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Survey Review 54, No 387. November/December 2022

1. Mapping and suitability analysis of existing electoral polling units in Katsina local government area of Katsina State, Nigeria
Adamu Bala, Saied Pirasteh, Yahaya Abbas Aliyu, AbdulAzeez Onotu Aliyu, Swafiyudeen Bawa & Ibrahim Abdulwahab

This research examined the mapping and analyses of existing polling units in the study area to provide scientific criteria for citing new polling units. The attribute data of the polling units were collected from the Independent National Electoral Commission (INEC), Katsina State, and spatial data was acquired through field observation, for geodatabase creation and query generation. For the suitability mapping, seven parameters criteria were adopted. The generated thematic maps of these criteria were standardised using the fuzzy logic approach. The geodatabase of the existing polling units created showed 281 polling units with their attributes. Also, the suitability map showed regions of suitability and unsuitability. The overlay map showed that 10 polling units were in the region of highly not suitable, 16 not suitable, 26 fairly suitable, then the rest were either highly suitable or suitable. It is recommended that INEC should adopt a scientific method in citing subsequent polling units.

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2. Non-linear block least-squares adjustment for a large number of observations
Vahid Mahboub & Somayeh Ebrahimzadeh

In this contribution two algorithms are developed to solve non-linear system of equations which can contain a large number of measurements. These algorithms are based on nonlinear block least-squares (BLS). Although block least squares was investigated by some researchers, the non-linear case was not examined by now. The first algorithm is proposed to solve a special case of non-linear problems that do not require linearization. Such an algorithm can be called total block least-squares. The second algorithm is based on linearization within a general nonlinear mixed model using a new notation which is in agreement with the rigorous linearization presented by Pope. Both of these algorithms can handle constraints on the parameters. By use of these algorithms, big data processing is feasible with inexpensive computers. Furthermore, expensive processors can solve systems with a large number of equations faster. Two case studies with more than 120,000 equations show that fast and accurate computations are possible by applying these algorithms without any loss of accuracy.

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3. Creation of Ahafo region and local land market dynamics; evidence from Goaso and Nkaseim stool land areas in Ghana
Joseph Kwaku Kidido

This study examined land market dynamics in the new Ahafo Region. The study employed qualitative survey design and interviewed varied stakeholders in Goaso and Nkaseim stools areas. The results revealed that there is a growing land market characterised by rising land access cost, land use changes and adjustments in the local landholding profile within the market frontiers. This development is underpinned by new investment opportunities associated with the new region. The local land market is currently devoid of land guards’ activities and multiple sales. Again, almost all the state institutions and allied offices mandated to carryout land administration were yet to be established at the regional level. The study underscores the need for government to speed up with the decentralisation of regional offices of the land sector agencies to support the local land governance structures as impetus for efficient land market, growth and investments in the new region.

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4. Improving accuracy of local geoid model using machine learning approaches and residuals of GPS/levelling geoid height
Mosbeh R. Kaloop, Samui Pijush, Mostafa Rabah, Hamad Al-Ajami, Jong Wan Hu & Ahmed Zaki

This study aims to use GPS/Levelling data and machine learning techniques (MLs) to model a high precision local geoid for Kuwait. To improve the accuracy of a local geoid the global geopotential model and local terrain effect should be incorporated. The geoid model was improved based on the modelling of geoid residuals using three MLs. Minimax Probability Machine Regression (MPMR), Gaussian Process Regression (GPR), and Multivariate Adaptive Regression Splines (MARS) MLs were developed for modelling the calculated geoid residuals. The results show that the accuracy of the three MLs was improved compared to previous studies, and the accuracy of the GPR model was better than the other models. The standard deviations of Kuwait geoid undulation determined by GPS/Levelling, gravimetric, and developed GPR models were 1.377, 1.375, 1.375 m, respectively. Thus, the developed GPR model has successfully predicted an accurate geoid height of Kuwait with maximum variation approaches ±0.02 m.

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5. Associating land registry and cadastre transactions with LADM-based external archive data model: a case study of Turkey
Zeynel Abidin Polat & Mehmet Alkan

In Turkey, during the realisation of the land registry and cadastre transactions, manually checking the official documents exceeding 20 million annually causes some problems in document management and security. This study focuses on managing the official documents as online requested by the land registry and cadastre directorates from the other institutions during these transactions. Therefore, a general external data model based on the LADM has been proposed to manage requested documents during transactions. If web-based applications support the proposed model, access to documents will be faster and easier, and security risk will be reduced.

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6. Unification of GNSS CORS coordinates in Thailand
Somchai Kriengkraiwasin, Chaiyut Charoenphon, Korakod Butwong, Vichien Kovitpongkajorn, Peera Yomwan, Thayathip Thongtan & Chalermchon Satirapod

This study estimates station coordinates of GNSS CORS networks in Thailand, based on ITRF2014, by applying the Precise Point Positioning (PPP) technique computed by the GipsyX software. Datum transformation parameters between ITRF2005 and ITRF2014 were investigated to transform station coordinates from ITRF2005 to ITRF2014. The Molodensky-Badekas model provides more reliable results than the Bursa-Wolf model on these transformations. The accuracy of coordinate transformations can be increased by interpolating the remained residuals from transformed coordinates into grid residual corrections. The analyses show that the seven parameters with the grid residual corrections can significantly improve the accuracy of the coordinate transformation.

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7. Simple computation of coordinates and uncertainty of ‘hidden’ points from two coordinated points that are collinear with the hidden point
Stig-Göran Mårtensson

Estimating the measurement uncertainties of coordinates of points that are not accessible by direct geodetic surveying (hidden points) is the topic of this study. The simplicity by which the uncertainties can be found for such hidden points when practicing indirect observations by total station or by Global Navigation Satellite System (GNSS) is demonstrated. A three-dimensional solution is obtained by total station observations using a two-prism hidden-point rod and a two-dimensional solution by GNSS observations on the ground. An intention with the study is that methods and results should apply for general geodetic purposes, like engineering surveying. The derived uncertainty formulae have been verified by Monte Carlo simulations. An important finding is their geometric dependence by the quotient between the two distances involved when two coordinated points are collinear with a third hidden point.

