Multimedia environmental monitoring involves capturing valuable visual and audio information from the field station. This will permit the environmentalists and researchers to analyze the habitat and vegetation of a region with respect to other environmental specifics like temperature, soil moisture, etc. This thesis deals with the development of a test bed for multimedia monitoring by capturing image information and making it available for the public. A USB camera and a Single board computer are used to capture images at a specified frequency. A web-client is designed to display the image data and establish a secured remote access to reconfigure the field station. The development includes two modes of image acquisition including a basic activity recognition algorithm. Good quality images are captured with the cost for development of the system being less than 2 hundred dollars.

<p dir="ltr">Road safety analysis typically relies on the correlation between road surface conditions, lane marking status, or lane width and crash data. Traditionally, this data is surveyed in the field after road construction or car accidents, which is labor-intensive, time-consuming, and hazardous. With the development of mobile mapping systems (MMS) in recent years, the ability to collect lane marking retroreflectivity or lane width information has been greatly improved. By utilizing Light Detection and Ranging (LiDAR) point clouds and RGB images captured by MMS, it is possible to establish lane marking inventory that includes the conditions of pavement markers (such as lane marking retroreflectivity and lane width) for road safety analysis.</p><p dir="ltr">This dissertation aims to develop a comprehensive framework to extract lane markings and report their characteristics using MMS datasets for transportation safety. The proposed approaches include geometric/morphological and deep learning-based approaches based on the LiDAR point clouds acquired by MMS. A normalization strategy is developed to ensure consistent intensity values across laser beams/LiDAR units/MMS for the same objects, thereby enhancing the lane marking extraction. In addition, an image-aided LiDAR approach is proposed to improve the extraction process further. Following the extraction, lane marking classification and characterization, including intensity profile generation and lane width estimation, are conducted to establish comprehensive lane marking inventory.</p><p dir="ltr">To evaluate the proposed strategies, lane marking extraction with and without intensity normalization is also conducted. The results show that the proposed intensity normalization significantly improves the performance of lane marking extraction, regardless of the approach or data used. The geometric approach using normalized intensity achieves F1-scores higher than 90%, outperforming the learning-based models. Furthermore, the intensity derived from two different MMS is compared for performance evaluation, and the agreement of normalized intensity values is within a range of 3.1 to 3.8 (the used MMS provide intensity as an integer number within 0 to 255). Through the normalization, a positive linear relationship between LiDAR normalized intensity and retroreflectivity is found, with the strongest relationship providing an R² of 0.72 and a Pearson's correlation coefficient of 0.85. A comparison of the correlation between original/normalized intensity and retroreflectivity revealed a stronger correlation between original intensity and retroreflectivity. For image-aided LiDAR approach, the image information indeed enhanced the LiDAR-based lane marking extraction approach, as evidenced by the highest F1-score (92.5%) of the image-aided LiDAR approach, outperforming the LiDAR-based (90.3%) and image-based (77.8%) ones. Specifically, the recall increases by 4.0% – from 87.6% (LiDAR-based) to 91.6% (image-aided LiDAR) – surpasses the slight improvement in the precision of 0.2% – from 93.2% (LiDAR-based) to 93.4% (image-aided LiDAR).</p><p dir="ltr">Finally, a Potree-based web portal is developed to visualize the results derived through the proposed lane marking extraction/classification/characterization strategies. This portal includes a function that enables the projection between 2D images and 3D point clouds, as well as tools for displaying intensity profiles and lane width estimates. It is capable of rendering a large dataset of {approximately 4.2 billion LiDAR points} in around ten seconds and allows for the visualization of intensity profiles and lane width estimates. Users can select points of interest in an intensity profile/lane width plot. This selection will result in the corresponding point being showcased in the LiDAR data on the web portal. Furthermore, the LiDAR point can be projected onto the corresponding image.</p><p dir="ltr">The above proposed strategies facilitate the investigation of the relationship between LiDAR intensity and mobile retroreflectivity. To ensure quality control, lane markings derived from geometric and learning-based extraction approaches were compared. These strategies were evaluated using two MMS (equipped with multiple imaging and LiDAR sensors), covering extensive road segments exceeding 400 miles. Furthermore, a reporting mechanism based on multi-modal data from various MMS sensors was implemented to visualize the results derived from the proposed strategies and to serve as a quality control tool. Consequently, the proposed strategies are easily adaptable for different MMS or the regular updating of lane marking inventory.</p>

