Browsing by Subject "Geomatics"

Now showing 1 - 20 of 25
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    3D property objects in South African local government: the necessity of representing and managing the third dimension in the City of Cape Town property management system
    (2021) Humby, Lara; Whittal, Jennifer; Simon Hull
    The objective of this research was to analyse whether there is a need for a form of 3D Land Administration System (LAS)in South Africa (SA) based on the land administration functions of land tenure, land use, land development and land value. The investigation can be divided into two key focus areas that align with subsystems of the LAS: (i) the Land Tenure System (LTS) that is responsible for land tenure; and (ii) the Property Management System (PMS) that is responsible for land use, development and value. These two key areas fall within the SA LAS and make use of the cadastre as a foundation. Humby (2014) focussed on the first subsystem and found that there may be a significant need within the LTS for a 3D cadastral record or a 3D legal property object (LPO). The second subsystem is the focus of this study. To analyse the need for 3D in the PMS, the City of Cape Town (CCT) was adopted as a single case study, and modelled using systems thinking tools. The model focussed on the definition, use and management of property information, or the conceptual 3D property management object (PMO), to fulfil the land administration functions of land use, development and value within the CCT PMS. Established land administration theory, including the Land Management Paradigm, the good governance principles and RRR requirements, was used as a foundation against which the CCT PMS was analysed. This allowed for an increased understanding of the current CCT PMS's ability to achieve its land administration goals, policies and sustainable development. Following this, the current use of 3D within the CCT PMS was presented and analysed, along with the potential resulting benefits, uses and challenges of introducing 3D into that system. Semi-structured in-depth interviews, documentation evidence and participant and direct observations were employed in this section of the research. Furthermore, international land administration and 3D experiences, as presented in the literature review, were incorporated in this analysis. This study concludes that introducing a third dimension into the CCT PMS would have its challenges, but the uses and benefits that have been seen globally and that are recognised within the CCT, may outweigh those challenges. The research illustrates how a 3D Property Management Object would clarify the records and aid the land administration functions. Preferably, 3D would be introduced into the cadastre and LTS initially, and the PMS could then adopt that real RRRs LPO record as a foundation for the PMO records. However, the LTS has fallen behind in technology and it appears the CCT PMS will have to take the lead in introducing 3D into the SA LAS. It is recommended that a full cost-benefit analysis is conducted prior to any further research or development within the CCT.
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    A way to use GIS (incl. geomasking) to understand homelessness: a focus on the spatial characteristics of and around sleeping locations of the homeless in Cape Town City Bowl
    (2020) Kekana, Dime; Smit, Julian
    Background: The homeless individuals/groups are the most vulnerable and less dignified member of the society. The evidences lie in the nature of their sleeping locations in the urban spaces, amongst other aspects. An internationally unique and integrated approach (GIS/socio-spatial) is utilized to enhance the knowledge and understanding of homelessness through analyzing the spatial characteristics of and around the sleeping locations of the homeless community in the urban public spaces, Cape Town City Bowl (South Africa) case study. Data Source and Method: Through the quantitative approach, the individual sleeping locations of The Homeless, including their surrounding characteristics, are observed daily for two weeks, 13-26 Oct. 2018 (total of all locations: n = 9515, daily average, n = 680) between 06:00 am and 08:30am. The analyses entail sequential application of eight analytical methods; spatial distribution, attribute analysis, proximity analysis, weather analysis, and obfuscation/geographic masking Results: (a) The daily individual sleeping locations of the homeless individuals and groups increase over time but their geographic distributions are similar or display insignificant/little variations. (b) Majority of these locations are situated in marginalized urban spaces that deny The Homeless personal privacy/security, human dignity and perpetuate stigmatization and social isolation. (c) The sleeping locations of The Homeless are far from the sources of basic needs to enhance their livelihoods (e.g., water resources). (d) Although more data is needed, however, the limited data in this research show that weather conditions are (in)directly related to the changes in the numbers of sleeping locations. (d) The voronoi masking and weight rand perturbation are best presenting the sleeping location of The Homeless without compromising the spatial confidence of The Homeless, and the spatial distributions/patterns of these locations. Conclusion: GIS (geographic information system) is capable of enhancing the knowledge and understanding of homelessness, and therefore, it can inform establishments and improvements of initiatives/measures that seek to reduce the vulnerability of the homeless community and/or integrate them with the public community, especial in the urban spaces.
