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1.
《测量评论》2013,45(48):50-56
AbstractIn the memoir of the late Capt. G. T. McCaw which appeared in the January number of this Review (vii, 47,2), reference was made to the part which the late Sir David Gill played in the origin of the work on the survey of the Arc of the 30th Meridian in Africa. This year is the centenary of Gill's birth, as he was born in June 1843, and it is therefore timely to give some account of his work during his long term of office as Her Majesty's Astronomer at the Cape which resulted inthe inception and completion of the Geodetic Survey of South Africa and the survey of the Arc to the southern shores of Lake Tanganyika. He died on 24th January 1914. 相似文献
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《测量评论》2013,45(18):203-218
AbstractThe gear used for the measurement of the Kate Base of the East African Arc was specially designed by McCaw in conjunction with Messrs. Cooke, Troughton, & Simms, as a result of considerable experience in the measurement of geodetic bases in Fiji, Sweden, and in various parts of Africa; it is now known by the trade name of the “Macca” Base Measurement Gear. It has since been used in Southern Rhodesia, Tanganyika, Mauritius, and South Africa, and if the central pool of instruments recommended at the recent Empire Surveyors Conference is approved, it seems likely that its beat will soon be still more extended. It must be about the only first model of a surveying instrument which has not occasioned widespread controversy and complaint, and for this desirable state of affairs it is not unreasonable to suppose that the rare co-operation between the practical surveyor and the instrument-maker in its design is responsible. 相似文献
3.
Abstract The Arc of the Geodesic.—In the first part of this paper a method was given for computing the azimuth of a geodesic. The method gives the convergence of the geodesic correctly up to the second power of e the eccentricity. The formula (9), however, also depends on the assumption that σ, the arc-length of the geodesic, can be obtained with sufficient accuracy from the Supplemental Dalby Theorem, that is to say, by a purely spherical computation. It is, therefore, needful to show that this supposition is justifiable; a means must in fact be indicated for verifying the assumption. 相似文献
4.
《测量评论》2013,45(43):258-269
AbstractWork on the original Geodetic Tavistock Theodolite was commenced in the autumn of 1931, and after suitable tests this instrument was sent out to East Africa and used on the East African Arc. Bt Major M. Hotine, R.E., writing in the E.S.R. of April 1935 (no. 16, vol. iii), stated: “The Tavistock instrument, although a first model, gave uniformly satisfactory service throughout and was used for over half the main angular observations.” 相似文献
5.
《测量评论》2013,45(82):159-163
AbstractThis project, which is now well known to surveyors not only in Africa but all over the world, was first visualised by Sir David Gill, who for many years was H.M. Astronomer at the Cape Observatory. It is fitting to commence by giving in his own words his conception of the work, the part of which from South Africa to the Equator has now been completed. The following extracts are taken from the paper “On the Origin and Progress of Geodetic Survey in South Africa, and of the African Arc of Meridian”, by Sir David Gill,K.C.B., F.R.S. 相似文献
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Mengmeng Wang Natarajan Ishwaran Tianhua Hong Andy Bell Zhaoming Zhang 《International Journal of Digital Earth》2020,13(3):393-409
ABSTRACTEast Rennell of Solomon Island is the first natural site under customary law to be inscribed on UNESCO’s World Heritage List. Potential threats due to logging, mining and agriculture led to the site being declared a World Heritage in Danger in 2013. For East Rennell World Heritage Site (ERWHS) to ‘shed’ its ‘Danger’ status the management must monitor forest cover both within and outside of ERWHS. We used satellite data from multiple sources to track forest cover changes for the entire East Rennell island since 1998. 95% of the island is still covered by undisturbed forests; annual average normalized difference vegetation index (NDVI) for the whole island was above 0.91 in 2015. However, vegetation cover in the island has been slowly decreasing, at a rate of –0.0011 NDVI per year between 2000 and 2015. This decrease less pronounced inside ERWHS compared to areas outside. While potential threats due to forest clearing outside ERWHS remain the forest cover change from 2000 to 2015 has been below 15%. We suggest ways in which the Government of Solomon Islands could use our data as well as unmanned air vehicles and field surveys to monitor forest cover change and ensure the future conservation of ERWHS. 相似文献
8.
