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Abstracts 2006
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Vol.38, No. 302. October 2006 1. Re-instating parcel boundaries by real time kinematic GPS J. Jarroush and G. Even-Tzur Cadastre is a method for registration of land ownership. Due to
the major legal importance of marking parcel boundary points in
the field, constant re-measuring, reinstating and marking of boundary
points are required. In Israel this process is characterized by
a predominant and continuous difficulty in the consistent renewal
of boundary points due to the different measurement descriptions
in the field notebooks, as well as the inhomogeneous measurements.
This difficulty is increased due to the use of the “old”
horizontal control network as the basis for the measurements, especially
as the “old” network is inhomogeneous and is characterized
by low accuracy. 2. A range of ED50-ETRS89 datum transformation models tested on the Spanish geodetic network J. González-Matesanz, A. Dalda and J.A. Malpica A set of datum transformation models for performing ED50-ETRS89
datum transformation in Spain are presented. These comprise 5/7
parameters, complex and real polynomials and distortion modelling.
The latter case includes several tests using external points for
the three methods explored: Rubber Sheeting, Minimum Curvature Surfaces
and Least Squares Collocation. The Spanish ED50 geodetic network
is linked with the European network through the Pyrenees, the westernmost
part of ED50. This implies that the ED50 network compensation errors
are bigger than elsewhere in the network. In addition, the particular
low order network adjustment procedure applied in the past, in which
each province was computed separately, and then its monuments were
used as the boundary fixed points for the next province, has given
rise to a non-homogeneous network, as compared to fully consistent
networks such as ETRS89. The finished REGENTE campaign has provided
dual coordinate monuments every 30Km allowing a complete test to
be conducted for the different transformation models presented here. 3. Land management strategy formulation in post-conflict societies C. Augustinus and M. B. Barry Developing a sustainable strategic action plan for land management
and administration in post-conflict societies is extremely difficult.
We will argue that it is not feasible to use conventional conceptual
frameworks to underpin strategic action planning in post-conflict
environments and, in fact, to do so might prove both inefficient
and biased. This argument is based on work in Afghanistan, South
Africa, Somalia, Mozambique, Uganda and Kosovo. Instead we argue
that a soft systems approach, such as that developed by Barry and
Fourie in post-conflict South Africa, should ensure that the most
appropriate activities are prioritised. By using examples based
on cadastral systems and land administration, we show how a more
appropriate strategic action plan for land administration in post-conflict
situations can be developed using this framework. This approach
should improve both national reconciliation, as well as the efficiency
of the land market. 4. Single epoch algorithm based on Tikhonov regularization for deformation monitoring using single frequency GPS receivers Zhenjie Wang, Chris Rizos and Samsung Lim A new single epoch algorithm for deformation monitoring using
single frequency GPS receivers, based on Tikhonov Regularization,
is proposed in this paper. At first, the characteristic of the normal
matrix for carrier phase measurements is analyzed. Since the normal
matrix is rank-deficient, Tikhonov regularization theorem is applied
to the least squares problem, and a regulariser is chosen to transform
the matrix from the rank-deficient to the full rank. Then, the float
ambiguity solutions and their Mean Squared Error Matrix (MSEM) are
obtained. MSEM can be used to determine the search space for the
integer ambiguities, combined with other integer ambiguity fixers
such as LAMBDA. The proposed single epoch algorithm is tested using
carrier phase measurements of two single frequency GPS receivers
with a baseline over 3km and the results show that the success rate
of the integer ambiguity fix is greater than 90%. 5. Conversión of Cassini coordinates to UTM coordinates on the Excel spreadsheet T G Gacoki A procedure for transforming Cassini grid coordinates (planimetric
only) to UTM coordinates on the Excel spreadsheet is outlined. A
general second degree polynomial is used to compute six parameters
which includes a scale, a rotation two translation elements and
two other unknowns. Three interconnected worksheets are used to
compute the transformation. The first worksheet is used for data
entry. The second worksheet computes the six transformation parameters
necessary for the transformation by use of entries in the first
worksheet, while the third worksheet computes the transformed coordinates
in UTM by use of the entries in the first worksheet and the computed
parameters in the second worksheet. Ellipsodial Cassini co-ordinates
for the common points can be also computed on the excel spreadsheet,
and where corresponding ellipsoidal coordinates in UTM are available,
