Taming Mode Collapse in Score Distillation for Text-to-3D Generation
Authors: Peihao Wang, Dejia Xu, Zhiwen Fan, Dilin Wang, Sreyas Mohan, Forrest Iandola, Rakesh Ranjan, Yilei Li, Qiang Liu, Zhangyang Wang, Vikas Chandra

Despite the remarkable performance of score distillation in text-to-3D generation such techniques notoriously suffer from view inconsistency issues also known as "Janus" artifact where the generated objects fake each view with multiple front faces. Although empirically effective methods have approached this problem via score debiasing or prompt engineering a more rigorous perspective to explain and tackle this problem remains elusive. In this paper we reveal that the existing score distillation-based text-to-3D generation frameworks degenerate to maximal likelihood seeking on each view independently and thus suffer from the mode collapse problem manifesting as the Janus artifact in practice. To tame mode collapse we improve score distillation by re-establishing the entropy term in the corresponding variational objective which is applied to the distribution of rendered images. Maximizing the entropy encourages diversity among different views in generated 3D assets thereby mitigating the Janus problem. Based on this new objective we derive a new update rule for 3D score distillation dubbed Entropic Score Distillation (ESD). We theoretically reveal that ESD can be simplified and implemented by just adopting the classifier-free guidance trick upon variational score distillation. Although embarrassingly straightforward our extensive experiments demonstrate that ESD can be an effective treatment for Janus artifacts in score distillation.