is located at 31°—32°N,122.5°—124°E,with the upwelling core near 31.5°N.These areas are noted for their high fisheries production.Upwelling looks like a long tongue in shape in Zhejiang coastal zones,the sea surface thermal front exists obviously in its southeastern edge.The temperature difference between the upwelling and non-upwelling areas is about 3—4℃ for July;the low temperature in the study area is about 24—27℃,with a mean value of 25℃;the size of upwelling is about 1000016000 km2,with a mean value of 13690 km2.The seasonal variability is obvious in 2004,upwelling started to appear in June and achieved powerfully in July and August,it assumed the weaken ed tendency until vanished in September.Chlorophyll-a data of MODIS-derived and SeaWiFS-derived showed that high Chl-a areas coincided with low SST areas in terms of location,time and shape.The relationship between upwelling intensity and sea surface wind field is analyzed by using AVHRR SST and QuikSCAT wind field,the result shows that the variations of sea surface wind speed as well as wind direction coincide with the variations of upwelling,which indicates the southwest wind alongshore off Zhejiang coast is an important factor for the variations of upwelling.关键词：Upwelling;Zhejiang;AVHRR/SST;Chl-a;QuikSCAT wind field;satellite remote sensing
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发布时间：2021-06-10 - 摘要：Geo-info Tupu methodology is a new explored direction for geography,and it’s not only a way for presentation but also a method of analysis in geo-information science.Mountain altitudinal belts（MABs） are distributed at different elevations in high mountains,mainly owing to varying climatic conditions as altitude increases.The MABs is combined in various vertical "spectra",and is the representative Geo-info Tupu because of its characteristics,but its data sources and presentation patterns are limited by the classical research methods.It is difficult to deal with altitudinal belts and to illustrating their patterns at different scales with traditional techniques.In this paper,we discuss the digitalization and visualization of the MABs with a view of fulfilling the identification of the MABs in the way of computerization.Based on the idea and system of Geo-info Tupu and digital mountain altitudinal belts,this paper discusses the digital identification method of the MABs and constructs feasible technical programmes.The data sources of the digital identification of the MABs are vegetation maps,and the products of our arithmetics would be distribution patterns of altitudinal belts.The paper provides two models of digital identification for the MABs at different geographical scales,such as the single flank pattern and the single peak pattern.We have fulfilled the digital identification of the MABs in the northern flank of the Kunlun Mountains with the arc macro language（AML）,and the result responds to the structure-thinning model which has been validated by some scientific reports.The arithmetic of single flank is applicable in the long and narrow mountain system,which could provides the general information and distribution patterns of the altitudinal belts.The paper also shows our efforts in the digital identification of the MABs in 360°aspects by using Matlab programme.This method of identification provides the single peak pattern of the MABs relative to the single flank pattern.It helps us develop the object-oriented software because this arithmetic has its capability in flexibility and speed,especially used in large areas.In addition,the paper briefly introduces the potential capabilities of the Matlab programme which could resolve the problem of identifying the upper and lower limits of the MABs.By comparing the two methods,we indicate the relative merits of the different techniques in digital identification and Tupu visualization,and show clearly their spatial scale for the study regions.The MABs from the digital identification have an agreement with those from the field notes in the Daqing Mountains,and the accuracy of the MABs from digital identification is decided by the original vegetation maps.In other words,the digital identification of the MABs is a process of data integration and information digging without appending unnecessary information.If we obtained more refined vegetation maps as from higher resolution images,we could enhance the accuracy of the MABs to a more satisfactory degree.The study reveals that the digital identification of the MABs could enrich the source materials of mountain researches and enhance the digital comparison and analytic methods of the MABs.The digital identification models of altitudinal belts could potentially help standardize the understanding of altitudinal belts and their relation to various environmental factors.And it also could reveal more geographical information than ever before and is an effective attempt for Geo-info Tupu practices.关键词：Mountain altitudinal belts spectra;digital identification;Geo-info Tupu;GIS
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发布时间：2021-06-10 - 摘要：In the program of geolocation with environmental meteorological satellite,the earth location software makes use of earth ellipsoid and terrain surface data in conjunction with satellite orbit parameter and geometry attitude,and information of the sensor and satellite geometry to compute data including geodetic longitude and latitude coordinates,height,ground to satellite direction vector and range,and solar vector.The satellite orbit propagation model and the mathematical procedure which intersects the sensor’s line of sight with the terrain surface of the Earth are most important in the program.In order to meet the requirement of high precision geolocation for environmental satellite remote sensing data,we have developed a new generation orbital motion forecast and remote sensing geolocation software system.This system is based on the variable order,and stepsize orbital motion numerical integration model（DE/DEABM）,and