2014 Vol. 39, No. 8
Objective Geographic information technology is evolving from a Geographic Information System to aGeographic Information Service,given the increasingly widespread use of the Internet.Not only aregeospatial data and information shared online,but also geospatial knowledge is disseminated via theInternet.Geosciences'rules,models,and processes can be registered to the web,and provided to va-rious users through geospatial knowledge web services based on the Internet.In this paper,the back-ground for this transition from geospatial information to geospatial knowledge services is introduced,and key concepts of geospatial knowledge,geospatial knowledge services and the technologies are e-laborated.Finally based on this foundation,an implementation of a geospatial knowledge services isdiscussed.
Objective A supervised classification method of polarimetric sythetic aperture radar(PoSAR)data u-sing watershed segmentation and Decision Tree C5.0with many polarimetric channels is proposed.First,the PolSAR data was filtered using the 5×5refined Lee PolSAR speckle filter,and then a PauliRGB color image and many polarimetric channels were obtained using various algorithms.Then,wa-tershed segmentation on gradient map was made for a homogeneous area and the features of every areawere worked out.At last,Decision tree C5.0was used to deal with the data.The result shows thatthis method performs better than methods based on pixels,and the classification accuracy is improvedwith the quantity of polarimetric characteristic increase.
Objective An image matching method based on a rigorous orientation model is presented that exploitsthe characteristics of optical imagery acquired from domestic satellites from different sensors.Firstly,this paper improves the method for scan line iterative search on the basis of the existing methods,andproposes the rapid correspondence prediction method.Next,with the help of the global SRTM(Shut-tle Radar Topography Mission)data,the approximate epipolar line is constructed by projection track-ing.The geometric and radiometric deformation in the matching window is eliminated by the correc-tion of local distortion.At last,in original level,the MPGC algorithm is adopted to refine the matc-hing results.This paper proposes a matching algorithm based on the geometric correction of the facetand the matching growth algorithm of a control network,which improves matching accuracy and thedistribution of the matching points.A test with imagery data from the TH1、ZY02Cand ZY3satellitesshowed that the proposed method can combine the characteristics of the optical imagery acquired fromdomestic satellites,and yield multi-source image matching from multi-source sensors.A well distribu-ted set of matching points can be obtained.
Objective Traditional satellite scheduling method has difficulties to meet the need for timely responsein emergency observation missions.In this paper,an improved single-orbit scheduling method is pro-posed for agile imaging satellites as a tentative solution.This method first dynamically calculates theobservation angle,swath,and duration of the agile imaging satellite.Cutting of area targets are thenperformed using parallel strip,followed by the acquisition of minimum attitude transition time.A spe-cialized step-size search algorithm is employed to find the best observation point towards the area tar-get.In our experiments,the STK simulation scenario is constructed with four agile imaging satellites.The simulation results show that the new method improves the coverage of area target while reducesthe image acquisition time.
Objective This paper proposes a geographical object-based method for change detection with high reso-lution images based on the changing areas distributed as a clustered type.This algorithm utilizes theMean-Shift segmentation algorithm to extract a geographic object,and then uses the gray informationof the geographic object with the EM algorithm to automatically extract changed and unchanged areas.This method considers spatial neighborhood information which can avoid the isolation and discrete dis-connected areas in change results when using apixel-based method.This method also reduces inter-vention when determining the change threshold value.Groups of three different spatial resolution ima-ges(QuickBird,SPOT,TM images)are used to verify this proposed geographic object-based changedetection algorithm and compared the accuracy and precision with a pixel-base method.Our resultsshow that the accuracy with object-based change detection method on QuickBird,SPOT and TM ima-ges was 91.1%,87.3% and 84.3%,while for the pixel-based method are 86.41%,82.48% and81.02%respectively.These results illustrate that the object-based change detection method has high-er change detection accuracy than the pixel based approach.Moreover,the object-based method hasbetter accuracy for high spatial resolution than in middle or low resolution images.
