This thesis presents a stereo coding architecture for the ITU-T G.719 fullband mono codec. G.719 is suitable for teleconferencing applications with a competitive audio quality for speech and audio signals that are encoded at 32, 48 and 64 kbps. The proposed stereo architecture comprises parametric stereo coding where the spatial properties of the stereo channels are modeled with the use of parameters, which are encoded and transmitted to the decoder together with an encoded downmix of the stereo channels. The stereo architecture has been implemented in MATLAB with an external mono coding using a floating point ANSI-C implementation of the ITU-T G.719 codec. Two parametric stereo models have been implemented in a framework operating in the complex-valued Modified Discrete Fourier Transform (MDFT) domain. The first model is based on the inter-channel cues that represent level differences, time differences and coherences between the stereo channels. The cues approximate the corresponding interaural cues that characterize our localization of sound in space. The second model is based on the Karhunen-Loève Transform (KLT) with the associated rotation angles, the inter-channel time differences and the residual scaling parameters. An improved MDFT domain extraction of the inter-channel time difference between the stereo channels has been used for both stereo models. The extracted stereo parameters have been non-uniformly quantized based on the spatial accuracy and the frequency dependency of the human auditory system. The data rate of the stereo parameters has been estimated for each model to around 4 kbps. As a result G.719 has been used as a core codec at 44 and 60 kbps in order to subjectively evaluate the performance of the fullband stereo codec at 48 and 64 kbps. In the comparison with G.719 dual mono coding, i.e. independent mono coding of the stereo channels, the evaluation showed a higher performance of the proposed stereo models for complex clean and reverberant speech signals. However, no consistent gain of the parametric stereo coding was revealed for noisy speech, mixed content and music signals. In addition, the first stereo model showed consistently a slightly higher performance than the second model in the subjective evaluation but with no significant difference. The results revealed a high potential for parametric stereo coding using the ITU-T G.719 codec. In comparison to the existing stereo codecs 3GPP AMR-WB+ and 3GPP eAAC+ the average performance was better at the equal bitrate of 48 kbps.

Modern cars can be bought with camera systems that watch the road ahead. They can be used for many purposes, one use is to alert the driver when other cars are in the path of collision. If the warning system is to be reliable, the input data must be correct. One input can be the depth image from a stereo camera system; one reason for the depth image to be wrong is if the vergence angle between the cameras are erroneously calibrated. Even if the calibration is accurate from production there's a risk that the vergence changes due to temperature variations when the car is started. This thesis proposes one solution for short-time live calibration of a stereo camera system; where the speedometer data available on the CAN-bus is used as reference. The motion of the car is estimated using visual odometry, which will be affected by any errors in the calibration. The vergence angle is then altered virtually until the estimated speed is equal to the reference speed. The method is analyzed for noise and tested on real data. It is shown that detection of calibration errors down to 0.01 degrees is possible under certain circumstances using the proposed method.

General 3D stereo vision is composed of two major phases. In the first phase, an image and its corresponding depth map are generated using stereo matching. In the second phase, depth-based image rendering (DIBR) is employed to generate images of different view angles. Stereo matching, a computation-intensive operation, generates the depth maps from two images captured at two different view positions. In this thesis, we present hardware designs of three different stereo matching methods: pixel-based, window-based, and dynamic programming (DP)-based. Pixel--based and window-based methods belong to the local optimization stereo matching methods while DP, one of the global optimization methods, consists of three main processing steps: matching cost computation, cost aggregation, and back-tracing. Hardware implementation of DP-based stereo matching usually requires large memory space to store the intermediate results, leading to large area cost. In this thesis, we propose a tile-based DP method by partition the original image into smaller tiles so that the processing of each tile requires smaller memory size.

Depth-Based Image Rendering (DIBR) is a popular method to generate 3D virtual image at different view positions using an image and a depth map. In general, DIBR consists of two major operations: image warping and hole filling. Image warping calculates the disparity from the depth map given some information of viewers and display screen. Hole filling is to calculate the color of pixel locations that do not correspond to any pixels in the original image after image warping. Although there are many different hole filling methods that determine the colors of the blank pixels, some undesirable artifacts are still observed in the synthesized virtual image. In this thesis, we present an approach that examines the geometry information near the region of blank pixels in order to reduce the artifacts near the edges of objects. Experimental results show that the proposed design can generate more natural shape around the edges of objects at the cost of more hardware and computation time.

