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171.
Three-dimensional urban cartography is needed for city changes’ assessment. The variety of studies using 3D calculations of urban elements grows each year. Building and vegetation volumes are necessary to assess and understand spatio-temporal urban changeable environments. However, there are technical questions as to which method can improve 3D urban cartographic accuracy. The innovative part of this current study is the creation of a six-band hybrid obtained from LIDAR and WorldView2 synergy. Two different enhancement algorithms demonstrated the most important spectral features for the urban development and vegetation classes. Results indicated an improvement in accuracy by up to 21.3%, according to the Kappa coefficient. Both infra-red band and intensity band were the most significant, according to the principal components analysis. The synergy delimited classes and polygons, as well as the direct display of information regarding heights of elements and improving the extraction of roads, buildings and vegetation classes. 相似文献
172.
Geomasking sensitive health data and privacy protection: an evaluation using an E911 database 总被引:2,自引:0,他引:2
Allshouse WB Fitch MK Hampton KH Gesink DC Doherty IA Leone PA Serre ML Miller WC 《国际地球制图》2010,25(6):443-452
Geomasking is used to provide privacy protection for individual address information while maintaining spatial resolution for mapping purposes. Donut geomasking and other random perturbation geomasking algorithms rely on the assumption of a homogeneously distributed population to calculate displacement distances, leading to possible under-protection of individuals when this condition is not met. Using household data from 2007, we evaluated the performance of donut geomasking in Orange County, North Carolina. We calculated the estimated k-anonymity for every household based on the assumption of uniform household distribution. We then determined the actual k-anonymity by revealing household locations contained in the county E911 database. Census block groups in mixed-use areas with high population distribution heterogeneity were the most likely to have privacy protection below selected criteria. For heterogeneous populations, we suggest tripling the minimum displacement area in the donut to protect privacy with a less than 1% error rate. 相似文献
173.
This study assesses surface urban heat island (UHI) and its associated surface physical characteristics using remote sensing approaches. TERRA/MODIS images acquired in 2005 in three different seasons were selected to generate land surface tem-perature and surface characteristics for the Changsha-Zhuzhou-Xiangtan metropolitan area in China. The intensity of urban heat is-land effects and its seasonal variations were examined. The result showed that UHI effects were significant both in the summer and the spri... 相似文献
174.
Kinematic precise point positioning at remote marine platforms 总被引:6,自引:2,他引:6
Precise kinematic differential positioning using the global positioning system (GPS) at a marine platform usually requires
a relatively short distance (e.g. <500 km) to a land-based reference station. As an alternative, precise point positioning
(PPP) is normally considered free from this limiting requirement. However, due to the prerequisite of network-based satellite
products, PPP at a remote marine platform may still be affected by its distance to the reference network. Hence, this paper
investigates this scenario by configuring rings of reference stations with different radii centered on a to-be-positioned
marine platform. Particularly, we applied ambiguity resolution at a single station to PPP by estimating uncalibrated phase
delays (UPDs). We used three rings of reference stations centered on a vessel, with radii of roughly 900, 2,000 and 3,600 km,
to determine satellite clocks and UPDs independently. For comparison, we also performed differential positioning based on
a single reference station with baseline lengths of about 400, 1,700 and 2,800 km. We demonstrate that, despite the increasing
ring-network radius to a few 1,000 km, the overall change in accuracy of the satellite clocks that are used at the vessel
is smaller than 0.02 ns, and the RMS values of differences between the three sets of narrow-lane UPD estimates are around
0.05 cycles only. Moreover, the kinematic positioning accuracy of PPP is affected by the increasing ring-network radius, but
can still achieve several centimeters after ambiguity resolution when the vessel is over a few 1,000 km away from the ring
network, showing better performance than that of differential positioning. Therefore, we propose that ambiguity-fixed PPP
can be used at remote marine platforms that support precise oceanographic and geophysical applications in open oceans. 相似文献
175.
176.
Bovolo F. Bruzzone L. Capobianco L. Garzelli A. Marchesi S. Nencini S. 《Geoscience and Remote Sensing Letters, IEEE》2010,7(1):53-57
177.
Automated GPS Data Analysis Service 总被引:4,自引:1,他引:4
James F. Zumberge 《GPS Solutions》1999,2(3):76-78
Automatic analysis of geodetic-quality GPS data is available with the use of e-mail and ftp (file transfer program) as an
interface to a computer at the Jet Propulsion Laboratory (JPL), where precise transmitter parameters – GPS ephemerides and
clock errors – are computed regularly. The interface is such that e-mail from an external user causes the JPL computer to
fetch the user's data. The computer than analyzes the data, and places the results in an area accessible to the user. An e-mail
to the user gives information on the location of the analysis results, which the user can subsequently fetch. Operations on
the JPL computer are entirely automatic, and require essentially no labor. ? 1999 John Wiley & Sons, Inc. 相似文献
178.
A GPS-Supported Gravity Survey in the Amazon of Ecuador 总被引:1,自引:0,他引:1
Mamadou Balde Jeremy Fishman Carlos L. V. Aiken Mohamed Abdel-Salam Mauricio F. de la Fuente 《GPS Solutions》1999,2(3):3-17
The growing importance and effectiveness of the Global Positioning System (GPS) in positioning geophysical surveys is now
well established. In Ecuador's Amazon basin the use of GPS was the determining factor in the successful completion of a gravity
survey carried out in 1994. Over 500 gravity stations, spaced from 1 to 5 km apart and positioned by GPS, were collected in
the jungle environment in the country's southeast, where the preexisting data, of variable and unknown quality, were mostly
confined to areas along the major rivers. This station densification, which includes the reoccupation of selected points,
contributed to increase the gravity coverage; it also allowed us to evaluate and correct 1100 preexisting data points in the
area, so that the different surveys can be merged. The composite data set is used for a geologic analysis of the study area,
where previously unknown structures are discovered. ? 1999 John Wiley & Sons, Inc. 相似文献
179.
We present an automated extraction method based on the continuous wavelet transform (CWT) for analyzing solar magnetic loops. The aim of the work is to extract, from the images taken from solar EUV telescopes, the traces of bright loops presumably shaped by the magnetic field of the solar corona. The technique is that of wavelet analysis, using the two-dimensional Morlet wavelet, because of its efficiency in detecting oriented features, which allows us to follow closely the curvature of the loops. Next, we segment the wavelet modulus image and we threshold it, both globally and locally (i.e., adaptively), in order to eliminate the remaining noise. Altogether, our method performs well, it is robust and fast, and could be used as a standard tool for analyzing large data sets expected from missions like SDO. 相似文献
180.
Corridor location: the multi-gateway shortest path model 总被引:1,自引:1,他引:1
Maria P. Scaparra Richard L. Church F. Antonio Medrano 《Journal of Geographical Systems》2014,16(3):287-309
The problem of corridor location can be found in a number of fields including power transmission, highways, and pipelines. It involves the placement of a corridor or rights-of-way that traverses a landscape starting at an origin and ending at a destination. Since most systems are subject to environmental review, it is important to generate competitive, but different alternatives. This paper addresses the problem of generating efficient, spatially different alternatives to the corridor location problem. We discuss the weaknesses in current models and propose a new approach which is designed to overcome many of these problems. We present an application of this model to a real landscape and compare the results to past work. Overall, the new model called the multi-gateway shortest path problem can generate a wide variety of efficient alignments, which eclipse what could be generated by past work. 相似文献