Current Abstracts


Current Abstracts
Past Abstracts

Email: Peter Collier


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Survey Review 55, No 390. May/June 2023

1. Allowing context to speak: the progressive case study method for cadastral systems research
Simon Hull & Jennifer Whittal

For research involving customary land rights, ‘context is key’ because every context brings specific nuances for consideration. Failure to account for context runs the risk of irrelevance, unintended consequences and/or failure. We present a research method that allows context to speak: the progressive case study. The approach combines deductive case study with inductive grounded theory approaches. The results are used to propose a framework for guiding cadastral systems development in customary land rights contexts. This paper presents the methodology, which should be useful for researchers, NGOs and multinational organisations doing development programming in developing contexts.

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2. Optimisation of doppler search space to improve acquisition speed of GPS signals
K. Bahmani, M. Nezhadshahbodaghi & M. R. Mosavi

The acquisition section has some serious problems to increase the speed of acquiring the Global Positioning System (GPS) signals. In this study, we propose three new methods to optimise the Doppler search space and improve the acquisition speed of the GPS signals. The experimental results represent that our proposed methods have a superior performance compared to the conventional bin-fixed method so that the first (sub-frequency band), second (multi-frequency bins), and third (integration of the first and second methods) suggested methods outperform the bin-fixed method in terms of the execution time and computational complexity by approximately 26–19%, 33–19%, and 36–20%, respectively.

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3. Temporal GIS models for cadastral data management: the knowns, unknowns and future
J. Mango, J. Ngondo, D. Xu, D. Zhang & X. Li

Numerous temporal GIS models for cadastral data management have been proposed, and to understand the state of their art, a study that critically assesses their designs is needed. This study reviewed 11 models and noted that except with earlier designs; most of the reviewed models could store temporal land parcels with their tracks of changes. However, they lack to maintain the semantics of their data, valid times and potential records of changes, and the alternative techniques to accelerate queries. Thus, a semantical and bi-temporal modelling framework is proposed. Future studies could use the framework and focus on implementation designs to obtain more robust models.

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4. Field comparison of the total station-based QDaedalus and the zenith telescope-based CODIAC astrogeodetic systems for measurements of the deflection of the vertical
Müge Albayrak, Daniel Willi & Sébastien Guillaume

The precision and accuracy of a Leica MultiStation 60-based QDaedalus astrogeodetic measurement system are determined through observations at two locations in Switzerland. The precision of the QDaedalus was determined as 0.1″ for the N-S and E-W deflections of the verticals (DoVs) through 118 series of observations collected over 13 nights (in a 44-day observation period) at the HEIG-VD test station. The accuracy of the QDaedalus system was established by simultaneous parallel observations over two nights using the CODIAC system at the Zimmerwald Observatory. The differences between them were found to be 0.09″ and 0.02″ for the N-S and E-W DoV components, respectively. From these results, the accuracies of both DoV components can be interpreted as 0.1″. We also found a large systematic trend in the observed N-S DoV data at the HEIG-VD test station (0.008″/day). This study is the most extensive thus far for determining the precision and accuracy of the QDaedalus system for astrogeodetic measurements; it is also the first time that QDaedalus system’s accuracy has been established using parallel observations.

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5. Accuracy assessment of the Croatian height transformation model
Blaženka Bukač, Ivan Razumović & Nevio Rožić

The Croatian height transformation model (HTMV) enables the transformation of absolute heights of discrete points with known horizontal positions from the Trieste 1875 reference system used throughout the former Republic of Yugoslavia and in Croatia known as HVRS1875 to the new height reference system of the Republic of Croatia (HVRS71) and vice versa. The HTMV is realised as a grid transformation model based on separate modelling of datum and distortion components comprised in height differences. The quality of the transformation model is assessed by comparing the difference in height values at benchmarks that were not used in the model derivation against height differences at the benchmark locations interpolated from the model. The results indicate a high external and internal accuracy of the transformation process, which points to the adequacy of the HTMV utilisation for engineering purposes.

