During orthopaedic surgery, preoperative CT scans can be aligned to the patient to assist the guidance of surgical instruments and the placement of implants. Registration (i.e. alignment) can be accomplished in many ways: by registering implanted fiducial markers, by touching a probe to the bone surface, or by aligning intraoperative two dimensional flouro images with the the three dimensional CT data. These approaches have problems: They require exposure of the bone, subject the patient and surgeons to ionizing radiation, or do both. Ultrasound can also be used to register a preoperative CT scan to the patient. The ultrasound probe is tracked as it passes over the patient and the ultrasound images are aligned to the CT data. This method eliminates the problems of bone exposure and ionizing radiation, but is computationally more difficult because the ultrasound images contain incomplete and unclear bone surfaces. In this work, we compare three methods to register a set of ultrasound images to a CT scan: Iterated Closest Point, Mutual Information and a novel method Points-to-Image. The average Target Registration Error and speed of each method is presented along with a brief summary of their strengths and weaknesses. / Thesis (Master, Computing) -- Queen's University, 2009-01-22 04:21:22.569

Submitted by Mario BC (mario@bc.ufrpe.br) on 2016-08-24T13:21:38Z No. of bitstreams: 1 Fernanda Andrea Fernandes Silva.pdf: 2425640 bytes, checksum: 503cb9560b6d95b13d950e13a8ad6c9c (MD5) / Made available in DSpace on 2016-08-24T13:21:39Z (GMT). No. of bitstreams: 1 Fernanda Andrea Fernandes Silva.pdf: 2425640 bytes, checksum: 503cb9560b6d95b13d950e13a8ad6c9c (MD5) Previous issue date: 2013-03-05 / This research proposes to investigate what are the meanings and the representations of the rational numbers that are contemplated in the National High School Exam – ENEM. Therefore, then we take as reference the studies of Romanatto (1997) and Gomes (2010) and we adopted the following meanings for the rational numbers: measure (part-whole), quotient, reason, multiplicative operator, probability, a number in straight numerical and percentages. To we analyze the records of representations of the rational numbers that are contemplated in ENEM, We use the Theory of the Representations semiotics Raymond Duval who considers that mathematical objects are not directly perceptible and that access to them is possible only through a system of representation. The methodological route that we have adopted consisted of the two stages. In step I we analyze the tests general knowledge of the ENEMs 1998 to 2008 and math tests and their technologies of the ENEMs from 2009 to 2011, in the sense of identify items that mobilized the concept of rational numbers in their different meanings. In step II, we analyze the items identified in step I, regarding the math tests and their technologies of ENEM 2009 to 2011, as to records of representations contained in the structure of the item and in particular of the records of the rational numbers, and also, regarding as to records of representations, treatments and conversions that could be mobilized during the resolution of the item. We concluded that, in the evidence of general knowledge of the ENEMs 1998 to 2008, approximately 5.6% of the items (3.9 items per tests) involved the concept of rational numbers. While in math tests and their technologies of the ENEMs 2009 to 2011 (new ENEM), approximately 21% of the items (9.6 items per tests) mobilized this concept. The meanings identified in the items relative at the ENEM 1998 to 2008 were virtually the same identified in the period of the ENEM new, part-whole, reason, percentages and probability. Being the meaning, percentage, as the more addressed. Some items involved more than one meaning. The items related to math tests and their technologies of the ENEMs 2009 to 2011 had a predominance in its structure (enunciated, bracket, command, and alternatives of the answer), among the records of semiotic representations of rational numbers, the numeric registration, percentages. The semiotic register of rational numbers who else could be mobilized during for the resolutions of the items was the record fractional numerical. Conversions between the records of rational numbers only occurred in only one direction, with the exception of one item of the ENEM 2010. / Essa pesquisa se propõe a investigar quais são os significados e as representações dos números racionais que são contemplados no Exame Nacional do Ensino Médio – ENEM. Para tanto, tomamos como referência os estudos de Romanatto (1997) e Gomes (2010) e adotamos os seguintes significados para os números racionais: medida (parte-todo), quociente, razão, operador multiplicativo, probabilidade, um número na reta numérica e porcentagem. Para analisarmos os registros de representações dos números racionais que são contemplados no ENEM, utilizamos a Teoria das Representações Semióticas de Raymond Duval que considera que os objetos matemáticos não são diretamente perceptíveis e que o acesso a esses só é possível por meio de um sistema de representação. O percurso metodológico constou de duas etapas. Na etapa I analisamos as provas de conhecimentos gerais dos ENEM de 1998 a 2008 e as provas de matemática e suas tecnologias dos ENEM de 2009 a 2011, no sentido de identificar os itens que envolviam o conceito de números racionais nos seus diferentes significados. Na etapa II, analisamos os itens identificados na etapa I, referente às provas de matemática e suas tecnologias dos ENEM de 2009 a 2011, quanto aos registros de representações contidos na estrutura do item e, em particular os registros dos números racionais, e, também, quanto aos registros de representações, os tratamentos e as conversões que podiam ser mobilizados, durante a resolução do item. Concluímos que nas provas de conhecimentos gerais dos ENEM de 1998 a 2008, aproximadamente 5,6% dos itens (3,9 itens por prova) envolviam o conceito de números racionais. Enquanto que nas provas de matemática e suas tecnologias dos ENEM de 2009 a 2011 (novo ENEM), aproximadamente, 21% dos itens (9,6 itens por prova) abordavam esse conceito. Os significados identificados nos itens relativos aos ENEM de 1998 a 2008 foram praticamente os mesmos identificados no período do novo ENEM, parte-todo, razão, porcentagem e probabilidade. Sendo o significado porcentagem o mais abordado. Alguns itens envolveram mais de um significado. Os itens referentes às provas de matemática e suas tecnologias dos ENEM de 2009 a 2011tiveram um predomínio na sua estrutura (enunciado, suporte, comando e alternativas de resposta), entre os registros de representações semióticas dos números racionais, o registro numérico porcentagem. O registro semiótico dos números racionais que mais pôde ser mobilizado durante as resoluções dos itens foi o registro numérico fracionário. As conversões entre os registros dos números racionais, só ocorreram apenas num sentido, com exceção de um item do ENEM 2010.

