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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Nonattribution Properties of JPEG Quantization Tables

Tuladhar, Punnya 17 December 2010 (has links)
In digital forensics, source camera identification of digital images has drawn attention in recent years. An image does contain information of its camera and/or editing software somewhere in it. But the interest of this research is to find manufacturers (henceforth will be called make and model) of a camera using only the header information, such as quantization table and huffman table, of the JPEG encoding. Having done research on around 110, 000 images, we reached to state that "For all practical purposes, using quantization and huffman tables alone to predict a camera make and model isn't a viable approach". We found no correlation between quantization and huffman tables of images and makes of camera. Rather, quantization or huffman table is determined by the quality factors like resolution, RGB values, intensity etc.of an image and standard settings of the camera.
102

Determinação da difusividade térmica do esmalte e dentina em função da temperatura, utilizando termografia no infravermelho / Thermal diffusivity measurement of dental hard tissue as function of temperatura obtained by infrared thermography.

Pereira, Thiago Martini 04 September 2009 (has links)
Neste trabalho foi desenvolvido um software que calcula, de forma automatizada, o valor da difusividade térmica em função da temperatura em materiais. A técnica de Termografia no Infravermelho foi utilizada para a aquisição dos dados de distribuição de temperatura em função do tempo, os quais foram utilizados para ajustar uma função de temperatura encontrada por meio da equação de calor homogênea, aplicando as condições de contorno do problema. Para isso, uma câmera termográfica operando no infravermelho distante (8 m - 9 m) foi calibrada para captar temperaturas entre 185º C e 1300º C, e aquisição com frequência de 300 Hz. Foram empregadas como material de avaliação, 10 amostras de esmalte e 10 amostras de dentina, com dimensões de 4 x 4 x 2 mm, obtidas de dentes incisivos inferiores bovinos, as quais foram irradiadas de forma pontual com o laser pulsado de Er:Cr;YSGG (l = 2,78 m), por 10 segundos. Durante as irradiações, foi efetuado o registro das temperaturas atingidas nas amostras que começou 2 segundos antes da irradiação e continuou por mais 2 segundos após o término daquelas. Após as irradiações, as sequências de imagens térmicas digitalizadas obtidas foram processadas no software desenvolvido durante este trabalho, que gerou um arquivo com os dados da difusividade térmica em função da temperatura atingida, assim como forneceu os valores da difusividade térmica para o intervalo de decaimento da temperatura após cada pulso laser. O resultado médio de difusividade térmica obtido para o esmalte dental neste trabalho foi 0,0084±0,001 cm2/s para a região de temperatura de 220-550ºC. Este valor é aproximadamente constante até a temperatura de 550 ºC. O valor médio de difusividade térmica obtido para a dentina foi de 0,0015 0,0004 cm2/s na região de temperatura de 300-360 ºC, porém a difusividade térmica para a dentina aumenta para temperaturas mais altas. De acordo com os resultados obtidos, pode-se concluir que o uso da termografia no infravermelho, associado ao software desenvolvido, apresenta-se como um método eficiente para a determinação dos valores de difusividade térmica em função da temperatura de diferentes materiais. / Neste trabalho foi desenvolvido um software que calcula, de forma automatizada, o valor da difusividade térmica em função da temperatura em materiais. A técnica de Termografia no Infravermelho foi utilizada para a aquisição dos dados de distribuição de temperatura em função do tempo, os quais foram utilizados para ajustar uma função de temperatura encontrada por meio da equação de calor homogênea, aplicando as condições de contorno do problema. Para isso, uma câmera termográfica operando no infravermelho distante (8 m - 9 m) foi calibrada para captar temperaturas entre 185º C e 1300º C, e aquisição com frequência de 300 Hz. Foram empregadas como material de avaliação, 10 amostras de esmalte e 10 amostras de dentina, com dimensões de 4 x 4 x 2 mm, obtidas de dentes incisivos inferiores bovinos, as quais foram irradiadas de forma pontual com o laser pulsado de Er:Cr;YSGG (l = 2,78 m), por 10 segundos. Durante as irradiações, foi efetuado o registro das temperaturas atingidas nas amostras que começou 2 segundos antes da irradiação e continuou por mais 2 segundos após o término daquelas. Após as irradiações, as sequências de imagens térmicas digitalizadas obtidas foram processadas no software desenvolvido durante este trabalho, que gerou um arquivo com os dados da difusividade térmica em função da temperatura atingida, assim como forneceu os valores da difusividade térmica para o intervalo de decaimento da temperatura após cada pulso laser. O resultado médio de difusividade térmica obtido para o esmalte dental neste trabalho foi 0,0084±0,001 cm2/s para a região de temperatura de 220-550ºC. Este valor é aproximadamente constante até a temperatura de 550 ºC. O valor médio de difusividade térmica obtido para a dentina foi de 0,0015 0,0004 cm2/s na região de temperatura de 300-360 ºC, porém a difusividade térmica para a dentina aumenta para temperaturas mais altas. De acordo com os resultados obtidos, pode-se concluir que o uso da termografia no infravermelho, associado ao software desenvolvido, apresenta-se como um método eficiente para a determinação dos valores de difusividade térmica em função da temperatura de diferentes materiais.
103