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8. A fast satellite selection algorithm for multi-GNSS marine positioning based on improved particle swarm optimisation
Xiaoguo Guan, Hongzhou Chai, Guorui Xiao, Jie Han, Shijing Han & Miao Shufeng

This paper introduces an improved particle swarm optimisation algorithm (IPSO), to select satellites rapidly in multi-GNSS marine positioning. The traditional particle swarm optimisation (PSO) may be trapped into local optimisation. To avoid the disadvantage, the proposed algorithm uses linear inertia weight factor and two functions of the immune system, i.e. the memory function and the self-regulatory function. Several experiments are carried out by adopting real survey data collected by the SiNan receiver that is installed on the Snow Dragon scientific research ship during the 9th China Arctic expedition. Compared with the minimum Geometric dilution of precision (GDOP) method, PSO and IPSO significantly reduce the computing time (96.25% and 95.61%). The variance of IPSO is 0.063, which is much lower than that of PSO (0.087). As for the positioning accuracy, the IPSO can reach the centimetre level in the kinematics condition.

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Survey Review 54, No 386. September/October 2022

1. A high-resolution gravimetric geoid model for Kingdom of Saudi Arabia
Ahmed Zaki & Saad Mogren

A high-resolution gravimetric geoid model for the Kingdom of Saudi Arabia area was determined. A data set of 459,848 land gravity, 80,632 shipborne marine gravity data, DTU17 altimetry gravity model, and XGM2019e global geopotential model. The computation strategy followed for modelling of the gravimetric geoid is based on the Remove-Compute-Restore with Residual Terrain Model reduction and the 1D- Fast Fourier Transform approach technique. The geoid heights have been determined by using the Stokes integral with Wong–Gore modification. The accuracy of the resulting geoid models was evaluated by comparing them with 5385 GPS/levelling points. The geoid accuracy over all the kingdom is better than 11 cm in STD sense and the comparison in sub-areas obtained accuracy range from 2.8 to 11.9 cm according to the density of gravity observations.

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2. Construction of spatial information model of 3D real estate: case study of the Nanjing gulou central business district
Changbin Wu, Xinxin Zhou, Hua Tang & Yuan Ding

Complexity of urban construction and land use is increasing which cannot be represented adequately by 2D systems. The successful construction of a Spatial Information Model of 3D Real Estate (SIM-3RE) is valuable to achieving a refined administration of 3D space and property-rights of urban real estate in China. In this paper, the Nanjing Gulou Central Business District was selected as an experimental region, and the historical data of surveys and maps of the parcels and buildings were collected. After the supplementation of some missing data (such as height) by surveying, the SIM-3RE was constructed using the 3D partitioned units for buildings and 3D parcels of land.

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3. Adaptive block modeling of time dependent variations of datum reference points in a tectonically active area
Chun-Yun Chou & Jen-Yu Han

Although a dynamic or semi-dynamic datum has been adopted in some countries, it remains a challenge if a long-term stable datum is to be established in a tectonic active area. This study presents an approach to realistically reflect the time dependent behaviors of ground reference points while maintaining the long-term stability of a datum. An adaptive approach coupled with the Euler motion model is proposed for dividing an area into blocks. A least-squares collocation is then applied for modeling the residual velocities in each block. A case study using the data from 375 continuously operated GNSS stations in Taiwan is presented. It is illustrated that the complex surface kinematics in this region can be divided into three blocks. Significant reductions up to 64% of residual velocities were obtained. This shows that a stable datum can be established in a region with active and complicated surface kinematics by implementing the proposed.

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4. Automated detection of discontinuities in EUREF permanent GNSS network stations due to earthquake events
Sergio Baselga & Joanna Najder

The EUREF Permanent GNSS Network (EPN) provides the users with data and products such as station coordinate time series. These are subject to possible discontinuities and trend changes, being earthquake events one of the possible natural causes for these variations. We present here a fully automated tool for the analysis of the coordinate time series of EPN stations located in the desired neighbourhood of an earthquake epicentre. The tool is made freely available to the public and applied here to two significant earthquake events occurred in Europe in recent years, where several trend changes and jumps are revealed.

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5. Robust estimation of model parameters of the probability integral method based on CA-rPSO
Zhengshuai Wang, Chuanguang Zhu, Hongzhen Zhang, Jianrong Kang & Jinshan Hu

This paper introduces a framework for robustly estimating the parameters of the probability integral method (PIM). According to the framework, the initial robust estimates of the PIM parameters are firstly obtained by combining the cultural algorithm and rand particle swarm optimisation (CA-rPSO) with the LTS method. As a byproduct, an initial standard deviation can be calculated and used to determine the initial weights of the measurements according to the Institute of Geodesy and Geophysics (IGGIII) down-weighting scheme. Meanwhile, a modified CA-rPSO (referred to as CA-rPSO-IGGIII) is constructed, where the IGGIII scheme is introduced to alleviate the adverse influence of outliers. Then, the initial robust estimates and the standard deviation can act as a priori information for the CA-rPSO-IGGGIII to search for the optimal estimates. Experiments with simulated and real data demonstrate that the proposed method can robustly estimate the PIM parameters.

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6. An artificial neural network-based critical values for multiple hypothesis testing: data-snooping case
Vinicius Francisco Rofatto, Marcelo Tomio Matsuoka, Ivandro Klein, Maria Luísa Silva Bonimani, Bruno Póvoa Rodrigues, Caio Cesar de Campos, Mauricio Roberto Veronez & Luiz Gonzaga da Silveira Jr

Data Snooping is the most best-established method for identifying outliers in geodetic data analysis. It has been demonstrated in the literature that to effectively user-control the type I error rate, critical values must be computed numerically by means of Monte Carlo. Here, on the other hand, we provide a model based on an artificial neural network. The results prove that the proposed model can be used to compute the critical values and, therefore, it is no longer necessary to run the Monte Carlo-based critical value every time the quality control is performed by means of data snooping.