The subject of this thesis is the electronic registration of sales and its efects on reducing the grey economy in the Czech republic. The electronic registration of sales is a system designed to ensure that entrepreneurs selling goods or services in return for cash report every instance of such transaction directly to the tax authority so opportunities for tax evasion are significantly reduced. FIK, a code unique to every transaction that serves as a proof that the report has been done is subsequently sent back and receipt for transaction with FIK included is issued to the customer who can check, using special internet aplication, whether transaction has been in deed reported. The work is divided into five chapters. The first one describes accounting and similar systems that record information needed to administration of taxes. The next chapter describes occasions when issuing invoices not related to electronic evidence of sales is required. The third chapter analyses the Registration of Sales Act which introduces the electronic evidence of sales into Czech law. This chapter is further divided into seventeen subchapters focused on the most important provisions of the act, for example those setting out exactly what transactions are required to be reported, what are the details of the receipt and the rules of...

Cette thèse commence par une étude approfondie des méthodes d’estimation de décalage sous-pixeliques rapides. Une comparaison complète est effectuée prenant en compte problèmes d’estimation de décalage existant dans des applications réelles, à savoir, avec différentes conditions de SNR, différentes grandeurs de déplacement, la non préservation de la contrainte de luminosité constante, l’aliasing et, surtout, la limitation des ressources de calcul. Sur la base de cette étude, en collaboration avec le CNES (l’agence spatiale française), deux problèmes qui sont cruciaux pour l’optique numérique des satellites d’observation de la terre sont analysés. Nous étudions d’abord le problème de correction de front d’onde dans le contexte de l’optique actif. Nous proposons un algorithme pour mesurer les aberrations de front d’onde sur un senseur de type Shack-Hartmann (SHWFS en anglais) en observant la terre. Nous proposons ici une revue de l’état de l’art des méthodes pour le SHWFS utilisé sur des scènes étendues (comme la terre) et concevons une nouvelle méthode pour améliorer l’estimation de front d’onde, en utilisant une approche basée sur l’équation du flot optique. Nous proposons également deux méthodes de validation afin d’assurer une estimation correcte du front d’onde sur les scènes étendues. Tandis que la première est basée sur une adaptation numérique des bornes inférieures (théoriques) pour le recalage d’images, la seconde méthode défausse rapidement les paysages en se basant sur la distribution des gradients. La deuxième application de satellite abordée est la conception numérique d’une nouvelle génération de senseur du type Time Delay Integration (TDI). Dans ce nouveau concept, la stabilisation active en temps réel du TDI est réalisée pour étendre considérablement le temps d’intégration, et donc augmenter le RSB des images. Les lignes du TDI ne peuvent pas être fusionnées directement par addition parce que leur position est modifiée par des microvibrations. Celles-ci doivent être compensées en temps réel avec une précision sous-pixellique. Nous étudions les limites fondamentales théoriques de ce problème et proposons une solution qui s’en approche. Nous présentons un système utilisant la convolution temporelle conjointement à une estimation en ligne du bruit de capteur, à une estimation de décalage basée sur les gradients et à une méthode multiimage non conventionnelle pour mesurer les déplacements globaux. Les résultats obtenus sont concluants sur les fronts de la précision et de la complexité. Pour des modèles de transformation plus complexes, une nouvelle méthode effectuant l’estimation précise et robuste des modèles de mise en correspondance des points d’intérêt entre images est proposée. La difficulté provenant de la présence de fausses correspondances et de mesures bruitées conduit à un échec des méthodes de régression traditionnelles. En vision par ordinateur, RANSAC est certainement la méthode la plus utilisée pour surmonter ces difficultés. RANSAC est capable de discriminer les fausses correspondances en générant de façon aléatoire des hypothèses et en vérifiant leur consensus. Cependant, sa réponse est basée sur la seule itération qui a obtenu le consensus le plus large, et elle ignore toutes les