Skeleton based importance sampling for path tracing

International audienceWhen working with large and complex scenes, situations arise where light flux takes complex paths to reach the observer. In such cases, traditional stochastic algorithms, like ray tracing algorithms, will have difficulties to compute noise-free images. Our present research aims to solve this problem using the 3d scene skeleton as a coarse representation. Indeed, curvilinear skeletons can be used to find light paths with higher energy. This article presents our research to use these skeletons for any ray tracing algorithm, allowing a knowledge-based choice when choosing light paths. Our method adds little computation time while producing a more accurate image

Characterizing and Detecting Loops in n-Dimensional Discrete Toric Spaces

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Simple guidelines to predict self-phase modulation patterns

We present a simple approach to predict the main features of optical spectra affected by self-phase modulation (SPM), which is based on regarding the spectral modification as an interference effect. A two-wave interference model is found sufficient to describe the SPM-broadened spectra of initially transform-limited or up-chirped pulses, whereas a third wave should be included in the model for initially down-chirped pulses. Simple analytical formulas are derived, which accurately predict the positions of the outermost peaks of the spectra

Characterisation and mitigation of self-phase modulation in optical fibres

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Potential and limits of InSAR to characterize interseismic deformation independently of GPS data: Application to the southern San Andreas Fault system

The evaluation of long-wavelength deformation associated with interseismic strain accumulation traditionally relies on spatially sparse GPS measurements, or on high spatial-resolution InSAR velocity fields aligned to a GPS-based model. In this approach the InSAR contributes only short-wavelength deformation and the two data sets are dependent, thereby challenging the evaluation of the InSAR uncertainties and the justification of atmospheric corrections. Here we present an analysis using 7 years of Envisat InSAR data to characterize interseismic deformation along the southern San Andreas Fault (SAF) and the San Jacinto Fault (SJF) in southern California, where the SAF bifurcates onto the Mission Creek (MCF) and the Banning (BF) fault strands. We outline the processing steps for using InSAR alone to characterize both the short- and long-wavelength deformation, and evaluate the velocity field uncertainties with independent continuous GPS data. InSAR line-of-sight (LOS) and continuous GPS velocities agree within ∼1–2 mm/yr in the study area, suggesting that multiyear InSAR time series can be used to characterize interseismic deformation with a higher spatial resolution than GPS. We investigate with dislocation models the ability of this mean LOS velocity field to constrain fault slip rates and show that a single viewing geometry can help distinguish between different slip-rate scenarios on the SAF and SJF (∼35 km apart) but multiple viewing geometries are needed to differentiate slip on the MCF and BF (<12 km apart). Our results demonstrate that interseismic models of strain accumulation used for seismic hazards assessment would benefit from the consideration of InSAR mean velocity maps

« Find your way from darkness to light » : la nuit et l’héritage de la tradition romantique dans Knight of Cups de Terrence Malick

Knight of Cups (2015) fait partie d’une trilogie contemporaine et expérimentale composée avec À la merveille (To the Wonder, 2012) et Song to Song (2017). À sa sortie, le film paraît déstabiliser le public et la critique en raison de son humeur sinueuse et mélancolique. On souhaite reconsidérer ces réactions en mettant au jour un motif : la « nuit ». Puisant dans les traditions platonico-chrétienne et romantique, Terrence Malick semble reprendre ce motif pour porter à l’écran une réflexion sur le désespoir et la fragmentation de la vie moderne. Tout en indiquant les principales sources d’inspiration du film, on s’attache à faire ressortir sa recherche esthétique et son originalité.Knight of Cups (2015) is part of a contemporary and experimental trilogy made up with To the Wonder (2012) and Song to Song (2017). On its release, the film seems to put off both the audience and reviewers by its meandering moodiness. This article wishes to reconsider such responses by shedding light on a particular motif: the “night”. Drawing from a Platonic, Christian and Romantic tradition, Terrence Malick seems to take up this motif to bring to the screen a reflection on despair and modern life. While indicating the film’s main sources of inspiration, this article aims to highlight its aesthetical research and originality

Megaeventos e a cidade: reflexos urbanos da Copa do Mundo 2014 na região metropolitana do Recife

