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Survey Review 51, No 365. March/April 2019

1. Human rights in tension: guiding cadastral systems development in customary land rights contexts
Simon Hull & Jennifer Whittal

Land reform in South Africa has failed to meet its objectives. The intended beneficiaries often do not have their land reform needs met. Failures may be attributed to multiple sources. We propose a conceptual framework to assist governments conducting land reform projects. It draws on aspects of human rights, good governance, and pro-poor policy. Existing frameworks are combined with these aspects to derive the conceptual framework. By using the framework, development projects in South Africa and similar contexts may become more Successful, Sustainable, and Significant. The paper holds interest for land tenure and cadastral systems researchers and developers.

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2. Geodetic network design and data processing for Hong Kong–Zhuhai–Macau link immersed tunnel
Shengxiang Huang, Guanqing Li, Xinpeng Wang & Wen Zhang

The immersed tunnel is composed of elements which are prefabricated elsewhere and floated to the tunnel site to be sunk into the prepared trench. Each element and the closure joint must line up exactly for the watertight gaskets to seal properly. For the construction of extra-long immersed tunnel, particular care should be taken in the perspective of geodetic control. Therefore, the design and implementation of the geodetic basis and hierarchical surface control networks are described. To decrease the influence of lateral refraction and to improve the configuration strength and increase the number of redundant observation compared with traverse, the design of underground surveying network named duo-linear joint chain is presented. The data-processing methodology, including outlier detection for excluding outliers from observation and variance component estimation for realistic precisions of observation, is described. Hong Kong–Zhuhai–Macau immersed tunnel surveying data are analysed and the performance of the geodetic networks and data processing methodology is demonstrated.

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3. Method for an automatic alignment of imagery and vector data applied to cadastral information in Poland
J. J. Ruiz-Lendínez, B. Maćkiewicz, P. Motek & T. Stryjakiewicz

Nowadays, an important problem in combining vector data and imagery is that they rarely align. This problem can become particularly acute in the case of cadastral systems. In this study, and as part of the partnership between the Universities of Jaén and Adam Mickiewicz (Poznań), we provide a methodological proposal to assess the conflation procedures between cadastral vector data and imagery, improving the alignment between both data sets. To do this, we use an automatic alignment algorithm which detects road intersections from both data sets as control points by using image texture characterisation. With this method, we first train the system on the imagery to learn the road texture distribution, then we can obtain its segmentation according to its texture, and finally the system locates road intersection points. The last step is to align vector data and imagery by using different techniques. This algorithm is based on an earlier one, detailed in [Ruiz, J.J., Rubio, T.J., and Ureña, M.A., 2011b. Automatic extraction of road intersections from images in conflation processes based on texture characterization. Survey review, 43 (321), 212–225.]. However, in the updated version we have solved the problem of not-well-defined intersection points, resulting in a substantial increase in the number of intersection points employed for the final adjustment to align both products and in a reduction of the computation time. On the other hand, the positional uncertainty assessment of parcel boundary lines both before and after applying our alignment procedure between them is provided. With regard to the experimental results, in the case of Polish cadastral data this procedure allows for significant improvement in the alignment between imagery and cadastral parcels boundaries.

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4. Domain model for cadastral systems with land use component
Đorđe Pržulj, Nataša Radaković, Dubravka Sladić, Aleksandra Radulović & Miro Govedarica

Well-structured and organised cadastral records and cadastral maps are a prerequisite for improving land administration services. In recent years, numerous problems and issues associated with cadastral data have been encountered in Serbia and attempts to overcome these problems have been made. The integration of land registry data with cadastral data containing land use component usually results in inconsistencies in land administration databases. To address this problem, an appropriate domain model has been developed using the Unified Process methodology and considering the land administration domain model and other ISO 19000 standards. Examples of verifying land administration data integrity in relational and object-oriented data models are presented.

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5. An alternative method for expropriation for lane-like projects in planned area: a case study from Trabzon in Turkey
V. Baser, B. Uzun & V. Yildirim

This study focuses on the Tanjant Road in Trabzon, in which public authorities expropriated a lot of parcels together with buildings then destroyed all of them and then finally finished the road. If Tanjant road was opened in accordance 3194/18th article, contribution rate was to be 39%. It is seen that contribution rate to be curtailed from the adjusted cadastral parcels has fallen to 18% on 337 cadastral parcels after the expropriation for Tanjant road. If LR was applied, the road field to be expropriated would be met via the area acquired from the LR, thanks to contribution rate. In both practices, it is aimed that keeping arrangement area wide; the benefits and problems Tanjant road and article 18 have brought are distributed to a wide area. It is seen that expropriation costs are met free of charge in inner-city route with LR.