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    A web of relations: co-production arrangements in urban sanitation infrastructure provision in informal settlements in Arusha City, Tanzania
    (2019) Abwe, Furaha; Odendaal, Nancy
    Many city governments and actors have tested approaches or models and technological developments to address urban service crises. But this has tended to be without much success, as the service delivery gap keeps widening, leading to governance failure. One response to this decline in governance capacity has been the evolution of co-production arrangements. The overarching aim of this thesis was to examine the co-production arrangements of urban sanitation infrastructure provision among multiple actors in informal settlements, and to interrogate whether the predominance of such arrangements was indicative of an alternative form of city governance. Two wards within Arusha city (Tanzania) were selected as case studies. A range of research methods was employed to uncover the landscape of actors involved, and to explore co-productive processes, socio-cultural aspects and other complexities shaping sanitation provision in the two selected informal settlements. Case study methodology was used with a range of data collection methods (household surveys, focus group discussions, document review and semi-structured interviews). The study adopted a relational approach informed by ActorNetwork Theory as the analytical framework for understanding the human-material interactions in the sanitation chain. Key findings indicate that co-production serves a public function, but it is not recognised as such in Tanzanian public policy. Individual and collective co-production arrangements have been established that bring together various state and non-state actors in the sanitation chain to form networks. These networks make service delivery possible, which one actor alone could not deliver. The study reveals that sanitation infrastructure in informal settlements is largely provided by the household, although some are either inactive or captured co-procuders. Further, the narratives indicate that complexities and the contextual factors (including gender-based power dynamics, social norms, values, traditions and culture) shape access to sanitation facilities in the city of Arusha. The study found that the exclusion of women and children from sharing toilet facilities motivated Maasai men to practice defection in open areas. Further, this study speculates on an alternative form of governing city affairs based on actor-networks in the co-production process: co-productive networked governance. Future research is needed to examine how co-productive networked governance could be integrated into the existing city governance structures and how informal governance arrangement could be recognised and enhanced.
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    Application of information systems in irregular settlement management and low-cost housing provision
    (1998) Crone, Simon Michael; Mason, Scott
    Information Systems, both paper-based and computer-based, are integral in the management of irregular settlements and the process of delivering low-cost housing in South Africa. An Irregular Settlement can be defined as an area where the 'shacks' have no fixed street address. Due to policies by previous regimes, under whose rule irregular settlements were almost ignored, there is often little or no spatial or socio-economic data available about existing irregular settlements. Thus for the use of the community, or to organisations interested in helping to improve the quality of life of the residents living in these settlements. As a prerequisite to quality of life, the basic need of shelter, along with food, healthcare and education need to be made available. The emphasis today is thus being placed on the provision of low-cost housing. A need thus arises to have up-to-date information about these irregular settlements in order to plan either for the upgrading of the settlement or for the relocation to new low-cost housing developments. Currently mostly paper-based systems are being used in these developments. There are two opportunities where computer-oriented information systems could be used at this time in 1996 and 1997 to assist with the management and upgrading of irregular settlements. The first is the stage of managing an existing irregular settlement; the second is managing the process of housing provision, taking advantage of the project-linked subsidy scheme. Two Cape Town based projects provide case studies for the application of information systems at the two stages identified above. The first is the Marconi Beam 'From Shacks to Houses' project located in Milnerton. The second is the Integrated Services Land Project (iSLP) of the Cape Flats. The Marconi Beam Settlement is an irregular settlement that has been accepted as part of the 'Project-Linked Subsidy Scheme' for the provision of new low-cost housing. Previously only paper-based systems were being used to manage the settlement and its move to the new Joe Slovo Park formal housing development. There was also found to be a lack of appropriate tools and awareness of which technology could be used in the process. Some of the specific application areas in which we were able to provide solutions in Marconi Beam included: ■ the identification of people directly affected by the fire that swept through the settlement in October 1996; ■ the residents who would be affected by the construction of a new road through the one area of the settlement could be identified, facilitating their movement away from the area; and ■ a system of tracking the internal moves of residents was devised by which we were able to maintain a record of the internal movements of residents whilst the system of the lottery was in place. Subsequently, with the use of the Block System, the identification of residents who were required to come in and have their applications for new houses processed, as a result of their spatial location in the settlement, was accomplished. The Indlu Management System, a computer based system, resulted from the need to keep track of, and process, large amounts of socio-economic data in order to speedily process the large number of applicants applying for national housing subsidies. As a result of the implementation of this system, the processing times per applicant have been reduced from 30 minutes to 10 minutes per applicant. The successful use of these systems in the two projects demonstrate that there is thus a definite role to be played in the use of information systems in relation to the management of irregular settlements and the provision of low-cost housing.