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7. Estimation of the ocean tide loading displacements by GPS and GLONASS kinematic Precise Point Positioning
Hong Zhao, Zhi Liu, Guangwei Jiang, Zhanke Liu, Yangyang Sun & Dan He

Ocean Tide Loading Displacement (OTLD) parameters, derived by Global Positioning System (GPS) approach, need more time to converge to a stable state and show poor precision of K1 and K2 constituents. Combining multi-system Global Navigation Satellite System (GNSS) data can greatly improve the positioning accuracy and significantly reduce the convergence time compared to single GPS PPP, combined GPS+GLONASS with ambiguity resolved in kinematic Precise Point Positioning (PPP) is improved on the basis of the algorithm of GPS kinematic PPP. We collected eight years of continuous observations of 11 worldwide sites from International GNSS Service to generate three dimensional OTLD parameters of eight constituents using GPS with ambiguity fixed, GLONASS with ambiguity free and combined GPS+GLONASS with ambiguity fixed kinematic PPP approach. The results show the eight constituents derived by GPS_FX and GPS+GLONASS_FX solution need four years and three years to converge to stable values, respectively. GLONASS can significantly improve the convergence rate of K1 and K2 constituents which needs only two years to converge to stable values, and S2 and P1 constituents which need three years to stable values. The results also show the GPS+GLONASS/reference misfits are the smallest for the most constituents in three components (less than 2mm) except for K2 and K1 in vertical and north directions. GLONASS can improve more than 40% in vertical and north components over GPS and GPS+GLONASS for K2 and K1 constituents and show very close agreement with GPS_FX solution in vertical and north component for S2 and P1 constituents. Ambiguity resolved in OTLD estimation can significantly accelerate the convergence and improve the accuracy for eight constituents, especially for combined GPS+GLONASS kinematic PPP mode, but no single constellation mode solution for all eight major constituents exists.

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Survey Review 54, No 385. July/August 2022

1. Beyond accuracy: evaluating alternative measurement methods in context of Flexible Land Tenure System in Namibia
Roswitha Lauterbach & Walter Timo de Vries

Namibia currently undergoes a rapid process of urbanisation of 4% annually, visible through an exponential informal settlement growth. Alternative measurement methods in cadastral mapping could secure land tenure in these settlements and fasten land registration. This article investigates the performance of five alternative measurement methods within the Flexible Land Tenure System (FLTS): orthophoto-based boundary demarcation, mapping applications on mobile devices, hand-held GPS, low-cost GNSS with u-blox receiver and GNSS RTK based on the Namibian CORS. The article evaluates all five methods on technical performance, affordability, time efficiency, feasibility, and simplicity. Based on the evaluation, all methods are appropriate for Namibia except for the hand-held GPS method. Low-cost approaches are appropriate for starter titles, whereas high-technology methods are better when requiring higher positioning accuracy (land hold title). Orthophoto-based boundary demarcation is surprisingly less suitable for the Namibian case. Overall, the results support a fit-for-purpose land administration in Namibia.

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2. Mixed geographically and temporally weighted regression for spatio-temporal deformation modelling
Zhijia Yang, Wujiao Dai, Wenkun Yu, Qiang Shi & Rock Santerre

When the regression coefficient of independent variable has both global stationarity and spatio-temporal non-stationarity properties, the deformation model based on the geographically and temporally weighted regression (GTWR) will no longer be applicable. In order to resolve this problem, we propose an improved method to establish the spatio-temporal deformation model using mixed geographically and temporally weighted regression (MGTWR). In this method, both the global regression coefficient and the variable regression coefficient are selected for regression coefficient hypothesis test, and the local linear two-step estimation method is used to fit the MGTWR model. A dam deformation modelling example shows that the MGTWR model improves the average prediction accuracy by 57.6% compared to the GTWR model when the regression coefficients have both global stationarity and spatio-temporal non-stationarity properties.

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3. Detection of GNSS no-line of sight signals using LiDAR sensors for intelligent transportation systems
T. Hassan, T. Fath-Allah, M. Elhabiby, A. Awad & M. El-Tokhey

The reliability and robustness of positioning systems in urban and suburban environments are intrinsic. This is obvious following the continuous increase of Intelligent Transportation Systems (ITS) applications in such challenging environments. Global Navigation Satellite Systems (GNSS) represent the primary positioning technique used for navigation purposes in these applications, which can be satisfying in open-sky areas. However, GNSS cannot provide the same level of navigation performance in urban environments. One of the main reasons for this is the No-Line of Sight (NLOS) signals. In this study, the integration of GNSS and Light Detection and Ranging (LiDAR) sensors is exploited, and a new algorithm is proposed for the detection of NLOS signals. Real field data are used to test and validate the proposed strategy and algorithm. Phase-smoothed code observations are employed to evaluate the accuracy improvement after excluding the NLOS observations. The results show that the horizontal direction's positional accuracy can be improved significantly after applying the proposed algorithm. This improvement reaches 10.403 m with a mean value of 2.162 m (62.2% improvement) over all epochs with detected NLOS signals. After analysing this improvement in the Cross-Track (CT) and Along-Track (AT) directions, it is found that the accuracy improvement reaches 8.641 m with a mean value of 1.699 m in the CT direction and 6.879 m with a mean value of 1.303 m in the AT direction.

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4. Determination of sea level variations in Turkish Mediterranean coast using GNSS reflectometry
Cansu Beşel & Emine Tanır Kayıkçı

Global Navigation Satellite System Reflectometry (GNSS-R) can be used to measure sea level heights based on reflected signals recorded as oscillations in signal-to-noise ratio (SNR) data. This study utilizes the SNR data from an existing MERS, located in Erdemli, Mersin on the Mediterranean coast of Turkey over a one-year time period. The dominant multipath frequency in the SNR data is derived with two methods presented in this study: the Lomb-Scargle periodogram (LSP) and the LSP with the Moving Average (MA) filtering. The results of both methods are compared in terms of the accuracy and correlation with respect to sea level records from the nearby Erdemli tide gauge. The correlations between the GNSS-R and tide gauge by using the LSP are 0.88 and 0.84 for GPS L1 and L5 signals, respectively. With the LSP with MA method, the correlations are increased by 0.91 and 0.88 for GPS L1 and L5 signals, respectively.