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6. Data model design for qualified natural-protected area in Turkey
Merve Özlem Saralioğlu, Osman Demir, Yakup Emre Coruhlu & Ekrem Saralioğlu

Natural protected areas (NPAs) in Turkey are generally determined on standard topographic maps at a scale of 1/25 000, as opposed to cadastral border detection measurements. This situation generates a variety of problems with land management issues where the borders overlap an NPA region, as all NPA-related verbal and spatial data must be produced according to certain standards. Moreover, land management policies should be developed in relation to sustainable use and management of these areas. In line with this aim, the necessity for a protected area management system has emerged in which all spatial and verbal data are stored and can be used when needed. Before the creation of such a system, it is necessary to design a geographic information system (GIS)-based data model. This study examined the current situation of NPA site borders in a selected area using spatial data. It was revealed that the current system has no specific standards, the process is not being carried out systematically and the applied technical and legal criteria are not being properly followed. Therefore, the necessity has arisen for a data model design that contains all the necessary data in order to identify site boundary requirements. The data model design was generated using object-oriented Unified Modelling Language diagrams. Care was taken to ensure that the developed model was in compliance with the European Union-defined data standards (INSPIRE) and that it was implemented according to the environmental policy and standards set by the Land Administration Domain Model.

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7. On the errors-in-variables model with inequality constraints of dependent variables for geodetic transformation
W. Zeng, X. Fang, Y. Lin, X. Huang & Y. Yao

The Total least-squares (TLS) adjustment with inequality constraints has received increased attention in geodesy over the last three years. In the most recent work, inequality constraints have been presented that can restrict unknown parameters and independent variables, but no one has provided an inequality-constrained adjustment for restricting dependent variables. In this work, we review the TLS adjustment methods in terms of different model formulations and then investigate the errors-in-variables model with inequality constraints for dependent variables. Finally, we demonstrate the practicality of our approach with a planar geodetic transformation, where the uncertainty of the target observations is reduced via the inequality constraints for dependent variables.

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8. Analysis of ocean tide loading displacements by GPS kinematic precise point positioning: a case study at the China coastal site SHAO
H. Zhao, Q. Zhang, R. Tu & Z. Liu

Ocean tide loading (OTL) displacement amplitudes and phase lags of SHAO site are estimated by global positioning system (GPS), kinematic precise point positioning (PPP) and spectral analysis using 19 years of continuous GPS observations. In kinematic PPP, the 66 additional harmonic displacement parameters are replaced by the three time-varying displacement parameters without a priori modelled OTL displacements. By comparing the results with predictions from hybrid regional/global models, we are able to demonstrate that GPS/model agreements are at the level of 0.2 mm (horizontal) and 0.6 mm (vertical) for the four lunar constituents, 0.4 mm (horizontal) and 1.35 mm (vertical) for the four solar/sidereal constituents, and 0.2 mm (horizontal) and 0.3 mm (vertical) for the three long-period constituents. Finally, we conclude that GPS-derived lunar constituents can substitute for the model corrections in GPS data processing and the accuracy of GPS-derived solar/sidereal constituents needs to be improved by further studies.

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9. Impact of predicting real-time clock corrections during their outages on precise point positioning
Ahmed El-Mowafy

Real-time precise point positioning (RT-PPP) is a popular positioning method for natural hazard warning systems (NHWS) such as for monitoring tsunami and earthquakes. PPP relays on the use of precise orbits and clock corrections. Hence, the positioning accuracy of RT-PPP will significantly deteriorate when experiencing a discontinuity in receiving these corrections, for instance due to a temporary modem failure. The best available approach in this case would be to use the International Global Navigation Satellite Systems Service ultra-rapid (IGU) orbits and clocks that would result in a low positioning accuracy. In this paper, we present a simplified approach to a method that we recently proposed to bridge outages in the corrections and improve the RT-PPP accuracy compared with the use of IGU. In this method, the most recent IGU orbits are used as they are compatible with the RT orbits; however, the clock corrections are predicted as a time series using a linear model with four sinusoidal terms. The prediction errors resulting from this method, age of the model and its validity period are discussed. The impact of using the proposed approach is evaluated at a number of sites of known positions by comparing its performance to using IGU orbits and clocks. Moreover, the impact of using predicted corrections is assessed in different scenarios. The experimental results proved validity of the presented approach where positioning mean RMSE of less than 20 cm was maintained during the outage period.

