OPTIMIZATION OF PHOTOGRAMMETRIC 3D ASSETS

The photogrammetric 3D reconstruction pipeline has emerged in recent years as the prominent technology for a variety of use cases, from heritage documentation to the authoring of high-quality photo-realistic assets for interactive graphics applications. However, the reconstruction process is prone to introduce modeling artifacts, and models generated with such tools often require careful post-processing before being ready for use in downstream applications. In this thesis, we face the problem of optimizing 3D models from this particular data source under several quality metrics. We begin by providing an analysis of their distinguishing features, focusing on the defects stemming from the automatic reconstruction process, and then we propose robust methods to optimize high-resolution 3D models under several objectives, addressing some of the identified recurring defects. First, we introduce a method to reduce the fragmentation of photo-reconstructed texture atlases, producing a more compact UV-map encoding with significantly fewer seams while minimizing the resampling artifacts introduced when synthesizing the new texture images. Next, we design a method to address texturing defects. Our technique combines recent advancements in image inpainting achieved by modern CNN-based models with the definition of a local texture-space inpainting domain that is semantically coherent, overcoming limitations of alternative texture inpainting strategies that operate in screen-space or global texture-space. Finally, we propose a method to efficiently represent densely tessellated 3D data by adopting a recently introduced efficient representation of displacement-mapped surfaces that benefits from GPU hardware support and does not require explicit parametrization of the 3D surface. Our approach generates a compact representation of high-resolution textured models, augmented with a texture map that is optimized and tailored to the displaced surface.