is different from conventional Brouwer perturbation analytical model.During the research of this system,we have studied variety of perturbations that affect orbital motion.These perturbations are pronounced for satellite at low altitudes.We use high order precise EGM-96（Earth gravity model） data to improve computing precision of perturbation for asphericity of the Earth.What we put into consideration also includes the perturbation that arises from the gravitational attraction of the Sun and the Moon,solar radiation pressure and atmospheric drag in our works.As case studies,we develop Earth location algorithms and software for two sensors,one is FY-1D VIRR launched on May 2002,and the other is FY-3A MERSI which will be launched in early 2008.In the progress,we analyse details of the optics geometry coordinates relationship of detector,focal plane,main optics system and scan mirror,which are key parts of sensors.As a result,the precision of coordinates transformation model have been developed in this software.After several days of data computing of orbital motion and Earth location test for FY-1D VIRR,we find that the precision of the new software system reaches the range from centimeters to meters.It is a great improvement compared with the 1km precision of old perturbation analytical method.Overall,it is found that the software system of FY-1D VIRR can provide navigation accuracies of within 1 km at nadir.关键词：FY-1D satellite;orbit numerical integration model;satellite remote sensing data geolocation
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发布时间：2021-06-10 - 摘要：In this study,we try to improve the understanding of polarization of signal reflected by water surface and within water body for which an accurate knowledge is necessary in remote sensing applications.Polarized characteristics of the reflected light above water surface and the scattered light in water body together with their applications in ocean color remote sensing are reviewed.Elimination of the sunglint and skyglint,and inversion methods of polarized ocean color remote sensing are summarized in detail.polarization of sunglint reflected by the sea surface is routinely used to extract information in remote sensing studies,such as oil spill detection and remote sensing of sea state.The first and foremost thing is to eliminate reflected light from water surface radiance for remote sensing of subsurface material. The scope and limitations of the efficiency of Brewster’s angle technique in eliminating reflected light from water surface radiance is discussed for both flat and wind roughened sea surface.Several key problems are pointed out,including atmospheric polarization correction,vector radiance transfer calculation,calibration of polarization sensitivity of sensor and polarization characteristics of the incident source above water surface,the polarization of roughened airwater surface and water body.Some suggestions are put forward to improve the research of polarization information in ocean optics and ocean color remote sensing,such as development of predictive numerical models for polarized underwater radiance distribution and quantification of the relationship of Mueller matrix and the concentration of water quality parameters.关键词：ocean color remote sensing;polarization;Brewster’s angle;Sunglint
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发布时间：2021-06-10 - 摘要：Net primary productivity（NPP） estimation is an important study field of global change and terrestrial ecosystems（GCTE）.Many models used to estimate GPP and NPP have been established,such as CASA、Bio-BGC、BEPS、GLO-PEM,TURC,PSN and so on.Among them,the model based on light use efficiency（LUE） is very popular in estimating GPP and NPP at large scale,because it needs low computation cost,few bio-parameters and easy to be incorporated with remote sensing data.Therefore,estimating LUE accurately is valuable for both the ecological and global change studies.There have been several attempts to model seasonal variation of LUE,mainly as a function of air temperature,water vapour pressure deficit and soil water deficit.However,LUE’s variation with environmental conditions is very complex,it is interrupted by many factors such as air temperature,soil moisture,plant functional type,disease,nutrition condition,light intensity,light component,and so on.The existing models are either too simple to describe or lack reliability.LUE can be estimated directly by remote sensing,and it will be more desirable.A number of studies have revealed that photochemical reflectance index（PRI）,derived from narrow band reflectance at 531 and 570 nm,is related well with LUE in some conditions,which provides possibility in estimating LUE by PRI.Some studies have confirmed this relationship at leaf scale,canopy scale and landscape scale.Meanwhile,many studies have also found that the relationship between PRI and LUE is not robust enough,which is interrupted seriously by many disturbances,such as soil background,species composition,canopy structure,sun zenith,view zenith,atmosphere,and so on.Results from simulation and experiment both revealed that the relationship between PRI and LUE keeps well even under very strict condition,such as high LAI（leaf area index）,single specie and so on.Therefore,it still needs more research for wide application of PRI.This paper reviews the definition of PRI,physiological mechanism leading to the relationship between PRI and LUE,and introduced some case studies to establish the relationship between PRI and LUE through remote sensing.Then some disturbances at leaf scale,canopy scale and landscape scale were analyzed.In the end,a summary about achievements,existing problems and prospective studies are concluded.Although there are still many problems in estimation of LUE through PRI,a few studies have tried to conquer these problems and made some progress.They found that the relationship between PRI and LUE would be more robust by incorporating with other vegetation indices.