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5. What is the relation between smearing effect of least squares estimation and its influence function?
Utkan Mustafa Durdag, Serif Hekimoglu & Bahattin Erdogan

In some cases, tests for outliers and robust methods based on the Least Square Estimation (LSE) fail to detect and isolate outliers. LSE 'smears the effect' of an outlier on all estimates of the residuals, the unknowns, and the a posteriori variance of unit weight. Therefore as bias goes to infinity, the Influence Function (IF) also goes to infinity. This study aims to investigate the effect of an outlier on the unknown parameters, etc., compared to the IF concept. Moreover, how the ratio of the resulting outlier effect is related to the redundancy of the geodetic network has been shown through the concepts of Sensitivity Curve (SC) and smearing effect by Monte Carlo Simulation. Also, it has proved that the SC of LSE was almost equal to the ‘smearing effect’ of LSE, which behaves systematically as a function of the partial redundancy that varies from one residual to another in the geodetic network.

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6. The San Joaquin experimental range geoid is compared against xGEOID20A&B
M. Berber & Y. Wang

The National Geodetic Survey began publishing a series of experimental geoid (xGEOID) models annually since 2014. The latest experimental model is xGEOID20. The San Joaquin Experimental Range (SJER) in Fresno County, California is surveyed using Static GPS and precise levelling and a local geoid (SJER Geoid) is created. In this study, SJER Geoid is compared against xGEOID20A&B models and the results are tabulated. The results indicate that xGEOID20A&B slopes agree with the GPS/levelling data well even in such a small area. SJER Geoid model agrees with the xGEOID20 models at 7 mm level. The biases about 80 cm are within the expected range between the North American Vertical Datum of 1988 (NAVD88) and North American-Pacific Geopotential Datum of 2022 (NAPGD2022).

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7. Combined observables in different inter-satellite line-of-sight directions from simulated satellite gravity mission architectures for retrieving total water storage – regional case study: the Nile River Basin
Basem Elsaka

Numerous studies for improving gravity field determination from future gravity missions beyond the GRACE/GRACE-FO missions have been proposed during the last decade. In this contribution, full-scale simulated observations of four satellite missions, namely Bender-, Cartwheel-, Helix- and Pendulum-type, in addition to GRACE-FO as a reference mission will be used to retrieve the total water storage over the Nile River Basin (NRB). The findings show a superiority of investigated configurations in retrieving the total water storage (TWS) w.r.t. the GRACE-FO mission. Moreover, the Bender-type provides improved global TWS recovery showing the least standard deviations (STD) of about 3.43cm in terms of equivalent water heights (EWH) (up to d/o 80). The Pendulum, Cartwheel and Helix missions provide STD of about 6.34cm, 8.35cm and 5.78cm in terms of EWH, respectively. In addition, the Bender-type provides improved local TWS recovery over the NRB without any distortion w.r.t. both the “simulated” and “real” GRACE-FO solutions.

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8. Evaluation of the GSRM2.1 and the NUVEL1-A values in Europe using SLR and VLBI based geodetic velocity fields
Mina Rahmani, Vahab Nafisi, Sigrid Böhm & Jamal Asgari

The NUVEL1-A is one of the old and popular plate tectonic models. While the NUVEL1-A is a geological-based model, recently a model has been proposed (GSRM2.1 model) which is based on the results of space geodetic techniques. In this work, we investigate the consistency of these models with the VLBI and SLR results in Europe. Direction and magnitude of the horizontal motion from NUVEL-1A and GSRM2.1 models are compared with corresponding values from both geodetic techniques. This comparison provides valuable deductions such as: (1) The values of geodetic-based model (GSRM2.1) show better agreement with SLR and VLBI results (2) In each comparison between geodetic results and modelled values, direction divergence is larger than magnitude difference.

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9. Advancements in underground mine surveys by using SLAM-enabled handheld laser scanners
Artu Ellmann, Kaia Kütimets, Sander Varbla, Erik Väli & Sander Kanter

Applicability of SLAM (simultaneous localization and mapping) technology for mine surveys and subsequent 3D modelling of post-extracted surfaces is assessed. The resulting surface geometry is validated via terrestrial laser scanner (TLS) acquired reference data. Typical discrepancies remained within 2 and 5 cm in horizontal and vertical directions, respectively. Discrepancies between TLS, SLAM-enabled handheld scanner and conventional surveying results are small and fully satisfy the contemporary accuracy requirements, yet evidence that the conventional mine survey results are affected by the subjectivity of the surveyors. The SLAM-enabled laser scanning hence appears to be the most suitable method for underground mining surveys.

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Survey Review 54, No 384. May/June 2022

1. Building Information Modelling (BIM) for property valuation: A new approach for Turkish Condominium Ownership
Nida Celik Simsek & Bayram Uzun

In Turkey, calculation of the factors affecting the value of the condominium units of a building via 2D architectural project data leads to problems. One of the biggest problem is the land share calculation. The aim of this study was to establish a mechanism by which the properties of the factors affecting the value can be determined mathematically and to arrive at a value-based land share. For this purpose, the study utilized a 3D virtual Building Information Modelling (BIM) model. The value factors and weights were determined via a questionnaire, 3D BIM model of the structure was created, metric values of the factors were calculated and the nominal values of the condominium units were calculated. This study demonstrate that a building nonexistent in the real world can be represented in a virtual environment and comparable information source can be presented to the expert who will carry out the valuation process.

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2. Total least squares adjustment in inequality constrained partial errors-in-variables models: optimality conditions and algorithms
Jian Xie, Dongfang Lin & Sichun Long

The partial errors-in-variables (PEIV) model is a structured form of errors-in-variables (EIV) model reformulated by collecting all the independent random elements of the coefficient matrix. When some reliable inequality constraints are taken into account, the adjustment results of inequality constrained PEIV (ICPEIV) model are probably improved. In this contribution, we first present the optimality conditions for inequality constrained weighted total least squares (ICWTLS) solution in ICPEIV model. Then we modified the existing linear approximation (LA) approach to make it suitable for cross-correlated data. The sequential quadratic programming (SQP) method is proposed based on the optimality conditions. Since the Hessian matrix is difficult to compute in the SQP algorithm and it converges slowly or even not converges when the Hessian matrix is indefinite positive, the damped quasi-Newton (DQN) SQP method is proposed. Finally, three examples are given to show the feasibility and performance of the proposed algorithms.

