共查询到20条相似文献，搜索用时 24 毫秒
1.
O. Remmer 《Journal of Geodesy》1969,43(2):99-122
A method for filtering of geodetic observationwhich leaves the final result normally distributed, is presented. Furthermore, it is shown that if you sacrifice100.a% of all the observations you may be (1−β).100% sure that a gross error of the size Δ is rejected.
Another and, may be intuitively, more appealing method is presented; the two methods are compared and it is shown why Method
1 should be preferred to Method 2 for geodetic purposes.
Finally the two methods are demonstrated in some numerical examples. 相似文献
2.
Kenneth Field 《The Cartographic journal》2013,50(2):93-94
AbstractThis paper presents the cartographic elements of a system for classifying and visualizing high-dimensional geographic datasets. The system has been developed as part of the Land Ocean Interactions in the Coastal Zone (LOICZ) project. The goal of the system is to develop regional and global typologies of coastal zones using large multi-variable datasets. Our implementation bring together statistical clustering algorithms with visualization capabilities to allow easy analysis and comprehension of the result. The two main tasks of the visualization are to allow for discrimination of multiple classes and to show relationships between those classes. These are accomplished in two different visual presentations. In both cases, the system selects colors appropriate to the purpose. In the latter case — showing relationships — the system uses a novel iterative refinement algorithm to select the colors. The result show that the system is successful at both generation the classes and visualizing the relationships between them. 相似文献
3.
《测量评论》2013,45(5):214-217
AbstractIn order to minimize errors in Precise Levelling it is usual to stipulate a maximum distance at which a staff shall be held from the instrument. The determination of such a distance must result from a compromise between the demands of accuracy and economy, and this distance must of course fall between the lower limit, when because of nearness the instrument cannot be focussed on the staff, and the upper limit, above which the staff cannot be read distinctly. 相似文献
4.
none 《The Cartographic journal》2013,50(2):147-149
AbstractThis is a summary of the problems which are involved in the apparently trivial task of measuring the length of a sinuous line on a map. It represents an extended review of the publication Cartometric Measurements, by H. Kishimoto. It is concerned with three basic problems: (1) the sorts of errors which may result from using different instruments and methods of measurement and how these may be corrected: (2) the sorts of errors which may occur in the map and how these may be corrected: 3) the fundamental problem of what is 'length'. Extensive use is made of East European literature on these subjects. 相似文献
5.
《测量评论》2013,45(88):86-87
AbstractThe usual procedure in breaking down a primary network of triangulation is to go through a secondary scheme to a system of tertiary points. These are usually of the order of 1½ imiles apart, and are the co-ordinated points to which the detail survey, of whatever kind it may be, is fastened. 相似文献
6.
R. H. Rapp 《Journal of Geodesy》1969,43(1):47-80
A set of2261 5°×5° mean anomalies were used alone and with satellite determined harmonic coefficients of the Smithsonian' Institution to determine
the geopotential expansion to various degrees. The basic adjustment was carried out by comparing a terrestrial anomaly to
an anomaly determined from an assumed set of coefficients. The (14, 14) solution was found to agree within ±3 m of a detailed geoid in the United States computed using1°×1° anomalies for an inner area and satellite determined anomalies in an outer area. Additional comparisons were made to the
input anomaly field to consider the accuracy of various harmonic coefficient solutions.
A by-product of this investigation was a new γE=978.0463 gals in the Potsdam system or978.0326 gals in an absolute system if −13.7 mgals is taken as the Potsdam correction. Combining this value of γE withf=1/298.25, KM=3.9860122·10
22
cm
3
/sec
2
, the consistent equatorial radius was found to be6378143 m. 相似文献
7.
E. Mittermayer 《Journal of Geodesy》1972,46(2):139-157
Summary The system of normal equations for the adjustment of a free network is a singular one. Therefore, a number of coordinates
has to be fixed according to the matrix. The mean square errors and the error ellipses of such an adjustment are dependent
on this choice.
This paper gives a simple, direct method for the adjustment of free networks, where no coordinates need to be fixed. This
is done by minimizing not only the sum of the squares of the weighted errorsV
T
PV=minimun but also the Euclidean norm of the vectorX and of the covariance matrixQ X
T
X=minimum trace (Q)=minimum This last condition is crucial for geodetic problems of this type. 相似文献
8.