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发布时间：2021-06-10 - 摘要：The theory of map space cognition is a basis of cartography.The proposition that "map is a spatial cognitive tool of human being" is a basic proposition of the theory and cognitive map is its core conception.The theory of space cognition focuses on the essential methodology and principles of human being in the process of spatial cognition,so it is very meaningful to various scientists.This paper summarizes the cognitive map formation comprehensively.It proposes a framework of it,and discusses essential elements and supplementary elements of cognitive map.A series of cognitive experiments using paper maps,electronic maps,remote-sensing images and VGEs（virtual geographical environment） of small scale and large scale have been finished.While the scale was fixed,all these kinds of experiment data were in the same place in order to facilitate the comparison of the experiment results.This paper analyzes the results of each kind of experiment data.Conclusions of the analysis are: the cognitive effect of data of small scale from better to worse by order are paper map,electronic map,VGE and remote-sensing image;the cognitive effect of data of big scale from better to worse by order are VGE,remote-sensing image,paper map and electronic map;cognitive map formation based on reading is a process from whole to parts which differs from the formation based on personal experience;and the formations with data of small or large scales are different;the cognitive sketch map based on reading is a "spatial" sketch map which is guided by position and direction;supplementary elements of cognitive map are proved existing.关键词：map space cognition;cognitive map;electronic map;remote sensing image;virtual geographic environment
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发布时间：2021-06-10 - 摘要：Spatial cognition deals with the cognition of spatial properties of the world,including location,size,distance,direction,shape,pattern,movement,and inter-object relations.Mental map is the representation result of spatial cognition about such spatial characteristics of the real geographic world.It has the following properties: heterogeneously representing space,subjectively selecting objects,uncertainly locating entity,and inaccurately measuring scale.The mental map consists of discrete pieces,such as landmarks,routes and regions,which is determined by physical,perceptual,or conceptual boundaries.For the content organization,the pieces have multiple levels without complete connection revealed by patterns of errors.In order to represent and visualize this kind of map,special visualization methods are required rather than the traditional map.This study investigates some qualitative visualization approaches presenting three methods to represent mental maps focused on different contents.They are the schematic map representing road network cognition,the cartogram map representing the area distribution information cognition and the cybermap representing the topological cyberspace cognition.The schematic map is a linear abstractions of functional networks including roads,railways,shipping lanes and footpaths.The network representation clarifies the operational relationships and describes the topology in simplified form.The schematic map suits for representing network cognition because it closely mimics the way we store the road cognition information about our physical environment in our memory.The orientation and distance representation is coarse but the relative connection relationship is accurate.This kind of qualitative visualization focuses on the topological relationship which is important in our quickly searching for the navigation information.In our mind we also use the simple map to represent and to justify the spatial orientation and distance.In contrast,the traditional cartographic road map is difficult to get the navigation although it is accurate.The cartogram,also called value-by-area map is a type of graphic that depicts attributes of geographic objects as the object’s area.The value-by-area mapping technique encodes the mapped data in a simple and efficient manner.The attribute can be a country’s population,its literacy rate,or GDP.In our memory the important attribute usually gets a large image patch and the spatial relation distributes in a topological connection rather than accurate connection.We don’t care the exact spatial relation,object shape and orientation.The cartogram converts the background data to a visualization representation so that the attribute information is easy to recognize.So the cartogram map is adaptable to represent attribute information cognition.The cyberspace is defined as a computer-generated landscape,the virtual space of a global computer network,linking all people,computer and sources of various information in the world through which one could navigate.As the virtual space cognition tool,the cyber map provides the user with quick ways to access what he wants,to navigate the hit paths.It focuses on the topological information representation in virtual space cognition and navigation.This kind of map can be used to represent the cognition information about virtual space.Three qualitative representation maps have the same property that concerns on the topological information to describe the coarse cognition result in our mind.From the perspective of the map definition,the paper examines the measurement characteristics and proves that they have measurement properties at order scale level.关键词：spatial cognition;mental map;qualitative representation;geo-information visualization