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3. A new algorithm for rank-deficient problems with inequality constraints
Zhao Shaojie, Song Yingchun & Li Wenna

In geodesy, in addition to observation information, there are also parameters additional useful information. Making full use of them can make up for the lack of observation information and form effective constraints on unknown parameters. In order to make the adjustment results unique and stable, we build a function model to solve inequality constraints, and based on the linear complementarity theory, propose to use the potential function descent interior point algorithm to solve the rank deficient problem. After that, we also extend this idea to the study of the ill-posed problem in this paper. Finally, examples are given to demonstrate the efficiency of the proposed algorithm. It is shown that this algorithm satisfies the uniqueness and stability of the solution, and provides a new reference for the research of rank-deficient and ill-posed problems in the future.

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4. Comparison between Gaussian and decorrelation filters of GRACE-based RL05 temporal gravity solutions over Egypt
Basem Elsaka & Mohamed El-Ashquer

This contribution provides a comparison between the Gaussian and decorrelation filters as derived from GRACE products (RL05) estimated by the official GRACE Science Data System centres (GFZ, CSR and JPL) as well as the ITSG-GRACE2016 solutions over Egypt. The outcome of this study will help in finding out which of these centres provides improved temporal gravity solutions as well as the most promising GRACE time series over Egypt. The obtained results regarding Gaussian filters show that the GFZ centre provides the most promising solutions w.r.t. CSR and JPL. Whereas the ITSG-GRACE2016 products provide improvements, especially at Gaussian radius 200 km, of about 56%, 68% and 60% w.r.t. CSR, JPL and GFZ solutions, respectively. Regarding the decorrelation filtering, the ITSG-GRACE2016 provides the least Std. w.r.t. CSR, JPL and GFZ solutions showing for the DDK8 improvement of about 48%, 64% and 68% w.r.t. the three centres GFZ, JPL and CSR, respectively.

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5. Evaluation of global gravity field models using shipborne free-air gravity anomalies over the Gulf of Guinea, Central Africa
Kamto Paul Gautier, Yap Loudi, Zanga Amougou Alain, Kandé Houetchak Ludovic, Nguiya Sévérin & Kamguia Joseph

In this work, the principal aim is to evaluate some recent GGMs on the Gulf of Guinea region using shipborne free-air gravity data. Two types of GGMs are evaluated in this study: combined models (EGM2008, EIGEN-6C4, GECO, SGG-UGM-1, GOCO05C and XGM2016) and satellite-only models (DIR_R5, ITU_GGC16, SPW_R5, TIM_R5, GGM05G and NULP_02S). The comparisons between these GGMs and the preliminary filtered shipborne gravity data were performed before and after the Spectral Enhancement Method (SEM). The statistical results have shown that the combined models have a better performance than the satellite-only models. Before and after SEM, we note that the EGM2008 model presents the best statistical results compared to the shipborne gravity anomalies (RMS and SD values respectively changes from 3.87 to 3.55 mGal and from 3.57 to 3.32 mGal). However, the DIR_R5 model is the best of the satellite-only GGMs of this study.

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6. Assessing the positioning performance of GNSS receivers under different geomagnetic storm conditions
Chao Yan, Qing Wang, Bo Zhang, Jiujing Xu & Hao Zhang

GNSS signals are affected when solar activity causes sudden variations in the density of the ionosphere. Few studies concentrate on positioning performance of IGS stations using different GNSS receivers under different geomagnetic storm conditions. This paper for the first time presents IF and UC PPP positioning performance of stations with different receivers during the quiet, moderate, intense, and super storms period. Firstly, a comprehensive investigation of geomagnetic storms effects on the occurrence of GPS cycle-slip and PPP positioning performance have been presented. Secondly, the influences of geomagnetic storms on the occurrence of cycle-slip and IF PPP positioning performance for stations using receivers provided by ‘JAVAD’, ‘LEICA’, and ‘TRIMBLE’ manufacturers have been comprehensively studied. Finally, this study investigates the geomagnetic storms effects on IF PPP positioning performance of stations using receiver types ‘JAVAD TRE_G3TH DELTA’, ‘JAVAD TRE_3 DELTA’, ‘LEICA GR25’, and ‘TRIMBLE NETR9’ by analysing observed data collected at mid-latitude region.

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7. Determination of local gravimetric geoid model over Egypt using LSC and FFT estimation techniques based on different satellite- and ground-based datasets
Ahmed Saadon, Mohamed El-Ashquer, Basem Elsaka & Gamal El-Fiky

In this contribution, two gravimetric geoid models for Egypt; EGY-LGM2019 and EGY-FGM2019 are developed using the least-squares collocation and the Fast-Fourier Transformation methods, applying Remove-Restore procedure. Different datasets are used in terms of gravity anomalies obtained from GOCE-based SPW-R5 and EGM2008 models, and from 1015 terrestrial gravity stations. Two gravimetric geoid models, EGY-FLGM2019 derived by the LSC method and EGY-FFGM2019 derived by 1D-FFT method are computed and fitted using the 17 GPS/levelling measurements to adjust the gravimetric geoid model with the national local vertical datum for Egypt. Our findings between the 6 GPS/levelling geoid undulations and the developed fitted geoid models EGY-FFGM2019 and EGY-FLGM2019 are about 7.57 and 18.46 cm, respectively. In addition, the former model improves the geoid heights of about 72-65% over Egypt w.r.t. the EGM2008 and GECO models, respectively. Therefore, the EGY-FFGM2019 model is recommended as a reliable model that improves the geoid heights over Egypt.

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8. Estimation for the accumulated errors in determining the road grade to improve the accuracy of a geodetic survey
Kostiantyn Mamonov, Yevhen Orel, Svetlana Kamchatnaya, Oleksandr Saiapin & Dmytro Borodin

During designing a railway track, the accumulated errors in the transmission of coordinates affect the construction cost, change the conditions for designing tracks and the value of operating costs. If the grade of the track comes closer to the limiting grade, more accuracy is required to draw up the survey plan and terrain profile, and the more often geodetic control points are necessary. It is indicated that the calculation for the entire track is wrong based on errors in length due to errors in marks. The article provides a mathematical rationale for computation the error of the route survey grade as a function of the section length of the lines that have a steep slope. The influence of errors in determining the elevation and length on the line grade is considered. It is shown that the steeper the limiting grade the shorter should be the traverse of geodetic control.

