Browsing by Author "Rojo, Irene Baeza"

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    Controllable Caustic Animation Using Vector Fields
    (The Eurographics Association, 2020) Rojo, Irene Baeza; Gross, Markus; Günther, Tobias; Wilkie, Alexander and Banterle, Francesco
    In movie production, lighting is commonly used to redirect attention or to set the mood in a scene. The detailed editing of complex lighting phenomena, however, is as tedious as it is important, especially with dynamic lights or when light is a relevant story element. In this paper, we propose a new method to create caustic animations, which are controllable through constraints drawn by the user. Our method blends caustics into a specified target image by treating photons as particles that move in a divergence-free fluid, an irrotational vector field or a linear combination of the two. Once described as a flow, additional user constraints are easily added, e.g., to direct the flow, create boundaries or add synthetic turbulence, which offers new ways to redirect and control light. The corresponding vector field is computed by fitting a stream function and a scalar potential per time step, for which constraints are described in a quadratic energy that we minimize as a linear least squares problem. Finally, photons are placed at their new positions back into the scene and are rendered with progressive photon mapping.
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    Objective Finite-Time Saddles and their Connection to FTLE
    (The Eurographics Association, 2019) Bujack, Roxana; Dutta, Soumya; Rojo, Irene Baeza; Zhang, Duan; Günther, Tobias; Johansson, Jimmy and Sadlo, Filip and Marai, G. Elisabeta
    Based on an intuitive physical definition of what a finite-time saddle-like behavior is, we derive a mathematical definition. We show that this definition builds the link between two FTLE-based saddle generalizations, which is not only of theoretical interest but also provides a more robust extraction of finite-time saddles.