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6. Digitisation and analysis of historical vertical deflections in India
W. E. Featherstone & R. Goyal

We describe the [somewhat tedious] process of digitising from a 1955 report that lists over 1000 vertical deflections in India and some surrounding countries. It involved error-checking with closed-loop tests and resolution of an ambiguity surrounding the meridional vertical deflection at the Kalianpur origin of the datum. We transformed these Kalianpur coordinates to geodetic coordinates on geocentric datum to compute absolute vertical deflections. However, due to many changes to the Everest spheroid due to different feet to metre conversions and readjustments of the Kalianpur datum, we were restricted to using the abridged Molodensky transformation parameters for the 1975 Kalianpur datum and Everest 1956 spheroid based on only seven common points from the WGS84 technical manual. We compared these transformed absolute vertical deflections with EGM2008 and GGMplus (for both models: meridional standard deviation: ∼±2″; prime vertical standard deviation: ∼±3″), showing that the effort of digitisation and scrutiny of historical geodetic data is indeed worthwhile.

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7. Ambiguity resolution method using BDS/INS model
F. Wu, J. Zhao, J. Xue & D. Li

Due to the highly dynamic changes of the environment, the frequent loss of signal will seriously reduce the accuracy of realtime dynamic positioning. Meanwhile, the ambiguity resolution for medium/long baseline is more affected by atmospheric delay. To solve this problem, an Inertial Navigation System (INS) assisted Beidou Navigation System (BDS) medium/long baseline partial ambiguity resolution (PAR) method is designed. Firstly, constructing the BDS/INS tight integrated system that uses INS provided initial information to ambiguity resolution when the signal outages. Secondly, the atmospheric delay constraint is introduced to improve the precision of float ambiguity. Finally, the PAR based on the elevation angle information is applied to enhance fixed speed and accuracy. The vehicle experiments show that the proposed algorithm can quickly fix the ambiguity of medium/long baseline when the satellite signal outages for a short time, and improve the positioning accuracy of medium/long baseline in the dynamic environment.

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8. Establishment of Taiwan’s standard operating procedure for network-based RTK in cadastral surveying
Ta-Kang Yeh, Hsuan-Chang Shih, Chuan-Sheng Wang & Tzu-Yi Lien

Taiwan completed construction of GNSS reference stations for the network-based RTK system in 2007. The legal mode of operation used in Taiwan requires that each point be repeatedly observed for at least two observation sets separated by 60 min. This study presents a simplified field operating procedure, which measures 10 epochs of fixed solutions during each observation set and reinitializes observations 10 times. In addition, the national and local network-based RTK system were used. The average horizontal positioning accuracies were 1-3. Finally, a workflow is presented for using the network-based RTK to measure the control points in cadastral surveys.

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Survey Review 55, No 389. March/April 2023

1. Modelling and integrating public-law restrictions on urban areas for future cadastral system of Turkey
Arif Cagdas Aydinoglu, Rabia Bovkir & Sahin Il

The importance of evaluating cities with historical, environmental and liveability parameters have become critical for effective urban management. Modern cadastre and land administration need to register Public-Law Restrictions (PLRs) to ensure the completeness of various transactions. To develop a comprehensive PLR data model for real estate management integrated with National GDI models, this study investigates the urban-related PLRs. An interoperable data model was designed within the Management-Restriction-Regulation Zones data model as an extension with relation to the Cadastre data model. In future cadastral applications, all property-related restrictions can be accessible as in case of the designed data model.

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2. Identifying critical factors to enhance SDI performance for facilitating disaster risk management in small island developing states
Gregorio Rosario Michel, María Ester Gonzalez-Campos, Fernando Manzano Aybar, Teodoro Jiménez Durán & Joep Crompvoets

Small Island Developing States (SIDS) are highly exposed to disaster risk events that frequently overwhelm their capacity to generate and share spatial information to reduce human–economic losses. The Spatial Data Infrastructure (SDI) has been widely implemented to support information sharing and management in different domains. In this paper, we aim to identify critical factors to enhance SDI performance to facilitate Disaster Risk Management (DRM) in SIDS. We make use of a three-round Delphi survey and Kendall W coefficient to assess consensus among 28 key international experts in SDI, surveying and DRM. Our results illustrate strong experts’ consensus on identifying a list of 23 most critical factors. We found that people and policy factors matter the most. The insights reported here would assist decision-makers to design roadmaps to enhance sharing of spatial knowledge to build more resilient SIDS and to support their achievement of the Sustainable Development Goals.

