The influence of subpixel measurement on digital camera calibration

The aim of this work is to evaluate the influence of point measurements in images, with subpixel accuracy, and its contribution in the calibration of digital cameras. Also, the effect of subpixel measurements in 3D coordinates of check points in the object space will be evaluated. With this purpose, an algorithm that allows subpixel accuracy was implemented for semi-automatic determination of points of interest, based on Fõrstner operator. Experiments were accomplished with a block of images acquired with the multispectral camera DuncanTech MS3100-CIR. The influence of subpixel measurements in the adjustment by Least Square Method (LSM) was evaluated by the comparison of estimated standard deviation of parameters in both situations, with manual measurement (pixel accuracy) and with subpixel estimation. Additionally, the influence of subpixel measurements in the 3D reconstruction was also analyzed. Based on the obtained results, i.e., on the quantification of the standard deviation reduction in the Inner Orientation Parameters (IOP) and also in the relative error of the 3D reconstruction, it was shown that measurements with subpixel accuracy are relevant for some tasks in Photogrammetry, mainly for those in which the metric quality is of great relevance, as Camera Calibration.

Digital filtering of oscillations intrinsic to transmission line modeling based on lumped parameters

A correction procedure based on digital signal processing theory is proposed to smooth the numeric oscillations in electromagnetic transient simulation results from transmission line modeling based on an equivalent representation by lumped parameters. The proposed improvement to this well-known line representation is carried out with an Finite Impulse Response (FIR) digital filter used to exclude the high-frequency components associated with the spurious numeric oscillations. To prove the efficacy of this correction method, a well-established frequency-dependent line representation using state equations is modeled with an FIR filter included in the model. The results obtained from the state-space model with and without the FIR filtering are compared with the results simulated by a line model based on distributed parameters and inverse transforms. Finally, the line model integrated with the FIR filtering is also tested and validated based on simulations that include nonlinear and time-variable elements. © 2012 Elsevier Ltd. All rights reserved.

Generating virtual images from oblique frames

Image acquisition systems based on multi-head arrangement of digital camerasare attractive alternatives enabling a larger imaging area when compared to a single framecamera. The calibration of this kind of system can be performed in several steps or byusing simultaneous bundle adjustment with relative orientation stability constraints. Thepaper will address the details of the steps of the proposed approach for system calibration,image rectification, registration and fusion. Experiments with terrestrial and aerial imagesacquired with two Fuji FinePix S3Pro cameras were performed. The experiments focusedon the assessment of the results of self-calibrating bundle adjustment with and withoutrelative orientation constraints and the effects to the registration and fusion when generatingvirtual images. The experiments have shown that the images can be accurately rectified andregistered with the proposed approach, achieving residuals smaller than one pixel. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

Implementação de um controle digital para o compensador regenerativo de potência ativa

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Conteúdo educativo para a televisão digital interativa

Pós-graduação em Televisão Digital: Informação e Conhecimento - FAAC

Educação para as mídias na formação de professores: uma proposta transmídia entre Web e TV digital

Pós-graduação em Televisão Digital: Informação e Conhecimento - FAAC

Projeto, processo e produto: cartografia do design de conexões na televisão digital

Pós-graduação em Televisão Digital: Informação e Conhecimento - FAAC

A pauta jornalística na convergência digital: outros caminhos e novos desafios

Pós-graduação em Televisão Digital: Informação e Conhecimento - FAAC

Televisão digital nos espaços públicos: promoção da hospitalidade social

Pós-graduação em Televisão Digital: Informação e Conhecimento - FAAC

Documentários e redes sociais na televisão digital

Pós-graduação em Televisão Digital: Informação e Conhecimento - FAAC

As contribuições do design instrucional na elaboração de ambiente de aprendizagem para a TV digital interativa

Pós-graduação em Televisão Digital: Informação e Conhecimento - FAAC

Roteiros e produção de conteúdos interativos para celulares nos cursos de educação a distância na televisão digital interativa

Pós-graduação em Televisão Digital: Informação e Conhecimento - FAAC

Interface antropométrica digital: parâmetros antropométricos de populações extremas

Pós-graduação em Design - FAAC

Mediação do processo ensino-aprendizagem com o jogo de empresas mercado virtual: uma pesquisa de opinião

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Repositório digital como ambiente de inclusão digital e social para usuários idosos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)