Object tracking and matting for A class of dynamic image-based representations

Image-based rendering (IBR) is an emerging technology for photo-realistic rendering of scenes from a collection of densely sampled images and videos. Recently, an object-based approach for a class of dynamic image-based representations called plenoptic videos was proposed. This paper proposes an automatic object tracking approach using the level-set method. Our tracking method, which utilizes both local and global features of the image sequences instead of global features exploited in previous approach, can achieve better tracking results for objects, especially with non-uniform energy distribution. Due to possible segmentation errors around object boundaries, natural matting with Bayesian approach is also incorporated into our system. Furthermore, a MPEG-4 like object-based algorithm is developed for compressing the plenoptic videos, which consist of the alpha maps, depth maps and textures of the segmented image-based objects from different video plenoptic streams. Experimental results show that satisfactory renderings can be obtained by the proposed approaches. © 2005 IEEE.published_or_final_versio

An object-based approach to plenoptic videos

This paper proposes an object-based approach to plenoptic videos, where the plenoptic video sequences are segmented into image-based rendering (IBR) objects each with its image sequence, depth map and other relevant information such as shape information. This allows desirable functionalities such as scalability of contents, error resilience, and interactivity with individual IBR objects to be supported. A portable capturing system consisting of two linear camera arrays, each hosting 6 JVC video cameras, was developed to verify the proposed approach. Rendering and compression results of real-world scenes demonstrate the usefulness and good quality of the proposed approach. © 2005 IEEE.published_or_final_versio

An object-based approach to image/video-based synthesis and processing for 3-D and multiview televisions

This paper proposes an object-based approach to a class of dynamic image-based representations called "plenoptic videos," where the plenoptic video sequences are segmented into image-based rendering (IBR) objects each with its image sequence, depth map, and other relevant information such as shape and alpha information. This allows desirable functionalities such as scalability of contents, error resilience, and interactivity with individual IBR objects to be supported. Moreover, the rendering quality in scenes with large depth variations can also be improved considerably. A portable capturing system consisting of two linear camera arrays was developed to verify the proposed approach. An important step in the object-based approach is to segment the objects in video streams into layers or IBR objects. To reduce the time for segmenting plenoptic videos under the semiautomatic technique, a new object tracking method based on the level-set method is proposed. Due to possible segmentation errors around object boundaries, natural matting with Bayesian approach is also incorporated into our system. Furthermore, extensions of conventional image processing algorithms to these IBR objects are studied and illustrated with examples. Experimental results are given to illustrate the efficiency of the tracking, matting, rendering, and processing algorithms under the proposed object-based framework. © 2009 IEEE.published_or_final_versio

On the rendering and post-processing of simplified dynamic light fields with depth information

This paper studies the rendering and post-processing of a dynamic image-based representation called the simplified dynamic light fields (SDLF) (or plenoptic videos) with depth information. The user viewpoints are limited to a camera line to simplify the capturing and compression processes. By associating each image pixel with its depth value, methods for improving the rendering quality and detecting occlusions are proposed. Due to the limited sampling at depth discontinuities, adaptive lowpass filtering is applied to the detected occluded regions near object boundaries in order to suppress the aliasing artifacts. Rendering results using computer-generated images show that considerable improvement in rendering quality even for dynamic scenes with large depth variations.published_or_final_versio

The Plenoptic videos: Capturing, Rendering and Compression

This paper presents a system for capturing and rendering a dynamic image-based representation called the plenoptic videos. It is a simplified version of light fields for dynamic environment, where user viewpoints are constrained along the camera plane of a linear array of video cameras. The system consists of a camera array of 8 Sony CCX-Z11 CCD cameras and eight Pentium 41.8 GHz computers connected together through a 100 baseT LAN. Important issues such as multiple camera calibration, real-time compression, decompression and rendering are addressed. Experimental results demonstrated the usefulness of the proposed parallel processing based system in capturing and rendering high quality dynamic image-based representation using off-the-shelf equipment, and its potential applications in visualization and immersive television systems.published_or_final_versio