No / Neonatal chest radiography is a frequently performed diagnostic examination, particularly in preterm infants where anatomical and/or biochemical immaturity impacts on respiratory function. However, the quality of neonatal radiographic images has been criticized internationally and a prevailing concern has been that radiographers (radiologic technologists) fail to appreciate the unique nature of neonatal and infant anatomical proportions. The aim of this study was to undertake a retrospective evaluation of neonatal chest radiography image acquisition techniques against key technical criteria. Methods Hundred neonatal chest radiographs, randomly selected from all those acquired in 2014, were retrospectively evaluated. Inclusion criteria for radiographs acquisition were as follows: anterior-posterior supine; within 30 days of birth; and with all preprocessed collimation boundaries visible. Image evaluation was systematically undertaken using an image assessment tool. To test for statistical significance, Student's t-test, χ2 test, and logistic regression were undertaken. Results Only 47% of the radiographs were considered straight in both upper and lower thoraces. The cranial collimation border extended beyond the upper border of the third cervical vertebra in 30% of cases, and the caudal border extended below the lower border of the first lumbar vertebra in 20% of cases, suggesting high possibility of neonatal overirradiation. Upper thorax rotation was significantly associated with head position (χ2 = 10.907; P < .001) as has been stated in many published textbooks internationally, but arm position had no apparent influence on rotation of the upper thorax (χ2 = 5.1260; P = .275). Birth weight was associated with accurate midline centering of central ray (logistic regression; OR = 1.0005; P = .009; CI, 1.00139–1.000957) with greater accuracy observed in images of neonates with higher birth weight. Conclusion This study has highlighted areas for neonatal chest radiography improvement. Importantly, the findings bring into question commonly advocated radiographic techniques relating to arm positioning and assessment of rotation while confirming the importance of other technical factors. These findings begin the work toward developing the evidence base to underpin neonatal chest radiograph acquisition, but further prospective work and multicenter/multinational data comparison are required to confirm the findings.

Thesis (PhD (Electronic Engineering))--University of Stellenbosch, 2010. / Contains bibliography and index. / ENGLISH ABSTRACT: Super-resolution imaging is the process whereby several low-resolution photographs of an object are combined to form a single high-resolution estimation. We investigate each component of this process: image acquisition, registration and reconstruction. A new feature detector, based on the discrete pulse transform, is developed. We show how to implement and store the transform efficiently, and how to match the features using a statistical comparison that improves upon correlation under mild geometric transformation. To simplify reconstruction, the imaging model is linearised, whereafter a polygon-based interpolation operator is introduced to model the underlying camera sensor. Finally, a large, sparse, over-determined system of linear equations is solved, using regularisation. The software developed to perform these computations is made available under an open source license, and may be used to verify the results. / AFRIKAANSE OPSOMMING: In super-resolusie beeldvorming word verskeie lae-resolusie foto's van 'n onderwerp gekombineer in 'n enkele, hoë-resolusie afskatting. Ons ondersoek elke stap van hierdie proses: beeldvorming, -belyning en hoë-resolusie samestelling. 'n Nuwe metode wat staatmaak op die diskrete pulstransform word ontwikkel om belangrike beeldkenmerke te vind. Ons wys hoe om die transform e ektief te bereken en hoe om resultate kompak te stoor. Die kenmerke word vergelyk deur middel van 'n statistiese model wat bestand is teen klein lineêre beeldvervormings. Met die oog op 'n vereenvoudigde samestellingsberekening word die beeldvormingsmodel gelineariseer. In die nuwe model word die kamerasensor gemodelleer met behulp van veelhoek-interpolasie. Uiteindelik word 'n groot, yl, oorbepaalde stelsel lineêre vergelykings opgelos met behulp van regularisering. Die sagteware wat vir hierdie berekeninge ontwikkel is, is beskikbaar onderhewig aan 'n oopbron-lisensie en kan gebruik word om die gegewe resultate te veri eer.