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3. Short-term satellite clock bias forecast based on complementary ensemble empirical mode decomposition and quadratic polynomial
Xiaorong Tan, Jiangning Xu, Hongyang He, Ding Chen, Yifeng Liang & Miao Wu

The nonlinear and nonstationary characteristics of satellite clock bias (SCB) have a harmful effect on the accuracy and stability of SCB forecast. To eliminate the influence of nonlinearity and non-stationarity, a hybrid forecast model was constructed that combines complementary ensemble empirical mode decomposition (CEEMD) and quadratic polynomial (QP), called CEEMD-QP. First, the SCB sequence is decomposed into several intrinsic mode function (IMF) components and one residual term by CEEMD. Second, permutation entropy (PE) and the correlation coefficient are used to quantitatively determine the IMF component with more noise and weak correlation with the original SCB signal. Finally, the SCB is reconstructed with the IMFs and residual components, and QP model is used to fit and forecast the clock bias. We adapt the observation part of ultra-rapid precise SCB data of GPS provided by IGS to forecast experiments. The results show that the CEEMD-QP method has obvious advantages of forecast accuracy and stability in short-term forecast.

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4. Assessing the extent of state regulation of surveying professions in Kenya
O. A. K’Akumu

This paper considers the regulation of three aspects of surveying profession namely, agency surveying, cadastral surveying, and valuation surveying in Kenya. The regulation boards are examined in the context of their enabling legislations. All the professions belong to one professional organisation, the Institution of Surveyors of Kenya (ISK), modelled in the like of self-regulation objectives of the Royal Institute of Chartered Surveyors (RICS). A review of the practice of professional regulations attempts to assess the level of state control in the regulation of these professions. Paper recommends injection of more self-regulatory culture in future.

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5. Developing a framework for assessing the efficacy of rural cadastral system in the Amhara region, Ethiopia
Adane Mehari Getie, Tadesse Amsalu Birhanu & Teshome Taffa Dadi

The fit-for-purpose rural cadastre has been implemented for several years in the Amhara region of Ethiopia. There are no internationally accepted methodologies to evaluate the efficacy of rural cadastral systems in developing countries. In this study, an evaluation framework was designed from the literature review and used to assess the quality of the rural cadastral system. A mixed research method was applied. Data were secured from the pertinent participants, and descriptive statistics was used to analyze the data. The findings indicated that the framework developed for the quality assessment was found to be an essential tool to evaluate the efficacy of rural cadastral systems. The study identified the strengths, weaknesses, opportunities, and threats of the cadastral systems of the Amhara region, which underpinned the understanding of the spatial, legal, and institutional arrangements and statuses. Further, this study identified sets of indicators and good practices of the system.

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6. A new algebraic solution for transforming Cartesian to geodetic coordinates
Jia-Chun Guo & Wen-Bin Shen

An exact and stable algebraic solution based on solving a quartic equation with respect to the cosine function of the reduced latitude is proposed to transform Cartesian into geodetic coordinates. The unique proper root of the equation appropriate to the transformation is chosen from all possible roots by rigorous analyses and the singular region of the transformation that in which there at least one component of the geodetic coordinates is indeterminate or non-single-valued characteristics are determined strictly. The new algorithm does not need any approximation and the instability problems incurred in other algebraic solutions are overcome. For practical applications, the algorithm performs comparably to that of [Vermeille, H., 2011. An analytical method to transform geocentric into geodetic coordinates. Journal of geodesy, 85 (2), 105–117.] and shows a certain superiority in the singular disc over Vermeille's algorithm.