《测量评论》2013,45(89):115-121
AbstractProbably the most important matter connected with computing is checking. Far more time is wasted by an incorrect result which has been passed as correct by the checker than by any other fault in computing. It is not necessary that a computer should always be perfectly accurate, but it is necessary that the method of checking used should always detect his errors. If the computer is sure that his accidental errors will be picked up he is relieved of anxiety and his work will be quicker and eventually more accurate for that reason. 相似文献
9.
An investigation was made of the behaviour of the variable
(where ρij are the discrepancies between the direct and reverse measurements of the height of consecutive bench marks and theR
ij
are their distance apart) in a partial net of the Italian high precision levelling of a total length of about1.400 km.
The methods of analysis employed were in general non-parametric individual and cumulative tests; in particular randomness,
normality and asymmetry tests were carried out. The computers employed wereIBM/7094/7040. From the results evidence was obtained of the existence of an asymmetry in respect to zero of thex
ij
confirming the well-known results given firstly by Lallemand. A new result was obtained from the tests of randomness which
put in evidence trends of the mean values of thex
ij
and explained some anomalous behaviours of the cumulative discrepancy curves. The extension of this investigation to a broader
net possibly covering other national nets would be very useful to get a deeper insight into the behaviour of the errors in
high precision levelling. Ad hoc programs for electronic computers are available to accomplish this job quickly.
Presented at the 14th International Assembly of Geodesy (Lucerne, 1967). 相似文献
10.
《测量评论》2013,45(88):84-85
AbstractIt is hardly surprising that the more elementary aspects of a subject come to be so taken for granted that the learned authors of text-books fall into the error of oversimplifying them. As a result, the student is very often given a distorted idea of what is of fundamental importance. 相似文献
11.
Burkhard Schaffrin 《Journal of Geodesy》2008,82(2):113-121
In a linear Gauss–Markov model, the parameter estimates from BLUUE (Best Linear Uniformly Unbiased Estimate) are not robust
against possible outliers in the observations. Moreover, by giving up the unbiasedness constraint, the mean squared error
(MSE) risk may be further reduced, in particular when the problem is ill-posed. In this paper, the α-weighted S-homBLE (Best homogeneously Linear Estimate) is derived via formulas originally used for variance component estimation on
the basis of the repro-BIQUUE (reproducing Best Invariant Quadratic Uniformly Unbiased Estimate) principle in a model with
stochastic prior information. In the present model, however, such prior information is not included, which allows the comparison
of the stochastic approach (α-weighted S-homBLE) with the well-established algebraic approach of Tykhonov–Phillips regularization, also known as R-HAPS (Hybrid APproximation Solution), whenever the inverse of the “substitute matrix” S exists and is chosen as the R matrix that defines the relative impact of the regularizing term on the final result.
The delay in publishing this paper is due to a number of unfortunate complications. It was first submitted as a multi-author
paper in two parts. Due to some miscommunication among the original authors, it was reassigned to one of the J Geod special
issues, but later reassigned at this author’s request to a standard issue of J Geod. This compounded with a difficulty to
find willing reviewers to slow the process. We apologize to the author. 相似文献
12.
《测量评论》2013,45(40):69-75
AbstractWhen a theodolite is used to measure an angle, the result will be subjected to certain instrumental and personal errors which affect the measurement. Such errors may be accidental or systematic. Those of the former type, which follow no law and which may with equal probability occur at any graduation, are more easily eliminated, since, if a very large number of readings is taken, it is probable that the errors will cancel out and that the mean will approximate very closely to the correct figure. Systematic errors are usually due to instrumental defects and rnay be expressed as a function of the reading itself; it is the object of the manufacturer to eliminate these as far as possible, since cancellation by reiteration or by repetition is not to be expected wholly. 相似文献
13.
《The Cartographic journal》2013,50(1):20-23
AbstractThe rapid development of physically-based hydrological information and modelling systems has necessitated enhanced data entry and display systems. A 'mapping tool' is developed for the manipulation and display of spatial information, which is a cost-efficient, self-contained utility system that is suitable for use on micro-computers. It has the ability to be integrated as part of any modelling or information system. Diverse applications using the 'mapping tool' are briefly described including resource management systems for planners, mass balance studies in urban catchments and data entry systems for physically based models. 相似文献
14.