Les techniques de reconstruction 3d sont devenues incontournables pour des applicationstelles que la caractérisation et l'analyse de surfaces. Les travaux réalisés au coursde cette thèse ont pour objectif d'améliorer la qualité des reconstructions 3d par stéréophotométrie.Cette méthode repose sur deux principes, l'inversion d'un modèle d'interactionlumière/matière (BRDF) et la configuration d'un système d'éclairage et de prises de vues.Pour des surfaces diffuses, la stéréo-photométrie est réalisée à partir d'un minimum detrois images acquises d'un point de vue fixe pour des directions d'éclairages différentes.Son avantage est d'extraire simultanément les propriétés géométriques et colorimétriquesdes surfaces analysées même en cas de forte rugosité. Néanmoins, son application exige laformulation de plusieurs hypothèses qui sont difficilement respectables dans un contexteréel. Ceci génère des erreurs significatives dans les reconstructions. Pour les réduire, nousproposons différentes contributions qui s'articulent autour de la prise en compte globale de lachaine d'acquisition. Les apports de nos travaux se situent aux niveaux de la caractérisationet de la modélisation du système d'éclairage, du capteur d'acquisition et de l'améliorationde la qualité des images. Nous nous sommes aussi intéressés à l'optimisation des protocolesde prises de vues dans le cas de spécularité surfacique ou d'ombrage dus à la présence derugosité. Les résultats obtenus montrent que la prise en compte de ces caractéristiques dansl'inversion d'un modèle de BRDF permet une nette amélioration des reconstructions et offrela possibilité de réduire la taille des systèmes d'acquisition. / Tridimensional reconstruction method has become essential for applications suchas the characterization and analysis of surfaces. In this thesis, aims are to increase the qualityof 3d reconstructions by photometric stereo. This method is based on two principles, reversinglight-matter interaction model and configuration of a lighting system. With diffuse surfaces,the photometric stereo use three captured images from a fixed point of view for differentillumination directions. Its main advantage is to extract the color and geometric propertiesfor the textured rough surfaces. However, its application requires to make assumptions thatare not credible in real cases. This problem generates significant errors in the reconstructions.To reduce them, we offer various solutions around the overall consideration of the acquisitionchain. Our contribution focuses on the characterization and modeling of the lighting system,the acquisition sensor and improved image quality. We are also interested to optimize acquisitionprotocol in the case of specular surface or shading due to the surface geometry. Ourresults show that the inclusion of these features in the inversion of a BRDF model allowsan improvement of 3d reconstructions as well as the possibility of reducing the size of theacquisition systems.

L'étude de l'apparence de surfaces par analyse photométrique est un domaine de recherche actif, avec de nombreuses applications par exemple pour étudier de la qualité de surfaces, la rugosité des objets, leur apparence, etc. Le sujet de cette thèse concerne plus particulièrement l'étude de surfaces opaques, par l'acquisition de la géométrie et de la réflectance. Cela nous a conduit à une analyse des modèles mathématique de réflectance, permettant de représenter les matériaux. Afin d'offrir une description physiquement plausible des matériaux opaques, notre première contribution principale concerne la mise en oeuvre d'un modèle à base de microfacettes Lambertiennes interfacées. Il généralise différents modèles de la littérature incluant des surfaces planes diffuses ou spéculaires et rugueuses diffuses ou spéculaires grâce à trois paramètres physiques : couleur, rugosité et indice de réfraction. Il permet de prendre en compte la transmission des flux lumineux pénétrant sous la surface ainsi que les réflexions multiples entre microfacettes et de restituer les effets de rétrodiffusion lumineuse et d’anisotropie. Notre seconde contribution principale concerne la réalisation d'un système complet d'acquisition de la géométrie et de la réflectance d'objets à partir d'images HDR. Notre méthodologie correspond à une chaîne de reconstruction complète et automatique, uniquement à partir d'images, permettant d'obtenir un niveau de précision intéressant et un faible coût de mise en place et de temps de traitement comparé aux méthodes existantes. Notre méthode permet d'extraire des échantillons de réflectance suffisamment nombreux pour identifier les paramètres de modèles de réflectance avec les données acquises. / The study of surface appearance by photometric analysis is an active area of research, with various applications concerning the analysis of surface roughness or appearance ... The subject of this PhD dissertation relates to the study of opaque surfaces, through the acquisition of their geometry. Our study leads us to an analysis of mathematical reflectance models, for representing materials appearance. To provide a physically plausible description of opaque surfaces, the first major contribution concerns the implementation of a model based on Lambertian interfaced microfacets. This model generalizes several approaches often referenced in the literature, and includes flat diffuse or specular surfaces as well as diffuse or specular microfacets with three physically-based parameters: color, roughness and refractive index. It makes it possible to take into account the transmission of the light flux entering below the surface as well as multiple reflections between microfacets, while handling backscattering and anisotropy. The second main contribution of this work concerns the impolementation of a complete acquisition system for estimating geometry and reflectance from HDR images. Our methodology is based on a complete and automatic reconstruction framework, achieving a higher level of precision, a lower cost of implementation and a shorter processing time compared to photometry-based existing methods.