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    Bridging local and external knowledge for disaster risk management planning: The perceived benefit of participatory 3D modelling in Umgungundlovu District Municipality, South Africa
    (2024) Wielenga, Rutger; Hull, Simon
    There are natural hazards affecting communities all over the world. These events also take place in South Africa. South African disaster management legislation emphasises the indigenous knowledge of people who are most affected when hazards turn into disaster. Participatory GIS in the form of activities building and using three-dimensional models (P3DM) has been used internationally to enhance community engagement and to ensure better information exchange between people who live in the area and the disaster officials and consultants who currently inform decisions. P3DM was introduced in uMgungundlovu District Municipality through a progressive case study methodology with workshops in four locations introduced by municipal officials. This research focused on the officials' perceived value of using P3DM activities to enhance their standard disaster risk management practices. Lightning, fires, earthquakes and strong winds are all natural hazards experienced by people living in communities. Over a period of several generations, these people have developed knowledge local to their area that is relevant in planning to reduce the risk of disasters in their area. The disaster risk management legislation governing this planning requires the sharing of local knowledge. The implementation of the legislation and the sharing of local knowledge are challenging. Participatory three-dimensional modelling (P3DM) has been used in the Global South as a novel method to promote knowledge sharing in this context. Although this method is commonly used elsewhere in the Global South, it has not yet been used or introduced in South Africa. Through a progressive case study in four locations in uMgungundlovu District Municipality, P3DM was introduced to stakeholders in disaster planning. There was an opportunity to analyse and assess the perceived value of P3DM to stakeholders at each location. Observational case study methods including semi-structured interviews allowed data collection and analysis to assess the perceived value of P3DM. P3DM was found to add value to stakeholders already familiar with incorporating local knowledge in disaster planning. Officials and community members attending workshops where P3DM activities were introduced recognized that building models and adding LIK to the models facilitates knowledge sharing.
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    A comparison of the least squares collocation and the fast Fourier transform methods for gravimetric geoid determination
    (2016) Mphuthi, Siphiwe M Matthews; Govind, Ramesh
    The objective of the research was to study the performance of the least squares collocation (LSC) and the fast Fourier transform (FFT) techniques for gravimetric geoid computation. The Land Levelling Datum (LLD) is the South African vertical datum based on more than 100 years old tide gauge measurements of mean sea level (MSL). The LLD is poorly defined so an alternative is required. The SAGEOID10 (Merry, 2009) hybrid geoid model was computed for the purpose of replacing the existing vertical datum. Two gravimetric geoid models were computed using different techniques for evaluation of the Stokes' integral, such as, LSC and one dimensional fast Fourier transform (1D-FFT) technique. The long wavelength component of the geoid models were computed using the EGM2008 geopotential model truncated at degree 720. The use of fast spectral techniques is required due to an increase of both quality and type of data available for geoid determination. The FFT method is most reliable than the LSC method, since it requires less computational time on large data set than the LSC. A system of linear equations of order equal to the number of data points is generated on the LSC method. The geoid model was computed over the province of Gauteng. It was then compared to the SAGEOID10 hybrid geoid model. The computed geoid models, SiPLSC and SiPFFT geoid model compared to the SAGEOID10 model with standard deviation of 5.6cm. The long wavelength component of the computed geoid model compared to the EGM2008 geopotential geoid model with a standard deviation of 4.2cm.
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    Design of a communal land tenure information system for Namibia
    (1999) Danso, Antwi Adjei; Barry, Michael B
    This thesis describes some of the communal land tenure systems pertaining to Namibia. Understandably, lands held under communal land tenure have tended to be neither fully documented nor legally and explicitly formalised; communal land tenure systems have been through the mercy of arbitrary action by the state, private individuals or other institutions (S.A Government, 1996: 43). The study attempts to examine the issues involved in the design of a communal land tenure information system for Namibia. It therefore seeks to examine the possibility of using information technology to plan and manage customarily held land, the requirement for an effective design and implementation of such a system and the method of designing such an information system to make room for continual improvement and the addition of finer detail. The research begins with an in-depth literature review of the communal land tenure systems in Namibia and a description of similar information systems. This is followed by the research methodology, which describes the technique used for collecting, analysing and presenting the results of the study. The needs analysis and the data structure contained in the atlas are outlined. The fundamental concepts of database design and the various steps taken by the author to design and construct the land tenure database model for the dissertation are also discussed. The pilot project is analysed, taking into account the capability of the system, its success in terms of a needs analysis, and the adequacy of the data. It specifically analyses the design in the light of social relationships, person or group interests and the spatial component of communal land tenure systems with respect to each area. In addition, it seeks to answer the question whether the tool fits the communal land tenure system, discusses the strengths and weaknesses of the overall system design and the implementation strategies. It is envisaged that, with the provision of the information system in union with its database, this will help to identify and document a communal land tenure system. For the rural dweller or farmer, this system will provide a pictorial image of what is really happening on the ground. The information system could later be upgraded and fully implemented, enabling individuals to effectively plan activities around the existing circumstances and conditions. The recommendation that came out from the study was that given the limited information available on communal land tenure systems, more effort should be spent to study and gather data on the system. It is strongly recommended, therefore, that research into conditions in the communal areas be regarded as a top pri01ity by the Government of Namibia. This could lead to a richer information base in the communal areas to be utilised to improve the lifestyle of the rural communities. Thus, the prototype project designed in this thesis should be implemented fully and later developed and incorporated into an information system which, in the past, has lacked communal land tenure input. The research could not touch on all the communal land tenure areas in Namibia. It is therefore advised that the rest should be investigated in more detail. The inheritance and conflict resolution mechanism which were not modelled effectively should also be reinvestigated.