Tests and characterization of gamma cameras for medical applications / Test et caractérisation de caméras gamma pour le médical

Fontana, Mattia 14 December 2018 (has links)
Ce travail de thèse a été effectué dans le cadre de la collaboration CLaRyS, qui a pour objectif le développement d'une caméra gamma multi-collimatée et d'une caméra Compton pour les applications médicales notamment pour le contrôle en ligne de l’hadronthérapie. La caméra Compton pourrait également être utilisée en médecine nucléaire. L’objectif principal de ce travail de thèse était la caractérisation complète des détecteurs qui composent les caméras et le test des deux systèmes complets avec des faisceaux d’ions cliniques. En parallèle, des études en simulation ont permis d'estimer les performances de la caméra Compton à la fois pour le contrôle de l’hadronthérapie et la médecine nucléaire / This thesis work has been carried out within the CLaRyS French collaboration, which is involved in the development of a multi-collimated gamma camera and a Compton camera for the application in ion beam therapy monitoring through prompt-gamma detection and in nuclear medicine examinations. The main goal of the thesis was the complete characterization of the camera detector components, and the test of the whole systems on clinical ion beams. In parallel, simulation works have been performed to assess the performance of the Compton camera for the measurement of ion range during proton and carbon therapy, and for single photon emission computed tomography application in the nuclear medicine field
104

Absolute depth using low-cost light field cameras

Rangappa, Shreedhar January 2018 (has links)
Digital cameras are increasingly used for measurement tasks within engineering scenarios, often being part of metrology platforms. Existing cameras are well equipped to provide 2D information about the fields of view (FOV) they observe, the objects within the FOV, and the accompanying environments. But for some applications these 2D results are not sufficient, specifically applications that require Z dimensional data (depth data) along with the X and Y dimensional data. New designs of camera systems have previously been developed by integrating multiple cameras to provide 3D data, ranging from 2 camera photogrammetry to multiple camera stereo systems. Many earlier attempts to record 3D data on 2D sensors have been completed, and likewise many research groups around the world are currently working on camera technology but from different perspectives; computer vision, algorithm development, metrology, etc. Plenoptic or Lightfield camera technology was defined as a technique over 100 years ago but has remained dormant as a potential metrology instrument. Lightfield cameras utilize an additional Micro Lens Array (MLA) in front of the imaging sensor, to create multiple viewpoints of the same scene and allow encoding of depth information. A small number of companies have explored the potential of lightfield cameras, but in the majority, these have been aimed at domestic consumer photography, only ever recording scenes as relative scale greyscale images. This research considers the potential for lightfield cameras to be used for world scene metrology applications, specifically to record absolute coordinate data. Specific interest has been paid to a range of low cost lightfield cameras to; understand the functional/behavioural characteristics of the optics, identify potential need for optical and/or algorithm development, define sensitivity, repeatability and accuracy characteristics and limiting thresholds of use, and allow quantified 3D absolute scale coordinate data to be extracted from the images. The novel output of this work is; an analysis of lightfield camera system sensitivity leading to the definition of Active Zones (linear data generation good data) and In-active Zones (non-linear data generation poor data), development of bespoke calibration algorithms that remove radial/tangential distortion from the data captured using any MLA based camera, and, a light field camera independent algorithm that allows the delivery of 3D coordinate data in absolute units within a well-defined measurable range from a given camera.
105

