HDHumans: A Hybrid Approach for High-fidelity Digital Humans

Photo-real digital human avatars are of enormous importance in graphics, asthey enable immersive communication over the globe, improve gaming andentertainment experiences, and can be particularly beneficial for AR and VRsettings. However, current avatar generation approaches either fall short inhigh-fidelity novel view synthesis, generalization to novel motions,reproduction of loose clothing, or they cannot render characters at the highresolution offered by modern displays. To this end, we propose HDHumans, whichis the first method for HD human character synthesis that jointly produces anaccurate and temporally coherent 3D deforming surface and highlyphoto-realistic images of arbitrary novel views and of motions not seen attraining time. At the technical core, our method tightly integrates a classicaldeforming character template with neural radiance fields (NeRF). Our method iscarefully designed to achieve a synergy between classical surface deformationand NeRF. First, the template guides the NeRF, which allows synthesizing novelviews of a highly dynamic and articulated character and even enables thesynthesis of novel motions. Second, we also leverage the dense pointcloudsresulting from NeRF to further improve the deforming surface via 3D-to-3Dsupervision. We outperform the state of the art quantitatively andqualitatively in terms of synthesis quality and resolution, as well as thequality of 3D surface reconstruction.<br

Image based surface reflectance remapping for consistent and tool independent material appearence

Physically-based rendering in Computer Graphics requires the knowledge of material properties other than 3D shapes, textures and colors, in order to solve the rendering equation. A number of material models have been developed, since no model is currently able to reproduce the full range of available materials. Although only few material models have been widely adopted in current rendering systems, the lack of standardisation causes several issues in the 3D modelling workflow, leading to a heavy tool dependency of material appearance. In industry, final decisions about products are often based on a virtual prototype, a crucial step for the production pipeline, usually developed by a collaborations among several departments, which exchange data. Unfortunately, exchanged data often tends to differ from the original, when imported into a different application. As a result, delivering consistent visual results requires time, labour and computational cost. This thesis begins with an examination of the current state of the art in material appearance representation and capture, in order to identify a suitable strategy to tackle material appearance consistency. Automatic solutions to this problem are suggested in this work, accounting for the constraints of real-world scenarios, where the only available information is a reference rendering and the renderer used to obtain it, with no access to the implementation of the shaders. In particular, two image-based frameworks are proposed, working under these constraints. The first one, validated by means of perceptual studies, is aimed to the remapping of BRDF parameters and useful when the parameters used for the reference rendering are available. The second one provides consistent material appearance across different renderers, even when the parameters used for the reference are unknown. It allows the selection of an arbitrary reference rendering tool, and manipulates the output of other renderers in order to be consistent with the reference