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    Developing an accurate close-range photogrammetric technique for extracting 3D information from spherical panoramic images
    (2017) Tagoe, Naa Dedei; Rüther, Heinz; Smit, Julian
    Panoramic images (panoramas) are wide-angle images that provide fields of view of up to 360°. They are acquired with a specialised panoramic camera or by stitching a series of images captured with a conventional digital camera. Panoramas have widely been used to texture 3D models generated from laser scanning, for creating virtual reality tour applications, documenting landscape and cultural heritage sites, advertising real estates and recording crime scenes. The goal of this research was to develop an accurate close-range photogrammetric technique for the semi-automatic extraction of 3D information from spherical panoramas. This was achieved by developing a non-parametric method for the removal of distortions from images acquired from fisheye lenses as well as an algorithm, here referred to as the Minimum Ray Distance (MRD), for the fully automated approximate relative orientation of spherical panoramic images. The bundle adjustment algorithm was then applied to refine the orientation parameters of the panoramas; thus enabling accurate 3D point measurement. Finally, epipolar geometry theory was applied to the oriented panoramas to guide the interactive extraction of additional conjugate points. The MRD algorithm has been extended to laser scanning technology for the first approximations of laser scan setup positions and scan orientation prior to a leastsquares based registration. The determination of approximate scanner orientation and position parameters were accomplished using panoramic intensity images derived from full dome laser scans. Thus, a technique for the semi-automatic extraction of 3D measurements from panoramic images has been developed in this research. The technique is most appropriate for applications which do not require dense point clouds and in situations with limited access to funds or as a quick field method to document many features in a short time. This is because a single image orientation is required for several overlapping images as compared to the normal stereo or multi-image photogrammetric approach. It is not suggested that 3D reconstruction from spherical panoramic images should replace traditional close-range photogrammetry or laser scanning; rather, that the user of panoramic images will be offered supplementary information to the conventional and modern cultural heritage documentation approaches.
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    Development of a land use-based spatial water requirements model for the Berg Water Management Area
    (2017) Van Der Walt, Marthinus; Smit, Julian
    This study was conducted to investigate the requirements for the spatial modelling of current and future water demand in the Berg River Water Management Area in the Western Cape of South Africa in order to produce a prototype model from which annual water requirements could be computed and spatially visualised. To accomplish this the spatial distribution of water demand within the study area was first investigated. The data required to perform spatial water demand modelling of diverse land uses and socio-economic activities were evaluated. Finally, the question of improving spatial water demand modelling at the catchment scale was considered from both a systems design and a technical perspective. The resulting model consists of two main modules; one performing a rudimentary monthly soil water balance to obtain monthly and annual irrigation requirements, and another applying preconfigured determinant layers derived from land use to town zone layers in order to determine annual urban water use intensities per areal unit. The resulting model prototype follows a sequential workflow based on a series of components that combine to produce a spatial overview of water use intensity within the study area. Water demand was found to be predominantly irrigated agriculture in the upper reaches of the Berg (mainly wine grape) and was found to be dominated by intensive industrial users in the central and lower reaches. The model was designed so that new data could be introduced in order to expand the system where required, as well as allowing for updated datasets to be incorporated as they become available. Due to the uncertainties inherent in the modelling and approximation of real world phenomena, the importance of establishing a set of structured, stable, predefined user requirements and system specifications were noted as a fundamental requirement for improving model development and design efficiency and ensuring model validity. It was further found that incorporating additional datasets, covering parameters related to the system, may serve to improve model accuracy, but could easily lead to compounded errors if not correctly parameterised or adequately validated.
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    Elements of design for indoor visualisation
    (2016) Gangraker, Muhammad Zaid; Sithole, George
    Indoor visualisation has received little attention. Research related to indoor environments have primarily focussed on the data structuring, localisation and navigation components (Zlatanova et al., 2013). Visualisation is an integral component in addressing the diverse array of indoor environments. In simple words, 'What is the most efficient way to visualise the surrounding indoor environment so that the user can concisely understand their surroundings as well as facilitating the process of navigation?' This dissertation proposes a holistic approach that consists of two components. The significance of this approach is that it provides a robust and adaptable method in providing a standard to which indoor visualisation can be referenced against. The first component is a theoretical framework focussing on indoor visualisation and it comprises of principles from several disciplines such as geovisualisation, human-perception theory, spatial cognition, dynamic and 3D environments as well as accommodating emotional processes resulting from human-computer interaction. The second component is based on the theoretical framework and adopts a practical approach towards indoor visualisation. It consists of a set of design properties that can be used for the design of effective indoor visualisations. The framework is referred to as the "Elements of Design" framework. Both these components aim to provide a set of principles and guidelines that can be used as best practices for the design of indoor visualisations. In order to practically demonstrate the holistic indoor visualisation approach, multiple indoor visualisation renderings were developed. The visualisation renderings were represented in a three-dimensional virtual environment from a first-person perspective. Each rendering used the design framework differently. Also, each rendering was graded using a parallel chart that compares how the different visual elements were used per the rendering. The main findings were that the techniques/ renderings that used the visual elements effectively (enhanced human-perception) resulted in better acquisition and construction of knowledge about the surrounding indoor environment.