We examine the electromagnetic coupling of a GPS antenna–monument pair in terms of its simulated affect on long GPS coordinate
time series. We focus on the Earth and Polar Observing System (POLENET) monument design widely deployed in Antarctica and
Greenland in projects interested particularly in vertical velocities. We base our tests on an absolute robot calibration that
included the top ~0.15 m of the monument and use simulations to assess its effect on site coordinate time series at eight
representative POLENET sites in Antarctica over the period 2000.0–2011.0. We show that the neglect of this calibration would
introduce mean coordinate bias, and most importantly for velocity estimation, coordinate noise which is highly sensitive to
observation geometry and hence site location and observation period. Considering only sub-periods longer than 2.5 years, we
show vertical site velocities may be biased by up to ±0.4 mm/year, and biases up to 0.2 mm/year may persist for observation
spans of 8 years. Changing between uniform and elevation-dependent observation weighting alters the time series but does not
remove the velocity biases, nor does ambiguity fixing. The effect on the horizontal coordinates is negligible. The ambiguities
fixed series spectra show noise between flicker and random walk with near-white noise at the highest frequencies, with mean
spectral indices (frequencies <20 cycles per year) of approximately −1.3 (uniform weighting) and −1.4 (elevation-dependent
weighting). While the results are likely highly monument specific, they highlight the importance of accounting for monument
effects when analysing vertical coordinate time series and velocities for the highest precision and accuracy geophysical studies. 相似文献
9.
《International Journal of Digital Earth》2013,6(1):85-102
ABSTRACTThis paper aims to demonstrate results and considerations regarding the use of remote sensing big data for archaeological and Cultural Heritage management large scale applications. For this purpose, the Earth Engine© developed by Google© was exploited. Earth Engine© provides a robust and expandable cloud platform where several freely distributed remote sensing big data, such as Landsat, can be accessed, analysed and visualized. Two different applications are presented here as follows: the first one is based on the evaluation of multi-temporal Landsat series datasets for the detection of buried Neolithic tells (‘magoules’) in the area of Thessaly, in Greece using linear orthogonal equations. The second case exploits European scale multi-temporal DMSP-OLS Night-time Lights Time Series to visualize the impact of urban sprawl in the vicinity of UNESCO World Heritage sites and monuments. Both applications highlight the considerable opportunities that big data can offer to the fields of archaeology and Cultural Heritage, while the studies also demonstrate the great challenges that still are needed to be overcome in order to make the exploitation of big data process manageable and fruitful for future applications. 相似文献
10.
Hiroshi Munekane 《Journal of Geodesy》2013,87(4):393-401
The sub-daily noise in horizontal global positioning system (GPS) kinematic time series arising from monument tilts is quantitatively evaluated using tiltmeter data at GPS stations from the Japanese nationwide global navigation satellite system network. The estimated tilt-induced monument displacements show characteristics that are typical of those caused by thermal tilts of the monuments. The root mean square of the displacements is typically a few millimetres, with notable inter-seasonal variations. The stacked amplitude spectra of the monument displacements have peaks at the tidal bands S1 and S2, and their higher tones. The peaks at the S1 and S2 bands in the amplitude spectra are reduced by 41 and 43 % for the north–south component and 36 and 53 % for the east–west component, respectively, after correcting for the monument displacements. The monument displacements due to the thermal tilts of the monuments may also be a favourable candidate for sub-daily noise at the S1 and S2 bands found in other GPS networks. 相似文献
11.
Delineation of potential zones for artificial recharge using gis 总被引：2，自引：0，他引：2
V Jothiprakash G Marimuthu R Muralidharan N Senthilkumar 《Journal of the Indian Society of Remote Sensing》2003,31(1):37-47
In the present study, potential zones for artificial recharge in Agniar-Ambuliar-Southvellar river basins in Tamilnadu, India have been delineated through integration of various thematic maps using Arc view GIS. The study area, covers an area of 4566 km2. Thematic maps pertaining to geology, permeability, effective soil depth, drainage intensity, soil texture, water holding capacity and physiography were prepared on 1:2,50,000 scale using conventional methods. These maps were scanned and registered with reference to a base map and are prepared as separate layers or coverages using Arc view. GIS has been used for the integration of various thematic maps to delineate the potential zones for artificial recharge. Each theme was assigned a weightage depending on its influence on groundwater recharge. Each class or unit in the map was assigned a knowledge based ranking from one to four depending on its significance in storage and transmittance of groundwater. The final map has been prepared showing four different categories of potential zones for artificial recharge. 相似文献
12.
none 《The Cartographic journal》2013,50(2):181-182
AbstractNo statement appears to have been made at the time of why the national survey was put in hand in 1791. How far the Ordnance launched it in furtherance of its own responsibilities for the defence of the realm, and was therefore right to confer on the ordnance survey the prestige of its name, is a question which this article considers.The Board of Ordnance was a department of state which was already by then two and a half centuries old. Furnishing the ordnance survey with scientific and administrative skills and Ordnance also lumbered it with the political difficulties which led to its own demise. 相似文献
13.
AbstractReaders will notice that this issue of the Review is numbered 100 and, as it has always been published quarterly, this means that it has now been in existence for 25 years and so celebrates its silver jubilee. 相似文献
14.