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发布时间：2021-06-10 - 摘要：As a new field of visualization,knowledge visualization is to use maps,graphics,or images to construct and transfer insights and knowledge between at least two persons.In view of geovisualization,geographic diagram,geo-informatic Tupu,and visual analytics are cutting edge researches on visual and graphic representation and discovery of geographic knowledge.Thus,this paper focuses on the discussion of geographic knowledge visualization in terms of general knowledge visualization and geographic diagram.In the paper,the concept and characteristics of knowledge maps in geographic knowledge visualization are mainly explored according to the dual coding theory of representation of mental images,features of geospatial thinking,and need for supporting visual exploration of geo-knowledge.Geo-knowledge maps are defined as cognitive and abstract maps related to geo-problems,geographic spatiotemporal distribution,relationship of geographic factors,and so on.They should be fit for mental image representation and cognitive process,and helpful for human spatial memory,thinking and imagination to improve capability to handle geo-problems.Considering images like digital photos and remote sensing images,they all mimic the physical world in real life without any abstract contents of human thinking and reasoning.Therefore,this paper defines these mimic images as geo-information images which have differences from geo-knowledge maps that express human knowledge about the real world.Geo-knowledge maps have two kinds: weak and strong.Weak geo-knowledge maps have more objective,concrete,and mimic description,while strong maps are more subjective and abstract.Geo-knowledge maps have two classes: concept propositional maps and analogue diagrammatic maps.Concept propositional maps highlight verbal handling of geographic phenomena,while analogue diagrammatic maps represent geographic graphics and images.With regard to analogue diagrammatic maps,there are further four types: logic and topological similar maps,spatial structure similar maps,variable-relationship similar maps,and process similar maps.As a case study,a few of practical knowledge maps for supporting spatial planning of dam systems in watersheds are presented.
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发布时间：2021-06-10 - 摘要：The problem existing in current GISs is that they all use quantitative methods to store and retrieve spatial information.However,people usually use qualitative terms to describe spatial relations.Current GIS models are limited in their capacities of representation of spatial information about geographic space.If we want to ’translate’ natural languages about spatial information to formal languages which computers can understand,we must know how natural languages construct and understand spatial relations.The description of a spatial relation is the reflection of human’s cognition of spatial objects.It is not only affected by the topology and metric,but also affected by the individual characteristics of describers.To disclose the effects of culture and language on people’s perceiving and understanding of spatial relations,this paper first compared the syntactic expressions of spatial relations in English and in Chinese,then three human-subject tests about spatial relations between two linear geographic objects were conducted in two groups of people who are native speakers of Chinese and English: native English speakers were tested on English expressions;native Chinese speakers were tested on Chinese expressions;and native Chinese speakers tested on English expressions.The results of the tests were analyzed to find whether different groups of people have different understanding on the natural-language description of spatial relations between two linear objects.It was found that in some cases two groups of people have completely different opinions about the descriptions of spatial relations.Native English speakers have more extreme opinions of "strongly agree" and "strongly disagree" for every spatial relation determination,while native Chinese speakers have more moderate opinions.It indicated that cultures and languages might have effects on spatial cognitions.But when the same group of people were tested with different languages,the results showed there is no much difference,which indicated that when they read a description of spatial relation in English,Chinese speakers translated it to corresponding Chinese words and actually understood the meanings of those Chinese words,although the meaning of these two expressions are slightly different.It also suggested the corresponding words that we use to translate between two languages are actually not exactly the same.The experiments help us in discovering how people in different cultures and languages perceive and express spatial relations,so that we can build an intelligent GIS based on common sense of geography.关键词：spatial relations;natural languages;linear geographic objects;human-subject test
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发布时间：2021-06-10 - 摘要：In practice,vagueness is a common phenomenon of geographical features.The vagueness of a feature often comes from human conceptualization of the real world.Modeling of vague features will undoubtedly contribute to more precisely handling spatial knowledge.In recent studies,a number of theoretical methods have been employed to model vague features,where fuzzy set theory is in common use.Following that theory,the degree that an element belongs to a fuzzy set can be expressed by a number between 0 and 1.We can thus establish a corresponding membership function（MF） for a fuzzy set.Recently,much literature focuss on vague features and proposes approaches to establish corresponding MFs.They include approaches based on cognitive experiment,remotely sensed data and GIR（Geographical Information Retrieval）.Due to the subjectivity of vagueness,spatial cognitive experiments provide a direct way to represent the vagueness of individuals’ conceptualization of corresponding features.However,previous methods based on cognition cost highly and are somewhat hard to control the result,since subjects in such