Concurrent validity and reliability of a time of-flight camera on measuring muscle’s mechanical properties during sprint running

Stattin, Sebastian January 2019 (has links)
Recent advancements in 3D data gathering have made it possible to measure the distance to an object at different time stamps through the use of time-of-flight cameras. Therefore, the purpose of this study was to investigate the validity and reliability of a time-of-flight camera on different mechanical sprint properties of the muscle. Fifteen male football players performed four 30m maximal sprint bouts which was simultaneously recorded with a time-of-flight camera and 1080 sprint device. By using an exponential function on the collected positional- and velocity-time data from both the devices, following variables were derived and analyzed: Maximal velocity (nmax), time constant (t), theoretical maximal force (F0), theoretical maximal velocity (V0), peak power output (Pmax), F-V mechanical profile (Sfv) and decrease in ratio of force (Drf). The results showed strong correlation in vmax along with a fairly small standard error of estimate (SEE) (r = 0,817, SEE = 0,27 m/s), while t displayed moderate correlation and relatively high SEE (r = 0,620, SEE = 0,12 s). Furthermore, moderate mean bias (>5%) were revealed for most of the variables, except for vmax and V0. The within-sessions reliability using Intraclass correlation coefficient (ICC) and standard error of measurement (SEM) ranged from excellent to poor with Pmax displaying excellent reliability (ICC = 0,91, SEM = 72W), while vmax demonstrated moderate reliability (ICC = 0,61, SEM = 0,26 m/s) and t poor(ICC = 0,44, SEM = 0,11 s). In conclusion, these findings showed that in its current state, the time-of-flight camera is not a reliable or valid device in estimating different mechanical properties of the muscle during sprint running using Samozino et al’s computations. Further development is needed.
106

Transformations between Camera Images and Map Coordinates with Applications

Börjesson, Nils January 2005 (has links)
<p>The quality of cameras is currently increasing very fast meanwhile the price of them is decreasing. The possibilities of using a camera as a measurement and navigation instrument are thus getting bigger all the time. This thesis studies the transformation relations between a camera image and the scene in space that is projected to it. A theoretical derivation of the transform will be presented, and methods and algorithms for applications based on the transform will be developed.</p><p>The above mentioned transform is called the camera matrix, which contains information about the camera attitude, the camera position, and the internal structure of the camera. Useful information for several different applications can be extracted from the camera image with the help of the camera matrix.</p><p>In one of the applications, treated in this Master´s thesis, the camera attitude is estimated when the camera is calibrated and its position is known. Another application is that of absolute target positioning, where a point in a digital map is searched from its position in a camera image. Better accuracy in the measurements can though be obtained with relative target positioning i.e., estimation of distance and angle between two points in the digital map by picking them out in the image. This is because that the errors of the</p><p>absolute target positioning for each of the two points are dependent and thus partly will cancel each other out when their relative position and angle is measured.</p>
107

