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1.
AbstractFor a number of years topographers and air surveyors have regarded improved hypsometry as a desideratum. Of hypsometric instruments, the boiling-point thermometer and the barometer are practically the only two in use, and even the barometer is commonly represented solely by the aneroid. Since improvement of the lastnamed offered the best hope of success, a Service Committee was formed some three years ago to endeavour to secure at least some progress in both the construction and the use of the aneroid: it would seem that they should have no reason to be dissatisfied with their labours. The Committee was constituted of representatives of the Hydrographic Department of the Admiralty, the Geographical Section of the General Staff, the Meteorological Office of the Air Ministry, and of the National Physical Laboratory. It is obvious that not much material progress would have been made without the concurrence of the manufacturers; accordingly four of the leading makers of this kind of instrument took part in the later deliberations. The delivery of the requisite tables has taken much longer than was anticipated; on the other hand, one of the makers delivered instruments to the new specification with encouraging promptitude. 相似文献
2.
AbstractA Fully equipped theodolite is provided with plate levels, an alidade level, and a striding level. An instrument not so equipped has no title to be considered a “Universal Instrument”, that is to say, an instrument designed for every kind of both terrestrial and celestial measurement. Without a striding level, for example, nothing beyond relatively rough astronomical measures can be expected in general. Modern instruments, capable of giving considerable refinement in terrestrial measures, are frequently not furnished with a striding level; and it is sometimes assumed, with the tacit approval of the makers, that such instruments are equally capable of giving refined astronomical results. On the older type of instrument a striding level—rarely not supplied—could have been, and sometimes was, extemporized; it seems as if ignorance of astronomy of position has led, at least in part, to the construction of theodolites in such a manner as actually to render such extemporization difficult. 相似文献
3.
C. D. Burnside 《The Photogrammetric Record》1995,15(86):251-261
The paper entitled The Photogrammetric Society Analogue Instrument Project was published in The Photogrammetric Record, 14(82): 565-582 and contained, as Appendix A, an extract from the Archive concerned with the history of the Zeiss Stereoplanigraph in Great Britain. A further three extracts have since been published to provide details of direct optical projection instruments used in this country and of the Vivian Thompson Stereo-plotter.
This fifth extract deals with the Wild A5 and A6 instruments. Their introduction into the United Kingdom during and just prior to the Second World War, together with their important contributions to the war effort, make interesting reading. With a grand total of just five such instruments, they were well used throughout the period of hostilities.
This extract also includes a note on the Wild A4 instrument, designed for close range photogrammetry. This was the last instrument in which Wild made use of projector lenses but it has been included at this point so that all of the Wild instruments which are listed in the Catalogue (and therefore included in the Archive) are dealt with in numerical order. 相似文献
This fifth extract deals with the Wild A5 and A6 instruments. Their introduction into the United Kingdom during and just prior to the Second World War, together with their important contributions to the war effort, make interesting reading. With a grand total of just five such instruments, they were well used throughout the period of hostilities.
This extract also includes a note on the Wild A4 instrument, designed for close range photogrammetry. This was the last instrument in which Wild made use of projector lenses but it has been included at this point so that all of the Wild instruments which are listed in the Catalogue (and therefore included in the Archive) are dealt with in numerical order. 相似文献
4.
AbstractWhen the area to be sounded out extends seawards beyond the range of visibility of shore-marks or lies altogether out of sight of land, the hydrographic surveyor has to have recourse to floating marks anchored to the sea-bottom. Up to a few years ago the standard beacon used to form these marks was known as the Egeria beacon. This consisted of two 27-gallon wooden casks placed vertically between two stout planks which were secured to each other by six iron stays. Sufficient room was left between the casks to allow a spar tapering from 6 inches in diameter at its heel to 4 inches at its head to pass through holes cut in the planks. This spar is known as the beacon spar, is about 35 feet long, and is held in place above and below by two iron pins attached to two protecting steel sleeves enclosing it. On its heel is shackled a 1¾-cwt. sinker to make the beacon float upright. It projects from 8 to 10 feet above the upper side of the beacon; to this projection is lashed with three hemp lashings a 38-foot bamboo which carries a 16- by 10-foot calico flag, the height of the mark giving a range of visibility in clear weather of 12 miles from the bridge of a surveying ship. A wire strop is fitted round the beacon with a large eye stopped up the bamboo for hoisting in and out of the ship; a length of chain, secured round the beacon spar above and below the beacon, carries a slip to which the moorings are attached. 相似文献
5.