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7. An experiment on the role of participatory GIS in the adjudication process of customary lands
Kwabena Asiama & Anthony Arko-Adjei

This study presents the results from an experiment conducted in two peri-urban areas of Northern Ghana using Participatory GIS (PGIS) to identify land tenure and use rights on customary and statutory lands. P-Mapping was used to uncover indigenous knowledge on the changes in land ownership, land use rights and land-use types over ten years. The paper finds that properly trained local people can reliably delineate and indicate land rights and land uses in their environment on photomaps with little support from professionals. The experiment results show that PGIS can accelerate land adjudication processes on customary lands.

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8. Performance analysis of BDS B1C/B2a PPP using different models and MGEX products
Mengfei Sun, Li Liu, Wei Yan, Jian Liu, Tong Liu & Guochang Xu

To assess the precise point positioning performance of the new BDS signals, the observation data of 56 MGEX stations for 30 consecutive days were used to carry out dual-frequency PPP experiments. The positioning results showed that the best positioning performance could be achieved with CODE precise products, followed by IAC, GFZ, and WHU products, with SHA products performing the worst. For Ionosphere-free and undifferenced and uncombined models, the performance of the two was comparable. In addition, our study indicated that station location and time were not the main factors affecting the performance of BDS-3 PPP.

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Survey Review 55, No 388. January/February 2023

1. The novelty hybrid model development proposal for mass appraisal of real estates in sustainable land management
Suleyman Sisman, Ali Utku Akar & Sukran Yalpir

In this study, a new methodology has been developed for a sustainable mass appraisal system. A mathematical model was created with the combination of the Cobb-Douglas and the linear regression model. With the Analytic Hierarchy Process (AHP) method, real estate value criteria were grouped and weighted in a hierarchical structure. The weights obtained with AHP were integrated into the coefficients regarding the criteria weights and densities in the Cobb-Douglas hybrid model. The new hybrid model was confirmed with the features and price equivalents of 435 parcels for sale from the market. Besides, the model analysis results were compared with the Multiple Regression Analysis (MRA) modelling using market prices. While creating the methodology, Geographic Information Systems (GIS) was used to organize the geographic and regional data of the region. After developing the new hybrid model, criteria groups that developed the model and relevant sub-criteria were evaluated using Pearson's correlation analysis.

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2. Filtering airborne LIDAR data by using fully convolutional networks
Abdullah Varlik & Firat Uray

The classification of LIDAR point clouds has always been a challenging task. Classification refers to label each point in different categories, such as ground, vegetation or building. The success of deep learning techniques in image processing tasks have encouraged researchers to use deep neural networks for classification of LIDAR point clouds. In this paper, we proposed a U-Net based architecture capable of classifying LIDAR data. The results indicated that our network model achieved an average F1 score of 91% over all three classes (ground, vegetation and building) for our best model.

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3. Comparison of different machine learning models for mass appraisal of real estate
Süleyman Sefa Bilgilioğlu & Hacı Murat Yılmaz

The present study aimed to compare five machine learning techniques, namely, artificial neural network (ANN), support vector machine (SVM), chi-square automatic interaction detection (CHAID), classification and regression tree (CART), and random forest (RF) for mass appraisal of real estate. Firstly, 1982 precedent data was collected throughout the entire study area for train and test models. Secondly, a total of 68 variables were considered for the mass appraisal. Subsequently, the five machine learning techniques were applied. Finally, the receiver operating characteristic (ROC) and various statistical methods were applied to compare five machine learning techniques.

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4. Performance investigation of Trimble RTX correction service with multi-GNSS constellation
Omer Faruk Atiz, Abbas Qader Shakor, Sermet Ogutcu & Salih Alcay

In the middle of 2011, Trimble introduced the RTX correction service to support RT-PPP applications. In this study, the performance of Trimble RTX correction service is investigated over a one-month period using five different GNSS constellations – namely, GPS-only, GPS + GLONASS, GPS + Galileo, GPS + GLONASS + Galileo, and GPS + GLONASS + Galileo + BeiDou. The results show that positioning accuracy and convergence time are significantly improved with the use of the multi-GNSS constellation compared with the GPS-only solution. The result of the converged positioning accuracy indicates that the GPS + GLONASS + Galileo + BeiDou combination improves the accuracy by 63%, 54%, and 60% for north, east, and up components, respectively, compared with the GPS-only solution. The mean convergence time is reduced by the GPS + GLONASS+ Galileo + BeiDou combination by 70%, 71%, and 38.6% compared with the GPS-only solution in the north, east, and up components, respectively. 1.2 (north), 1.5 (east), and 2.3 cm (up) root mean square errors (RMSEs) of converged positioning from the GPS + GLONASS + Galileo + BeiDou combination are computed.

