Dense real-time 3D reconstruction from multiple images

The rapid increase in computer graphics and acquisition technologies has led to the widespread use of 3D models. Techniques for 3D reconstruction from multiple views aim to recover the structure of a scene and the position and orientation (motion) of the camera using only the geometrical constraints in 2D images. This problem, known as Structure from Motion (SfM) has been the focus of a great deal of research effort in recent years; however, the automatic, dense, real-time and accurate reconstruction of a scene is still a major research challenge. This thesis presents work that targets the development of efficient algorithms to produce high quality and accurate reconstructions, introducing new computer vision techniques for camera motion calibration, dense SfM reconstruction and dense real-time 3D reconstruction. In SfM, a second challenge is to build an effective reconstruction framework that provides dense and high quality surface modelling. This thesis develops a complete, automatic and flexible system with a simple user-interface of `raw images to 3D surface representation'. As part of the proposed image reconstruction approach, this thesis introduces an accurate and reliable region-growing algorithm to propagate the dense matching points from the sparse key points among all stereo pairs. This dense 3D reconstruction proposal addresses the deficiencies of existing SfM systems built on sparsely distributed 3D point clouds which are insufficient for reconstructing a complete 3D model of a scene. The existing SfM reconstruction methods perform a bundle adjustment optimization of the global geometry in order to obtain an accurate model. Such an optimization is very computational expensive and cannot be implemented in a real-time application. Extended Kalman Filter (EKF) Simultaneous Localization and Mapping (SLAM) considers the problem of concurrently estimating in real-time the structure of the surrounding world, perceived by moving sensors (cameras), simultaneously localizing in it. However, standard EKF-SLAM techniques are susceptible to errors introduced during the state prediction and measurement prediction linearization.

NASA Tech Briefs, December 1992

Topics include: Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences

Microscopic imaging and photo-stimulation using micro-structured light emitting diodes

Imperial Users onl

Investigation into the cellular radiosensitivity of the LEC rat and analysis of candidate genes

Recent work has underlined the importance of animal models in discovery and characterisation of molecular mechanisms determining radiosensitivity and radioresistance. Enhanced sensitivity of LEC rats to ionizing radiation in terms of the acute radiation syndrome was investigated in the present work on the cellular level and compared to that of LE rats. To understand the molecular basis for the increased radiation sensitivity a series of studies were performed, which included the classical clonogenic survival assay, investigation of double strand break repair by means of PFGE and gH2AX evaluation, comet assay for evaluation of repair of single strand breaks and alkaline labile sites, and analysis of cell cycle progression of asynchronous fibroblast population. Survival assay, PFGE, and H2AX analysis were performed in a standardised experimental system - confluent fibroblasts, synchronized in G1 phase of cell cycle, and comet assays were performed in G0 lymphocytes. The data suggests a mild radiosensitization of LEC fibroblasts compared to LE. The results of studies using the selected model did not reflect the degree of animal sensitivity on the molecular level, since values of dose modifying factor (DMF) were much lower in fibroblasts (DMF2 = 1.32) compared to that of animal sensitivity (DMF = 2.36 for bone marrow syndrome (LD50/30) and DMF = 1.95 of intestinal death (LD50/7)). The investigation of DNA repair and cell cycle did not reveal a significant defect in the studied pathways in synchronized fibroblasts and cell cycle progression was not different from wild type cells. The presented data contradict the published LEC cellular phenotype. Of the possible candidate genes, which are located in the radiosensitivity locus, several were further analysed. Among those, Gata-2 appeared to be the most promising of the positional and functional candidates. However, no mutation in the coding sequence could be identified and mRNA expression levels were similar between control and LEC cells. The presented data suggests that radiosensitivity of LEC rats might be attributed to a mechanism specific for certain target tissue, like bone marrow, or enhanced in cell cycle stages other than G0/G1

Computer analysis of left ventricular cineangiograms

The heart is in continuous and rhythmic motion. For centuries this unique property has fascinated clinicians and scientists, although their attempts to get a better insight in the mechanisms which govern heart wall motion were seriously hampered by the almost complete absence of effective measurement tools. A dramatic change took place in the course of this century thanks to the technological revolution which changed cardiology more than any other of the biomedical sciences. The introduction of roentgen rays into medical practice enabled physicians for the first time to observe the beating heart in the intact human being. In cases of myocardial infarction, assessed by the new electrocardiographic technique, the fluoroscopy screen revealed abnormal motion of the epicardial contour. Numerous tools and methods were designed and developed to preclude the subjectivity and inaccuracy inherent with naked eye observation of heart wall motion. However, as only the epicardial contour could be determined, the information thus obtained remained limited. In 1929 Forssman introduced a catheter into his right heart. This act set the pace for the development of angiocardiography which after a hesitating start became one of the fastest growing areas in the medical field. As a consequence of the rapidly increasing number of cardiac catheterizations paralleled by an explosive growth of the amount of data obtained during each procedure, automated data processing became indispensible. In 1967 cardiologists of Stanford University in Palo Alto, California, described their flrst experiences with the use of a computing device in the cardiac catheterization procedure. This example was soon followed by cardiologists and technicians of the Thoraxcenter who developed a computer system, tailored to their catheterization laboratory, which became operative in 1973 and comprised facilities to process pressure signals on line and under control of the operator. To pursue the automation of data processing in the catheterization laboratory two more systems had to be developed: a system to detect automatically coronary artery contours and an analysis system for left ventriculograms. For this automated detection of the left ventricular endocardial contour from cineangiograms, a hard-wired system was designed and constructed. It was called the "Contouromat'. The aim of this thesis is to describe work to evaluate and validate this tool and its applicability in clinical practice and research. The first question which arises is whether an automated angie processing system has any benefit. Indeed in some clinics left ventriculo