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    An empirical assessment of real-time progressive stereo reconstruction
    (2016) Westaway, Matthew; Sithole, George
    3D reconstruction from images, the problem of reconstructing depth from images, is one of the most well-studied problems within computer vision. In part because it is academically interesting, but also because of the significant growth in the use of 3D models. This growth can be attributed to the development of augmented reality, 3D printing and indoor mapping. Progressive stereo reconstruction is the sequential application of stereo reconstructions to reconstruct a scene. To achieve a reliable progressive stereo reconstruction a combination of best practice algorithms needs to be used. The purpose of this research is to determine the combinat ion of best practice algorithms that lead to the most accurate and efficient progressive stereo reconstruction i.e the best practice combination. In order to obtain a similarity reconstruction the in t rinsic parameters of the camera need to be known. If they are not known they are determined by capturing ten images of a checkerboard with a known calibration pattern from different angles and using the moving plane algori thm. Thereafter in order to perform a near real-time reconstruction frames are acquired and reconstructed simultaneously. For the first pair of frames keypoints are detected and matched using a best practice keypoint detection and matching algorithm. The motion of the camera between the frames is then determined by decomposing the essential matrix which is determined from the fundamental matrix, which is determined using a best practice ego-motion estimation algorithm. Finally the keypoints are reconstructed using a best practice reconstruction algorithm. For sequential frames each frame is paired with t he previous frame and keypoints are therefore only detected in the sequential frame. They are detected , matched and reconstructed in the same fashion as the first pair of frames, however to ensure that the reconstructed points are in the same scale as the points reconstructed from the first pair of frames the motion of the camera between t he frames is estimated from 3D-2D correspondences using a best practice algorithm. If the purpose of progressive reconstruction is for visualization the best practice combination algorithm for keypoint detection was found to be Speeded Up Robust Features (SURF) as it results in more reconstructed points than Scale-Invariant Feature Transform (SIFT). SIFT is however more computationally efficient and thus better suited if the number of reconstructed points does not matter, for example if the purpose of progressive reconstruction is for camera tracking. For all purposes the best practice combination algorithm for matching was found to be optical flow as it is the most efficient and for ego-motion estimation the best practice combination algorithm was found to be the 5-point algorithm as it is robust to points located on planes. This research is significant as the effects of the key steps of progressive reconstruction and the choices made at each step on the accuracy and efficiency of the reconstruction as a whole have never been studied. As a result progressive stereo reconstruction can now be performed in near real-time on a mobile device without compromising the accuracy of reconstruction.
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    Enhancement of digital elevation models using tree-based ensemble machine learning algorithms
    (2023) Okolie, Chukwuma; Whittal, Jennifer; Smit, Julian
    Geospatial practitioners and national mapping agencies (NMAs) in Africa are constrained to rely on open-access remote sensing datasets, even as they struggle to meet up with best practices on spatial data infrastructure and topographic map revision. Thus, global digital elevation models (DEMs) have gained worldwide prominence due to their free availability; a prime advantage when compared to prohibitively expensive airborne topographic surveys. However, the accuracies of global DEMs are affected by several anomalies that diminish their quality and compromise their adequacy for applications where precise and accurate terrain information is needed. This research proposes an explainable tree-based ensemble feature-level fusion framework for enhancing satellite DEMs using Cape Town, South Africa as a case study. The enhancement methodology combines elevation and terrain features data alignment (co-registration and resampling) with feature-level fusion (ensemble learning) into a DEM enhancement framework. The training datasets are comprised of eleven predictor variables including elevation, slope, aspect, surface roughness, topographic position index, terrain ruggedness index, terrain surface texture, vector ruggedness measure, percentage bare ground, urban footprints and percentage forest cover as an indicator of the overland forest distribution. The target variable (elevation error) was derived with respect to highly accurate airborne LiDAR. Initially, the qualities of two satellite-derived interferometric DEMs (NASADEM and Copernicus) and two photogrammetric DEMs (ASTER and AW3D) were comparatively examined in a series of qualitative and quantitative tests in five different landscapes spread across Cape Town: urban/industrial, agricultural, mountain, peninsula and grassland/shrubland. Based on their performances, Copernicus and AW3D DEMs were selected for further analysis. The next phase involved a comparative evaluation of ten treebased ensembles for enhancement of Copernicus DEM over agricultural lands. At two implementation sites, there was a 6 – 13% reduction in the MAE and 15 – 29% reduction in the RMSE, and the corrected Copernicus DEM showed several topographic improvements such as smoothing of rough edges, enhanced stream channel conditioning and diminution of coarse/grainy pixels. Following the comparison, three recent implementations of gradient boosting, the extreme gradient boosting (XGBoost), light boosting machine (LightGBM) and categorical boosting (CatBoost) were selected for the development of a robust DEM enhancement framework. After training and testing, the models were applied for correcting the DEMs at two implementation sites spread across the five landscapes. Going further, a rigorous hyperparameter tuning strategy was