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Survey Review 54, No 383. March/April 2022

1. Collaborative positioning method via GPS/INS and RS/MO multi-source data fusion in multi-target navigation
Rui Liu, Klaus Greve, Pengyu Cui & Nan Jiang

This paper aims to design a method of multi-source data fusion in multi-target collaborative navigation. First, the respective features of GPS/INS/RS/MO data in the navigation process are clarified. Then a multi-source data fusion method is designed including GPS/INS data fusion with adaptive Kalman filter, RS/MO data fusion with ranging table matching of observation targets, and joint adjustment with fused GPS/INS and RS/MO data. Finally, a simulation experiment is carried out to verify the improvement in positioning efficiency and precision. The results show that collaborative navigation based on multi-source data fusion can increase the stability and accuracy of the navigation service.

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2. Estimation of the height datum geopotential value of Hong Kong using the combined Global Geopotential Models and GNSS/levelling data
Panpan Zhang, Lifeng Bao, Dongmei Guo & Qianqian Li

The advent of the Gravity Recovery and Climate Experiment (GRACE) and Gravity field and steady-state Ocean Circulation Exploration (GOCE) has changed the global contribution in the determination of high-accuracy global geopotential models (GGMs). In this paper, a spectral expansion method is used to determine the combined GGMs, using the high-resolution EGM2008 model and residual terrain model (RTM) to effectively bridge the spectral gap between the satellite and terrestrial data. The accuracy of the combined GGMs shows improvement compared with GOCE/GRACE-based GGMs and EGM2008 in determining the geopotential of the Hong Kong Principal Datum (HKPD). As a result of the DIR_R5/EGM2008/RTM model and GNSS/levelling, the geopotential value of HKPD is estimated to be 62,636,860.52 m2s−2 with respect to the global geoid W0 = 62,636,853.4 m2s−2. Therefore, the vertical offset between the HKPD and global geoid is about −72.8 cm, which means that the HKPD is 72.8 cm below the global height datum.

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3. A search step optimization in an ambiguity function-based GNSS precise positioning
Slawomir Cellmer, Krzysztof Nowel & Artur Fischer

The search procedure, as a part of the Modified Ambiguity Function Approach (MAFA), is conducted in the coordinate space. The main advantage of searching for a fixed solution in the coordinate domain, instead of in the ambiguity domain, is the constant search space dimension, which amounts to three. In contrast, an ambiguity space dimension can presently achieve over twenty when the positioning is based on multi-system data. Thus, in the MAFA method, the computational complexity is independent of the number of satellites. We propose a new method of estimating the length of the search step. In this method, the actual satellite configuration determines the size of the search step. Therefore, the data-driven search step is always optimal, regardless of the current satellite configuration. The mathematical model of the new approach is provided together with a detailed algorithm. The numerical experiment follows the description of the search procedure.

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4. History of geodetic works in Vojvodina (Northern Serbia) and use of old maps in Serbian national spatial data infrastructure
Sofija Naod, Oleg Odalović, Ljiljana Brajović & Rajko Savanović

Imperial hegemony established by the Habsburg Monarchy relied upon proper mapping during its conquests. The need for the development of geodesy and establishing reference frames was important. Until the end of the First World War, Vojvodina belonged to the Austrian-Hungarian Empire, so all of its surveys were carried out as part of many organized land surveys in the Monarchy. Today, more than 100 years after Vojvodina became the Autonomous Province of Serbia, the network developed by the Monarchy and cadastral plans from that period are still in use. In this paper, in addition to a historical overview of military and cadastral surveys in Vojvodina, we will show data that have historical significance and are available on the Internet and in historical archives. We will also emphasize how the maps available in historical archives of the neighbouring countries could have been used to set up Serbian national spatial data infrastructure.

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5. Consideration on how to introduce gamification tools to enhance citizen engagement in crowdsourced cadastral surveys
Konstantinos Apostolopoulos & Chryssy Potsiou

The major objective of this research is to investigate the progress of citizen participation in cadastral surveying and to consider ways on how to introduce gamification tools for further improvement. A brief literature review is presented in the areas of the Sustainable Development Agenda 2030 related to land administration and citizen engagement, e-government and citizen participation and gamification tools for citizen engagement. This paper, also, includes an investigation of the progress in introducing volunteerism and citizen participation to the Hellenic Cadastre. A case study is held by a group of volunteers in order to assess the developed tools designed either by the private sector or by the cadastral agency.

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6. Lake water level variability determination from SAR backscatter of discrete objects, GNSS levelling and satellite altimetry
R. Reyes, M. Nagai & A. Blanco

In the absence of enough gauging stations for monitoring lake water level, three (3) methods are presented in this research: (1) Synthetic Aperture Radar (SAR) backscatter from discrete object; (2) Global Navigation Satellite System (GNSS) levelling; and (3) satellite altimetry. The results showed that the Laguna Lake water level is not homogeneous but instead varies at different locations. The GNSS leveling showed that water level varies from −0.64 to 1.26 m from water gauge data. Using the fish pen guard house as discrete object for double bounce scattering a correlation of 0.86 was computed between the gauge data and sigma 0 the equation derived through linear regression was used to predict water level from SAR images at different periods. The satellite altimeter data correlated with water level from graduated staff at 0.97 with a difference of about 0.29 m. It also showed an increasing water level trend from north to south.

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7. Comparing results of online GNSS services: A case study from Turkey
Özge Güneş & Deniz Öz Demir

The goal of this paper is to compare academic and online GNSS processing services for CORS-TR. To determine whether differences in the coordinate components were statistically significant, statistical significance test and 3D coordinate transformation were applied. Furthermore, local coordinates analysed to show jumps that occurred to seismic events. While there are significant differences only in the Z coordinate component between GIPSY and GAPS in the Cartesian coordinate system, all differences in local coordinate components are insignificant. 3D coordinate transformation results included random errors and there are insignificant differences in terms of transformation parameters between GIPSY and online GNSS processing services.