autres hypothèses. Nous montrons ici que la précision peut être améliorée en agrégeant toutes les hypothèses envisagées. Nous proposons également une stratégie simple qui permet de moyenner rapidement des transformations 2D, ce qui réduit le coût supplémentaire de calcul à quantité négligeable. Nous donnons des applications réelles pour estimer les transformations projectives et les transformations homographie + distorsion. En incluant une adaptation simple de LO-RANSAC dans notre cadre, l’approche proposée bat toutes les méthodes de l’état de l’art. Une analyse complète de l’approche proposée est réalisée, et elle démontre un net progrès en précision, stabilité et polyvalence. / This thesis starts with an in-depth study of fast and accurate sub-pixel shift estimationmethods. A full comparison is performed based on the common shift estimation problems occurring in real-life applications, namely, varying SNR conditions, differentdisplacement magnitudes, non-preservation of the brightness constancy constraint, aliasing, and most importantly, limited computational resources. Based on this study, in collaboration with CNES (the French space agency), two problems that are crucial for the digital optics of earth-observation satellites are analyzed.We first study the wavefront correction problem in an active optics context. We propose a fast and accurate algorithm to measure the wavefront aberrations on a Shack-HartmannWavefront Sensor (SHWFS) device observing the earth. We give here a review of state-of-the-art methods for SHWFS used on extended scenes (such as the earth) and devise a new method for improving wavefront estimation, based on a carefully refined approach based on the optical flow equation. This method takes advantage of the small shifts observed in a closed-loop wavefront correction system, yielding improved accuracy using fewer computational resources. We also propose two validation methods to ensure a correct wavefront estimation on extended scenes. While the first one is based on a numerical adaptation of the (theoretical) lower bounds of image registration, the second method rapidly discards landscapes based on the gradient distribution, inferred from the Eigenvalues of the structure tensor.The second satellite-based application that we address is the numerical design of a new generation of Time Delay Integration (TDI) sensor. In this new concept, active real-time stabilization of the TDI is performed to extend considerably the integration time, and therefore to boost the images SNR. The stripes of the TDI cannot be fused directly by addition because their position is altered by microvibrations. These must be compensated in real time using limited onboard computational resources with high subpixel accuracy. We study the fundamental performance limits for this problem and propose a real-time solution that nonetheless gets close to the theoretical limits. We introduce a scheme using temporal convolution together with online noise estimation, gradient-based shift estimation and a non-conventional multiframe method for measuring global displacements. The obtained results are conclusive on the fronts of accuracy and complexity and have strongly influenced the final decisions on the future configurations of Earth observation satellites at CNES.For more complex transformation models, a new image registration method performing accurate robust model estimation through point matches between images is proposed here. The difficulty coming from the presence of outliers causes the failure of traditional regression methods. In computer vision, RANSAC is definitely the most renowned method that overcomes such difficulties. It discriminates outliers by randomly generating minimalist sampled hypotheses and verifying their consensus over the input data. However, its response is based on the single iteration that achieved the largest inlier support, while discarding all other generated hypotheses. We show here that the resulting accuracy can be improved by aggregating all hypotheses. We also propose a simple strategy that allows to rapidly average 2D transformations, leading to an almost negligible extra computational cost. We give practical applications to the estimation of projective transforms and homography+distortion transforms. By including a straightforward adaptation of the locally optimized RANSAC in our framework, the proposed approach improves over every other available state-of-the-art method. A complete analysis of the proposed approach is performed, demonstrating its improved accuracy, stability and versatility.