C. D. Burnside 《The Photogrammetric Record》1997,15(90):883-899
The paper entitled The Photogrammetric Society Analogue Instrument Project was published in The Photogrammetric Record 14(82): 565-582 (October 1993). Extracts have appeared in each subsequent issue such that all the standard types of analogue instruments mentioned in the catalogue have now been included, some 28 instruments in all. In this final extract, the three remaining instruments listed in the catalogue are dealt with. All are of a type usually known as approximate solution instruments because they did not attempt any form of accurate space intersection but relied on applying a number of corrections to a model formed on the assumption that the photographs being used were true verticals taken at the same altitude. The accuracies achieved by such instruments depended both on how close the photography being used was to this ideal situation and on the degree of sophistication in the design of the analogue correctors incorporated in any particular instrument. The raison d'être for such a genre of instrument was essentially one of cost. Any organization faced with the requirement to produce small scale topographic mapping of an extensive region within a reasonable period of time might consider spending its available funds on a larger number of cheaper approximate solution instruments, always provided that an acceptable degree of accuracy could be maintained. Fortunately for such projects the specification would normally be for mapping of a graphical order of accuracy produced from high altitude photography. At such altitudes, stable flying conditions and small camera tilts of the order of 3° to 4° could realistically be expected. However, to obtain the best possible results from such photography, the best images possible should be provided for the operator, a factor sometimes overlooked by some manufacturers in their attempts to produce cheaper instruments. In view of the background to the development of British photogrammetry mentioned in previous extracts, it is perhaps surprising that a successful instrument of this type was not produced in the UK at a much earlier point in the era of analogue photogrammetry. Approximate methods were certainly favoured and promoted but only as far as planimetric maps were concerned. For these, form lines rather than contours were drawn when height information was considered necessary. However, when it was finally produced, the Thompson CP1 (manufactured by Cartographic Engineering Ltd.) proved to be an excellent instrument of its type and less approximate in its solution than most of its competitors. The other two instruments described in this extract are the Zeiss Stereotope and the Galileo-Santoni Stereomicrometer. The instruments are introduced in the order of their appearance on the market, which is also the order of the degree of sophistication found in the analogue computers they employed to reduce the errors introduced by any camera and airbase tilt present in the photography. 相似文献
6.
《地理信息系统科学与遥感》2013,50(4):522-540
Landscape assessment of soil moisture is critical to understanding the hydrological cycle at the regional scale and in broad-scale studies of biophysical processes affected by global climate changes in temperature and precipitation. Traditional efforts to measure soil moisture have been principally restricted to in situ measurements, so remote sensing techniques are often employed. Hyperspectral sensors with finer spatial resolution and narrow band widths may offer an alternative to traditional multispectral analysis of soil moisture, particularly in landscapes with high spatial heterogeneity. This preliminary research evaluates the ability of remotely sensed hyperspectral data to quantify soil moisture for the Little River Experimental Watershed (LREW), Georgia. An airborne hyperspectral instrument with a short-wavelength infrared (SWIR) sensor was flown in 2005 and 2007 and the results were correlated to in situ soil moisture values. A significant statistical correlation (R 2 value above 0.7 for both sampling dates) for the hyperspectral instrument data and the soil moisture probe data at 5.08 cm (2 inches) was determined. While models for the 20.32 cm (8 inches) and 30.48 cm (12 inches) depths were tested, they were not able to estimate soil moisture to the same degree. 相似文献
7.
C. D. Burnside 《The Photogrammetric Record》1997,15(89):791-802
This eighth and penultimate extract from the Archive is an unusual one for a number of reasons. Of these the most important one is the fact that it is concerned solely with instruments produced in Great Britain. It is therefore concerned mainly with the Thompson-Watts plotter, the only British instrument to go into full-scale commercial production. Strictly speaking the other instrument included in this extract should not have had a separate entry at all, simply because no instrument of this type exists now and so cannot have an entry in the catalogue of instruments. However, in order to trace the development of the Thompson-Watts Mk 2 plotter, produced in 1963, from the remarkable work of Henry Fourcade carried out in the 1920s, the Barr and Stroud ZA2 plotter based on his work has been accorded an Appendix of its own.
Both instruments in this extract are based on an optical-mechanical solution to the photogrammetric problem of space intersection and the Thompson-Watts is in fact the only instrument of this type to be found in the catalogue. This particular solution did not find great favour on the continent and so few instruments of this type were produced commercially. 相似文献
Both instruments in this extract are based on an optical-mechanical solution to the photogrammetric problem of space intersection and the Thompson-Watts is in fact the only instrument of this type to be found in the catalogue. This particular solution did not find great favour on the continent and so few instruments of this type were produced commercially. 相似文献
8.
9.
