共查询到20条相似文献，搜索用时 15 毫秒
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Peter Vujaković 《The Cartographic journal》2013,50(3):300-301
AbstractCartography in general, and building solid landscape models in particular, requires an interdisciplinary set of skills in order to be done well. Traditional handcrafted construction methods provide quality results, but are extremely labour-intensive and therefore costly. Modern methods using digital terrain models (DTMs) and computer numerical control (CNC) milling are fast and accurate, but the finished models are visually less than optimal. Solutions are proposed using DTMs and CNC milling to create landscape models in which the initial shaping is done mechanically and the fine details are carved by hand. This ‘balanced approach’ to landscape modelling combines the time- and cost-advantages of modern digital technology with the quality of traditional handcrafted techniques resulting in highly accurate landscape models which still retain the artistic ‘feel’ of the human touch. 相似文献
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Calibration of the clock-phase biases of GNSS networks: the closure-ambiguity approach 总被引：2，自引：2，他引：0
In global navigation satellite systems (GNSS), the problem of retrieving clock-phase biases from network data has a basic rank defect. We analyse the different ways of removing this rank defect, and define a particular strategy for obtaining these phase biases in a standard form. The minimum-constrained problem to be solved in the least-squares (LS) sense depends on some integer vector which can be fixed in an arbitrary manner. We propose to solve the problem via an undifferenced approach based on the notion of closure ambiguity. We present a theoretical justification of this closure-ambiguity approach (CAA), and the main elements for a practical implementation. The links with other methods are also established. We analyse all those methods in a unified interpretative framework, and derive functional relations between the corresponding solutions and our CAA solution. This could be interesting for many GNSS applications like real-time kinematic PPP for instance. To compare the methods providing LS estimates of clock-phase biases, we define a particular solution playing the role of reference solution. For this solution, when a phase bias is estimated for the first time, its fractional part is confined to the one-cycle width interval centred on zero; the integer-ambiguity set is modified accordingly. Our theoretical study is illustrated with some simple and generic examples; it could have applications in data processing of most GNSS networks, and particularly global networks using GPS, Glonass, Galileo, or BeiDou/Compass satellites. 相似文献
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探讨采用1：50000 DOM作为主要数据源,通过对影像的解译,进行1：50000 DLG生产。 相似文献
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Lena Halounová 《地球空间信息科学学报》2021,24(1):22-26
PREFACE
The paper contains a brief overview of the professional activities of Professor Gottfried Konecny,Professor Emeritus at the Institute of Photogrammetry and GeoInformation,Leibniz University Hannover,Germany,and his influence on photogrammetry,remote sensing and geospatial infor-mation science during his time at the University of New Brunswick,Canada,and at the Leibniz University.His work can be divided into educational,scientific,application,organizational,and work in international societies.Additional activities comprised of giving courses in various languages,consultancy activities,and various other cooperations which took place in many South American countries,in Africa and Asia,for organizations such as the World Bank,United Nations,German Space Agency DLR,to name only a few.Activities in connection with international societies mainly took place during Prof.Konecny's engagement in the Council of the International Society for Photogrammetry(ISP),renamed the International Society for Photogrammetry and Remote Sensing(ISPRS),and the European Association of Remote Sensing Laboratories(EARSeL)Bureau.He was a key figure in bringing many countries and organizations to ISPRS as Ordinary and Sustaining Members.Professor Konecny has always been aware of the importance of international cooperation at various levels,also with sister societies such as the International Cartographic Association and the United Nations-Global Geospatial Information Management(UN-GGIM).His application activities span from the photogrammetry-oriented projects he was awarded in Canada,to remote sensing topics and geospatial sciences,combined with cartography during his Hannover period.His vision and endless effort are exemplary for a person who has always been devoted to the three geosciences mentioned above.Professor Konecny is the author of a number of books,journal papers and papers presented at international and national conferences.He has been a recognized keynote speaker at many conferences throughout the world due to his vast experience.This paper describes 75 years of a man who is an expert in fields which arose during his academic life. 相似文献
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W. Prószyński 《Journal of Geodesy》1997,71(10):652-659
For a linear least-squares parametric model analysis is carried out of the structure of the projection operator transforming
the vector of standardised observations into the vector of standardised residuals. On this basis the properties of the model
responses to observational disturbances (i.e. gross errors or blunders) are derived. A final outcome of the research can be
summarised as: (1) proposing the robustness characteristics of a model and linking them with the local measures of internal
reliability, being the diagonal elements in the projection operator; (2) determining the internal reliability levels satisfying
specified robustness requirements, i.e. the possibility of detecting at least one of the k observational disturbances (k=1,2,…) having most disadvantageous locations in the system. The theory and a numerical example show that for the systems
which have been designed to a proper level of internal reliability, the least-squares estimation can demonstrate an accordingly
high level of robustness.