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5. Comparative analysis of real-time precise point positioning method in terms of positioning and zenith tropospheric delay estimation
Omer Faruk Atiz, Salih Alcay, Sermet Ogutcu & Ilkay Bugdayci

The positioning performance of widely used real-time precise point positioning (RT-PPP) software packages BNC, RTKLIB, and PPP-WIZARD were tested in terms of convergence time and accuracy. The convergence time of PPP-WIZARD solutions is reduced by ambiguity resolution (AR). The GPS + GLONASS + GALILEO (GRE) mode improved the convergence time of GPS + GALILEO (GE) mode by 22.0%, 15.5%, 17.1%, and 11.4% for the BNC, RTKLIB, PPP-WIZARD (AR) and PPP-WIZARD, respectively. For the GRE mode, RMSEs of the BNC, RTKLIB, PPP-WIZARD (AR), and PPP-WIZARD software packages in the horizontal/vertical component are 3.8/5.6, 2.6/6.2, 3.3/6.5, 4.3/7.0 cm, respectively. In comparison with the IGS-ZTD (International GNSS Service ZTD), BNC, RTKLIB, PPP-WIZARD (AR), and PPP-WIZARD solutions show a mean bias of 0.28, −0.72, 2.80, and 2.83 cm, respectively in GE mode. The GRE mode reduced the RMSEs of the ZTD estimations of BNC, RTKLIB, PPP-WIZARD (AR) and PPP-WIZARD by 2.9%, 5.1%, 0.6%, and 0.4% respectively.

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6. Positioning performance of GNSS-PPP and PPP-AR methods for determining the vertical displacements
Burak Akpınar

This study investigates the accuracy of vertical displacements monitored by Global Navigation Satellite Systems (GNSS) precise point positioning (PPP) with float-ambiguity solution and with ambiguity resolution (PPP-AR). For this purpose, a simulation was designed. The static GNSS observations were collected at a test point during different observation times over seven periods involving vertical displacements produced with a precision of less than one mm. Each set of GNSS observations was processed with both GNSS-PPP and PPP-AR methods. The results revealed that RMS values of PPP-AR solutions are about twice better than RMS values of PPP solution for all observation times and all vertical displacement values.

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7. Investigating the latest contribution of BeiDou-3 FOC to GPS/GLONASS/Galileo PPP
Sermet Ogutcu, Yuksel Kama Erkavas, Abbas Qader Shakor & Haitham Talib Farhan

In this study, the latest contribution of the BeiDou-3 FOC satellites to GPS/GLONASS/Galileo/BDS-2 combined static and kinematic precise point positioning (PPP) is investigated over a one-month period in 2021 considering the three different cut-off angles (7°, 15°, and 30°). The results show that the contribution of BDS-3 to GPS/GLONASS/Galileo PPP is generally marginal for 7° and 15° cut-off angles. The largest BeiDou-3 contributions to static and kinematic positioning accuracy are found to be 9%, 6%, and 19% (for 3-h sessions with the 15° cut-off angle) and 9%, 15%, and 8% (with the 30° cut-off angle) for the north, east, and up components, respectively. The largest reductions in static and kinematic convergence time by adding BDS-3 to GPS/GLONASS/Galileo are found to be 13%, 10%, and 6% (for the 30° cut-off angle) and 17%, 7%, and 6% (for the 30° cut-off angle) for the north, east, and up components, respectively.

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8. Book Review: Land surveying in Ireland, 1690–1830 by Finnian Ó. Cionnaith, Dublin, Four Courts Press, 272 pp., €35.00/£30.00 ISBN 978-1-80151-014-1
Peter Collier

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