a seven parameter transformation can be obtained. 6. GPS height measurement of Peak Bolivar, Venezuela O. J. Pérez, M. Hoyer, J. Hernández, C. Rodríguez, V. Márques, N. Sué, J. Velandia, J. Fernandes and D. Deiros Based on a series of GPS observations made in 2002 on the summit
of Peak Bolívar, the highest Venezuelan mountain, and on
seven other nearby sites along the Venezuelan Andes, including another
three of the highest peaks of the country; and using a recently
derived local geoid for Venezuela, we have determined the orthometric
height of Peak Bolívar as 4978.4 ? 0.4 m. This height is
23.6 m smaller than the height obtained by combining trigonometric
triangulation techniques and barometric measurements in the nearby
town of Mérida in 1912, and 28.6 m smaller than the current
official altitude that dates from 1928. 7. Calibration of terrestrial laser scanners Callidus 1.1, Leica HDS 3000 and Leica HDS 2500 Y. Reshetyuk The paper presents the results of the self-calibration of three commercial terrestrial laser scanners (TLS) – Callidus 1.1, Leica HDS 3000 and Leica HDS 2500 – performed at the specially established indoor 3D calibration field. The systematic instrumental errors have been estimated in the self-calibration assuming that they were similar to those in the total station. Afterwards, we compared the ranges, horizontal directions and vertical angles derived from the scanning with the true ones in order to reveal the possible presence of some non-modelled systematic trends. In this way, a significant vertical scale error in the scanner Callidus 1.1 has been found, presumably due to the maladjustment of the scanning mirror. Other significant errors are the vertical index error in Leica HDS 3000 and horizontal axis error in Leica HDS 2500. Due to the physical limitations of the calibration field, the estimation of some of the instrumental errors, especially collimation error, was complicated by their significant correlation with the Helmert transformation parameters. We have also estimated the target coordinate accuracy. The RMS errors in the position of the calibration targets are 2.9 mm, 1.6 mm and 0.3 mm, for Callidus 1.1, Leica HDS 3000 and Leica HDS 2500, respectively, at the distances to the scanner of up to 10 m. In spite of the problems encountered during the self-calibration, the results are believed to contribute to a better knowledge of TLS performance.
Survey Review Vol. 38, No. 301 July 2006 1. Horizontal datum transformation by distortion modeling in Korea H. S. Yun, D. S. Song and J. M. Cho This paper describes the development of a transformation grid for transforming horizontal spatial data from the local geodetic datum to a geocentric datum in Korea. We used least squares collocation as the method for modelling the distortion that remains after the application of a standard seven-parameter similarity transformation. In the experimental tests, the RMSEs in latitude and longitude coordinates are ±0.016m and ±0.007m, respectively, after the distortion modelling, whereas it was indicated that transformation accuracy is improved about 98% by distortion correction. This is a reasonable result, which should give users confidence in transforming data from the local geodetic datum to the geocentric and vice versa for medium scale maps.
S. Nassar and N. El-Sheimy Any integrated navigation system that consists of an Inertial
Navigation System (INS) and a Global Positioning System (GPS) suffers
sometimes from a major problem: the existence of frequent GPS signal
blockages (GPS outage periods). In this case the INS is used for
navigation but navigation errors increase rapidly with time. One
of the main factors that affect such obtained errors is how the
INS sensor errors are modelled. For most IMUs, a 1st order Gauss-Markov
(GM) process is usually used. In this paper, it will be shown that
this process is not always fitted with the behaviour of inertial
sensor errors. Instead, Autoregressive (AR) processes of orders
higher than one are suggested. Numerical analyses are performed
to compare the accuracy of GM and AR parameters that are obtained
from experimental data. Using GPS and a tactical-grade IMU, a kinematic
INS/GPS data set is used for testing the performance of GM and AR
models during GPS outages. The results showed a considerable reduction
of position errors in these periods when implementing AR processes
instead of GM ones. 3. Fitting AUSGeoid98 to the Australian height datum using GPS-levelling and least squares collocation application of a cross-validation technique W. E. Featherstone and D. M. Sproule In an absolute sense and over long (>100 km) baselines, the
AUSGeoid98 gravimetric-only geoid model does not always allow the
accurate transformation of Global Positioning System (GPS)-derived
ellipsoidal heights to Australian Height Datum (AHD) heights in
all regions of Australia. This is due predominantly to the well-known
biases and distortions in the AHD, but long-wavelength errors in
the gravimetric geoid model or GPS errors cannot be ruled out. Until
the AHD is rigorously redefined, an interim solution is sought where
co-located GPS and AHD heights are used to distort AUSGeoid98 such
that it provides a better model of the separation between the base
of the AHD and the GRS80 reference ellipsoid. This data combination
was implemented using least squares collocation (LSC) gridding.