《测量评论》2013,45(15):14-16
AbstractTHE mapping of flat country from the ground always entails much more work than the mapping of hilly country for the obvious reason that the nearness of the horizon, coupled with the obstruction of trees, buildings, and vegetation, restricts the view, and long lines are not possible. In contrast to this, mapping from air-photographs becomes much more simple when the country is flat, for the photographic projection is not complicated by height distortions, and it is only necessary to correct for distortions caused by the impossibility of keeping the camera perfectly horizontal at the instant of exposure. During the past four years in Bengal and the United Provinces, where the alluvial plains scarcely vary a foot from monotonous flatness, many thousands of square miles have been surveyed photographically, and excellent maps have been made on a scale of 16 inches to 1 mile and are being used by Settlement Officers for purposes of land assessment. 相似文献
10.
11.
星差分(星基差分)GPS接收机SF2050G使用NAVCOM公司在全球建立的StarFire系统,可在全球范围内使用无自架基站实时差分服务,标称可得到WGS-84坐标系下分米级的定位精度,为将该仪器应用于控制测量中,对4台仪器进行了一个工作日测试,采集数据40个,分析测试数据得出了该机型机器在本工作日内的精度,将仪器应用于地理国情普查项目内蒙古部分测区的像控作业,与已知控制点坐标对比得出该仪器的精度,并对该仪器未来的应用方法与方向做出了一定的探索性设想。 相似文献
12.
Ambiguity validation with combined ratio test and ellipsoidal integer aperture estimator 总被引：4，自引：3，他引：1
Shengyue Ji Wu Chen Xiaoli Ding Yongqi Chen Chunmei Zhao Congwei Hu 《Journal of Geodesy》2010,84(10):597-604
To ensure reliable ambiguity resolution, ambiguity validation is an indispensable step. It has been a challenge for many years
and is far from being resolved. Over the past years, various ambiguity validation methods have been proposed, such as F-ratio test, R-ratio test, difference test, projector test, ellipsoidal integer aperture (EIA) estimator and penalized integer aperture
(PIA) estimator. In this paper, through analysis and testing, we find that, when the aperture region of EIA is not allowed
to be overlapped, the efficiency of ambiguity resolution with EIA is low and it is not applicable to fast static positioning
or real-time kinematic (RTK) applications. Then EIA with overlapped aperture regions is recommended and the resulted fail-rate
becomes upper bound of the actual one. After that, it is suggested that combined use of overlapped EIA and R-ratio test can increase the reliability of ambiguity resolution. Finally, numerical tests are carried out based on practical
buoy data and simulated Galileo data. 相似文献
13.
14.
C. D. Burnside 《The Photogrammetric Record》1996,15(87):419-435
The paper entitled The Photogrammetric Society Analogue Instrument Project was published in The Photogrammetric Record, 14(82): 565-582 and contained, as Appendix A, an extract from the Archive concerned with the history of the Zeiss Stereoplanigraph in Great Britain. Further extracts have appeared in each of the subsequent issues.
This extract, the sixth of the series, completes the history of the use of the various types of Wild instrument in the United Kingdom. It is concerned with the later post-war instruments, in numerical order, from the A7 Autograph to the A10 and therefore includes a note on one of the most popular and successful analogue plotting instruments ever produced, the Wild A8 Stereoplotter.
At the moment, none of the instruments dealt with in this extract appear to be under immediate threat. However, their role as production instruments is fading fast in most organizations but they are being retained, often for training purposes.
The Archive contains no mention of the last and most refined range of analogue instruments produced by Wild as their Aviomap (AM) series. With the benefit of hindsight it is now obvious that, at the time of their introduction, the transition from analogue to analytical techniques was about to take place at an accelerating pace. There is therefore no entry in the Archive for any AM or AM-U instrument; none (or perhaps only a very few) seem to have been imported into the United Kingdom. 相似文献
This extract, the sixth of the series, completes the history of the use of the various types of Wild instrument in the United Kingdom. It is concerned with the later post-war instruments, in numerical order, from the A7 Autograph to the A10 and therefore includes a note on one of the most popular and successful analogue plotting instruments ever produced, the Wild A8 Stereoplotter.
At the moment, none of the instruments dealt with in this extract appear to be under immediate threat. However, their role as production instruments is fading fast in most organizations but they are being retained, often for training purposes.
The Archive contains no mention of the last and most refined range of analogue instruments produced by Wild as their Aviomap (AM) series. With the benefit of hindsight it is now obvious that, at the time of their introduction, the transition from analogue to analytical techniques was about to take place at an accelerating pace. There is therefore no entry in the Archive for any AM or AM-U instrument; none (or perhaps only a very few) seem to have been imported into the United Kingdom. 相似文献
15.