Received: 11 June 1996 / Accepted: 28 April 1997 相似文献
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K. Le Bail 《Journal of Geodesy》2006,80(8-11):541-565
The noise spectrum in DORIS ground- station motion is investigated by means of the Allan variance method applied to the decomposition of the 3D signal into its principal components in the time domain. Sets of weekly position time-series from 1994 to 2005 derived by three IDS Analysis Centres (IGN-JPL, INASAN, and LEGOS-CLS) for 119 stations at 69 sites are considered. The observing satellites are SPOT-2, SPOT-3, SPOT-4, and SPOT-5, TOPEX/Poseidon, and ENVISAT. Annual and semi-annual perturbations, as well as the 117.3-day term associated with the TOPEX/Poseidon orbit, are found at most stations. Their amplitudes reach up to 19.3, 23.7, and 13.3 mm, respectively, for the three analysis centres (ACs). When corrected for these components and a linear drift, the time-series dominantly show white noise (WN) at the 10–45mm level the noise level is the highest in the East direction, probably in connection with the high orbit inclinations. The noise level is minimum for the high latitude stations, mostly and intensively observed by the SPOT satellites, and the determination of the noise type is unclear; longer observation spans would be needed to decide between interannual variations and flicker noise. The improvement in positioning due to the DORIS constellation extension from three to five satellites in 2002, and the network rejuvenation program initiated in 2000, results in a decrease of the noise level by a factor of 1.7 in a WN context, both before and after the changes. One example of the benefit of studying the signal in the time eigenspace domain is the detection of anomalously large WN in the East direction for station HBKB (Hartebeesthoek, Africa) that masks the above-mentioned improvement. Studying the projection on the local frame of the second and third time-eigenspace components, a noise excess is detected in the North direction for some of the ACs. Station stability derived from our time-series analysis confirms, in general, the expected performance based on the careful technical review of the station components (antenna, pillar, etc.). The respective merits of our noise qualification method, based on direct time-series analysis in the time-eigenspace domain without any a priori statistical model, in comparison with other methods, such as the selection of a mixed-noise model by maximum likelihood estimation, are discussed. 相似文献
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Although visible in research in the 1980s and 1990s, works concerning language-mapping issues are recently rather absent. This is an unfortunate oversight given current GIS capability and its potential to tackle visualization issues that were previously simply acknowledged and accepted. Given that there are no established guidelines for language map construction, this work aims to renew attention to language mapping, beginning with a survey documenting the characteristics of published language maps. The survey components address the problematic aspects described in the literature, such as boundary representation and depicting linguistic diversity, and reveal their usage and frequency. The noted map characteristics include, but are not limited to: publication type, publication year, coverage area, language data or variable used, and symbology details. For consistent classification, we use a language-map symbology classification scheme found in previous research. In general, chorochromatic maps using polygonal map units dominate our survey. We also find further evidence supporting the problems outlined in language mapping literature with the widespread use of solid-line boundaries and depiction of only one language or feature per place. However, we also note some unique strategies used for handling uncertainty and linguistic plurality. Observations of tactics not captured by the existing 20-year-old typology lead us to create an updated language map symbology typology consistent with the trends observed in our survey. Overall, we document language mapping strategies in practice and provide direction for future research by highlighting the pros and cons of current cartographic approaches for depicting language. 相似文献
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随着数字摄影测量技术、LiDAR和InSAR等测绘高新技术的发展,数字高程模型在数据获取、生产技术和工艺等方面较以往发生了很大变化。2001年首次发布的行业标准《基础地理信息数字产品1：100001：50000数字高程模型》在很大程度上已经不能反映当前我国DEM生产的实际状况,有必要对该标准进行修订。深入分析和研究美国、英国、加拿大等国DEM相关标准,并充分考虑我国测绘生产的实际状况,对该标准的相关内容和技术指标进行修订,提高标准的现势性,保证相关标准之间的协调性和完整性,能更好地满足测绘生产和用户的实际需要。 相似文献