Forensisk längdmätning i bilder

Brolund, Per January 2006 (has links)
<p>Detta examensarbete undersöker forensisk längdmätning i bild, t ex längduppskattning av människor i bilder rörande brottsmål. Problemen identifieras och några av dagens befintliga längdmätningsmetoder diskuteras.</p><p>Den metod som bäst uppfyller de i arbetet ställda kraven, d v s snabb handläggning, minimal systeminformation, minimalt arbete på plats och exakthet, har valts ut, anpassats och utvärderats. Metoden bygger på att hitta s k gränspunkter och grundplanets gränslinje i bilden och utifrån en i världen känd referenslängd beräkna den sökta längden. Den bakomliggande teorin presenteras och metoden beskrivs i detalj. Funktioner, algoritmer och ett användargränssnitt har implementerats i beräkningsprogrammet MatLab. Tester har utförts för att validera metodens noggrannhet och parameterberoende. Metoden visar sig ge mycket bra resultat då rätt förutsättningar ges, men har konstaterats vara känslig för variation på gränslinjen. En rad förbättringsförslag presenteras för att utveckla metoden och stabilisera resultatet.</p><p>Examensarbetet omfattar 20 högskolepoäng och utgör ett obligatoriskt moment i utbildningsprogrammet civilingenjör i datateknik som ges av Linköpings universitet. Arbetet är utfört vid och på uppdrag av Statens kriminaltekniska laboratorium (SKL) i Linköping.</p>
108

Re-examining the Traditional Principles of Cinematography of Modern Movies : a Case Study of Children of Men and Clerks II

Håkansson, Cornelia January 2013 (has links)
This thesis addresses the principles of cinematography and their significance for the visual outcome of a film. The purpose is to examine the importance of the principles for modern film and this is done through a study on how the principles are used and not used in the films Children of Men and Clerks II. The two films investigated are both known for being experimental and modern in their use of cinematography, and was therefore found suitable for this thesis. The limitation with this study is that only the four main principles of cinematography are analysed: camera angles, framings, points of view and camera movement, and they are only analysed in one shot from each film examined. In the results, the four main principles were investigated when and when not applied in the specific shot from each film. In the film Children of Men the breaking of the principle of point of view was most central, but the principle of framings and camera movement were in some cases also not applied. The only principle actually followed in this shot was the principle of camera angles. In the other film examined, Clerks II, the breaking of the principle of camera movement and camera angles was most central together with the breaking of the 180 degree rule. The principles that were followed in this clip were framings and points of view. In the conclusion the results were discussed and also the possibility of effects on the viewer, when breaking the principles. Different ideas of possible effects on the viewer were presented, but they all had disorientation in common. The possible outcome of disregarding the principles of cinematography ended up being misleading the viewer away from the narrative.
109