implemented for the three models using a principled, robust and computationally efficient Bayesian optimisation scheme. The optimisations were operationalised with ten steps of random exploration for diversification of the exploration space, and 40 - 50 iterations to increase the likelihood of finding an optimal combination of hyperparameter values. The uniqueness of the optimisation scheme is the very wide diversification of the search space for random exploration. The performance of the models was compared based on default hyperparameters versus Bayesianoptimised hyperparameters. The result is a sequential correction and fusion scheme to increase the vertical accuracy and reduce errors in the final DEMs. The corrections achieved significant and highly competitive accuracy gains of up to 64% RMSE (68% MAE) reduction in Copernicus DEM and up to 78% RMSE (82% MAE) reduction in AW3D DEM. The robustness of the proposed framework was proven in several performance evaluations and comparative assessments. Summarily, it outperformed a globally acclaimed corrected DEM and the authoritative South Africa national DEM, and surpassed the achievable accuracies of several previously proposed strategies, including multiple linear regression. Moreover, three-dimensional terrain analysis and lineament mapping showed the potential of the proposed scheme for enhancing deliverables in topographic and geologic mapping. The proposed approach also incorporates explainability measures to describe the interactions between predictor variables and their influence on the predicted DEM errors. It provides a cost-effective framework and ‘minimal' computation expense. The innovative DEM enhancement scheme proposed in this research is applicable to other global landscapes.
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    Environmental information systems : the development and implementation of the Lake Rukwa Basin integrated project environmental information system (LRBIP-EIS) database, Tanzania
    (2003) Paradzavi, Charles; Rüther, Heinz
    The quest for sustenance inevitably forces mankind to exploit natural resources found within their environs. In many cases, the exploitation results in massive environmental degradation that disrupts the ecosystem and causes loss of bio-diversity. There is generally a lack of information systems to monitor and provide quantitative information on the state of the affected environment. Decision-makers usually fail to make informed decisions with regard to conservation strategies. The need to provide decision-makers with quantitative environmental information formed the basis of this thesis. An integrated environmental information system (EIS) database was developed according to the Software Development Methodology for three of the identified environmental sectors. This involved detailed user needs assessment to identify the information requirements (both spatial and textual) for each sector. The results were used to design separate data models that were later merged to create an integrated data model for the database application. A fisheries application prototype was developed to implement the proposed database design. The prototype has three major components. The Geographic Information System (GIS) handles the spatial data such as rivers, settlements, roads, and lakes. A relational database management system (RDBMS) was used to store and maintain the non-spatial data such as fisherman ' s personal details and fish catch data. Customized graphical user interfaces were designed to handle the data visualization and restricted access to the GIS and RDBMS environments.
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    Establishment of Accuracy Testing Facilities for Terrestrial Laser Scanners
    (2018) Davison, Wayne; Smit, Julian Lloyd
    Measurement instruments that are required for high precision and reliable work need to have regular checks to ensure they are always performing at the required level of accuracy. A Terrestrial Laser Scanner is one such instrument and with the vast amount of information that this machine is able to capture, it is especially important to run regular accuracy checks. This research is building on the work that has been done by previous researchers on the assessment of instrument accuracy and the establishment of facilities specialized for this assessment. Theoretical principles are investigated in the form of Least Squares Adjustments, similarities to panorama photography and photogrammetric accuracy. Terrestrial Laser Scanners are reviewed with respect to their scanning principles and data acquisition. The methodology incorporated in this research encompasses the positioning of targets, their survey to establish high accuracy coordinates through various methods of adjustment and thereafter the scanning of those targets. Comparisons were done using derived angles and distances between the targets to discover the point accuracy of the Laser Scanner. This was done for two facilities; a short range facility (1 to 15 meters) and a medium range facility (1 to 75 meters). The medium range facility also included a range testing baseline for distance accuracy assessments. The outcomes from the comparisons between the surveyed control data and the laser scanner observed data indicated that the laser scanner is performing below the accuracy of the surveyed data. The laser scanner was further compared against the manufacturer quoted performance specifications and revealed the laser scanner to be performing below the quoted values. The laser scanner in question showed stronger results in the horizontal measurements over the vertical measurements. All results suggested the laser scanner was delivering weak results in the vertical observations due to a mis-alignment of individual scan halves. This research was able to establish two accuracy assessment facilities specialized for Terrestrial Laser Scanners under these same conditions. Both facilities were used in conjunction, to analyze the Z+F Imager 5010C laser scanner and determine the point accuracy in terms of the observed angles and distances from this machine. The results are also able to identify errors in the performance of the laser scanner and whether or not it is performing within the manufacturer specifications by noticing any large values such as in the case of the vertical observations for this instrument.
