Enhancing High-Resolution 3D Generation through Pixel-wise Gradient
  Clipping
Authors: name: Zijie Pan, name: Jiachen Lu, name: Xiatian Zhu, name: Li Zhang

High-resolution 3D object generation remains a challenging task primarily due
to the limited availability of comprehensive annotated training data. Recent
advancements have aimed to overcome this constraint by harnessing image
generative models, pretrained on extensive curated web datasets, using
knowledge transfer techniques like Score Distillation Sampling (SDS).
Efficiently addressing the requirements of high-resolution rendering often
necessitates the adoption of latent representation-based models, such as the
Latent Diffusion Model (LDM). In this framework, a significant challenge
arises: To compute gradients for individual image pixels, it is necessary to
backpropagate gradients from the designated latent space through the frozen
components of the image model, such as the VAE encoder used within LDM.
However, this gradient propagation pathway has never been optimized, remaining
uncontrolled during training. We find that the unregulated gradients adversely
affect the 3D model's capacity in acquiring texture-related information from
the image generative model, leading to poor quality appearance synthesis. To
address this overarching challenge, we propose an innovative operation termed
Pixel-wise Gradient Clipping (PGC) designed for seamless integration into
existing 3D generative models, thereby enhancing their synthesis quality.
Specifically, we control the magnitude of stochastic gradients by clipping the
pixel-wise gradients efficiently, while preserving crucial texture-related
gradient directions. Despite this simplicity and minimal extra cost, extensive
experiments demonstrate the efficacy of our PGC in enhancing the performance of
existing 3D generative models for high-resolution object rendering.