Context-based Innovative Mobile User Interfaces

Zhou, Yun 08 October 2012 (has links) (PDF)
Avec le développement de différents capteurs et des dispositifs, l'informatique ne se limite plus à la mode bureautique. Cependant, l'interface utilisateur traditionnelle, utilisée sur l'ordinateur de bureau, n'est plus approprié pour l'informatique ubiquitaire. La complexité de l'environnement mobile demande la conception d'interfaces dédiées impliquant des techniques d'entrée et la sortie qui contiennent les nouvelles caractéristiques émergentes au-delà des techniques traditionnelles. L'une des solutions possibles pour permettre l'interaction omniprésente soit le nomadisme, soit la mobilité. Nous proposons trois interfaces liées à ces deux solutions: L'interface fixé dan l'environnement (abréviation de IEI en anglais), interface dépendante de l'environnement (EDI) et Interface Indépendante de l'environnement (EII). Tout d'abord, nous présentons globalement notre approche sur la conception de ces trois interfaces innovantes (IEI, EDI et EII), leurs configurations portées (dispositif d'affichage portée sur les lunettes plus caméra et dispositif d'affichage pico-projecteur plus caméra), des exemples réels d'utilisation et une évaluation préliminaire des techniques d'entrée de sélection pour prouver la faisabilité de nos prototypes. Par la suite, nous proposons sur les dispositifs portées, et seule les EDI et les EII seraient étudié plus en détail. Afin de concrétiser l'EDI et l'EII, nous proposons un continuum allant de l'interface physique, l'interface mixte physique-numérique, jusqu'à l'interface totalement numérique. Basé sur l'interface physique, nous proposons le système MobilePaperAccess qui sur le dispositif d'affichage portée sur les lunettes plus caméra permettant l'accès à l'information numérique à partir d'une interface imprimé du papier. Ce système est conçu pour valider nos concepts de l'EDI et de l'EII. Les deux types d'interfaces (EDI et EII) et trois techniques d'entrée (doigt, masque et carnet) ont été évaluées par les méthodes quantitatives et qualitatives avec ce système. Basé sur l'interface numérique projetée multi-échelle, le système PlayAllAround est sur dispositif d'affichage pico-projecteur plus caméra, et il pouvoir fournir un affichage à différentes tailles, à la plus petite, individuelle et portée, à la plus grande, partageable et publique. Pour la conception de ce système, nous proposons une décomposition de l'interface basée sur une de cellule de référence de taille fixé pourrait la mise à l'échelle de l'interface en fonctionne de la taille de projection. Le geste de sélection sur un vol et l'interface multi-échelle ont été évalués avec ce système. Les résultats de nos expériences ont montré que PlayAllAround fonctionne bien avec le geste de sélection sur un vol et l'interface multi-échelle. Pour aller plus loin, nous explorons les gestes de la main, y compris le geste stationnaire, le geste de pincement et le geste de fermeture du poing. Nous employons le geste de pincement et le geste de fermeture du poing comme entrée pour pointer, l'action de glisser-déposer et la action de tracer. Afin de satisfaire aux exigences de l'interaction dans la vie quotidienne, nous étudions comment l'utilisateur peut interagir avec ces gestes à l'arrêt ou en marchant. Nous comparons les interactions du geste de sélection sur un vol et geste de pincement dans trois situations que debout, assis et en marchant. En outre, l'évaluation de l'interface projetée, ainsi que la satisfaction sur le fonctionnement de la configuration porté sur la tête a été faite et discutée. Enfin, le long du continuum, nous continuons à étudier sur l'interface mixte par un dispositif pico-projecteur plus caméra dans le but de concrétiser les concepts de l'EDI et de l'EII. L'interface mixte contient une partie physique basée sur des marqueurs d'ARToolkit et une partie numérique projetée. Comme l'écran de projection est une méthode alternative pour afficher plus d'information sans aucun support physique, l'interface mixte a la capacité de contenir davantage d'informations ainsi que de fournir plus de choix dynamiques par rapport à l'interface physique seul. En conclusion, dans cette thèse, nous avons étudié de manière théorique, la conception innovante, et nous avons proposons les prototypes concrètes et les avons évalués par les deux études quantitatives et qualitatives avec des utilisateurs. Plus généralement, ce travail est une étude multi-facette sur les interfaces portées innovantes, ainsi que les techniques avancées d'entrée et de sortie, ce qui ouvre des prospectives pour futures recherches sur les interfaces portées.
110

Transformations between Camera Images and Map Coordinates with Applications

Börjesson, Nils January 2005 (has links)
The quality of cameras is currently increasing very fast meanwhile the price of them is decreasing. The possibilities of using a camera as a measurement and navigation instrument are thus getting bigger all the time. This thesis studies the transformation relations between a camera image and the scene in space that is projected to it. A theoretical derivation of the transform will be presented, and methods and algorithms for applications based on the transform will be developed. The above mentioned transform is called the camera matrix, which contains information about the camera attitude, the camera position, and the internal structure of the camera. Useful information for several different applications can be extracted from the camera image with the help of the camera matrix. In one of the applications, treated in this Master´s thesis, the camera attitude is estimated when the camera is calibrated and its position is known. Another application is that of absolute target positioning, where a point in a digital map is searched from its position in a camera image. Better accuracy in the measurements can though be obtained with relative target positioning i.e., estimation of distance and angle between two points in the digital map by picking them out in the image. This is because that the errors of the absolute target positioning for each of the two points are dependent and thus partly will cancel each other out when their relative position and angle is measured.

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