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Survey Review 51, No 364. January/February 2019

1. Assessment of along-normal uncertainties for application to terrestrial laser scanning surveys of engineering structures
Tarvo Mill & Artu Ellmann

A method for estimating the range and spatial distribution of terrestrial laser scanning uncertainties occurring during the survey of engineering structures is presented and numerically verified. The emphasis is on the assessment of along-normal uncertainties of the surface to be surveyed. To investigate the behaviour of such uncertainties, various surveying scenarios are simulated and studied. Theoretical derivations are numerically verified, and these results are compared with those of previous empirical studies. The influence of along-normal noise on geometric modelling of surveyed surfaces is studied. In addition, suggestions are provided for how to optimising scanning locations, yielding the reduced ANU.

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2. Research into GNSS levelling using network RTK in Taiwan
Yi-Shan Li & Fang-Shii Ning

Modern height surveying obtains orthometric heights through geoid undulations and ellipsoidal heights derived from global navigation satellite system (GNSS), a process referred to as ‘GNSS levelling’. In this study, an efficient survey technology, the e-global navigation satellite system (e-GNSS), was used instead of static satellite surveying to execute GNSS levelling. The e-GNSS in Taiwan is based on Virtual Reference Station-Real-Time Kinematic technology and networks. The orthometric heights were calculated by subtracting the geoid undulations, derived from three geoid models (gravimetric, hybrid, and geometric models), from the ellipsoidal heights, derived from the e-GNSS. Additionally, two corrector methods, namely the difference and the corrector surface method, were adopted to improve the accuracies and the systematic errors. The experiment showed that the two corrector methods improved the accuracies of the orthometric heights in the gravimetric model by approximately 66.3 and 80.0% and mitigated the systematic errors in the gravity model by approximately 96.2 and 99.9%.

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3. On constrained integrated total Kalman filter for integrated direct geo-referencing
Vahid Mahboub, Mohammad Saadatseresht & Alireza A. Ardalan

A constrained integrated total Kalman filter algorithm is developed. It considers a quadratic constraint which may appear in some problems of integrated direct geo-referencing in particular when INS data is used as system equations of a Kalman filter algorithm. In such a case one encounters with a dynamic errors-in-variables (DEIV) model for system equations, although DEIV model has been already considered for equations of the Kalman filter algorithm and a solution namely integrated total Kalman filter (ITKF) has been given to it. Also this algorithm can be simplified to unconstraint case which is useful for some problems. It considers DEIV model for both observation equations and system equations of the Kalman filter algorithm. The predicted residuals for all variables including the random noise at the first epoch, the observational noise, the random system noise and the corresponding noise of two coefficient matrixes (in the system equations and the observation equations) besides the variance matrix of the unknown parameters are obtained. In two numerical examples, integrated direct geo-referencing problem is solved for a GPS-INS system.

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4. Optimisation of GNSS networks – considering baseline correlations
M. Amin Alizadeh-Khameneh, Lars E. Sjöberg & Anna B. O. Jensen

By considering global navigation satellite system (GNSS) observations, one can perform optimisation according to some pre-defined criteria and come up with the best location of receivers and optimum number of baselines. In practice, it is quite common to neglect the effect of correlations between baselines, and instead assume single-baseline-adjusted data in the optimisation procedure. However, in each session of observation, usually more than two receivers are simultaneously taking data from a number of common GNSS satellites, implying that the single- or double-difference observations are correlated. Our study designs an optimal observation plan for a GPS network in Skåne in southern Sweden, with the aim of determining possible displacements. Assuming three receivers in each session of observations leads to correlation between the GPS baselines, and consequently a fully populated weight matrix for each session of observation. A bi-objective optimisation model of precision and reliability is chosen to optimise the variance factor of each session, and eventually, design an observation plan. It is shown in this study that observing six out of ten possible sessions is sufficient to enable the network to detect a 5 mm displacement at each station. Assuming that the double-difference phase observations are uncorrelated changes the observation plan by retaining two more sessions. However, defining the weight matrix based on the double-difference observations requires the correlations to be taken into account, and neglecting them leads to incorrect results.

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5. Analysis of GPS satellite clock prediction performance with different update intervals and application to real-time PPP
H. Yang, C. Xu & Y. Gao

The GPS satellite clock offset prediction is investigated and applied to a real-time PPP system. First, the current situation of GPS satellite clock is introduced and analysed with respect to their stability. Then the satellite clock prediction with different update intervals is presented, in which the satellite clock day boundary jump is addressed. Afterwards, the investigation of the satellite clock prediction model for GPS satellite IIF clocks is carried out and the effects of periodic terms are discussed. After that, the verification of the satellite clock offset prediction will be carried out both in the time and positioning domain. Positioning accuracy at 0.021, 0.049, and 0.017 m in the east, north, and vertical directions can be obtained for 6-h static positioning using the predicted clock offset updating every hour, while the 3D RMS for kinematic real-time PPP is 0.360 m, with 28% improvement over that utilising the IGU predicted products.