Tailings storage facilities (TSFs) serve as structures for storing tailings, i.e., waste materials generated by the mining industry. In recent years, tailings dam failures and collapse of these constructions have been reduced due to the establishment of regulations to control these structures, nevertheless, the consequences are catastrophic when tailings dam failures occur. There are some different construction methods for tailings dams. One common construction method is the upstream method; where the dam is raised by constructing embankments on top of the tailings stored in the impoundment. Thus, it is essential to understand the mechanical and geochemical behavior of deposited tailings to be able to perform safety assessments of tailings dams.  Material properties must be assessed for the present time as well as over a longer time since aging and continuous deposition might change the mechanical behavior over time. Continuous deposition leads to continuous increased vertical stress on particles, and there is a need to study if increased vertical stress can lead to a possible change of the mechanical properties of tailings. Therefore, this study has investigated the characteristics of tailings particles after being subjected to vertical stepwise loading. This study focuses on investigating the impact of particle breakage (or crushing) on tailings by analyzing material recovered from a tailings dam in Sweden. The research was performed on disturbed tailings material from a borehole of approximately 40 m depth. The study was conducted on four samples recovered 10 m apart, developing a characterization of the material and laboratory tests on each of them. The characterization consisted of the determination of intrinsic properties such as particle size distribution, particle shape, and mineralogy before and after testing; while the laboratory tests were conducted by means of the odometer test. The laboratory tests employed the oedometer test, which applies a vertical load in slow increments under K0 conditions to simulate the behavior of tailings consolidated in the impoundment. The results obtained from the oedometer tests showed interesting observations regarding changes in particle size distribution (PSD) before and after testing. Based on this study it is hard to conclude if the change in PSD solely is caused by crushing. Three samples show a PSD after oedometer which have slightly more fines than before oedometer, while the last sample has neglectable change in PSD. Theoretically, this small change in PSD indicates that larger tailings particles exhibited a higher susceptibility to some degree of crushing, but since the change is so small it cannot be excluded that the changes origins from the accuracy of determining the PSD.  The samples taken at different depths were prepared using the tamping method, and the oedometer testing indicated minimal differences in their compression characteristics, and since the soil fabric was destroyed under sampling and then reconstituted through tamping this is expected. To investigate the influence of particle arrangement on the compression and potential crushing, one of the samples was tested in a slurry configuration. This test demonstrated that particle arrangement appears to be a contributing factor to crushing, as it showed less deviation in particle size distribution compared to the tamped sample. To contextualize and validate the findings, the results were correlated, evaluated, and compared with previous studies conducted on tailings from the same tailings storage facility (TSF). Although future research on crushing in correlation of mineralogy respectively and changes in particle shape are needed, this comparative analysis has provided input that can contribute to enhanced understanding of tailings behavior under increased vertical load.

International Telemetering Conference Proceedings / October 17-20, 1994 / Town & Country Hotel and Conference Center, San Diego, California / This paper describes a system in which multiple embedded processors are used for real-time processing of telemetry streams from satellites and radars. Embedded EPC-5 modules are plugged into VME slots in a Loral System 550. Telemetry streams are acquired and decommutated by the System 550, and selected parameters are packetized and appended to a mailbox which resides in VME memory. A Windows-based program continuously fetches packets from the mailbox, processes the data, writes to log files, displays processing results on screen, and sends messages via a modem connected to a serial port.

