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Deterministic, stochastic, hybrid and band-limited modifications of Hotine’s integral 总被引:2,自引:1,他引:1
W. E. Featherstone 《Journal of Geodesy》2013,87(5):487-500
Global Navigation Satellite System positioning of gravity surveys permits geoid computation via Hotine’s integral. A suite of modifications is presented so that the user can tune the relative contributions of truncation and data errors in a combined solution for a regional geoid model from gravity disturbances. 相似文献
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Rashmi Kandwal C. Jeganathan Valentyn Tolpekin S. P. S. Kushwaha 《Journal of the Indian Society of Remote Sensing》2009,37(2):275-290
Invasive species have been the focus of environmentalists due to their undesired impact on the ecosystem. Spread of Lantana
(Lantana camara L.), an invasive plant species, has been found in diverse geophysical environments causing a threat to the native flora.
Various eradication programmes have been attempted such as burning, chemical sprays, bio-control agents and physical plugging
mechanism for removing such invasive species in India. The efforts and success of these programmes need to be augmented with
a correct, quick and cost effective technique of mapping in order to locate them, understand their spatial extent and hence
make the process comprehensive. Also Lantana’s appearance as dense vegetation patches in remote sensing data causes problems
for estimating forest canopy density. Remote sensing provides a possible solution in qualitatively and quantitatively evaluating
terrestrial surface vegetation cover using spectral measure-ments. This research paper addresses issues and techniques adopted
to detect and extract Lantana, and can be used for various applications in forestry as well as in eradication programmes.
This study attempted to understand the appropriate band combination using Landsat data and generating vegetation indices in
order to extract Lantana patches in an accurate manner. Twenty nine different vegetation indices were analyzed for their effectiveness
in differentiating Lantana from other classes. The study showed that SAVI (Soil Adjusted Vegetation Index) is most favorable
in discriminating Lantana followed by Perpendicular Vegetation Index-3 in the optimum bio-window (February to April). 相似文献
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Cartographica incognita: ‘Dijital Jedis’, Satellite Salvation and the Mysteries of the ‘Missing Maps’ 总被引:1,自引:0,他引:1
Catherine Turk 《The Cartographic journal》2017,54(1):14-23
Like Participatory Geographic Information Systems (PGIS) and Public Participation Geographic Information Systems (PPGIS) crowdsourced collaborative mapping is often imagined as an alternative to conventional cartographic practice. This paper examines collaborative mapping projects designed to assist in humanitarian work and respond to catastrophes. These projects, their technological complexity and wide range of collaborators, including affected locals, international Non-Government Organisations (NGOs) and anonymous online contributors, invite closer consideration. In this article I unpick the gnarly question of how the remote sourcing of information through cloud collaboration and satellite imagery jostles with grounded work encouraging local control of local geoinformation. My critical analysis of these projects explores: (1) justifications for action – what is being promised through digital mapping as aid or satellite salvation?; (2) forms of participation – the role of ‘hotties’ ‘nodders’ and ‘digital jedis’; and (3) contingencies of mapping practices and the assemblages of actors within which they are embedded – as the mysteries of the ‘missing maps’. The conclusion considers differing approaches towards the inclusion of local knowledges within participatory digital aid mapping and identifies remote mapping practices that are both incognito and incognisant. 相似文献
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Evaluation of Goddard’s LiDAR,hyperspectral, and thermal data products for mapping urban land-cover types 总被引:1,自引:0,他引:1
Goddard’s LiDAR (Light Detection And Ranging), hyperspectral and thermal (G-LiHT) airborne imager is a new system to advance concepts of data fusion for worldwide applications. A recent G-LiHT mission conducted in June 2016 over an urban area opens a new opportunity to assess the G-LiHT products for urban land-cover mapping. In this study, the G-LiHT hyperspectral and LiDAR-canopy height model (LiDAR-CHM) products were evaluated to map five broad land-cover types. A feature/decision-level fusion strategy was developed to integrate two products. Contemporary data processing techniques were applied, including object-based image analysis, machine-learning algorithms, and ensemble analysis. Evaluation focused on the capability of G-LiHT hyperspectral products compared with multispectral data with similar spatial resolution, the contribution of LiDAR-CHM, and the potential of ensemble analysis in land-cover mapping. The results showed that there was no significant difference between the application of the G-LiHT hyperspectral product and simulated Quickbird data in the classification. A synthesis of G-LiHT hyperspectral and LiDAR-CHM products achieved the best result with an overall accuracy of 96.3% and a Kappa value of 0.95 when ensemble analysis was applied. Ensemble analysis of the three classifiers not only increased the classification accuracy but also generated an uncertainty map to show regions with a robust classification as well as areas where classification errors were most likely to occur. Ensemble analysis is a promising tool for land-cover classification. 相似文献
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Results are presented for Michibiki, the first satellite of Japan’s Quasi-Zenith Satellite System. Measurements for the analysis
have been collected with five GNSS tracking stations in the service area of QZSS, which track five of the six signals transmitted
by the satellite. The analysis discusses the carrier-to-noise density ratio as measured by the receiver for the different
signals. Pseudorange noise and multipath are evaluated with dual-frequency and triple-frequency combinations. QZSS uses two
separate antennas for signal transmission, which allows the determination of the yaw orientation of the spacecraft. Yaw angle
estimation results for an attitude mode switch from yaw-steering to orbit-normal orientation are presented. Estimates of differential
code biases between QZSS and GPS observations are shown in the analysis of the orbit determination results for Michibiki.