Relatório de estágio: Novadelta Comércio de Cafés España, SAU

O presente relatório enquadra-se no estágio curricular do Mestrado em Auditoria Empresarial e Pública ministrado pelo Instituto Superior de Contabilidade e Administração de Coimbra. O estágio teve lugar na empresa Novadelta Comercio de Cafés España, S.A.U, no Departamento de Contabilidade, tendo decorrido entre 2 de maio e 30 de outubro de 2012. As atividades do estágio visaram fundamentalmente percecionar de que forma a contabilidade é executada nesta organização, em particular no que respeita aos processos que envolvem pagamentos e recebimentos, bem como os procedimentos de controlo interno nas diversas áreas do negócio, mormente os relativos à informação financeira. Os procedimentos de controlo interno relativos à informação financeira (contabilidade) existentes nesta Empresa são de extrema importância, porque permitem que os utilizadores da informação financeira tenham maior confiança nas suas demonstrações financeiras. O controlo existente em cada área de atividade assume-se como um ponto forte para a Empresa, contribuindo para que o contacto direto com clientes, fornecedores e outras entidades seja assente na confiança, honestidade e amizade. Por outro lado, permite responder melhor à exigência de qualidade dos serviços. O estágio na Novadelta Espanha foi muito gratificante, na medida em que foi possível pôr em prática os conhecimentos teóricos adquiridos ao nível da contabilidade e controlo interno, bem como o desenvolvimento de novas competências, a autonomia no desenvolvimento das tarefas nessas áreas, adaptação a novos ambientes e fomentar o relacionamento interpessoal e intercultural

Preparation of Fe3O4Spherical Nanoporous Particles Facilitated by Polyethylene Glycol 4000

Much interest has been attracted to the magnetic materials with porous structure because of their unique properties and potential applications. In this report, Fe3O4nanoporous particles assembled from small Fe3O4nanoparticles have been prepared by thermal decomposition of iron acetylacetonate in the presence of polyethylene glycol 4000. The size of the spherical nanoporous particles is 100–200 nm. Surface area measurement shows that these Fe3O4nanoporous particles have a high surface area of 87.5 m2/g. Magnetization measurement and Mössbauer spectrum indicate that these particles are nearly superparamagnetic at room temperature. It is found that the morphology of the products is greatly influenced by polyethylene glycol concentration and the polymerization degree of polyethylene glycol. Polyethylene glycol molecules are believed to facilitate the formation of the spherical assembly

Nanofluids Containing γ-Fe2O3 Nanoparticles and Their Heat Transfer Enhancements

Homogeneous and stable magnetic nanofluids containing γ-Fe2O3 nanoparticles were prepared using a two-step method, and their thermal transport properties were investigated. Thermal conductivities of the nanofluids were measured to be higher than that of base fluid, and the enhanced values increase with the volume fraction of the nanoparticles. Viscosity measurements showed that the nanofluids demonstrated Newtonian behavior and the viscosity of the nanofluids depended strongly on the tested temperatures and the nanoparticles loadings. Convective heat transfer coefficients tested in a laminar flow showed that the coefficients increased with the augment of Reynolds number and the volume fraction

The Influences of H2Plasma Pretreatment on the Growth of Vertically Aligned Carbon Nanotubes by Microwave Plasma Chemical Vapor Deposition

The effects of H2flow rate during plasma pretreatment on synthesizing the multiwalled carbon nanotubes (MWCNTs) by using the microwave plasma chemical vapor deposition are investigated in this study. A H2and CH4gas mixture with a 9:1 ratio was used as a precursor for the synthesis of MWCNT on Ni-coated TaN/Si(100) substrates. The structure and composition of Ni catalyst nanoparticles were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The present findings showed that denser Ni catalyst nanoparticles and more vertically aligned MWCNTs could be effectively achieved at higher flow rates. From Raman results, we found that the intensity ratio of G and D bands (ID/IG) decreases with an increasing flow rate. In addition, TEM results suggest that H2plasma pretreatment can effectively reduce the amorphous carbon and carbonaceous particles. As a result, the pretreatment plays a crucial role in modifying the obtained MWCNTs structures