CEIG16

Permanent URI for this collection

https://diglib.eg.org/handle/10.2312/2630887

Browse

Browsing CEIG16 by Subject "I.3.7 [Computer Graphics]"

Now showing 1 - 5 of 5
  • No Thumbnail Available
    Item
    Bidirectional Rendering of Polarized Light Transport
    (The Eurographics Association, 2016) Jarabo, Adrian; Gutierrez, Diego; Alejandro Garcia-Alonso and Belen Masia
    On the foundations of many rendering algorithm is the symmetry between the path traversed by light and its adjoint from the camera. However, several effects, including polarization or fluorescence, break that symmetry and are defined only on the direction of light. This complicates the applicability of bidirectional methods, that exploit the symmetry for effective rendering light transport. In this work we focus on how to include polarization within a bidirectional rendering algorithm. For that, we generalize the path integral to support the constraints imposed by non-symmetric light transport. Based on this theoretical framework, we propose modifications on two bidirectional methods, namely bidirectional path tracing and photon mapping, extending them to support polarization.
  • No Thumbnail Available
    Item
    Characterisation of Position Based Dynamics for Elastic Materials
    (The Eurographics Association, 2016) Rodero, Cristóbal; Real, Pablo; Zuñeda, Pedro; Monteagudo, Carlos; Lozano, Miguel; García-Fernández, Ignacio; Alejandro Garcia-Alonso and Belen Masia
    Position Based Dynamics (PBD) methodology is a widely used approach for simulation of deformable bodies in the context of video games. Its main advantages over force based methods are its unconditional stability and its constraint based approach. However, it does not involve physically inspired parameters and its behaviour depends on time step size. This makes it difficult to reproduce a given elastic behaviour. In this work we perform an analysis of the mechanical properties in a PBD elastic system, and compare it to the Finite Element Method (FEM). We propose a methodology to fit the parameters of PBD to simulate a particular Young's modulus and Poisson's ratio.
  • No Thumbnail Available
    Item
    Crossmodal Perception in Immersive Environments
    (The Eurographics Association, 2016) Allue, Marcos; Serrano, Ana; Bedia, Manuel G.; Masia, Belen; Alejandro Garcia-Alonso and Belen Masia
    With the proliferation of low-cost, consumer level, head-mounted displays (HMDs) such as Oculus VR or Sony's Morpheus, we are witnessing a reappearance of virtual reality. However, there are still important stumbling blocks that hinder the development of applications and reduce the visual quality of the results. Knowledge of human perception in virtual environments can help overcome these limitations. In this paper, within the much-studied area of perception in virtual environments, we chose to look into the less explored area of crossmodal perception, that is, the interaction of different senses when perceiving the environment. In particular, we looked at the influence of sound on visual motion perception in a virtual reality scenario. We first replicated a well-known crossmodal perception experiment, carried out on a conventional 2D display, and then extended it to a 3D headmounted display (HMD). Next, we performed an additional experiment in which we increased the complexity of the stimuli of the previous experiment, to test whether the effects observed would hold in more realistic scenes. We found that the trend which was previously observed in 2D displays is maintained in HMDs, but with an observed reduction of the crossmodal effect. With more complex stimuli the trend holds, and the crossmodal effect is further reduced, possibly due to the presence of additional visual cues.
  • No Thumbnail Available
    Item
    A new Potential-based SPH Method
    (The Eurographics Association, 2016) Perea, Juan J.; Cordero, Juan M.; Alejandro Garcia-Alonso and Belen Masia
    In Computer Graphics the fluid simulation plays a relevant role. Amongst the existing methods, the SPH method is highlighted by its simplicity, versatility and adaptability. Nevertheless, several research show some limitations that affect both the stability and the realism of simulation. These limitations are related with the calculation of the mass density and the pressure gradient, mainly when the number of neighbouring particles is low as boundary and discontinuities. Also, the simulation realism is compromised when the incompressibility constraint is enforced and the fluid heating is not dissipated. To overcome these limitations, we present a new technique to simulate the fluid flow. It involves of a hybrid technique that allow us to calculate a stable pressure gradient and the mass density even when the number of neighbouring particle is low. Also, we directly control the incompressibility and dissipate the fluid heating with accurate. Thus, we obtain stable and realistic fluid simulation, even with higher time steps.
  • No Thumbnail Available
    Item
    Phase Space Data-Driven Simulation of Elastic Materials
    (The Eurographics Association, 2016) Monteagudo, Carlos; Lozano, Miguel; García-Fernández, Ignacio; Martinez-Gil, Francisco; Alejandro Garcia-Alonso and Belen Masia
    The use of data driven models in computer animation offers several benefits. We present an analysis of a regression model as a method to simulate cloth. In our approach, we generate data from a simple mass-spring system and we fit a regressor. Then, we assemble more complex mass-spring systems and use the learnt model to simulate them. To validate the approach we perform several tests. We analyze the elastic properties of a single learnt spring, measuring its stiffness coefficient, and compare it to the original, physics-based, model. We also build several test scenarios which include the simulation of a piece of cloth under gravity, comparing the regression model and the physics-based model. Finally we test the behaviour of the regression model for systems with high stiffness coefficient and compare its stability properties with a semi-implicit Euler integration method.