PoseDiff: Pose-conditioned Multimodal Diffusion Model for Unbounded Scene Synthesis from Sparse Inputs

Novel view synthesis has been heavily driven by NeRF-based models, but these models often hold limitations with the requirement of dense coverage of input views and expensive computations. NeRF models designed for scenarios with a few sparse input views face difficulty in being generalizable to complex or unbounded scenes, where multiple scene content can be at any distance from a multi-directional camera, and thus generate unnatural and low quality images with blurry or floating artifacts. To accommodate the lack of dense information in sparse view scenarios and the computational burden of NeRF-based models in novel view synthesis, our approach adopts diffusion models. In this paper, we present PoseDiff, which combines the fast and plausible generation ability of diffusion models and 3D-aware view consistency of pose parameters from NeRF-based models. Specifically, PoseDiff is a multimodal pose-conditioned diffusion model applicable for novel view synthesis of unbounded scenes as well as bounded or forward-facing scenes with sparse views. PoseDiff renders plausible novel views for given pose parameters while maintaining high-frequency geometric details in significantly less time than conventional NeRF-based methods.