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Urbanismo, História e Arquitetura da Cidade, Florianópolis, 2015.Esta pesquisa trata dos reflexos no espaço urbano causados por megaeventos, evidenciando os impactos da Copa do Mundo FIFA 2014 com foco na Região Metropolitana do Recife. Megaeventos já demonstraram diferentes significados ao longo do tempo, mas foram sempre caracterizados pelo forte apelo popular. No Brasil, as expectativas de legado recaíram sobre a exposição mundial, que poderia contribuir na busca por investimentos, e na melhoria da infraestrutura urbana. No âmbito do planejamento urbano, a Copa se mostrou ligada a modelos de gestão voltados ao empreendedorismo urbano, como o planejamento estratégico e o city marketing. A pesquisa em escala nacional mostrou que há diferentes cenários na relação das intervenções com o tecido urbano nas cidades-sede brasileiras. Assim, as doze cidades foram divididas em três categorias: cidades selecionadas pelo caráter simbólico, cidades com reforço na atual direção predominante de crescimento e cidades com inflexão na atual direção predominante de crescimento. Os critérios para esta separação foram o direcionamento e a localização das obras. Em Pernambuco, a pesquisa em escala local apontou a intencionalidade do governo Estadual em utilizar as novas intervenções para promover a integração regional. Desse modo, além das obras de mobilidade para melhorar o tráfego na Região Metropolitana, foi prevista uma nova centralidade urbana que abriga a Arena esportiva e que seria responsável por atrair o desenvolvimento em direção ao oeste metropolitano. Em São Lourenço da Mata, onde foi construída a Arena Pernambuco, juntamente com as leis que viabilizam a construção da Cidade da Copa, foram aprovadas outras alterações ao plano diretor municipal. Essas alterações na regulamentação, somadas às possibilidades de financiamento criadas pelo Programa Minha Casa Minha Vida, tem potencial de mudar a situação da dinâmica imobiliária local. No Recife, a Via Mangue, uma intervenção com mínima relação com o evento causou a remoção de 900 famílias que viviam próximo ao mangue e dinamizou setor imobiliário nos bairros do Pina e de Boa Viagem.Abstract : This research deals with the reflections in urban areas caused by mega-events, showing the impact of the FIFA World Cup 2014 with a focus in the Metropolitan Region of Recife. Mega-events have shown different meanings over time, but have always been characterized by the strong popular appeal. In Brazil, the legacy of expectations fell on the world exhibition, which could help in the search for investments, and in improving urban infrastructure. In the context of urban planning, World Cup proved to be linked to management models aimed at urban entrepreneurship, such as Strategic Planning and City Marketing. The research at the national level showed that there are different scenarios in respect of interventions to the urban net in Brazilian host cities. Thus, the twelve cities were divided into three categories: cities selected by the symbolism, cities with reinforcement in the current predominant direction of growth and cities with an inflection in the current predominant direction of growth. The criteria for this separation were the direction and location of the works. In Pernambuco, the research at the local level indicated the intention of the State Government to use new interventions to promote regional integration. Therefore, besides the mobility to improve traffic in the metropolitan area, it was made for a new urban center that houses the Sports Arena and would be responsible for attracting development toward the metropolitan West. In Sao Lourenco da Mata, where the Arena Pernambuco was built, along with laws that enable the construction of the World Cup City, were approved other amendments to the municipal director plan. These changes in the regulation, together with the funding opportunities created by the Minha Casa Minha Vida, has the potential to change the situation of the local real estate dynamics. In Recife, the Via Mangue, an intervention with minimal relation to the event caused the removal of 900 families living near the swamp and an intense stimulation of real estate in the neighborhoods of Pina and Boa Viagem

MOLECULAR LINE-SHAPE MODELING FROM FIRST PRINCIPLES

International audienceWe present an ab initio approach to spectral line-shape modeling and the comparison of the results with experimental data

Femtosecond time resolved CARS spectroscopy of H2-N2 mixtures in the Dicke regime: Experiments and modeling of velocity effects

International audienceIn this paper, we present measurements and modeling of femtosecond time resolved CARS signal in H2-N2 mixtures at low densities. Three approaches have been used to model the CARS response. The first is the usual sum of Voigt profiles. In the second approach, the speed dependent Voigt profile is used. In the last approach, a new model of the CARS signal is developed which takes into account the velocity changes induced by collisions and the speed dependence of the collisional parameters. The velocity changes are modeled using the Keilson and Storer memory function; the radiator speed dependences of the collisional parameters are determined from their temperature dependences. The results show that the changes of the velocity have important effects for the H2/N2 system at the Dicke density regime

Do moderno ao trágico: lições de Bresson e Grotowski Florianópolis, 16

TCC (graduação) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Cinema.Este ensaio pretende aproximar a poética do cineasta Robert Bresson com a do diretor de teatro Jerzy Grotowski. Discutem-se noções de intuição, em Bresson, e impulso, em Grotowski, a partir dos conceitos de cinematógrafo, automatismo, modelo, encontro, teatro pobre, ato total, sunyata. Busca-se a superação da ideia de modernidade para, a partir de Nietzsche, sugerir uma dinâmica entre abertura para o irracional e formalização racional comuns aos dois diretores