No description available.

<p>Detta examensarbete är genomfört i samarbete med Thorbjörn Birging. Birging arbetar med RFID[1] och är även VD för CombiQ på Science Park i Jönköping. Under lång tid har han velat skapa en produkt som hjälper människor med sömnproblem, depression, ångest och stress. Författarens roll som ingenjörsstudent blev att utveckla hans ide till en färdig produkt. Birging upptäckte efter att ha läst en artikel om sömnproblem att det finns studier som visar att det är enklare att somna med ett svagt ljud i rummet för att andra personer i rummet inte skall störas. Birging fokuserade på att skapa en ny ljudkudde med denna teori som grund.</p><p> Målet med detta examensarbete blev att skapa en kudde med fokus på utmärkt stereoljud som hjälpredskap för människor med sömnproblem. Med ljudets användning blir insomningen betydligt lättare. Många människor söker hjälp för sina problem på sjukhus, men ofta får de bara recept på lugnande och antidepressiva mediciner. Ett annat problem med sömntabletter är risken för att utveckla ett beroende och en längre tids användning av medicinerna kan störa kroppens normala sömnfunktion, vilket läkaren Anders Isaksson som driver en privatklinik i Örebro kan intyga. Birging har haft kontakt med Anders under detta arbete och kan intyga detta.</p><p> Ett sätt att lindra sömnproblem är genom att patienten får lyssna till lugnande musik före insomnandet, vilket alltså är tanken med denna kudde. Författaren genomförde en undersökning för att ta reda på vad som är bra och dåligt med dagens ljudkuddar. En idégenerering och kravspecifikation påbörjades med hjälp av Birging. För att kunna veta vad kunderna önskar sig med denna nya produkt gjordes bland annat en designbrief, funktionsanalys och en QFD-matris. Designbriefen skapades både verbalt och visuellt för att se hur den nya produkten skall se ut på markanden. QFD-matrisen rangordnar kraven och konkurrenternas kuddar i förhållande till Birgings krav på den nya prototypen. QFD ger inte svar på vad kunden får för upplevelse med produkten vilket designbriefen kan åstadkomma. Konstruerandet av prototypen kan börja först när designbriefen och funktionsanalysen är klara. Materialvalet gjordes genom testfaser som ljudåtergivning och komfort. Skumplast materialen kommer ifrån Recticel AB i Gislaved och ett intresse för denna nya produkt finns i den framtida utvecklingen.</p><p> Denna nya produkt blev betydligt bättre än de ljudkuddar som finns på marknaden. Den nya produkten har egenskaper som tryckavlastning samt bättre ljudkvalitet vilket innebär att volymen inte behöver vara hög, vilket gör att omgivningen inte störs. Orsaken till att ljudet inte stör är att spridningen av ljudet mestadels riktas upp mot användaren. Kuddens mått är B50*H40*T5 cm innebär att man enkelt kan köpa vanliga örngott och att den inte ta onödig plats i sängen.</p><p>[1] Radio Frequency IDentification</p> / <p>This exam is done with the cooperation of Thorbjörn Birging. Birging does work with RFID[1] and he is also CEO at CombiQ at Science Park in Jönköping. For a long time he wanted to make an innovation to help people with sleeping problems, depression, anxiety and stress. The author’s role as an engineer student where to make his idea come true from scratch to prototype. Birging discovered after reading an article about sleeping problems that there were studies which showed that it is easier to sleep with a faint sound in the room so other people in the room does not get disturbed. Birging then focused to create a new pillow with sound integrated that should stand out from today’s pillows.</p><p> The goal with this exam was to create a pillow with excellent stereo sound with amplifiers, which help peoples sleeping problems. Many people with these problems seek help at hospitals, but they only get prescriptions for tranquillizer and anti-depressive pills. Another issue with sleeping pills is the risk of getting addicted and long time use might disturb the normal sleeping function, which Anders Isaksson can confirm. Birging He runs a private clinic in Örebro and has helped Birging in a previous project. Birging has been in contact with Anders under this project and can confirm this statement.</p><p> One way of relive sleeping problems might be to let the patient listen to calming music before the sleep period begins, which is the idea for this project. The author did an investigation to find any positives or negatives in today’s pillows with sound ability. Idea generating and require specification started soon after this with help of Birging. To know what the customers want with this new product a designbrief, function analytic and a QFD-matrix. The designbrief where made both verbal and visual to know how the product should look like as a customer. With the QFD-matrix we can rank the preferences with the competitors pillows in relation to Birgings requirements on the new prototype. The QFD doesn’t give any answers how the customer experience the product that the designbrief can accomplish. A prototype construction can only begin when the designbrief and function analytic are finished. The material selection was made by different test-phases with sound and comfort. Recticel AB in Gislaved has provided the author with different types of foam for the pillow and for this new product there is an interest to follow the development in the future. </p><p> The new developed product did manage to become better than the competitor’s pillows in many ways. The new product is pressure relieving, gives better sound which means the volume does not have to be high, and disturbance in the surroundings is minimized. The reason is that the material does spread the sound waves straight upwards the users ears. The pillows measurement are B50*H40*T5, that means you can have much space in bed and easy find a standard pillowcase. The user will get a comfortably sleeping period the entire night with this new product.</p><p>[1] Radio Frequency IDentification</p>