experiments are asked to delineate boundaries of vague areal objects.Landmarks play an important role in individuals’ development of spatial cognition.It is thus relatively easy for individuals to perceive a landmark and decide whether it is within a given region or not.In this research,we took Zhongguancun in Beijing city as an example,since it is complex with different meanings,such as educational,political,and historical meanings.A questionnaire is designed to collect membership degrees of 30 landmarks which are in the region of Zhongguancun.These 30 landmarks,which are selected from the maximum potential region corresponding to Zhongguancun,can be abstracted to point features.They belong to different types,such as office building,hotel,school,recreation place,and natural feature.For each landmark,the subjects are asked whether it is within Zhongguancun,for which three optional answers are provided: YES,NO,and NOT SURE.By collecting all answer sheets,we can compute a score of each landmark.Such a value can be viewed as the membership degree that the corresponding position belongs to the concept of "Zhongguancun".However,since Zhongguancun is a two-dimensional vague object,it should be represented by a membership function（MF） like z=f（x,y）.We thus need to find out an appropriate interpolation method to obtain the MF.In this research,support vector regression（SVR） is adopted to compute the MF.Compared with conventional interpolation methods,such as IDW（Inverse Distance Weighted） method,the proposed approach is easy to implement and the results are convenient to be managed.Additionally,SVR provides a mechanism to obtain a trade-off between goodness of fit and generality by adjusting some parameters,such as γ for radial basis kernel functions.Based on the result of membership function,we also investigate spatial distribution properties of Zhongguancun and find out some interesting points.Since Zhongguancun has been viewed as "the silicon valley in China",it is closely related with such concepts as high-tech industry,university,and so on.Consequently,the landmarks associated with these concepts always have higher membership degrees.On the contrary,lower scores are assigned to some recreation places and natural features.In summary,from a point of view of behavior,the current concept of Zhongguancun is far beyond the scope as an administrative unit,both spatially and functionally,since many factors influence its internal representation of individuals.关键词：spatial cognition;vague geographical features;support vector regression;Zhongguancun
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发布时间：2021-06-10 - 摘要：Geospatial cognition is an important theme in the field of geo-information science and the study on it has sprung up since last century.In 1995,the report of Advancing Geographic Information Science was published.It put forward three important study fields,including the geospatial cognitive mode,geography concept mathematical method,geo-information and social study.In 2001,the geospatial cognition as a preferential sustaining project was supported by the committee of national natural science fund in China.Based on similar studies both at home and abroad and theories of geo-information science,psychology and tourists’ behavior,its study system has been shaped.The paper discusses the basic process and characteristics of tourists’ geospatial cognition,as well as the effect of tourist’ spatial cognition based on different geospatial forms.It aims to solve study difficulties of tourist’ cognition and tries to build the cognitive mode.In practice,the paper aims to help expression of geo-information,tourism resource development,tourism planning,products and design of traveling routes and tourism marketing.The data of this study came from field research about cross-bound tourists & domestic tourists in 1997—2005.The field research included what cognitive results of tourists was influenced by forms of different geospatial information and which was the emphasis of geospatial cognition.6353 questionnaires were totally obtained.Through statistical method and theory analysis,the research shows that the tourist’ geospatial cognition is mainly focused on the spatial characteristics perception,the spatial object cognition and the spatial pattern cognition,especially in distance cognition,direction cognition,scenic areas cognition and geospatial patterns cognition.The geospatial cognition takes place in cognitive space.As special group of people,tourists have different geospatial cognition compared with other people.The spatial characteristics perception is affected by tourism and geography environment.The spatial object cognition of tourists is determined by tourism elements,such as hotel,restaurant,traffic,shopping,amusement;Tourists pay more attention to cognitive distance.So the distance cognition is mainly determined by time;Tourists cognitive direction by the mode of typical land mark and different topological relation.The cognition of scenic areas is mainly based on tourists’ psychological image.Long-distance tourists make decisions according to the mode of the cultural difference,whereas medium and short distance tourists adopt the mode of functional difference.The cognition of tourist geospatial patterns is an integration of tourism functional features,spatial objects and perception of regional geographical features.Our current goal is to develop a geospatial cognitive mode of tourists.It can be used for expression of geo-information and design of tourism routes.A key aspect of this work is the field research and geospatial cognition type of tourists.The geospatial cognitive mode built,but the mode frame needs to be increased further.Other methods would be used for different tourists.关键词：tourist;geospatial cognition;mode;cognition map
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发布时间：2021-06-10
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