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  • BB

  • Assessing edge and area metrics for image segmentation parameter tuning and evaluation

    • Authors: Meyer, H.P.;  Advisor: -;  Participants: - (2016)

  • Image segmentation algorithms allow the creation of variables that influence the attributes of the resulting objects. There is currently no set way of identifying the best segmentation parameters for a specific application. It would consequently be useful to calculate the accuracy of a particular segmentation for determining how well it can delineate an object of interest. This article assesses the use of both an area and edge metric to evaluate and quantify the ability of a segmentation algorithm to delineate objects of interest based on manually collected reference data. SPOT 5 imagery was used for the segmentation of two 2x3km study areas in the Eastern-Cape of South Africa. The aims of this study were to use the area metric to identify a scale parameter for which the ratio betwe...
  • BB

  • Assessing downscaling limits of spatial resolution for awifs and landsat 8 data as compared to liss IV

    • Authors: Chauhan, A.;  Advisor: -;  Participants: - (2016)

  • Downscaling spatial information has a certain limit. Change in resolution of input image from its original resolution either loses or gains information. To understand this limit accuracy of the downscaled information has to be assessed. This research assesses the downscaled information of AWiFS and LANDSAT 8 as compared and validated by LISS IV. A total of 200 sample points were collected using Systematic Random Sampling. The results showed that the overall accuracy for the supervised classification was 95% for LISS IV where Kappa statistics was 0.92. As the resolution LANDSAT 8 was reduced from 10% to 50% the overall accuracy varied from 84% to 73.5% with 0.79 to 0.65 Kappa coefficient. For AWiFS at the same reducing resolutions, the overall accuracy varied from 80% to 67% with 0.7...
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  • Blending satellite observed, model simulated, and in situ measured soil moisture over Tibetan Plateau

    • Authors: Zeng, Yijian;  Advisor: -;  Participants: - (2016)

  • The inter-comparison of different soil moisture (SM) products over the Tibetan Plateau (TP) reveals the inconsistency among different SM products, when compared to in situ measurement. It highlights the need to constrain the model simulated SM with the in situ measured data climatology. In this study, the in situ soil moisture networks, combined with the classification of climate zones over the TP, were used to produce the in situ measured SM climatology at the plateau scale. The generated TP scale in situ SM climatology was then used to scale the model-simulated SM data, which was subsequently used to scale the SM satellite observations. The climatology-scaled satellite and model-simulated SM were then blended objectively, by applying the triple collocation and least squares method...
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  • Cadastral boundaries from point clouds?/ :Towards semi-automated cadastral boundary extraction from ALS data

    • Authors: Enemark, Stig;  Advisor: -;  Participants: - (2016)

  • Proponents of the new era for land administration argue that countries must explore alternatives to accelerate land administration completion. As an example, fit-for-purpose land administration is based on the use of printed imagery, community participation and hand-drawn boundaries. Digital solutions then convert the generated analogue data into useful digital information. However, the approach is manually intensive, and simple automation processes are continually being sought to cut time and costs. One approach gaining traction is the idea of using image processing and machine learning techniques to automatically extract boundary features from imagery – or point cloud data – prior to even entering the field. The approach could speed up activities both in the field and in the offic...
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  • Building Fit-For-Purpose Land Administration Systems: Guiding Principles :Guiding Principles

    • Authors: Enemark, Stig;  Advisor: -;  Participants: - (2016)

  • This paper describes the key principles for building sustainable and FFP land administration systems especially in developing countries where often less the 10 per cent of the land and population is included in the formal systems. It is argued that building such FFP land administration systems is the only viable solution to solving the global security of tenure divide. The FFP approach is flexible and includes the adaptability to meet the actual and basic needs of society today and having the capability to be incrementally improved over time. This will be triggered in response to social and legal needs of economic development, investments and also financial opportunities that may emerge over the longer term. In this FFP approach, land rights can be secured for all in a timely and af...
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  • Building Fit-For-Purpose Land Administration Systems :Providing Security of Tenure for All

    • Authors: Enemark, Stig;  Advisor: -;  Participants: - (2016)

  • This paper discusses the building of the FFP approach at country level. The paper provides some guidelines on “how to make it work”. In the view of the authors the focus of implementation is in providing secure land rights for all. Implementation of the FFP approach means to ‘recognise’, ‘record’ and ‘review’ land rights. This paper further highlights the importance of the development of an ICT environment.
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  • Comparison of three modelling approaches to simulate regional crop yield :a case study of winter wheat yield in western Germany

    • Authors: Soltani, A.;  Advisor: -;  Participants: - (2016)

  • The need for more comparisons among models is widely recognized. This study aimed to compare three different modelling approaches for their capability to simulate and predict trends and patterns of winter wheat yield in Western Germany. The three modelling approaches included an empirical model, a process-based model (LINTUL2), and a metamodel derived from the process-based model. The models outcomes were aggregated to general climate zones level of Western Germany to allow for a comparison with agricultural census data for validation purposes. The spatial patterns and temporal trends of winter wheat yield seemed to be better represented by the empirical model (R2= 70%, RMSE= 0.48 t ha-1 yr-1, and CV-RMSE= 8%) than by the LINTUL2 model (R2= 65%, RMSE= 0.67 t ha-1 yr-1, and CV-RMSE=1...
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  • Comparing machine learning classifiers for object-based land cover classification using very high resolution imagery

    • Authors: Qian, Yuguo;  Advisor: -;  Participants: - (2016)

  • This study evaluates and compares the performance of four machine learning classifiers—support vector machine (SVM), normal Bayes (NB), classification and regression tree (CART) and K nearest neighbour (KNN) —to classify very high resolution images, using an object-based classification procedure. In particular, we investigated how tuning parameters affect the classification accuracy with different training sample sizes. We found that: (1) SVM and NB were superior to CART and KNN, and both could achieve high classification accuracy (>90%); (2) the setting of tuning parameters greatly affected classification accuracy, particularly for the most commonly-used SVM classifier; the optimal values of tuning parameters might vary slightly with the size of training samples; (3) the size of tr...