Thesis (MSc (Mathematics))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: In this thesis we consider the essential topics relating to stereo-vision and the correspondence problem in general. The aim is to reconstruct a dense 3D scene from images captured by two spatially related cameras. Our main focus, however, is on speed and real-time implementation on a standard desktop PC. We wish to use the CPU to solve the correspondence problem and to reserve the GPU for model rendering. We discuss three fundamental types of algorithms and evaluate their suitability to this end. We eventually choose to implement a hierarchical version of the dynamic programming algorithm, because of the good balance between accuracy and speed. As we build our system from the ground up we gradually introduce necessary concepts and established geometric principles, common to most stereovision systems, and discuss them as they become relevant. It becomes clear that the greatest weakness of the hierarchical dynamic programming algorithm is scanline inconsistency. We nd that the one-dimensional LULU- lter is computationally inexpensive and e ective at removing outliers when applied across the scanlines. We take advantage of the hierarchical structure of our algorithm and sub-pixel re nement to produce results at video rates (roughly 20 frames per second). A 3D model is also constructed at video rates in an on-line system with only a small delay between obtaining the input images and rendering the model. Not only is the quality of our results highly competitive with those of other state of the art algorithms, but the achievable speed is also considerably faster. / AFRIKAANSE OPSOMMING: In hierdie tesis beskou ons die noodsaaklike onderwerpe wat in die algemeen verband hou met stereovisie en die ooreenstemmingsprobleem. Die mikpunt is om 'n digte 3D toneel te rekonstrueer vanaf beelde wat deur twee ruimtelik-verwante kameras vasgelê is. Ons hoofdoel is egter spoed, en intydse implementering op 'n standaard rekenaar. Ons wil die SVE (CPU) gebruik om die ooreenstemmingsprobleem op te los, en reserveer die GVE (GPU) vir model-beraping. Ons bespreek drie fundamentele tipes algoritmes en evalueer hul geskiktheid vir hierdie doel. Ons kies uiteindelik om 'n hiërargiese weergawe van die dinamiese programmeringsalgoritme te implementeer, as gevolg van die goeie balans tussen akkuraatheid en spoed. Soos wat ons ons stelsel van die grond af opbou, stel ons geleidelik nodige konsepte voor en vestig meetkundige beginsels, algemeen tot meeste stereovisie stelsels, en bespreek dit soos dit toepaslik word. Dit word duidelik dat skandeerlyn-strydigheid die grootste swakheid van die hiërargiese dinamiese programmeringsalgoritme is. Ons vind dat die een-dimensionele LULU- lter goedkoop is in terme van berekeninge, en e ektief aangewend kan word om uitskieters te verwyder as dit dwarsoor skandeerlyne toegepas word. Ons buit die hiërargiese struktuur van ons algoritme uit en kombineer dit met sub-piksel verfyning om resultate te produseer teen video tempo (ongeveer 20 raampies per sekonde). 'n 3D model word ook gekonstrueer teen video tempo in 'n stelsel wat aanlyn loop, met slegs 'n klein vertraging tussen die verkryging van die intree-beelde en die beraping van die model. Die kwaliteit van ons resultate is nie net hoogs mededingend met dié van die heel beste algoritmes nie, maar die verkrygbare spoed is ook beduidend vinniger.