Importantly, GPS-AHD data not used in the LSC combination were used
to assess the improvement using a cross-validation technique. Using
this cross-validation, RMS noise of 14 mm and correlation length
of 2500 km for the LSC covariance function were optimised empirically.
The standard deviation of the differences between the final combined
model and the unused GPS-AHD data is ?156 mm, compared to ?282 mm
for AUSGeoid98 alone. It is anticipated that the same technique
will be used to produce a new Australian “geoid” model. 4. Determination of areas on the plane, sphere and ellipsoid Lars E Sjöberg This paper shortly reviews various methods to determine the area
of a closed polygon on the plane, sphere and ellipsoid. A new method
is derived for calculating the area of a geodetic polygon, i.e.
a polygon on the ellipsoid limited by sections of geodesics. By
a recursive procedure the area can be determined to any desired
order of the eccentricity of the ellipsoid. Finally we also present
a direct method for numerical integration of the area under the
geodesic. 5. The use of GPS for the estimation of precipitable water vapour for weather forecasting and monitoring in South Africa R. T. Wonnacott and C.L. Merry The propagation of the Global Positioning System (GPS) signal
from the satellite to the receiver is affected by, among other factors,
the atmosphere through which it passes and, whereas the effects
of the ionosphere can be eliminated by the differencing of the two
transmitted frequencies, the effects of the troposphere remain one
of the major sources of noise in traditional geodetic and positioning
applications of GPS. This noise can, however, be turned into a signal
for the meteorologist and, by applying suitable constraints and
processing strategies, it is possible to estimate the amount of
precipitable water vapour (PWV) in the atmosphere. The application
of the GPS data for the estimation of PWV in the atmosphere is not
a new concept and has been described in many publications and reports
since the early 1990s. This project is, however, an attempt to test
the technique using the South African network of permanent GPS base
stations. 6. Geodetic reference frames transformations C. Mitsakaki, A. M. Agatza-Balodimou and K. Papazissi Local geodetic datums have been developed in the past, in order
to satisfy the surveying and mapping requirements of countries all
over the world. The broad use of GPS observations, as part of the
surveying routine, has shifted the interest from the local to the
world geodetic reference systems. The transformation of coordinates
between geodetic systems has always been of interest, but the new
needs have made it more important. Three dimensional similarity
transformations are being used in Geodesy in order to transform
coordinates between three dimensional geodetic datums, although
the two dimensional approach is often followed, especially for small
networks. 7. Geometric data for evaluation of the environmental performance of buildings in Hong Kong in estate or district-wide scales F. W. H. Yik, L. Pun, G. Shea and E. Mok Evaluation of the performance of building designs in facilitating
utilisation of daylight and natural ventilation has to take detailed
accounts of the influences of surrounding buildings and terrain.
This, in turn, requires three dimensional geometric data for modelling
the target building, the adjacent buildings and the nearby terrain.
Data for surround buildings and terrain are often compiled from
paper maps and supplementary survey data, which can be time and
resources intensive. The process can be greatly facilitated by converting
digital map data into the format required by various building performance
simulation software. The paper describes the method and tools developed
for producing such geometric data in a region covered by the digital
base map data obtained from the Hong Kong Government. An example
application of the data produced for a cluster of buildings to a
daylight availability analysis is briefly described. 8. Global positioning system in disaster monitoring of Koyna dam, Western Maharashtra M. N. Kulkarni, N. Radhakrishnan and D. Rai GPS measurements carried out over the last five years have been used to monitor the structural deformation of the Koyna dam, Western Maharashtra, India. A GPS network that has been established by the GPS research group of Indian Institute of Technology Bombay for the purpose of deformation measurements and analysis of the Koyna Dam has been observed over ten epochs, from December 2000 to September 2004. This paper highlights the methodology and analysis techniques used for determining deformation and the results of the research work being carried out. The analysis of the results determines the degree of correlation between the change in reservoir level and the observed structural deformation of the dam.
Vol. 38, No. 300 April 2006 This issue is specially enlarged to allow recognition of the 300th
consecutive appearance of Survey Review since its inception in 1931.