《International Journal of Digital Earth》2013,6(4):356-371
Abstract Administrative units reflect the territorial hierarchies established within all countries of the world. The units are addressable with geocodes that provide a bijective mapping between territories and unique identification codes. Early warning systems for natural or man-made hazards often map affected or threatened areas to administrative units to establish a spatial reference that is comprehensible to all parts of the population. Addressing these territories in an international context has several requirements, such as worldwide coverage, completeness and topicality, which must be met by geocode standards. In this paper, the practicability and suitability of international geocode standards are examined in the context of the requirements of large-scale early warning systems. This paper exposes the insufficiencies and limitations of existing geocode standards International Organization for Standardization (ISO)-3166, Second Administrative Level Boundaries data set project (SALB) and Nomenclature of the Territorial Units for Statistics (NUTS) and emphasises the suitability of the non-official hierarchical administrative subdivision codes (HASC). The analysis is framed in the context of addressing affected areas for an Indian Ocean tsunami early warning system. This system was developed within the Distant Early Warning Systems project according to the requirements of the United Nations Educational, Scientific and Cultural Organization (UNESCO) Intergovernmental Oceanic Commission for Regional Tsunami Watch Providers (RTWPs). 相似文献
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Abstract This study attempts to model the spatial extent of Franz Josef Glacier in the Southern Alps of New Zealand from environmental variables. Glacier tongue length, area, and equilibrium line altitude were measured in ArcView after 15 end‐of‐summer glacier termini were demarcated from a diverse source of remotely sensed materials that had been geometrically rectified. These tongue parameters were correlated with and regressed against mean winter (June to September) precipitation, summer (December to February) temperature, and terminal gradient. The regressed length model was used to simulate the spatial extent of the glacier tongue in ArcInfo. Modelling of the spatial extent was implemented in a two‐stage approach using Arc Macro Language. The terminus end of the glacier tongue was simulated with an empirical parabolic curve. It is found that the averaging duration of climatic variables plays a significant role in exploring their impact on the glacier tongue. Tongue area has a Pearson correlation coefficient of 0.70 and 0.60, respectively, with mean monthly winter precipitation and averaged monthly summer temperature. The underlying topography exerts a significant effect on tongue morphometry that is most reliably predicted from slope gradient (β) but less so from precipitation (PPT) and temperature (T). The best models for tongue length and area are Length=4100.779?1.2346×PPT+91.9162×T?29.30×β (R2=80.77%) and Area=308.3207?0.0342×PPT+3.3100×T?0.9893×β (R2=81.51%). Through its horizontal shifting and rotation, the empirical parabolic curve enabled the terminal end of the glacier tongue to be accurately and realistically modelled from the environmental variables. 相似文献
17.
《The Cartographic journal》2013,50(2):78-79
AbstractVarious point symbols have been employed by cartographers to represent component parts of certain phenomena. The pie graph is obviously the most popular of these symbols. At the same time, it is widely condemned for its inability to afford estimations that are close to the latent information. To help overcome this problem, the decagraph is suggested in this paper, as a substitute for the pie graph. 相似文献
18.
Precise photorealistic visualization for restoration of historic buildings based on tacheometry data
This paper puts forward a 3D reconstruction methodology applied to the restoration of historic buildings taking advantage of the speed, range and accuracy of a total geodetic station. The measurements representing geo-referenced points produced an interactive and photorealistic geometric mesh of a monument named ‘Neoria.’ ‘Neoria’ is a Venetian building located by the old harbor at Chania, Crete, Greece. The integration of tacheometry acquisition and computer graphics puts forward a novel integrated software framework for the accurate 3D reconstruction of a historical building. The main technical challenge of this work was the production of a precise 3D mesh based on a sufficient number of tacheometry measurements acquired fast and at low cost, employing a combination of surface reconstruction and processing methods. A fully interactive application based on game engine technologies was developed. The user can visualize and walk through the monument and the area around it as well as photorealistically view it at different times of day and night. Advanced interactive functionalities are offered to the user in relation to identifying restoration areas and visualizing the outcome of such works. The user could visualize the coordinates of the points measured, calculate distances and navigate through the complete 3D mesh of the monument. The geographical data are stored in a database connected with the application. Features referencing and associating the database with the monument are developed. The goal was to utilize a small number of acquired data points and present a fully interactive visualization of a geo-referenced 3D model. 相似文献
19.
《测量评论》2013,45(14):496-498
AbstractIn the Empire Survey Review for April 1934 (No. 12, pp. 382–4), the Editor has raised the question of the function of the cadastral map. As he remarks, the question is not simple, but it is easier to say what the function of the map is than to decide of what the map should consist in order that it may fulfil its function. Broadly speaking we may state that the function of the map is to record the boundaries of landed property in such a manner as not only to afford a pictorial representation but also to supply data for the identification of these boundaries on the ground when occasion requires. Apart from this the map should show the areas of properties, as this information may be required for taxation purposes. 相似文献