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8. Health monitoring and safety evaluation of bridge dynamic load with a ground-based real aperture radar
Sichun Long, Wenting Liu, Jinyu Ma, Aixia Tong, Wenhao Wu & Chuanguang Zhu

Through a series of experiments of dynamic deformation and destruction under time series loading on an indoor real model bridge, Ground-based real-aperture radar interferometry (GB-InRAR) discovered that before the structure of the bridge was damaged, its amplitude and acceleration increased with the increase of load; After its structure was damaged or cracked, such dynamic characteristics as natural frequency, damping ratio, stiffness and bearing capacity decreased obviously. Moreover, GB-InRAR dynamic load monitoring of Xiangtan Railway Bridge and Inter-city Railway Bridge. In the process of vehicle dynamic load, such important parameters as bridge deflection, natural frequency and damping ratio conform to the bridge loading procedures and dynamic characteristics. The results show that the GB-InRAR can accurately measure the deflection changes, natural vibration frequency and spectrum characteristics of bridges, and it can be used as effective means of the dynamic characteristics analysis in the safety detection and health evaluation of bridges.

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Survey Review 54, No 382. January/February 2022

1. Architecture for semantic web service composition in spatial data infrastructures
Deniztan Ulutaş Karakol & Çetin Cömert

The importance of geospatial data has rendered it to be used in decision-making in both public and private sectors. The purpose of this study was to employ Semantic Web Technology (SWT) for the problems of Web Service Composition (WSC) in the context of Spatial Data Infrastructures (SDI). Some of these problems are identifying the workflow sequence and the user goal, discovering services according to service parameters, and matching these parameters. As a suggestion for the solution of all these problems a semi-automated WSC architecture was proposed in this study. In terms of architecture, users state their ‘goal’ with a natural language sentence. By semantically matching this sentence with a Spatial Services Ontology (SSO), the corresponding ‘abstract’ WSC was ‘located’ and the ‘concrete’ WSC was formed. Although there are still problems waiting to be solved due to the scope of the work, this study makes a valuable contribution to the area.

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2. A comprehensive assessment of four-satellite QZSS constellation: navigation signals, broadcast ephemeris, availability, SPP, interoperability with GPS, and ISB against GPS
XuanPing Li, Lin Pan, Wenkun Yu, Wujiao Dai, Yanjie Li & Hui Peng

In this study, a comprehensive assessment of four-satellite Quasi-Zenith Satellite System (QZSS) constellation is conducted, including the quality of navigation signals, the accuracy of broadcast ephemeris, the availability of satellite constellation, the performance of single point positioning (SPP), the interoperability with GPS, and the inter-system bias (ISB) against GPS. Regarding the signal quality, no significant difference between QZSS and GPS can be found. The signal-in-space ranging error (SISRE) of QZSS satellites is 0.59–0.62 m. The service rate of QZSS-only positioning is 69.8–77.8% in QZSS service areas. A positioning accuracy of 5.70, 3.20 and 6.99 m in east, north and up directions can be achieved for the QZSS-only SPP. After introducing QZSS observations into GPS-only SPP processing, the positioning accuracy can be slightly improved. The ISB with a short-term stability of 1.75 ns behaves like systematic biases, and thus cannot be ignored in the GPS/QZSS combined SPP.

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3. Assessment of the GNSS PPP performance using ultra-rapid and rapid products from different analysis centres
Sermet Ogutcu & Haitham Talib Farhan

The performance of precise point positioning (PPP) mainly depends on satellite orbit and clock accuracy. Ultra-rapid and rapid orbit/clock products have been creating by analysis centres (ACs) for time-critical applications. In this paper, GPS-, GLONASS-, Galileo-, and BeiDou (BDS-2)-only PPP with ultra-rapid and rapid products from seven ACs (i.e. CODE, ESA, IGS, GFZ, JPL, NRCan, and WUHAN) are investigated for PPP performance. A two-month period in 2020 was chosen for conducting static and kinematic PPP using data from 32 Multi-GNSS Experiment (MGEX) stations. For GPS-only PPP with different ACs, GFZ/NRCan and CODE/NRCan rank first for ultra-rapid and rapid PPP processes, respectively. For GLONASS-only PPP, positioning performances using ultra-rapid products are comparable with each other except for CODE and ESA products. CODE rapid product ranks last for GLONASS-only PPP. For Galileo and BeiDou-only PPP, GFZ AC performs the best for ultra-rapid processes. For Galileo-only PPP using rapid products, CODE ranks first.

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4. Accuracy assessment of kinematic PPP versus PPK for GNSS flights data processing
Mert Gurturk & Metin Soycan

The integration of survey-grade Global Navigation Satellite Systems (GNSS) with photogrammetric measurement studies conducted with an aircraft has the potential to meet the need for the use of ground control points (GCP). In photogrammetric studies, there are different GNSS techniques to provide the precise positioning of the aircraft. The precise point positioning (PPP) technique has become an alternative method to post-processing kinematic (PPK) methods in the evaluation of GNSS data gathered with an aircraft at high speed. In this study, GNSS data gathered from two different flights conducted for photogrammetric surveys in Izmir, Turkey were processed with different software (RTKLIB, gLAB, CSRS-PPP, and GRAFNAV) through PPP technique with the ambiguity resolution (PPP-AR) method to analyse the performance of this method versus PPK. Three-dimensional (3D) positioning analyses of coordinate differences obtained from mapping flights demonstrated a variation pattern mainly between 0 and 6 cm for both kinematic PPP and PPK results.

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5. Empirical comparison between stochastic and deterministic modifiers over the French Auvergne geoid computation test-bed
R. Goyal, J. Ågren, W.E. Featherstone, L.E. Sjöberg, O. Dikshit & N. Balasubramanian

Since 2006, several different groups have computed geoid and/or quasigeoid (quasi/geoid) models for the Auvergne test area in central France using various approaches. In this contribution, we compute and compare quasigeoid models for Auvergne using Curtin University of Technology’s and the Swedish Royal Institute of Technology’s approaches. These approaches differ in many ways, such as their treatment of the input data, choice of type of spherical harmonic model (combined or satellite-only), form and sequence of correction terms applied, and different modified Stokes’s kernels (deterministic or stochastic). We have also compared our results with most of the previously reported studies over Auvergne in order to seek any improvements with respect to time [exceptions are when different subsets of data have been used]. All studies considered here compare the computed quasigeoid models with the same 75 GPS-levelling heights over Auvergne. The standard deviation for almost all of the computations (without any fitting) is of the order of 30–40 mm, so there is not yet any clear indication whether any approach is necessarily better than any other nor improving over time. We also recommend more standardisation on the presentation of quasi/geoid comparisons with GPS-levelling data so that results from different approaches over the same areas can be compared more objectively.