Because of this there are two sections to the Contents:- A series
of short contributions to celebrate 75 years of Survey Review, followed
by the usual refereed papers. 1. The changing role of National Mapping Organisations Vanessa Lawrence National mapping organisations (NMOs) are operating at a time
of unprecedented technological opportunities and challenges. These
issues provided a range of talking points for senior representatives
from across the world who gathered at Ordnance Survey's Southampton
head office for a three-day conference in July 2005. CC: The Exchange,
an interim event in the continuing Cambridge Conference series for
heads of NMOs, was an ideal opportunity to discuss the changing
role of NMOs nationally, regionally and globally. Common themes
for delegates were the constant need to review business models due
to evolving customer demands, changes in funding arrangements, new
partnering opportunities, rapidly changing technology and competition. A series of short contributions to celebrate
75 years of Survey Review 2. Not everything has changed M. A. R. Cooper This is the first of a few short papers by members of the Editorial
Board published to mark the 300th issue of “Survey Review”.
They express the author’s opinions on how and why the practice
of land surveying has changed in different parts of the world over
the last 75 years. 3. From theodolite to satellite Linyuan Xia On the occasion of the 300th consecutive issue for Survey Review
since the first was published in July 1931, we are granted an opportunity
to summarize the past developments in the field of land surveying
and geomatics. As the saying goes - one can not look forwards well
without looking backwards for reflection, - a rapidly changing and
developing history has been witnessed by the leading professional
journal Survey Review in the course of 75 years which dates back
to the employment of abacus. This initial counting tool was in wide
use when Survey Review commenced its opening publication page. It
can be compared with the contemporary computer as an advancement
tag. What meditated then has in turn, influenced my choice of topic
here. 4. Two centuries of surveying and mapping in India Madhav N. Kulkarni The history of surveying and mapping activities in India is, in
a true sense, a record of the history of the development of the
great Indian civilization itself. From the ancient maps of India,
belonging to the period of the great Mourya and Chandragupta dynasties,
to the use of the advanced positioning and mapping space technologies
of the modern age, historical records of mapping in the sub-continent
tell a very fascinating story of the significant progress made in
the art and science of map-making. With the establishment of Survey
of India, the premier mapping agency of India, in the later part
of the eighteenth century, these mapping activities formed the nucleus
of all developmental projects. A brief glimpse of the significant
progress made and the milestones reached in this silent revolution
in the fields of surveying and mapping in the Indian subcontinent
over the last two centuries is given here. 5. 75 years of change in survey technology Jean M. Rüeger The change in surveying instrumentation and technology, as documented
by the articles and advertisements in the first 300 issues of the
(Empire) Survey Review, is summarised. The review concentrates on
the changes in minor equipment (steel bands and tapes, plane tables,
barometers, magnetic compass, tripods and tribrachs), levelling
instruments, theodolites, electro-optical distance meters ('EDM
instruments'), electronic tacheometers ('total stations'), laser
scanners and trackers, north-seeking gyroscopes and satellite surveying
systems. Another few development areas are briefly mentioned. 6. Geomatics in Southern Africa – a perspective Charles L. Merry This paper reviews developments in geomatics/surveying over the
past forty years in southern Africa. It describes the impact of
global technological changes and highlights the achievements of
the geomatics industry in southern Africa. Current weaknesses, especially
in the realm of geomatics education, are also described. 7. Surveying in the United States 1930 to present Steven Frank Surveying and mapping in the United States have undergone dramatic
changes over the past 75 years. Surveyors have progressed from transits
and steel tapes to GPS, from logarithmic and trigonometric tables
to laptop computers, from dusty, old map repositories to online
digital media and more. The introduction of new technologies, along
with new surveying sciences such as photogrammetry, has changed
the face of the surveying profession dramatically over this period. 8. Surveying in Canada, 1931-2006 Alec McEwen During the discussion at the 1928 London Conference of Survey
Officers that led three years later to the first issue of Empire
Survey Review, as it was then called, Colonel Winterbotham, Chief
of the Geographical Section at the War Office, expressed the view
that Canada knew very little about the surveying activities undertaken
by the other British territories. No doubt the reverse was equally
applicable. The same speaker also advocated the exchange of maps
and other publications among the various survey departments to keep
them better informed about matters of common interest. 9. Reflections on the Cadastre P. F. Dale The last decade has seen a transformation in both the philosophy
and practice of cadastral surveying. This paper traces some of the
history and notes the way in which there has been a change from
‘top-down’ to ‘bottom-up’ in the provision
of land administration services. This is radically altering the
attitudes of governments and the people that they are there to serve. 10. The Editors A. L. Allan In his foreword to the first number of Empire Survey Review, (now Survey Review), W.C. Bottomley, the chairman of the Colonial Survey Committee, wrote "Between, and side by side with, such conferences, the Review will form a continuous record of achievement and of problems solved, or (why not?) unsolved, through which surveyors working all over the world may contribute to or draw from a common pool of experience and practice". The "conferences" mentioned were the Conferences of Empire Survey Officers, at the first of which in 1928 the ESR. was originated, and for the second of which the very first number appeared under the editorship of Captain G.T. McCaw. Since that date their have been five more editors, J. Clendinning, J.E. Jackson, A.L. Allan, W.M. Barnes and currently J.R. Smith.
