Browsing by Author "Rittig, Tobias"

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    SkyGAN: Towards Realistic Cloud Imagery for Image Based Lighting
    (The Eurographics Association, 2022) Mirbauer, Martin; Rittig, Tobias; Iser, Tomáš; Krivánek, Jaroslav; Šikudová, Elena; Ghosh, Abhijeet; Wei, Li-Yi
    Achieving photorealism when rendering virtual scenes in movies or architecture visualizations often depends on providing a realistic illumination and background. Typically, spherical environment maps serve both as a natural light source from the Sun and the sky, and as a background with clouds and a horizon. In practice, the input is either a static high-resolution HDR photograph manually captured on location in real conditions, or an analytical clear sky model that is dynamic, but cannot model clouds. Our approach bridges these two limited paradigms: a user can control the sun position and cloud coverage ratio, and generate a realistically looking environment map for these conditions. It is a hybrid data-driven analytical model based on a modified state-of-the-art GAN architecture, which is trained on matching pairs of physically-accurate clear sky radiance and HDR fisheye photographs of clouds. We demonstrate our results on renders of outdoor scenes under varying time, date, and cloud covers.