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none 《The Cartographic journal》2013,50(2):167-171
AbstractWhile attempting to devise a methodology for the assessment of the impact of planning decisions on the coastline of Scotland, it became apparent that a means of mapping information concerning the coastline and coastal zone was necessary. This meant that the maps had to be capable of being produced in bulk, they should be easy to alter and produce at different scales and with different information. It was therefore decided to investigate the potential of computational techniques to produce the required maps. This was performed by employing a d-Mac digitising table to generate the required coordinates and by processing the information on the University of Aberdeen's ICL system 4/70 computer, the output being on drum plotter. 相似文献
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《The Cartographic journal》2013,50(4):342-350
AbstractThis overview of the history of jigsaw puzzles highlights their connection with maps and the education of geography. The illustrations have been selected from the 125 slides which originally accompanied a talk presented at the BCS Symposium in Manchester, September 2006. 相似文献
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郑志煌 《测绘与空间地理信息》2011,34(3)
由于1:500与1:5 000两种比例尺地形图中等高线的技术指标差别极大,因此要实现从1:500到1:5 000地形图的缩编,如何在保证质量的前提下高效地对等高线进行缩编,是一个难度很大的技术问题.文章通过探索和实验,总结出基于GeoTIN的等高线缩编技术方法,这种方法在实际生产中被证明是有效的、可靠的和具有实用性的. 相似文献
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Mohammad Asadullah Khan 《Journal of Geodesy》1973,47(3):227-235
An intrresting variation on the familiar method of determining the earth's equatorial radius ae, from a knowledge of the earth's equatorial gravity is suggested. The value of equatorial radius thus found is 6378,142±5
meters. The associated parameters are GM=3.986005±.000004 × 1020 cm3 sec-−2 which excludes the relative mass of atmosphere ≅10−6 ξ GM, the equatorial gravity γe 978,030.9 milligals (constrained in this solution by the Potsdam Correction of 13.67 milligals as the Potsdam Correction
is more directly, orless indirectly, measurable than the equatorial gravity) and an ellipsoidal flattening of f=1/298.255. 相似文献
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Garrett Carr 《The Cartographic journal》2017,54(2):173-180
The author curates a touring exhibition of Northern Ireland cartography, called Mapping Alternative Ulster. The project emerged from a dissatisfaction with how Northern Ireland is represented in maps, and one example is given. To counter them, he sought independent cartographers making original maps. The curator discusses the criteria he applied when selecting work for the show. He wanted maps with politics, although not the region’s traditional sectarian politics. All the selected maps constitute arguments, critiquing problems in the lived environment or drawing attention to valuable things that may be at risk. The latter sections of the article discuss five of the contributors and looks at their work in detail. In the conclusion, the impact of the exhibition is assessed by examining visitor comments. The paper is illustrated. 相似文献
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IGS08: the IGS realization of ITRF2008 总被引：22，自引：6，他引：16
P. Rebischung J. Griffiths J. Ray R. Schmid X. Collilieux B. Garayt 《GPS Solutions》2012,16(4):483-494
On April 17, 2011, the International GNSS Service (IGS) stopped using the IGS05 reference frame and adopted a new one, called IGS08, as the basis of its products. The latter was derived from the latest release of the International Terrestrial Reference Frame (ITRF2008). However, the simultaneous adoption of a new set of antenna phase center calibrations by the IGS required slight adaptations of ITRF2008 positions for 65 of the 232 IGS08 stations. The impact of the switch from IGS05 to IGS08 on GNSS station coordinates was twofold: in addition to a global transformation due to the frame change from ITRF2005 to ITRF2008, many station coordinates underwent small shifts due to antenna calibration updates, which need to be accounted for in any comparison or alignment of an IGS05-consistent solution to IGS08. Because the heterogeneous distribution of the IGS08 network makes it sub-optimal for the alignment of global frames, a smaller well-distributed sub-network was additionally designed and designated as the IGS08 core network. Only 2?months after their implementation, both the full IGS08 network and the IGS08 core network already strongly suffer from the loss of many reference stations. To avoid a future crisis situation, updates of IGS08 will certainly have to be considered before the next ITRF release. 相似文献