L'expérience STEREO a été proposé afin de donner une réponse sans ambiguïté àl'idée d'un état de neutrino stérile léger ($Delta m^{2}sim 1eV^{2}$) comme l'origine del'anomalie réacteur des antineutrinos. Le but de l'expérience est de confirmer ou de rejetercette hypothèse en recherchant un patron d'oscillation à courte distance (9-11 m) dans lespectre en énergie des $overline{nu_{e}}$'s émis par le réacteur nucléaire de recherchede l'Institut Laue-Langevin à Grenoble (France). A cet effet, le détecteur estcomposé de 2 tonnes du liquide scintillant dopé au Gd et lu par un réseau detubes photomultiplicateurs, et est segmenté en 6 cellules dans la direction depropagation des antineutrinos. Les $overline{nu_{e}}$'s sont détectés par le processusIBD en observant un signal corrélé dans letemps d'un dépôt d'énergie rapide d'un positron et un signal retardé produitpar la capture d'un neutron. La mesure des petites oscillations deformantle spectre d'énergie des antineutrinos nécessite une bonne résolution en énergieet une excellente connaissance de la réponse du détecteur. Ce manuscrit présenteune étude de simulation détaillée basée sur le logiciel Geant4 STEREO, ce quia permis le développement du système de calibration par sources. Ce système aété conçu pour répondre à toutes les exigences physiques de STEREO: calibrerl'échelle de l'énergie et de l'efficacité de capture de neutrons au niveau de 2%,connaître la réponse en énergie dans le spectre d'énergie réacteur antineutrino(1-8 MeV), étudier et la caractériser la réponse et des non-uniformités dudétecteur. A cet effet, on propose un système de calibration consistant en trois sous-systèmes:un sous-système automatisé pour déplacer des sources radioactives autour dudétecteur pour calibrer l'échelle en énergie dans chaque cellule de manièreindépendante. Un second sous-système pour déplacer une source AmBe sous ledétecteur, dont l'objectif est d'inter-calibrerl'efficacité de capture de neutrons entre les cellules. Enfin, un troisième systèmemanuel qui consistent en trois tubes de calibration placés à l'intérieur du liquidescintillante pour évaluer l'efficacité absolue de la capture des neutrons danstrois cellules différentes. La dernièrepartie de ce manuscrit est consacré à l'étude et la caractérisation du bruite de fond gammaet les signaux neutrino attendus. / The STEREO experiment has been proposed to give an unambiguous responseto the hypothesis of a light sterile neutrino state ($Delta m^{2}sim 1 eV^{2}$)as the origin of the reactor antineutrino anomaly. Its goal is to confirm or reject thishypothesis by searching at short distance (9-11 m) for a neutrino oscillation patternin the energy spectrum of the $overline{nu_{e}}$’s emitted by the research nuclear reactorof the Laue-Langevin Institute in Grenoble (France). To this end, the detector iscomposed of 2 tons of Gd-loaded liquid scintillator read out by an array of PMTs, andis segmented in 6 cells in the direction of the $overline{nu_{e}}$’s propagation. Antineutrinosare detected via the IBD process by observing a time correlatedsignal composed of a prompt energy deposit from a positron and a delayed signal produced bythe neutron capture. Measuring small oscillations superimposed on the reactor antineutrinoenergy spectrum requires a good energy resolution and an excellent knowledge ofthe detector response. This manuscript presents a dedicated Geant4 simulation studyof a calibration system based on radioactive sources.This system has been conceived to fulfill all the STEREO physics requirements:calibrating the energy scale and the neutron capture efficiency at the 2 % level,knowing the energy response in the reactor antineutrino energy spectrum (0-8 MeV),and characterizing the detector response in a broader sense (non-uniformities, non-linearity,particle identification, etc). To this end, we proposethree calibration subsystems: one automated subsystem to moveradioactive sources around the detector, whose main role is to calibrate the energy scale in each cellindependently; a second subsystem to inter-calibrate the neutron captureefficiency between cells by moving an AmBe source under the detector; and finally,a third subsystem consisting in three manualcalibration tubes inside the liquid scintillator, necessary to assess the absolute neutron captureefficiency inside three different cells. The final part of this manuscript is devoted tothe study of the selection criteria, and the proposal of methods to reject the expected gammabackground.