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    Free adjustment of a triangulation net
    (1976) Jackson, Jonathan; Merry, Charles
    It is often useful to determine the measures of precision of the directly observed quantities in a triangulation net. Provided the net is not strained these measures are unique to a particular set of observations and weights. Unique measures for the precision of the indirectly observed quantities cannot be found by classical means although several ad hoc approaches can be used to approximate to this measure of the 'inherent strength' of a net. Bjerhammar's theory of generalised matrix inverses can be used to derive measures of precision for the indirectly observed quantities, which may be interpreted as reflecting the inherent strength of the net. The theory of adjustment of a triangulation net by the method of variation of co-ordinates is described, followed by an explanation of the theory bf generalised inverses. Methods for the practical derivation of particular inverses are described, following Mittermayer. The characteristics of Normal, Transnormal and Stochastic Ring inverses in solution of Normal equations BX = R, are described.
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    Integrating a web-based GIS in the optimization of the customer connection process for utility company: A case of Kenya Power; Lighting Company, Ltd.
    (2021) Munywoki, Margaret Ngeli; Singh, Kaveer
    Great strides have been made world over in the use of GIS as a tool for the management of resources and decision making in the utilities. Utilities are now integrating GIS with other company systems in a bid to reduce operational costs, maximize revenue as well as improve efficiency and care to customers. However, this use has been confined to ensuring optimised service delivery to existing customers and overlooks new prospective customers. With privatization and deregulations, utility companies are now faced with a new challenge to strive for the market share in the most efficient and cost-effective ways. This research sought to develop a complementary web-based GIS application that can be integrated with existing utility company systems to improve efficiency in the new customer connection process. Waterfall System Development Methodology (SDM) was adopted in this research. Its simplicity and straightforwardness gave it a niche over other SDMs in-terms of implementation as one only moved to the next stage once the previous stage had been fully completed and tested. Digital online map, counties information data, enquiry for supply forms as well as the supply contract forms were used as the main datasets in the study. The objectives of this research were achieved by the development of a geodatabase to record, store and retrieve customer information; and a web-based GIS application to facilitate recording and upload of this information. It is possible to develop a web based GIS application that can be integrated with existing company's systems. Through integration, the system will automate and augment most of the manual processes in the new connection work-flow. This development would greatly improve new customer connection efficiency, maximize revenue collection for the utility and elevate the customers' socio-economic statuses. The system would also provide a platform for the monitoring and analysis of the infrastructure development geared towards the achievement of Kenya's Vision 2030.
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    A line photogrammetry algorithm for 3D rectilinear object reconstruction
    (1998) Hill, Justin John Whatton; Mason, Scott; Rüther, Heinz
    This thesis introduces an alternative formulation for line photogrammetry. The aim was to develop and test a method of computing the position and orientation of a straight line in space using two or more oriented images of that line. The algorithm presented is intended for object reconstruction and is motivated by the need to reconstruct man-made objects in urban areas, such as buildings and the industrial inspection arena. The method aims to obtain a best-fit line through a "pencil of planes". The reconstructed 3D line is defined by two points as opposed to the conventional representation, which uses a point and a direction vector. The approach to this problem involves the calculation of a projection plane for each image containing the perspective centre and two transformed line-point observations in the image. A least squares adjustment involves fitting a straight line as near as possible to the projection planes from all images simultaneously. The adjusted line is referred to as a best-fitting line through a "pencil of planes" (POP). In this project, a mathematical model was formulated for the application of this concept. This algorithm was coded and tested on two cases. A set of scanned aerial images of a residential area with a scale of 1: 5000 provided the primary test case. Lines delineating three roofs visible in the aerial images were reconstructed using the POP method and compared with ground truth data. The lines reconstructed using the POP method were compared to those reconstructed using an existing method of line photogrammetry, proposed by Mulawa (1988). The second test was based on a set of close-range images captured using a small-format digital camera. Lines delineating the bars of a metal frame generally used as a precise control field for camera calibration, were reconstructed. In both test cases, X² tests were applied, and the standard deviations calculated. In the aerial case, standard deviations obtained were generally in the region of about 5cm. The ground resolution of the images was 7.Scm. In the close-range case the ground resolution was approximately 1.3mm, and the standard deviations obtained were generally of the order of 0.7mm. Of the lines computed, 84% of the adjustments passed the X² test. The results obtained confirmed that the POP algorithm is a practicable means of adjusting observations to obtain best-fitting 3D lines using observations made in a set of oriented images.