Objective Linear feature detection from remote sensing data is an importance step in automatic targetrecognition.A high spatial resolution remote sensing image is highly detailed,which causes problemsfor some linear feature detection methods with edge fractures and fuzzy,salt and pepper noise.In thispaper,a novel linear feature detection approach for high spatial resolution remote sensing imagesbased on sparse decomposition is proposed.First,an over-complete dictionary for linear feature detec-tion was designed with a K-SVD algorithm.Using the sparse decomposition model,high frequencycomponents were extracted from high spatial resolution remote sensing images,realizing initial detec-tion of linear features from high spatial resolution remote sensing images.Then,denoising with aCurvelet and hierarchical adaptive threshold was applied to the high frequency component,which im-proved the linear feature detection effect..Finally,a simulation based on QuickBird data was execu-ted.Experimental results verified that the proposed method is superior to the Canny and Sobel meth-ods for line continuity,low contrast line detection,and salt and pepper noise elimination.
Objective The relationship between the observed value and the latest World Magnetic ModelWMM2010,constructed with various satellite geomagnetic data,is studied;as well as the relationshipbetween the observed value and the International Geomagnetic Reference Field model IGRF11.First-928 ly,a comparison is made between IGRF11and the observed value.The precision and reliability of IG-RF was evaluated.Then,the difference between WMM2010and IGRF11 was analyzed.Indexes,such as absolute errors,mean square root errors,relative errors and weigh coefficients,are introducedto compare the two models.The results suggest that the WMM2010model has more reference valuefor the normal field correction in the geomagnetic abnormity field research,thus filling agap to im-prove the boundary effect.
Objective According to the requirements of high precision satellite navigation and ionosphere activitymonitoring,double-frequency measurement data from 238IGS stations are used to calculate verticalionosphere electron content(VTEC),DCB of GPS,GLONASS and the corresponding receiver basedon the spherical harmonic function model.The results show that this implemented model is reliable.The DCB precision of GPS and GLONASS obtained is less than 0.1ns when compared with the resultsof CODE and less than 0.2ns when compared with that of IGS.The DCB precision of GPS and GLO-NASS receivers are less than that 2ns,while the precision of VTEC is better than 3TECU in compar-ison with that of CODE and IGS,and better than before combination.
Objective Meteorological parameters are needed when ground-based GPS is used for the detection ofPWV(precipitable water vapor).However,a large amount of GPS data has not been sufficiently usedbecause of the lack of related meteorological data.In this paper,the methods and feasibility of deri-ving meteorological parameters from ERA-Interim reanalysis data and calculating GPS/PWV with theextracted parameters in China are assessed.The atmospheric pressure,temperature and relative hu-midity derived from ERA-Interim are compared with meteorological observation data at 24meteoro-logical stations from 2006to 2007,and the GPS/PWV calculated from the two data sets are also con-trasted.Results are as follows:① Atmospheric pressure derived from upper-air reanalysis data,tem-perature and relative humidity derived from surface reanalysis data,has relatively high precision.② The reanalysis parameters and meteorological observation data comparisons at 24stations show amean bias of 0.08hpa and a RMSD of 0.85hpa with atmospheric pressure,a mean bias of 0.05Kanda RMSD of 2.45Kwith temperature,a mean bias of 2.82%and a RMSD of 14.75% with relative hu-midity.③ The ERA-Interim reanalysis data is more reliable in the east of China than in the west.Theprecision of temperature and relative humidity data show seasonal variation.④ As compared withGPS/PWV calculated by the meteorological observation data,the GPS/PWV calculated by the ERA-Interim data give a mean difference of less than 0.5mm and a RMSD of less than 1mm.
Objective ERS-1/2tandem SAR images acquired in 1996were utilized to map the ice-flow velocity ofthe Polar Record and Dalk Glaciers using DInSAR.The horizontal component was derived from line-of-sight velocity estimates,and compared with the field measurements.The DInSAR results revealedan ice velocity map of the whole area.For the inland areas,the DInSAR results were in good agree-ment with field measurements.As for the front of the Dalk Glacier,the ice velocity derived from DIn-SAR was smaller than the field measurements because of the differences between data acquisitiontimes,tidal motion,etc.
