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Browsing by Author "De Villiers, Johan P"

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Centi-pixel accurate real-time inverse distortion correction

Author: De Villiers, Johan P ; Leuschner, FW ; Geldenhuys, R Date: Nov 2008 Inverse distortion is used to create an undistorted image from a distorted image. For each pixel in the undistorted image it is required to determine which pixel in the distorted image should be used. However the process of characterizing a ... Read more
Comparative investigation into Viterbi based and multiple hypothesis based track stitching

Author: Van der Merwe, LJ ; De Villiers, Johan P Date: Dec 2016 In this study a comparative analysis is performed between a novel Viterbi based and multiple hypothesis based track stitching algorithms. The track fragments in the Viterbi based track stitching algorithm are modelled as nodes in a trellis ... Read more c b
Comparison of image sharpness metrics and real-time sharpening methods with GPU implementations

Author: De Villiers, Johan P Date: Jun 2010 Improving the quality of an image increases the probability, speed and accuracy with which possible objects of interest can be located and identified. Image sharpening, in particular, can correct for soft focus and strengthen the outlines of ... Read more
Evaluation metrics for the practical application of URREF ontology: An illustration on data criteria

Author: De Villiers, Johan P ; Focke, Richard W ; Pavlin, G ; Jousselme, A-L ; Dragos, V ; Laskey, KB ; Costa, PC ; Blasch, E Date: Aug 2017 The International Society of Information Fusion (ISIF) Evaluation Techniques for Uncertainty Representation Working Group (ETURWG) investigates the quantification and evaluation of all types of uncertainty regarding the inputs, reasoning and ... Read more
An expert-driven causal model of the Rhino poaching problem

Author: Koen, Hildegarde ; De Villiers, Johan P ; Roodt, H ; De Waal, A Date: Mar 2017 A significant challenge in ecological modelling is the lack of complete sets of high-quality data. This is especially true in the rhino poaching problem where data is incomplete. Although there are many poaching attacks, they can be spread ... Read more
Interval algebra: an effective means of scheduling surveillance radar networks

Author: Focke, RW ; De Villiers, Johan P ; Inggs, MR Date: May 2015 Interval Algebra provides an effective means to schedule surveillance radar networks, as it is a temporal ordering constraint language. Thus it provides a solution to a part of resource management, which is included in the revised Data Fusion ... Read more
Joint inference of dominant scatterer locations and motion parameters of an extended target in high range-resolution radar

Author: De Freitas, A ; De Villiers, Johan P ; Nel, Willem AJ Date: Jun 2015 A target of interest measured by a high range resolution radar may be modelled by multiple dominant points of reflections referred to as dominant scatterers. In this study a non-linear state space setting is used to model the states and ... Read more
Maritime piracy situation modelling with dynamic Bayesian networks

Author: Dabrowski, James M ; De Villiers, Johan P Date: May 2015 A generative model for modelling maritime vessel behaviour is proposed. The model is a novel variant of the dynamic Bayesian network (DBN). The proposed DBN is in the form of a switching linear dynamic system (SLDS) that has been extended ... Read more
Modeling of radial asymmetry in lens distortion facilitated by modern optimization techniques

Author: De Villiers, Johan P ; Leuschner, FW ; Geldenhuys, R Date: 18 Jan 2010 Most current lens distortion models use only a few terms of Brown's model, which assumes that the radial distortion is dependant only on the distance from the distortion centre, and an additive tangential distortion can be used to correct ... Read more
Speeding up IA mechanically-steered multistatic radar scheduling with GP-GPUs

Author: Focke, RW ; De Villiers, Johan P ; Inggs, MR Date: Jul 2016 In this paper, the authors investigate speeding up the execution time of Interval Algebra (IA) mechanically-steered multistatic and multisite radar scheduling using a general-purpose graphical processing unit (GP-GPU). Multistatic/multisite ... Read more
System-level causal modelling of widescale resource plundering: Acting on the rhino poaching catastrophe

Author: Koen, Hildegarde S ; Roodt, H ; De Villiers, Johan P Date: Oct 2017 The initial goal of this study was to develop a predictive model that could serve as a pre-emptive method for curbing rhino poaching. During the development of the predictive model it became evident that only the tip of the iceberg, so to ... Read more
Systemic banking crisis early warning systems using dynamic bayesian networks

Author: Dabrowski, JJ ; Beyers, C ; De Villiers, Johan P Date: Nov 2016 For decades, the literature on banking crisis early-warning systems has been dominated by two methods, namely, the signal extraction and the logit model methods. However, these methods, do not model the dynamics of the systemic banking system. ... Read more c b
Uncertainty representation, quantification and evaluation for data and information fusion

Author: De Villiers, Johan P ; Laskey, K ; Jousselme, A-L ; Blasch, E ; Pavlin, G ; Costa, P Date: Jul 2015 Mathematical and uncertainty modelling is an important component of data fusion (the fusion of unprocessed sensor data) and information fusion (the fusion of processed or interpreted data). If uncertainties in the modelling process are not ... Read more
A unified model for context-based behavioural modelling and classification

Author: Dabrowski, JJ ; De Villiers, Johan P Date: Nov 2015 A unified Bayesian model that simultaneously performs behavioural modelling, information fusion and classification is presented. The model is expressed in the form of a dynamic Bayesian network (DBN). Behavioural modelling is performed by ... Read more

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Browsing by Author "De Villiers, Johan P"

Browsing by Author "De Villiers, Johan P"

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