11. An assessment of the precision of the observational data used in New Zealand’s National Cadastral system N. Donnelly and J. Hannah Most of New Zealand’s cadastral network has been converted
from a paper-based records system to a fully integrated digital
cadastral system known as Landonline. The complete data set contains
in the order of 18 million “observations”. This paper
describes both the data quality issues that had to be addressed
and the statistical analyses undertaken to assess the precision
of these observations. Variance component estimation was used to
determine the precision of the data which, as far as possible, have
been grouped into homogeneous categories. It is concluded, firstly,
that the precision of the input data generally exceeded the a priori
estimates used; secondly, that historical observational precisions
were lower than present day and, thirdly, that for any given time
period, the bearings and distances used in the cadastral framework
had similar precisions. 12. GPS-derived geoid using artificial neural network and least squares collocation B. Stopar, T. Ambrožic, M. Kuhar and G. Turk The geoidal undulations are needed for determining the orthometric
heights from the Global Positioning System GPS-derived ellipsoidal
heights. There are several methods for geoidal undulation determination.
The paper presents a method employing the Artificial Neural Network
(ANN) approximation together with the Least Squares Collocation
(LSC). The surface obtained by the ANN approximation is used as
a trend surface in the least squares collocation. In numerical examples
four surfaces were compared: the global geopotential model (EGM96),
the European gravimetric quasigeoid 1997 (EGG97), the surface approximated
with minimum curvature splines in tension algorithm and the ANN
surface approximation. The effectiveness of the ANN surface approximation
depends on the number of control points. If the number of well-distributed
control points is sufficiently large, the results are better than
those obtained by the minimum curvature algorithm and comparable
to those obtained by the EGG97 model. 13. Documentation for the preservation of traditional agro-industrial buildings in N.W. Spain using simple close-range photogrammetry P. Arias, C. Ordóñez, H. Lorenzo and J. Herraez Traditional agro-industrial buildings are an important part of
the heritage of the Autonomous Region of Galicia (Northwest of Spain).
Such heritage is nowadays in danger of disappearing. In order to
preserve it, an exhaustive and rigorous work of documentation should
be undertaken, as well as other actions. 14. Elimination of effects of earthquake in monitoring crustal movement by adaptive Kalman Filter C. T. Celik, W. Chen, R. M. Bingley and V. Ashkenazi The effect of an earthquake occurring within crustal monitoring period by geodetic method in analysis using Kalman Filter Method has been eliminated by a proposed approach. The proposed method was tested using a real/simulated data. The result of the test showed that the effect of a strong earthquake (Mw=7.1) which had occurred in the Gulf of Eilat/Aqaba was eliminated. Thus consequently the proposed method is capable of removing or eliminating a sudden effect in monitoring crustal movements in the analysis by using the Kalman Filter.
Vol. 38, No. 299. January 2006 1. Prototype Internet RTK GPS for bridge deformation monitoring X. Meng, A. H. Dodson, G. W. Roberts and M. Andreotti In this paper, the concept and design of an Internet based real-time kinematic (RTK) GPS for a prototype structural monitoring system are introduced. The proposed system consists of four basic segments, i.e. reference station segment, monitoring segment, control segment and user segment. To validate the feasibility of this prototype system, a platform is used to simulate large bridge movement. The test results show that 3D positioning precision of cm level at a sampling rate up to 10 Hz and a low rate of missing data with a negligible transmission delay of RTK corrections is achievable.
G. B. Vishnyatsky The proposed method is that the radial and tangential components
of the relative displacement vector of sites, which are situated
in arbitrary fixed direction - a, are proportional to the baseline
length and pairs of the unit elongation – e(a) and unit sliding
strain – g(a) form a circle in the coordinate system (e, g). 3. Return bootstrapping approach and its reliability Yangmei Zhou and Jingnan Liu In this paper, at first on the basis of the upper-triangular Cholesky decomposition algorithm, a return bootstrapping approach is proposed. Then according to the round-off principle, the definition for the admissible integer estimation is discussed further. Finally, an easy-to-compute formula for the success rate of this return bootstrapping approach is deduced.