《测量评论》2013,45(61):267-271
AbstractSome publications that have dealt with the question of convergence of meridians seem, to the present writer, to be clouded with misconception, and these notes are intended to clarify some points of apparent obscurity. For instance, A. E. Young, in “Some Investigations in the Theory of Map Projections”, I920, devoted a short chapter to the subject, and appeared surprised to find that the convergence on the Transverse Mercator projection differs from the spheroidal convergence; the explanation which he advanced can be shown to be faulty. Captain G. T. McCaw, in E.S.R., v, 35, 285, derived an expression for the Transverse Mercator convergence which is equal to the spheroidal convergence, and described this as “a result which might be expected in an orthomorphic system”. Perhaps McCaw did not intend his remark to be so interpreted, but it seems to imply that the convergence on any orthomorphic projection should be equal to the spheroidal convergence, and it is easily demonstrated that this is not so. Also, in the second edition of “Survey Computations” there is given a formula for the convergence on the Cassini projection which is identical, as far as it goes, with that given for the Transverse Mercator, while the Cassini convergence as given by Young is actually the spheroidal convergence. Obviously, there is some confusion somewhere, and it is small wonder that Young prefaced his remarks with the admission that the subject had always presented some difficulty to him. 相似文献
15.
《测量评论》2013,45(30):481-482
AbstractIn the above article by Mr H. L. P. Jolly published in a previous issue (E.S.R., vol. iv, no. 28) the author, after referring to the precision of the Nigerian traverses, makes the statement that measurements of the highest accuracy are worthy of the best possible methods of adjustment. But this argument cuts both ways. For in general the greater the accuracy of measurement the smaller will be the ultimate misclosure to be eliminated; so that different methods of adjustment will produce smaller and smaller variations in the corrections, until in the limit when there is no error we should obtain the same result however much latitude we permitted in the adjustment. 相似文献
16.
Y. Kozai 《Journal of Geodesy》1968,42(3):355-357
From periodic variations of the orbital inclinations of three artificial satellites 1959Alpha 1, 1960Iota 2, and 1962Beta Mu 1 Love’s number of the earth and time lag of the bodily tide due to the friction are determined, respectively,0.29±0.03 and(10±5) minutes in time.
While the previous paper on the determination of Love’s number of the earth (Kozai, 1967) was in press, a minor error was
discovered in the Differential Orbit Improvement program(DOI) of the Smithsonian Astrophysical Observatory(SAO). Since the analysis was based on time-variations of the orbital inclinations which were derived by theDOI from precisely reduced Baker-Nunn observations, it is likely that the results in the previous paper was affected by the error
in theDOI. Therefore, the analysis is iterated by using the revisedDOI. Three satellites, 1959Alpha 1 (Vanguard 2), 1960Iota 2 (rocket ofEcho 1), and 1962Beta Mu 1 (Anna) (see Table 1) are adopted for determining Love’s number in the present paper. The satellite, 1959Eta, which was used in the previous paper, is not adopted here, since the inclination of this satellite shows irregular variations
unexplained. Instead of 1959Eta 1962Beta Mu 1 is adopted as orbital elements from precisely reduced Baker-Nunn observations have become available for a long interval of
time for this satellite. 相似文献
17.
《测量评论》2013,45(26):234-243
AbstractTHE Gold Coast can now be said to have recovered from the slump which caused such disastrous consequences in 1931–2 and resulted in a heavy reduction in the establishment of the Survey Department. So far there has been no increase in staff, but more badly needed money for buying stores and increasing the labour staff has been available, and authority has now been given for an increase of 12 in the establishment of African Surveyors; this will result in the re-opening of the Survey School in 1937. 相似文献
18.
《测量评论》2013,45(37):410-429
Abstract1. In latter years a good deal has been written in English on precise traversing, both in regard to the field work and also the various methods of computation, whatever system of proj ection is used. A bibliography of publications known to the writer is given at the end of this article. But the ordinary traversing most frequently carried out by surveyors, which might be classed as secondary and tertiary, does not appear to have received the same attention in the printed word. 相似文献
19.
none 《The Cartographic journal》2013,50(2):91-92
AbstractA reconstruction is made of the methods by which the Ordnance Survey of Great Britain pioneered a system for establishing the place-name nomenclature on its maps in the nineteenth century. Until 1820 there was little to differentiate the practice of the Survey from that of earlier cartographers but, thereafter, official surveyors were encouraged to consult a wide range of written and oral authorities and were instructed to record their findings in special name books. By the mid-nineteenth century the essentials of the modern system had been laid down and many thousands of local names published in map form for the first time.This paper was read in a shorter form to the annual symposium of the Society in September 1970, at the University of Bristol. 相似文献
20.