Elastography, which is based on applying pressure and estimating the resulting deformation, involves the forward problem to obtain the strain distributions and inverse problem to construct the elastic distributions consistent with the obtained strains on observation points. This thesis focuses on the former problem whose solution is used as an input to the latter problem. The aim is to provide the inverse problem community with accurate strain estimates of a coronary artery vessel wall. In doing so, a new ultrasonic image-based elastography approach is developed. Because the accuracy and quality of the estimated strain fields depend on the resolution level of the ultrasound image and to date best resolution levels obtained in the literature are not enough to clearly see all boundaries of the artery, one of the main goals is to acquire high-resolution coronary vessel wall ultrasound images at different pressures. For this purpose, first an experimental setup is designed to collect radio frequency (RF) signals, and then image formation algorithm is developed to obtain ultrasound images from the collected signals. To segment the noisy ultrasound images formed, a geodesic active contour-based segmentation algorithm with a novel stopping function that includes local phase of the image is developed. Then, region-based information is added to make the segmentation more robust to noise. Finally, elliptical deformable template is applied so that a priori information regarding the shape of the arteries could be taken into account, resulting in more stable and accurate results. The use of this template also implicitly provides boundary point correspondences from which high-resolution, size-independent, non-rigid and local strain fields of the coronary vessel wall are obtained.

DL’objectif de cette thèse est le développement de techniques adaptées à l’application de la théorie de l’acquisition compressée en imagerie ultrasonore 3D et Doppler. En imagerie ultrasonore 3D une des principales difficultés concerne le temps d’acquisition très long lié au nombre de lignes RF à acquérir pour couvrir l’ensemble du volume. Afin d’augmenter la cadence d’imagerie une solution possible consiste à choisir aléatoirement des lignes RF qui ne seront pas acquises. La reconstruction des données manquantes est une application typique de l’acquisition compressée. Une autre application d’intérêt correspond aux acquisitions Doppler duplex où des stratégies d’entrelacement des acquisitions sont nécessaires et conduisent donc à une réduction de la quantité de données disponibles. Dans ce contexte, nous avons réalisé de nouveaux développements permettant l’application de l’acquisition compressée à ces deux modalités d’acquisition ultrasonore. Dans un premier temps, nous avons proposé d’utiliser des dictionnaires redondants construits à partir des signaux d’intérêt pour la reconstruction d’images 3D ultrasonores. Une attention particulière a aussi été apportée à la configuration du système d’acquisition et nous avons choisi de nous concentrer sur un échantillonnage des lignes RF entières, réalisable en pratique de façon relativement simple. Cette méthode est validée sur données 3D simulées et expérimentales. Dans un deuxième temps, nous proposons une méthode qui permet d’alterner de manière aléatoire les émissions Doppler et les émissions destinées à l’imagerie mode-B. La technique est basée sur une approche bayésienne qui exploite la corrélation et la parcimonie des blocs du signal. L’algorithme est validé sur des données Doppler simulées et expérimentales. / This thesis is dedicated to the application of the novel compressed sensing theory to the acquisition and reconstruction of 3D US images and Doppler signals. In 3D US imaging, one of the major difficulties concerns the number of RF lines that has to be acquired to cover the complete volume. The acquisition of each line takes an incompressible time due to the finite velocity of the ultrasound wave. One possible solution for increasing the frame rate consists in reducing the acquisition time by skipping some RF lines. The reconstruction of the missing information in post processing is then a typical application of compressed sensing. Another excellent candidate for this theory is the Doppler duplex imaging that implies alternating two modes of emission, one for B-mode imaging and the other for flow estimation. Regarding 3D imaging, we propose a compressed sensing framework using learned overcomplete dictionaries. Such dictionaries allow for much sparser representations of the signals since they are optimized for a particular class of images such as US images.We also focus on the measurement sensing setup and propose a line-wise sampling of entire RF lines which allows to decrease the amount of data and is feasible in a relatively simple setting of the 3D US equipment. The algorithm was validated on 3D simulated and experimental data. For the Doppler application, we proposed a CS based framework for randomly interleaving Doppler and US emissions. The proposed method reconstructs the Doppler signal using a block sparse Bayesian learning algorithm that exploits the correlation structure within a signal and has the ability of recovering partially sparse signals as long as they are correlated. This method is validated on simulated and experimental Doppler data.