In computational imaging, data acquired by sampling the same scene or object at different times or from different orientations result in images in different coordinate systems. Registration is a crucial step in order to be able to compare, integrate and fuse the data obtained from different measurements. Tomography is the method of imaging a single plane or slice of an object. A Computed Tomography (CT) scan, also known as a CAT scan (Computed Axial Tomography scan), is a Helical Tomography, which traditionally produces a 2D image of the structures in a thin section of the body. It uses X-ray, which is ionizing radiation. Although the actual dose is typically low, repeated scans should be limited. In dentistry, implant dentistry in specific, there is a need for 3D visualization of internal anatomy. The internal visualization is mainly based on CT scanning technologies. The most important technological advancement which dramatically enhanced the clinician's ability to diagnose, treat, and plan dental implants has been the CT scan. Advanced 3D modeling and visualization techniques permit highly refined and accurate assessment of the CT scan data. However, in addition to imperfections of the instrument and the imaging process, it is not uncommon to encounter other unwanted artifacts in the form of bright regions, flares and erroneous pixels due to dental bridges, metal braces, etc. Currently, removing and cleaning up the data from acquisition backscattering imperfections and unwanted artifacts is performed manually, which is as good as the experience level of the technician. On the other hand the process is error prone, since the editing process needs to be performed image by image. We address some of these issues by proposing novel registration methods and using stonecast models of patient's dental imprint as reference ground truth data. Stone-cast models were originally used by dentists to make complete or partial dentures. The CT scan of such stone-cast models can be used to automatically guide the cleaning of patients' CT scans from defects or unwanted artifacts, and also as an automatic segmentation system for the outliers of the CT scan data without use of stone-cast models. Segmented data is subsequently used to clean the data from artifacts using a new proposed 3D inpainting approach.

No description available.