Ce travail de thèse présente un nouveau modèle de projection pour les cameras fisheye, qui est mathématiquement simple et pourtant montre une haute précision une fois appliqué aux caméras réelles. Les propriétés géométriques de ce modèle ont été analysées en utilisant le concept de surface de projection, introduit dans ce travail. En particulier, une inverse analytique de ce modèle a été établie, ainsi qu'une équation implicite des projections de lignes droites. Cette dernière nous a permis de développer une méthode de reconstruction 3D directe basée vision pour les caméras fisheye sans rectifier les images. Cela a été fait grâce à une algorithme de rastérisation de courbes implicites. Cet algorithme de reconstruction nous permet d'employer le Semi-Global Matching pour obtenir une reconstruction 3D précise. Tous ces éléments ont été employés dans un système de localisation visuelle directe avec deux méthodes de recalage d'images : minimisation d'erreur photométrique et maximisation d'information mutuelle. L'étalonnage intrinsèque et extrinsèque d'un robot mobile équipé de caméras fisheye a été considéré et une toolbox d'étalonnage a été développée. / This thesis presents a novel projection model for fisheye cameras, which is mathematically simple and yet shows a high precision when applied to real cameras. Geometric properties of the model have been analyzed using the concept of projection surface, introduced in this work. In particular, a closed-form inverse mapping and an implicit equation for straight line projection have been found. This fact has been used to develop a method of direct stereo correspondence on raw fisheye images via rasterization of implicit curve. This correspondence algorithm allows us to apply the Semi-Global Matching algorithm to get an accurate 3D reconstruction using fisheye stereo systems. All these elements have been shown to be applicable to a direct visual localization system with two different methods of image registration: direct photometric error minimization and mutual information maximization. Intrinsic and extrinsic calibration of a mobile robot with fisheye cameras has been considered and a toolbox for such a calibration has been developed.

The problem of estimating depth from two or more images is a fundamental problem in computer vision, which is commonly referred as to stereo matching. The applications of stereo matching range from 3D reconstruction to autonomous robot navigation. Stereo matching is particularly attractive for applications in real life because of its simplicity and low cost, especially compared to costly laser range finders/scanners, such as for the case of 3D reconstruction. However, stereo matching has its very unique problems like convergence issues in the optimisation methods, and challenges to find matches accurately due to changes in lighting conditions, occluded areas, noisy images, etc. It is precisely because of these challenges that stereo matching continues to be a very active field of research. In this thesis we develop a binocular stereo matching algorithm that works with rectified images (i.e. scan lines in two images are aligned) to find a real valued displacement (i.e. disparity) that best matches two pixels. To accomplish this our research has developed techniques to efficiently explore a 3D space, compare potential matches, and an inference algorithm to assign the optimal disparity to each pixel in the image. The proposed approach is also extended to the trinocular case. In particular, the trinocular extension deals with a binocular set of images captured at the same time and a third image displaced in time. This approach is referred as to t +1 trinocular stereo matching, and poses the challenge of recovering camera motion, which is addressed by a novel technique we call baseline recovery. We have extensively validated our binocular and trinocular algorithms using the well known KITTI and Middlebury data sets. The performance of our algorithms is consistent across different data sets, and its performance is among the top performers in the KITTI and Middlebury datasets.