Objective Datong basin is one of the geological hazards development zones where geological disasterhas a high frequency,such as the ground subsidence,ground fissure and so on.In this paper,thesmall baseline subset(SBAS)InSAR technology was used to process 40scenes of Envisat SAR datacovering this area,and the surface deformation distribution characteristics were obtained.The timeseries deformation characteristics of the typical subsidence area were analyzed.The relationship amongthe regional ground subsidence,ground fissures and fault were also analyzed.The results show thatthe ground subsidence is influenced by groundwater exploitation and controlled by the faults.At thesame time,the horizontal and vertical activity characteristics of the Locomotive Factory ground fissurewere analyzed,and its relationship with precipitation.
Objective Due to the high mobility,rapid deployment and a wide range of monitoring,vehicle detec-tion and tracking system based on low-level mobile platform attract more and more attention.Cameralself-motion,outside interference and other reasons caused by low altitude mobile platforms impact theperformance of traditional vehicle detection algorithms.To resolve the above problems,a new methodon improved SURF color image stabilization is presented in this paper.From the experimental results,we can see,firstly,compared to other methods,the method proposed by the paper can achieve vehicledetection performance;secondly even in a complex background environment,the method in this papercan effectively detect moving vehicles.
Objective Trajectory processing and analysis are research issues in several related fields,such as geog-raphy,and database design.Inspired from the Stop/Move abstraction model of a trajectory,this pa-per explores the spatio-temporal relationships among trajectories by analyzing the spatio-temporal traj-ectory patterns and their relationships.Firstly,a spatio-temporal association Stop/Move Model,based on the Stop/Move conceptual model,is introduced to link trajectory with rich geographical in-formation;Next,trajectory spatio-temporal patterns,describing the trajectory movement of an agentwith respect to given geographical feature,are presented;Finally,the relationships between the spa-tio-temporal patterns of trajectories are discussed:Stop-Stop,Stop-Move and Move-Move.The po-tential application capabilities of this paper on trajectory relationship queries and analysis are also dem-onstrated through two typical examples.
Objective Volunteered geographic information(VGI)contributed by Internet users is more and morewidely used as data updating source for industries such as navigation,and for disaster emergencies.This way of data acquisition is faster and cheaper than traditional surveying and mapping data.Howto detect and extract changed information in massive amounts of VGI data in a timely way is a problemto be solved.The high precision results of vector feature matching can help to find the changed fea-tures faster.VGI vector data has rich geometric and semantic information,traditional vector featurematching algorithm is not suitable for this purpose.In this paper,we proposed a multilevel spreadingalgorithm in vector feature matching,and applied the city road network as the research content,tocompare VGI vector data to the data from the professional surveying and mapping departments to real-ize the change detection in a road network.
Objective The Gushanchuan basin was chosen as a study area which is prone to serious soil erosion inthe Loess Plateau to investigate the requirements of soil and water conservation benefit assessment andsoil loss control.We quantitatively studied the spatial-temporal dynamic features of the soil erosion ofthe area over the past three decades by applying soil science,remote sensing(RS)and geographic in-formation systems(GIS).We obtained three main results.Firstly,variations of the soil erosion in thestudy area in the past three decades(1975to 2006)were divided into two stages.The first stage wasbetween 1975and 1986,when soil erosion intensified and eroded area increased by 138.13km2,par-ticularly in the southeast part of the basin.The second stage was between 1986and 2006,when soil e-rosion weakened.The eroded area decreased by 163.09km2,and soil erosion decreased in the entirebasin,particularly in the east.Secondly,soil erosion above the medium degree mainly occurred in theelevation ranging from 1 070mto 1 300m,with the slope ranging from 18°to 35°correspondingly.The precipitation in 1975and 2006was scanty,and the erosion above the medium degree have a rain-fall erosivity ranging from 900MJ·mm·hm-2·h-1 to 1 150MJ·mm·hm-2·h-1.The erosion a-bove the medium degree in 1986and 1997have a rainfall erosivity ranging from 1 300MJ·mm·hm-2·h-1 and 1 800MJ·mm·hm-2·h-1.The area with serious soil erosion corresponded to the areadistributed with high rainfall erosivity.Thirdly,the soil erosion in the basin predominantly occurredin farmlands and woodlands.During the period between 1975and 2006,the farmland area decreased,and the woodland and pasture areas increased,and the soil erosion weakened as a whole.The develop-ment of the land use of the basin was in a positive way,and soil erosion showed an obvious weakeningtrend.These results would provide references for understanding soil erosion and macro decision -making for controlling soil erosion in the first Loess Hill and Gully area sub-region.