Expanding the magic circle in pervasive casual play

Dissertação para obtenção do Grau de Doutor em InformáticaIn this document we present proposals for merging the fictional game world with the real world taking into account the profile of casual players. To merge games with reality we resorted to the creation of games that explore di-verse real world elements. We focused on sound, video, physiological data, ac-celerometer data, weather and location. We made the choice for these real world elements because data, about those elements, can be acquired making use of functionality already available, or foreseen in the near future, in devices like computers or mobile phones, thus fitting the profile of casual players who are usually not willing to invest in expensive or specialized hardware just for the sake of playing a game. By resorting to real world elements, the screen is no longer the only focus of the player’s attention because reality also influences the outcome of the game. Here, we describe how the insertion of real world elements affected the role of the screen as the primary focus of the player’s attention. Games happen inside a magic circle that spatially and temporally delimits the game from the ordinary world. J. Huizinga, the inventor of the magic circle concept, also leaves implicit a social demarcation, separating who is playing the game from who is not playing the game [1]. In this document, we show how the insertion of real world elements blurred the spatial, temporal and social limits, in our games. Through this fusion with the ordinary world, the fictional game world integrates with reality, instead of being isolated from it. We also present an analysis about integration with the real world and context data in casual en-tertainment.Fundação para a Ciência e a Tecnologia - grant SFRH/BD/61085/200

Moonlab - Preliminary design of a manned lunar laboratory A Stanford/Ames summer faculty workshop study, 24 Jun. - 6 Sep. 1968

Detailed preliminary design study of semipermanent manned lunar laboratory Moonla

[¹⁸F]fluorination of biorelevant arylboronic acid pinacol ester scaffolds synthesized by convergence techniques

Aim: The development of small molecules through convergent multicomponent reactions (MCR) has been boosted during the last decade due to the ability to synthesize, virtually without any side-products, numerous small drug-like molecules with several degrees of structural diversity.(1) The association of positron emission tomography (PET) labeling techniques in line with the “one-pot” development of biologically active compounds has the potential to become relevant not only for the evaluation and characterization of those MCR products through molecular imaging, but also to increase the library of radiotracers available. Therefore, since the [18F]fluorination of arylboronic acid pinacol ester derivatives tolerates electron-poor and electro-rich arenes and various functional groups,(2) the main goal of this research work was to achieve the 18F-radiolabeling of several different molecules synthesized through MCR. Materials and Methods: [18F]Fluorination of boronic acid pinacol esters was first extensively optimized using a benzaldehyde derivative in relation to the ideal amount of Cu(II) catalyst and precursor to be used, as well as the reaction solvent. Radiochemical conversion (RCC) yields were assessed by TLC-SG. The optimized radiolabeling conditions were subsequently applied to several structurally different MCR scaffolds comprising biologically relevant pharmacophores (e.g. β-lactam, morpholine, tetrazole, oxazole) that were synthesized to specifically contain a boronic acid pinacol ester group. Results: Radiolabeling with fluorine-18 was achieved with volumes (800 μl) and activities (≤ 2 GBq) compatible with most radiochemistry techniques and modules. In summary, an increase in the quantities of precursor or Cu(II) catalyst lead to higher conversion yields. An optimal amount of precursor (0.06 mmol) and Cu(OTf)2(py)4 (0.04 mmol) was defined for further reactions, with DMA being a preferential solvent over DMF. RCC yields from 15% to 76%, depending on the scaffold, were reproducibly achieved. Interestingly, it was noticed that the structure of the scaffolds, beyond the arylboronic acid, exerts some influence in the final RCC, with electron-withdrawing groups in the para position apparently enhancing the radiolabeling yield. Conclusion: The developed method with high RCC and reproducibility has the potential to be applied in line with MCR and also has a possibility to be incorporated in a later stage of this convergent “one-pot” synthesis strategy. Further studies are currently ongoing to apply this radiolabeling concept to fluorine-containing approved drugs whose boronic acid pinacol ester precursors can be synthesized through MCR (e.g. atorvastatin)

Proceedings of the 7th Sound and Music Computing Conference

Proceedings of the SMC2010 - 7th Sound and Music Computing Conference, July 21st - July 24th 2010