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    Measuring tenure security of the rural poor using pro-poor land tools: A case study of Itaji-Ekiti, Ekiti State Nigeria
    (2018) Babalola, Kehinde Hassan; Hull, Simon Antony
    The sustainable development goals aim to improve the lives of rural dwellers by ensuring the security of tenure of the rural poor. This led researchers and nongovernmental organisations to investigate the security of tenure of the urban and rural poor in developing countries. To improve the security of tenure of the rural poor, many developing countries have initiated programmes that encompass reform of land tenure and land administration systems. To provide a solution to the insecurity of tenure, researchers and non-governmental organisations developed pro-poor land tools to address the gap created by the formal land administration system. To test the developed land tools, researchers apply them in selected case study areas. This study investigates and analyses the tenure security of the rural poor of Itaji-Ekiti, Ekiti State, Nigeria. The New Continuum of Land Rights Model (NCLRM) and the Social Tenure Domain Model (STDM) were applied to land rights types found in the case study. Techniques, theories and tools used were based on a single case study methodology. The mixed methods approach was used to analyse and evaluate the tenure situation in Itaji-Ekiti. This yielded an in-depth understanding of the case. The research further examines critical areas of the Land Use Act of 1978 using the conceptual framework for understanding cadastral system development in customary land rights context. The mixed methodology approach was used in analysing the vital areas of the Act. Land professionals, civil servants and students were the target group that contributed to the study. The research findings showed that security of tenure is weak because every land rights types found in Itaji-Ekiti can be affected by conflicts with customary and informal tenure. The results of this research showed that the Land Use Act is effective in some areas and dysfunctional in others. This is attributed to the age of the Act and many sections of the Act that are not pro-poor. The implementation of the Act showed that it is effective in urban areas while it is not solving land-related problems in rural areas. The research further revealed that the use of case study methodology using mixed methods are suitable for measuring tenure security of the rural poor. The findings provide an understanding of the current land policy in Nigeria and as well as understanding land tenure insecurity in Itaji-Ekiti. The research also provides information for researchers in the field of cadastral system research on the use of propoor land tools as alternative approaches to recording land rights and measuring tenure security of the rural poor.
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    Necropolis: burial & afterlives in Cape Town
    (2023) Maggs, Alexander; Papanicolaou, Stella
    Necropolis is a proposal for a public burial and memorial park in Cape Town for obliterated (cremated, aquamated etc) and bone remains. It explores an architecture for the final farewell to the body and spirit of the deceased, and for personal and collective remembrance. In contrast to other South African Cities, Cape Town is unique for the popularity of cremation, which accounted for 40% of recorded burials in 2019. Architectural responses however are often piecemeal. Burial places were once part of cities' symbolic centres, and mortality understood as an inevitable spiritual journey. During modernisation however, they were exiled to cities' peripheries, far from people's everyday lives. The chosen site is in Deer Park, at the edge of the City Bowl, through which runs a perennial stream linked to the city's historical centre. The Park has a varied heritage landscape which the design situates itself beside, together constituting a landscape of remembrance. The programme explores a secular spiritual and sacred response to burial, grief and memory. The architectural language explores a stereotomics of brick, stone and rubble in dialogue with the ground and Earth. The primary methodology is speculative design, through hand sketching, photographing, mapping, collaging, modelling, digital modelling and rendering. Design thinking is supported by a varied literature review: firstly a collection of Cape Town and colonial European burial histories and practices. Secondly, a phenomenology of the ground, geology, and stone and rubble building. Thirdly, precedent studies of sacred and burial architecture, supported by analysis through drawing.
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    Privacy protection in geographic information systems : guidelines for the protection of privacy in GIS in South Africa
    (1998) Schreiber, Renate Ingeborg; Barry, Michael B
    Personal privacy issues are relevant to the GIS community. The distribution and dissemination of personal data is greatly facilitated through GIS tools. The use of these tools has been expanded from traditionally geographical operations to applications in geodemographics, and it is particularly in geodemographics where the protection of privacy becomes an issue. This thesis examines existing privacy protection guidelines put forward by international commercial and governmental sectors; the current international position with regards to the protection of privacy is reviewed, and South African legislation pertaining to these issues is explored. On this basis, a set of privacy protection guidelines is developed which can assist GIS managers in South Africa in ensuring that data collection and management do not infringe on personal privacy.