Chalermchon Satirapod In order to achieve high-accuracy positioning results, GPS carrier phase observations have to be used in the data processing step. It is generally known that there are two important aspects to the optimal processing of GPS observations, the definitions of the so-called functional model and the corresponding stochastic model. The functional model describes the mathematical relationship between the GPS observations and the unknown parameters, while the stochastic model describes the statistics of the GPS observations. The functional model is nowadays sufficiently known, however the definition of the stochastic model still remains a challenging research topic. Data differencing techniques are extensively used for constructing the functional model as they can eliminate many of the troublesome GPS biases, such as the atmospheric bias, the receiver clock bias, the satellite clock bias, and so on. However, some unmodelled biases still remain in the GPS observations following such differencing. The challenge is to find a way to realistically incorporate information on such unmodelled biases into the stochastic model. Recently there has been interest in using three types of data, Signal-to-Noise Ratio, satellite elevation and least-squares residual, as quality indicators for a formulation of the stochastic model. In this paper, fundamental equations for processing of GPS data are explained. The three quality indicators used for a construction of the stochastic model are described. The recent development works in stochastic models for static GPS positioning are reviewed, followed by some concluding remarks and recommendations.
M. Soycan Most commonly used method for the determination of geoid is the evaluation of GPS (Global Positioning System) and levelling measurements together. Despite the fact that geometric levelling (GL) is in general easy and practicable, it is a measurement method that is hard and uneconomic to apply particularly in mountainous, hilly and rugged areas. This study aims the use of precise trigonometric levelling (PTL) method instead of GL for the determination of precise geoid heights. The method has been probed into in consideration of the accuracy, practicability, measurement and evaluation criteria, and has been compared with GL measurement results. In addition, geoid profiles that have been determined both (GPS_GL) and (GPS_PTL) measurements have been compared with TG-99A (Turkish Geoid-1999A) and IGNA (Istanbul GPS Network) geoid models to explore their consistency.
H. Z. Abidin, H. Andreas, M. Gamal, R. Djaja, D. Murdohardono, H. Rajiyowiryono and M. Hendrasto Bandung basin is a large intra-montane basin surrounded by volcanic highlands, inhabited by more than five million people. Based on four GPS (Global Positioning System) surveys conducted on February 2000, November 2002, July 2002 and June 2003, it can be concluded that in the period of 2000 to 2003 several locations in Bandung basin have experienced land subsidence. In this period of about 3 years, land subsidence in a few locations can reach the amount of 40 to 50 cm, with the speed of about 1-2 cm/month. This paper describes the technical and practical aspects of GPS surveys for land subsidence study in Bandung basin along with the obtained results. This study shows that the amount of land subsidence in several locations of Bandung basin do not show significant correlation with the registered abstraction volume of groundwater in that locations. Paper will sum up with some conclusions and recommendations. 7. Semiparametric model and its application in survey data processing Pan Xiong This paper gives a method for finding the values of the unknown
parameters of the semi-parametric model under the principle of penalized
least squares with a positive definite regularity matrix. Based
on the statistic characteristic of random errors, the mathematical
expectation, variance and mean square error of the parameters estimator
found from this method are discussed in detail. The difference between
the parameter values as given by semi-parametric models and by general
least squares is compared. It is shown clearly by the theoretical
analysis and the simulating computation that the method of semi-parametric
adjustment is better than that of least squares if the smoothing
parameter takes a suitable value. The study shows how to choose
a reasonable value of the smoothing parameter and its influence
to the precision of the mathematic model is also given. 8. Application of generalised approach to datum transformation between local classical and satellite-based geodetic networks Israel Kashani The major problem with transforming from a classical to a satellite-based network is the typically low and heterogeneous accuracy of the classical network coordinates, especially in the height component. The accuracies and the statistical correlations between the point coordinates are expressed in the variance-covariance matrix (VCV). There is a great advantage if this prior information is included in the transformation model, together with the VCV matrix of the satellite-based network. An analysis of the northern part of the geodetic network of the State of Israel was conducted, using real data coming from both classical and satellite-based networks. The detailed investigation of the VCV matrix of the northern part of the G1 network, the satellite geodetic geodynamic network, and the M points from the classical network, confirmed the suitability of the so-called “Generalized Approach” to datum transformation.
Index to Volume 38
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