Browsing by Author "Guérin, Eric"

Now showing 1 - 4 of 4
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    Authoring Terrains with Spatialised Style
    (The Eurographics Association and John Wiley & Sons Ltd., 2023) Perche, Simon; Peytavie, Adrien; Benes, Bedrich; Galin, Eric; Guérin, Eric; Chaine, Raphaëlle; Deng, Zhigang; Kim, Min H.
    Various terrain modelling methods have been proposed for the past decades, providing efficient and often interactive authoring tools. However, they seldom include any notion of style, which is critical for designers in the entertainment industry. We introduce a new generative network method that bridges the gap between automatic terrain synthesis and authoring, providing a versatile set of authoring tools allowing spatialised style. We build upon the StyleGAN2 architecture and extend it with authoring tools. Given an input sketch or existing elevation map, our method generates a terrain with features that can be authored, enhanced, and augmented using interactive brushes and style manipulation tools. The strength of our approach lies in the versatility and interoperability of the different tools. We validate our method quantitatively with drainage calculation against other previous techniques and qualitatively by asking users to follow a prompt or freely create a terrain.
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    Interactive Authoring of Terrain using Diffusion Models
    (The Eurographics Association and John Wiley & Sons Ltd., 2023) Lochner, Joshua; Gain, James; Perche, Simon; Peytavie, Adrien; Galin, Eric; Guérin, Eric; Chaine, Raphaëlle; Deng, Zhigang; Kim, Min H.
    Generating heightfield terrains is a necessary precursor to the depiction of computer-generated natural scenes in a variety of applications. Authoring such terrains is made challenging by the need for interactive feedback, effective user control, and perceptually realistic output encompassing a range of landforms.We address these challenges by developing a terrain-authoring framework underpinned by an adaptation of diffusion models for conditional image synthesis, trained on real-world elevation data. This framework supports automated cleaning of the training set; authoring control through style selection and feature sketches; the ability to import and freely edit pre-existing terrains, and resolution amplification up to the limits of the source data. Our framework improves on previous machine-learning approaches by: expanding landform variety beyond mountainous terrain to encompass cliffs, canyons, and plains; providing a better balance between terseness and specificity in user control, and improving the fidelity of global terrain structure and perceptual realism. This is demonstrated through drainage simulations and a user study testing the perceived realism for different classes of terrain. The full source code, blender add-on, and pretrained models are available.
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    Procedural Riverscapes
    (The Eurographics Association and John Wiley & Sons Ltd., 2019) Peytavie, Adrien; Dupont, Thibault; Guérin, Eric; Cortial, Yann; Benes, Bedrich; Gain, James; Galin, Eric; Lee, Jehee and Theobalt, Christian and Wetzstein, Gordon
    This paper addresses the problem of creating animated riverscapes through a novel procedural framework that generates the inscribing geometry of a river network and then synthesizes matching real-time water movement animation. Our approach takes bare-earth heightfields as input, derives hydrologically-inspired river network trajectories, carves riverbeds into the terrain, and then automatically generates a corresponding blend-flow tree for the water surface. Characteristics, such as the riverbed width, depth and shape, as well as elevation and flow of the fluid surface, are procedurally derived from the terrain and river type. The riverbed is inscribed by combining compactly supported elevation modifiers over the river course. Subsequently, the water surface is defined as a time-varying continuous function encoded as a blend-flow tree with leaves that are parameterized procedural flow primitives and internal nodes that are blend operators. While river generation is fully automated, we also incorporate intuitive interactive editing of both river trajectories and individual riverbed and flow primitives. The resulting framework enables the generation of a wide range of river forms, ranging from slow meandering rivers to rapids with churning water, including surface effects, such as foam and leaves carried downstream.
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    Segment Tracing Using Local Lipschitz Bounds
    (The Eurographics Association and John Wiley & Sons Ltd., 2020) Galin, Eric; Guérin, Eric; Paris, Axel; Peytavie, Adrien; Panozzo, Daniele and Assarsson, Ulf
    We introduce Segment Tracing, a new algorithm that accelerates the classical Sphere Tracing method for computing the intersection between a ray and an implicit surface. Our approach consists in computing the Lipschitz bound locally over a segment to improve the marching step computation and accelerate the overall process. We describe the computation of the Lipschitz bound for different operators and primitives. We demonstrate that our algorithm significantly reduces the number of field function queries compared to previous methods, without the need for additional accelerating data-structures. Our method can be applied to a vast variety of implicit models ranging from hierarchical procedural objects built from complex primitives, to simulation-generated implicit surfaces created from many particles.