Objective In order to applied the three-dimensional laser scanning technology to tunnel deformationfield,this paper proposed the overall tunnel deformation monitoring methods to replace the traditionalsingle-point monitoring with engineering experimental research tools.Described the operation proces-ses and pointed out what should pay attention to,discussed the point cloud registration and coordi-nates conversion problems.The study showed that the scanning stations distance can not exceed thediameter of the tunnel if ICP registration is taken,and set the reasonable scanning resolution to highresolution grade is appropriate.In order to avoid obstacles impact it is needed to scan on both sides ofthe tunnel centerline as scanning shielding rate is too large.The new method gives a fast,full accessto get the complete deformation data of the tunnel surface and overcomes the shortcomings of the tra-ditional methods.
Objective Hardware-related system errors of terrestrial 3Dlaser scanner can be reduced or eliminatedby calibration.Basic model and reference model of terrestrial 3Dlaser scanner system errors were es-tablished.Laboratory calibration adjustment model was deduced.After the adjustment was comple-ted,exterior orientation elements,global coordinates of targets,coefficients of system error and ob-servations of corrected random error can be acquired.Considering both physically interpretable andempirically identified components,phase-terrestrial FARO Focus3Dself-calibration test was conduc-ted in a laboratory calibration room.The influence of the number and distribution of control points onthe residual distribution of observations and system error modeling were analyzed by calibration exper-iments.The modified model of FARO Focus3Dsystem errors was established.The effectiveness ofmodified model was proved.
Objective As traditional 3Dface construction is too much complex and has low efficiency,therefore,an interactive approach is proposed to generate realistic 3Dfaces based on one photo.Firstly,we con-structed a standardized face model database,and interactively select the facial feature points from aninput picture,and then,the best-matched face model is selected based on the features.Secondly,atriangular deformation approach and bilinear interpolation are used to achieve texture mapping from aphoto to 3Dmodel.The Alpha Fig was introduced to realize a fusion transition from the photo textureto the neutral texture.At last,a model regulator to regulate the model hierarchically was designed togenerate realistic 3Dfaces.Experimental results show that this approach is user-friendly,and cangenerate a high-quality realistic character in real time with less characteristic points.
Objective This paper describes the design of a lamp box device that captures,from each flue-cured to-bacco leaf,transmission and reflection images in the same image position.According to the transmis-sion characteristics of tobacco leaves namely that the blue vector value in the leaf part of its RGBtransmission image is dramatically absorbed.Thus,this study proposes a novel segmentation methodto synchronously treat the transmission and reflection images of the same flue-cured tobacco leaf,combining it with a point-oriented and area-oriented statistical segmenting method to successfully ob-tain leaf parts in pairs which have the same effective pixel quantities and the same contours.The re-sults show that segmentation accuracy is higher than when only using point-oriented or area-orientedstatistical segmenting methods.Moreover,the boundary is smooth and continuous.These findingsare very helpful for digitally rating tobacco quality based on the combination of transmission and re-flection images.
Objective A new tone-reproduction algorithm for high-dynamic-range(HDR)images is proposed inthis paper.The image color appearance model is good at predicting color appearance of images,so thecalculation frame of the new algorithm is based on the latest image color appearance model iCAM06.The tone-compression function of iCAM06was improved significantly.The Hyperbola tone-compres-sion function of iCAM06was replaced by the tone-compression function based on the improved non-linear masking,and the new tone-compression function was used for tone-compression of the base lay-er image.In addition,in the rendering process of the HDR images,the new algorithm introduced the“Hunt effect”and“Stevens effect”predicting model proposed previously.Finally,the subjective eval-uation test and DRI model were used to evaluate preference and scene-reproduction accuracy of thenew algorithm respectively.The result of the evaluation test shows that the new algorithm has a verygood effect on preference and scene-reproduction accuracy.