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6. Non-contact detection algorithm and realisation of displacement of suspended cylinder
D. Xiao, L. Tan, Y. Su, B. Yu & Y. Yang

Large structures such as TV towers and suspension bridges often contain cylindrical components; the displacements of these suspended cylinders due to external agents are often of interest to ensure the integrity of the structure. This paper establishes an algorithm of the displacement monitoring for the suspended cylinder by non-contact surveying, which offers two main advantages over traditional contact-based methods. First, it does not require prisms to be physically mounted on the measuring target and second, the target consists of any three points on the same circle along the structure, which can be easily implemented. The algorithm is successfully applied in determining the displacement of suspended cylinder in high-rise structures such as a TV tower.

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7. Robust M-estimation using the equivalent weights constructed by removing the influence of an outlier on the residuals
H. Yu, Y. Shen, L. Yang & Y. Nie

The key issue in robust M-estimation is to construct the equivalent weights using the residuals of observations for down-weighting the outlying observations. However, the residuals of good observations are also possibly impacted by neighbouring outliers, thus directly down-weighting an observation according to its residual is not theoretically rigorous. Therefore, this paper focuses on the construction of equivalent weights for down-weighting the outlying and doubtful observations by removing the influence of the outlier on the correlated residuals. A down-weighting strategy using the corrected residuals to form the down-weighting factors is proposed. A simulated experiment and a practical experiment are respectively conducted to demonstrate the performances of the proposed down-weighting strategy compared to the direct down-weighting strategy (DDS) and recursive down-weighting strategy (RDS). The results show that the estimated performance of the proposed down-weighting strategy is comparable to that of RDS and the computation efficiency is obviously higher than that of RDS.

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8. DInSAR technique for slow-moving landslide monitoring based on slope units
Jiaxuan Huang, Mowen Xie, Asim Farooq & Edward J. Williams

Slow-moving landslides are one of the most widely distributed natural hazards in the world, with severe effects on the stability of structures. However, it is hard to be detected without monitoring method. In this paper, the Differential Interferometric Aperture Radar (DInSAR) technique is used to monitor the slow-moving landslides. But, the standardised procedures for the DInSAR technique are difficult to find the boundaries of landslides. The new segmentation method of slope units with the Digital Elevation Model is proposed. Moreover, the credible zone analysis is established based on slope units to filter the error value and improve the precision of monitoring results. Finally, according to the features of slow-moving landslides, the outcomes of DInSAR technique for slow-moving landslides inventory map are available. The methodology is tested at Wudongde valley area in the North-west China, where the SAR data and natural hazards inventory maps are available. The correctness of monitoring results will be verified.

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9. Calibration method of rotation and displacement systematic errors for ship-borne mobile surveying systems
Xiushan Lu, Chengkai Feng, Yue Ma, Fanlin Yang, Bo Shi & Dianpeng Su

Rotation and displacement errors between sensors and the Inertial Navigation System have significant effects on the accuracy of measured point clouds. In ship-borne mobile surveying systems, over and underwater targets are measured by a laser scanner and multibeam echo sounder, respectively. A simple calibration method and a universal calibration field are urgently needed to address both rotation errors and displacement problems for over and underwater sensors. First, a systematic error analytic function is established through the path that the geolocation expression of measured data is derived and substituted into the expression of known calibration planes. Then, the calibration expression that can calibrate both rotation errors and displacement is derived based on the least-squares criteria using a designed calibration pool. The calibrating results showed that for both over and underwater sensors, the accuracies of rotation errors and displacement estimation are better than 0.015° and 1.2 mm, respectively. After this calibration, the geolocation accuracy of measured points is better than 5 cm within a range of 30 m. The method can effectively calibrate systematic errors and serve as guidance to address the calibration problem for mobile surveying systems.

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10. Considerations on the land management system approach in Turkey by the experiences of a case study
Oktay Aksu & Muzaffer Can Iban

In Turkey, applications and activities for the use, acquisition and arrangements of land tenure rights are executed under the authorisation and responsibilities of a variety of public institutions in terms of concerned legislative framework. In this paper, a case study has been implemented for Istanbul not only to evaluate the quality and usability of existing data from different institutions but also to get conclusions and recommendations for future land management works. In the context of this sample work of preparing an inventory for land management and land use in 1:25 000 scale and related synthesis and pre-feasibility analyses; the inventory praxis for urban and rural areas have been undertaken separately. Layer overlay and synthesis of the data in the database are the essential parts of analysing and extracting the outputs supporting land management activities for the purpose of taking correct decisions. In that manner, an overview map of Istanbul's natural and settlement areas has been extracted.

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