The estimated orbits are compared with the broadcast ephemerides, and their accuracy is assessed with overlap comparisons. 相似文献
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《地球空间信息科学学报》2003,6(2)
Prof.&Ph .DZHUQingZHUQing ,professor,Ph .D ,Ph .Dsupervi sor ,wasborninRenshoucountyofSichuanprovincein 1 966.HegraduatedfromDepartmentofRailwayEngineeringofSouthwesternJiaotongUniversity (SWJTU)in 1 986,withB .E .degreemajoringinphotogrammetryandremotesensing .Inthesameyear,hewasrecommendedasapostgraduatesupervisedbyProf.MADeyan ,andmajoredinComputerAidedCartography (CAC) .In 1 989,hereceivedM .E .degreeandthenbe cameateacherinSWJTU .From 1 990to 1 991 ,heworkedintheThirdI… 相似文献
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《地球空间信息科学学报》2003,(1)
Prof.&Ph .DXUCaijunXUCaijun,professor,Ph .D ,Ph.Dsupervisor,wasborninJiangyincityofJiangsuprovincein 1 964.HegraduatedfromDepartmentofGeodesyofWuhanInstituteofSurveying&MappingandreceivedB .S .degreein 1 985 .Inthesameyear,hewasrecom mendedasapostgradusteandmajoredi… 相似文献
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The purpose of this study was to investigate and compare the capabilities of four machine learning methods namely LogitBoost Ensemble (LBE), Fisher’s Linear Discriminate Analysis (FLDA), Logistic Regression (LR) and Support Vector Machines (SVM) to select the best method for landslide susceptibility mapping. A part of landslide prone area of Tehri Garhwal district of Uttarakhand state, India, was selected as a case study. Validation of models was carried out using statistical analysis, the chi square test and the Receiver Operating Characteristic (ROC) curve. Result analysis shows that the LBE has the highest prediction ability (AUC = 0.972) for landslide susceptibility mapping, followed by the SVM (0.945), the LR (0.873) and the FLDA (0.870), respectively. Therefore, the LBE is the best and a promising method in comparison to other three models for landslide susceptibility mapping. 相似文献
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Journal of Geographical Systems - Auckland, the largest city of New Zealand, is one of the most diverse cities in the world, with more than 40% of its population born abroad, more than 200... 相似文献
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The usefulness of remote sensing (RS), geographical information systems, and ground observations for monitoring changes in urban areas has been demonstrated through many examples over the last two decades. Research has generally focused on the relief phase following a disaster, but we have instead investigated the subsequent phases involving early recovery, recovery, and development. Our aim was to determine to what extent integration of the available tools, techniques, and methods can be used to efficiently monitor the progress of recovery following an earthquake. Changes in buildings within the Italian city of L’Aquila following the 2009 earthquake were identified from Earth observation data and are used as indicators of progress in the recovery process. These changes were identified through (1) visual analysis, (2) automated change detection using a set of decision rules formulated within an object-based image analysis framework, and (3) validation based on a combination of visual and semiautomated interpretations. An accuracy assessment of the automated analysis showed a producer accuracy of 81% (error of omission: 19%) and a user accuracy of 55% (error of commission: 45%). The use of RS made it possible for the identification of changes to be spatially exhaustive, and also to increase the number of categories used for a recovery index. In addition, using RS allowed the area requiring extensive fieldwork (to monitor the progress of the recovery process) to be reduced. 相似文献
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