Jeffrey B Basara DeWayne Mitchell Daniel R Cheresnick Bradley G Illston 《Transactions in GIS》2007,11(4):531-554
Severe hail is a common event in the United States and few studies have been conducted using high‐resolution data to determine the spatial and temporal variability of hail occurrence. Given the coverage of Weather Surveillance Radar‐88 Doppler radars (WSR‐88D; Crum and Alberty 1993 ) over the Southern Plains of the United States, recent technological advancements including hail detection algorithms and powerful new geographic information systems (GIS) tools, a new methodology was developed to quantify the occurrence of severe hail. The methodology was tested using a dataset spanning 2001–2003 from 15 radar sites across eight states. The Hailswath algorithm developed at Weather Decision Technologies, Inc. was used to estimate severe and significant hail for each individual storm during the study period. Due to the discrete nature of the Hailswath algorithm output, it was manually contoured to create a coherent swath of the most likely area of severe (19 mm in diameter; 0.75 inches) and significant hail (51 mm in diameter; 2 inches). Finally, the results of these analyses were compiled monthly, annually, and for the total duration of the study period using a variety of GIS tools. A thorough demonstration of the data analysis process and results is presented, and the benefits and limitations of the method used to investigate the occurrence of severe hail are explained. 相似文献
16.
《测量评论》2013,45(84):282-283
Abstract1. The explanation of this fundamental operation in setting up surveying instruments, as well as of the theory of the level on which it is based, is, in my opinion, not sufficiently explained in text-books. I came across the problem while lecturing on the theory of surveying instruments. Below is an extract of the notes I made on the subject, which may have a didactical interest. 相似文献
17.
测绘仪器类型多样,同一类型包含不同名称的仪器,同一名称的仪器还可以有多台不同编号的仪器。为有效管理测绘仪器,从数据库设计与创建入手,对仪器的入库登记、出库（检定、外借、维修）等操作实现信息化管理,提出仪器查找的逐级过滤法及对应的仪器三段式编码,设计了7种仪器状态,并分析不同状态的转换关系,对报表自动添加条形码,实现了利用条码扫描枪对报表条码扫描,自动调出报表的仪器出库记录集,并快速加以返还的作业模式。 相似文献
18.
《测量评论》2013,45(49):99-107
AbstractThe problem of dividing the circle into equal parts has occupied the minds of astronomers and instrument makers from the earliest times, but little is known of the methods adopted by such renowned observers as Hevelius or Tycho Brahe, who are said to have divided their own instruments (I). It is possible, however, to trace the various steps by which progress was made and to appreciate the urgent need that was felt, particularly throughout the eighteenth century, for improvement in the accuracy of astronomical instruments, if only to satisfy the increasing demands for navigational charts and for the means of determining the position of a ship at sea. 相似文献
19.
In India the last 30 years had witnessed a radical transformation of urban scene. In particular, during this period, the one
lakh cities and million plus cities began to grow rapidly. In the present study, urban growth of Jaipur city in the last 31 years
(1975–2006) was assessed. Jaipur ranks 11th in India with a total population of 2.3 million and has shown a consistent increase
in the past 50 years. It is one of the fastest growing mega cities of the country with an annual average growth rate of 4.5%
which is quite high from the national urban growth rate. Remote sensing and GIS have been used to extract the information
related to urban growth-built up area and its spatial and temporal variation. The Shannon’s entropy at two levels (city as
a whole and ward wise) is computed in order to quantify the form and patterns of urban growth using built up area as spatial
phenomena. Further, multivariate statistical techniques have been used to establish the relationship between the urban growth
and its causative and determining factors. Results of this study reveal that the growth rate of built up in Jaipur has outstripped
the rate of population growth. Shannon’s entropy quantifies as dispersed form of urban growth till 2000 and after it, there
is relative compactness in 2006. 相似文献
20.
R. Reudink R. Klees O. Francis J. Kusche R. Schlesinger A. Shabanloui N. Sneeuw L. Timmen 《Journal of Geodesy》2014,88(6):617-622
We report on the susceptibility of the Scintrex CG-5 relative gravimeters to tilting, that is the tendency of the instrument of providing incorrect readings after being tilted (even by small angles) for a moderate period of time. Tilting of the instrument can occur when in transit between sites usually on the backseat of a car even using the specially designed transport case. Based on a series of experiments with different instruments, we demonstrate that the readings may be offset by tens of $\upmu $ Gal. In addition, it may take hours before the first reliable readings can be taken, with the actual time depending on how long the instrument had been tilted. This sensitivity to tilt in combination with the long time required for the instrument to provide reliable readings has not yet been reported in the literature and is not addressed adequately in the Scintrex CG-5 user manual. In particular, the inadequate instrument state cannot easily be detected by checking the readings during the observation or by reviewing the final data before leaving a site, precautions suggested by Scintrex Ltd. In regional surveys with car transportation over periods of tens of minutes to hours, the gravity measurements can be degraded by some 10 $\upmu $ Gal. To obtain high-quality results in line with the CG-5 specifications, the gravimeters must remain in upright position to within a few degrees during transits. This requirement may often be unrealistic during field observations, particularly when observing in hilly terrain or when walking with the instrument in a backpack. 相似文献