In recent years, computing power and biometric sensors have not only become more powerful, but also more affordable to the general public. In turn, there has been great interest in developing and deploying biometric personal ID systems. Unlike the conventional security systems that often require people to provide artificial identification for verification, i.e. password or algorithmic generated keys, biometric security systems use an individual's biometric measurements, including fingerprint, face, hand geometry, and iris. It is believed that these measurements are unique to the individual, making them much more reliable and less likely to be stolen, lost, forgotten, or forged. Among these biometric measurements, the iris is regarded as one of the most reliable and accurate security approaches because it is an internal organ protected by the body's own biological mechanisms. It is easy to access, and almost impossible to modify without the risk of damaging the iris. Although there have been significant advancements in developing iris-based identification processes during recent years, there remains significant room for improvement. This dissertation presents a novel approach to the iris localization and code matching. It uses a fixed diameter method and a parabolic curve fitting approach for locating the iris and eyelids as well as a k-d tree for iris matching. The iris recognition rate is improved by accurately locating the eyelids and eliminating the signal noise in an eye image. Furthermore, the overall system performance is increased significantly by using a partial iris image and taking the advantage of the k-d binary tree. We present the research results of four processing stages of iris recognition: localization, normalization, feature extraction, and code matching. The localization process is based on histogram analysis, morphological process, Canny edge detection, and parabolic curve fitting. The normalization process adopts Daugman's rubber-sheet approach and converts the iris image from Cartesian coordinators to polar coordinates. In the feature extraction process, the feature vectors are created and quantized using 1-D Log-Gabor wavelet. Finally, the iris code matching process is conducted using a k-dimensional binary tree and Hamming distance.

Particle simulation has become an important research technique in many scientific and engineering fields in latest years. However, these simulations will generate countless data, and database they required would therefore deal with very challenging tasks in terms of data management, storage, and query processing. The two-body correlation function (2-BCFs), a statistical learning measurement to evaluate the datasets, has been mainly utilized to measure the spatial distance histogram (SDH). By using a straightforward method, the process of SDH query takes quadratic time. Recently, a novel algorithm has been proposed to compute the SDH based on the concept of density map (DM), and it reduces the running time to ϴ(N(3/2)) for two-dimensional data and ϴ (N(5/3) ) for three-dimensional data, respectively. In the DM-SDH algorithm, there are two types of DMs that can be plugged in for computation: Quad-tree (Oct-tree for three-dimensional data) and k-d tree data structure. In this thesis paper, by using the geometric method, we prove the unre- solvable ratios on the k-d tree. Further, we analyze and compare the difference in the performance in each potential case generated by these DM-SDH algorithms. Experimental results confirm our analysis and show that the k-d tree structure has better performance in terms of time complexity in all cases. However, our qualitative analysis shows that the Quad-tree (Oct-tree) has an advantage over the k-d tree on aspect of space complexity.

This thesis deals with ray tracing methods and their acceleration. It gives partial study and review of algorithms from classical ray shooting algorithm to recursive approach up to distributed ray tracing algorithm. Significant part of this thesis is devoted to BSP tree structure and its subclass of k-D tree, it shows simple algorithm for its construction and traversal. The rest of thesis is dealing with k-D tree construction techniques, which are based on the right choice of the splitting plane inside the every cell of k-D tree. The techniques upon the thesis is based on are space median, object median and relatively new cost model technique named SAH, otherwise as surface area heuristic. All three techniques are put into testing and performance comparison. In the conclusion the results of tests are reviewed, from where SAH is coming out as a winner.

Image-based 3D reconstruction refers to the capture and virtual reconstruction of real scenes, through the use of ordinary camera sensors. A common approach is the use of the algorithms Structure from Motion, Multi-view Stereo and Poisson Surface Reconstruction, that fares well for many types of scenes. However, a problem that this pipeline suffers from is that it often falters when it comes to texture-less surfaces and areas, such as those found in man-made environments. Building facades, roads and walls often lack detail and easily trackable feature points, making this approach less than ideal for such scenes. To remedy this weakness, this thesis investigates an expanded approach, incorporating line segment detection and line cloud generation into the already existing point cloud-based pipeline. Texture-less objects such as building facades, windows and roofs are well-suited for line segment detection, and line clouds are fitting for encoding 3D positional data in scenes consisting mostly of objects featuring many straight lines. A number of approaches have been explored in order to determine the usefulness of line clouds in this context, each of them addressing different aspects of the reconstruction procedure.

Ce travail, réalisé dans le cadre du projet Geant4-DNA, consiste à concevoir un prototype pour la simulation des effets chimiques précoces des rayonnements ionisants. Le modèle de simulation étudié repose sur la représentation particule-continuum où toutes les molécules sont explicitement simulées et où le solvant est traité comme un continuum. La méthode proposée par cette thèse a pour but d'améliorer les performances de ce type de simulation. Elle se base sur (1) la combinaison d'une méthode de pas en temps dynamiques avec un processus de pont Brownien pour la prise en compte des réactions chimiques et afin d'éviter une simulation à pas en temps fixe, coûteuse en temps de calcul, et (2) sur la structure de données k-d tree pour la recherche du voisin le plus proche permettant, pour une molécule donnée, une localisation rapide du réactif le plus proche. La précision de l'algorithme est démontrée par la comparaison des rendements radiochimiques en fonction du temps et en fonction du transfert d'énergie linéaire avec des résultats d'autres codes Monte-Carlo et des données expérimentales. A partir de ce prototype, une tentative de prédiction du nombre et du type d'interactions radicaux-ADN a été entreprise basée sur d'une description simplifiée du noyau cellulaire. / The purpose of this work, performed under the Geant4-DNA project, is to design a prototype for simulating early chemical effects of ionizing radiation. The studied simulation model is based on the particle-continuum representation where all the molecules are explicitly simulated, and where the solvent is treated as a continuum. The method proposed by this thesis aims at improving the performance of this type of simulation. It is based on (1) a dynamical time steps method with a Brownian bridge process, to account for chemical reactions, which avoids the costly fixed time-step simulations, and (2) on the k-d tree data structure for quickly locating, for a given molecule, its closest reactants. The accuracy of the algorithm is demonstrated by comparing radiochemical yields over time and depending on the linear energy transfer with results obtained from other Monte Carlo codes and experimental data. Using this prototype, an attempt to predict the number and type of radical attacks on DNA has been performed using a simplified description of the cell nucleus.