Satellite laser ranging provides an opportunity to track spacecraft trajectory fluctuationsas well as contributes to study of Earth’s tectonic motions and parameters ofMoon motions. Routine operations of laser ranging are carried out during night-timewhen noise probability is low. Classical approach for distance estimation includesdistance prediction thus reflected signal is expected to arrive during known time intervalcalled gate, however this is not possible when targeted object trajectory is notknown. In these cases gateless registration mode can be applied, but this mode greatlyreduces signal-to-noise ratio. In this thesis filter for noise event reduction during gatelessor full event registration was successfully developed. The filter is applied duringthe post-processing stage to improve signal-to-noise ratio of gathered data from laserranging. Not only the application of filter resulted in reduction of noise events, butalso it provides an insight whether there is an actual useful signal being emitted fromspacecraft. Investigation of event loss during full registration showed loss probabilityof 7.6% for calculated noise rate of 19 events per 0.01 millisecond. The developedfilter in combination with gateless registration mode opens the door for precipitationaltitude determination.

Deep brain stimulation (DBS) surgery, a type of microelectrode-guided surgery, is an effective treatment for the movement disorders patients that can no longer be treated by medications. New rigid and non-rigid image registration methods were developed for the movement disorders patients that underwent DBS surgery. These new methods help study and analyze the brain shift during the DBS surgery and perform atlas-based segmentation of the deep brain structures for the DBS surgery planning and navigation. A diploë based rigid registration method for the intra-operative brain shift analysis during the DBS surgery was developed. The proposed method for the brain shift analysis ensures rigid registration based on diploë only, which can be treated as a rigid structure as opposed to the brain tissues. The results show that the brain shift during the DBS surgery is comparable to the size of the DBS targets and should not be neglected. This brain shift may further lengthen and complicate the DBS surgery contrary to the common belief that brain shift during the DBS surgery is not considerable. We also developed an integrated electrophysiological and anatomical atlas with eleven deep brain structures segmented by an expert, and electrophysiological data of four implant locations obtained from post-op MRI data of twenty patients that underwent DBS surgery. This atlas MR image is then non-rigidly registered with the pre-operative patient MR image, which provides initial DBS target location along with the segmented deep brain structures that can be used for guidance during the microelectrode mapping of the stereotactic procedure. The atlas based approach predicts the target automatically as opposed to the manual selection currently used. The results showed that 85% of the times, this automatic selection of the target location was closer to the target when compared to currently used technique.

The primary goal of this dissertation is to develop point-based rigid and non-rigid image registration methods that have better accuracy than existing methods. We first present point-based PoIRe, which provides the framework for point-based global rigid registrations. It allows a choice of different search strategies including (a) branch-and-bound, (b) probabilistic hill-climbing, and (c) a novel hybrid method that takes advantage of the best characteristics of the other two methods. We use a robust similarity measure that is insensitive to noise, which is often introduced during feature extraction. We show the robustness of PoIRe using it to register images obtained with an electronic portal imaging device (EPID), which have large amounts of scatter and low contrast. To evaluate PoIRe we used (a) simulated images and (b) images with fiducial markers; PoIRe was extensively tested with 2D EPID images and images generated by 3D Computer Tomography (CT) and Magnetic Resonance (MR) images. PoIRe was also evaluated using benchmark data sets from the blind retrospective evaluation project (RIRE). We show that PoIRe is better than existing methods such as Iterative Closest Point (ICP) and methods based on mutual information. We also present a novel point-based local non-rigid shape registration algorithm. We extend the robust similarity measure used in PoIRe to non-rigid registrations adapting it to a free form deformation (FFD) model and making it robust to local minima, which is a drawback common to existing non-rigid point-based methods. For non-rigid registrations we show that it performs better than existing methods and that is less sensitive to starting conditions. We test our non-rigid registration method using available benchmark data sets for shape registration. Finally, we also explore the extraction of features invariant to changes in perspective and illumination, and explore how they can help improve the accuracy of multi-modal registration. For multimodal registration of EPID-DRR images we present a method based on a local descriptor defined by a vector of complex responses to a circular Gabor filter.

No description available.