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6. An attempt to analyse Iterative Data Snooping and L1-norm based on Monte Carlo simulation in the context of leveling networks
Ivandro Klein, Stefano Sampaio Suraci, Leonardo Castro de Oliveira, Vinicius Francisco Rofatto, Marcelo Tomio Matsuoka & Sergio Baselga

The goal of this paper is to evaluate the outlier identification performance of iterative Data Snooping (IDS) and L1-norm in levelling networks by considering the redundancy of the network, number and size of the outliers. For this purpose, several Monte-Carlo experiments were conducted into three different levelling networks configurations. In addition, a new way to compare the results of IDS based on Least Squares (LS) residuals and robust estimators such as the L1-norm has also been developed and presented. From the perspective of analysis only according to the success rate, it is shown that L1-norm performs better than IDS for the case of networks with low redundancy (r¯<0.5), especially for cases where more than one outlier is present in the dataset. In the relationship between false positive rate and outlier identification success rate, however, IDS performs better than L1-norm, independently of the levelling network configuration, number and size of outliers.

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7. Spatial aspect of fit-for-purpose land administration for emerging land administration systems: a conceptual framework for evaluation approach
Didier Milindi Rugema, Tadesse Amsalu Birhanu & Gebeyehu Belay Shibeshi

Fit-for-purpose land administration (FFPLA) concept is widely applied in the emerging land administration systems (LASs). This paper aims to contribute to the development of evaluation of the spatial aspect of FFPLA. A review of evaluation models for LASs is made in relation with rationale of FFPLA to identify gaps related to evaluation of a FFPLA and to build up milestones and measurement criteria. The incorporation of possible manual land recordation and computer enabled LASs for evaluation approach is accentuated as milestones of a country’s strategy approach, and perspective of FFPLA as a process.

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8. Obituary: James (Jim) R. Smith 1 October 1935–12 August 2021
Arthur L. Allan & Peter Collier

Jim Smith, the former editor of Survey Review, started work as a surveyor with the National Coal Board Opencast Executive in 1958 before moving to Hertfordshire County Council’s Architects Department in 1960. It was while there that Jim qualified as a surveyor in 1961 and became an ARICS. He had studied surveying in the South-West Essex Technical College, now part of the University of East London. While studying, Jim was a founding member and first chairman of the Land Surveyors Society in the college. Being an active member of societies was to be a theme running throughout Jim’s subsequent career and extended into retirement.

In 1962 Jim moved to Nigeria to join the Department of Lands and Housing in the West Nigeria Government, working as a Provincial Surveyor and survey instructor. While in Nigeria he served the West Nigeria branch of the RICS. In 1964 Jim returned to Britain and joined the Survey Production Centre (Royal Engineers) where he worked as an Experimental Officer until 1968. In 1966 Jim served on the RICS Working Party “Metric System and the Ordnance Survey” and the Middlesex and Urban Essex branch committee of the RICS. In 1967 he became a member of the Land Survey Divisional Committee, a position he kept until 1996, serving as Honorary Secretary from 1968 to 1980. Jim also served as editor for the Land Survey Notes monthly page in The Chartered Surveyor from 1967 to 1979. From 1968 to 1980 he was technical organiser of Biennial Land Survey Conferences and from 1968 to 1981 chairman of the sub-committee for FIG exhibitions.

In 1968 Jim made his final career move when he joined Portsmouth Polytechnic’s Department of Civil Engineering. During much of Jim’s time in Portsmouth, he was one of four surveyors in the Department of Civil Engineering, making it one of the best survey resourced departments in Britain. Following his move to Portsmouth Jim became involved in examining for the RICS and an assessor for ONC while continuing to be involved in many other RICS activities. He also became more heavily involved with FIG. This included serving as a member of the FIG/CIB Working Party on tolerances in building (1975–96); as secretary of Commission 6 (1979–88); Commission 1 Group for the 250th anniversary of survey expeditions (1984–86); and was Secretary of FIG International Institution for the History of Surveying. His interest in the history of surveying led him to become a member of the Royal Society Committee for the 125th anniversary conference of the International Association of Geodesy (IAG) and his work on Sir George Everest and as secretary of the group running the Struve Arc Project.

The interest in the history of surveying also led to the writing of a number of books on the subject including From Plane to Spheroid, R.S. Webb (1892–1976) From Shropshire to Paarl via Geodesy and Lesotho: Everest and The Man and the Mountain. He also worked with Jan de Graeve on the translation of the Struve volumes. His interest in the work of Struve also resulted in a number of conference presentations and published papers. With Alan Wright and Brian Sturman he wrote The Tellurometer from Wadley to the MRA7. He also took on the task of editing the papers of R.S. Webb’s held in the South African Trig. Survey Library, a project that took from 1982 until 2018.

Jim also published numerous technical books including Optical Distance Measurement, which became a standard for survey students, and Desk Calculators in the series Modern Aspects of Land Surveying which Jim had initiated. He then acted as series editor of other books in the series. Four books were written in the 1970s for Hewlett-Packard on the use and programming of their calculators. Basic Geodesy followed in 1988, followed by Introduction to Geodesy in 1997. Jim also wrote some 132 papers on various survey topics, some of which appeared in Survey Review.

Jim served as editor of Survey Review from 2000 to the end of 2011 and continued to serve on the editorial board in an advisory capacity for a few more years. Jim’s tenure coincided with a number of important changes in the journal during which it went from being published by CASLE to being an independent journal and then being published by Maney for Survey Review Limited. Jim’s work during that time was invaluable in making sure that Survey Review continued to be published in a timely fashion while coping with an increasing number of submissions to the journal, and doing this while still working in a pre-electronic submission environment.

Jim was blessed with a pleasant personality and kind disposition towards others, which served him well in his relationships both in committee work and personal friendships. He was also favoured by a wife Ann who supported his work, augmented his hospitality and often accompanied him on his foreign travels. It is no happy accident that he made such a success of his life. He is survived by two daughters, Nicola Jones and Bridget Johns; two grandchildren Eleanor McCullagh (Johns) and Peter Johns; and his new baby great-granddaughter Annie McCullagh.

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