GD2-NeRF: Generative Detail Compensation via GAN and Diffusion for One-shot Generalizable Neural Radiance Fields

Core Concepts

GD2-NeRF is a coarse-to-fine generative detail compensation framework that hierarchically includes GAN and pre-trained diffusion models into One-shot Generalizable Neural Radiance Fields (OG-NeRF) to synthesize novel views with vivid plausible details in an inference-time finetuning-free manner.

Abstract

The paper proposes the GD2-NeRF framework to address the limitations of existing OG-NeRF methods, which suffer from blurry outputs due to the high reliance on the limited reference image.
At the coarse stage, the One-stage Parallel Pipeline (OPP) efficiently injects a GAN model into the OG-NeRF pipeline to capture in-distribution detail priors from the training dataset, achieving a good balance between sharpness and fidelity.
At the fine stage, the Diffusion-based 3D Enhancer (Diff3DE) further leverages the pre-trained image diffusion models to complement rich out-distribution details while maintaining decent 3D consistency. Diff3DE relaxes the input of the original Inflated Self-Attention (ISA) from all keyframes to neighbor keyframe sets selected based on view distance, enabling the processing of arbitrary views.
Extensive experiments on synthetic and real-world datasets show that GD2-NeRF noticeably improves the details while remaining inference-time finetuning-free.

Stats

Given a single reference image, our method GD2-NeRF synthesizes novel views with vivid plausible details in an inference-time finetuning-free manner.
Our coarse-stage method OPP shows noticeable improvements over the baseline methods with balanced sharpness and fidelity while with little additional cost.
Our fine-stage method Diff3DE can further compensate rich plausible details with decent 3D-consistency.

Quotes

"GD2-NeRF is a coarse-to-fine generative detail compensation framework that hierarchically includes GAN and pre-trained diffusion models into One-shot Generalizable Neural Radiance Fields (OG-NeRF) to synthesize novel views with vivid plausible details in an inference-time finetuning-free manner."
"At the coarse stage, the One-stage Parallel Pipeline (OPP) efficiently injects a GAN model into the OG-NeRF pipeline to capture in-distribution detail priors from the training dataset, achieving a good balance between sharpness and fidelity."
"At the fine stage, the Diffusion-based 3D Enhancer (Diff3DE) further leverages the pre-trained image diffusion models to complement rich out-distribution details while maintaining decent 3D consistency."

Key Insights Distilled From

GD^2-NeRF

by Xiao Pan,Zon... at arxiv.org 04-01-2024

https://arxiv.org/pdf/2401.00616.pdf

Deeper Inquiries

How can the proposed GD2-NeRF framework be extended to handle dynamic scenes or videos

To extend the GD2-NeRF framework to handle dynamic scenes or videos, several modifications and additions can be made:

Temporal Consistency: Incorporate temporal information by introducing a mechanism to maintain consistency between consecutive frames. This can involve leveraging optical flow or motion estimation techniques to ensure smooth transitions between frames.

Dynamic Object Handling: Implement algorithms to detect and track moving objects within the scene. This could involve object segmentation and tracking to ensure that moving objects are accurately represented in the synthesized views.

Adaptive Sampling: Adjust the sampling strategy to account for dynamic scenes, where the scene geometry or appearance may change over time. Adaptive sampling techniques can help capture the evolving nature of the scene.

Motion Prediction: Integrate motion prediction models to anticipate the movement of objects or camera viewpoints in the scene. This can help in generating more accurate and realistic novel views in dynamic scenarios.

What are the potential limitations of relying on pre-trained diffusion models, and how could the framework be adapted to work with limited training data

Relying solely on pre-trained diffusion models may have limitations, especially when working with limited training data. Some potential limitations include:

Overfitting to Pre-trained Data: The diffusion model may be biased towards the data it was trained on, leading to challenges in generalizing to new or different scenes.

Limited Adaptability: Pre-trained models may not be flexible enough to adapt to the specific characteristics of the input data, especially in cases of limited training data.

To adapt the framework to work with limited training data, the following strategies can be considered:

Fine-tuning: Fine-tune the pre-trained diffusion model on the limited training data to adapt it to the specific characteristics of the scenes being synthesized.

Data Augmentation: Use data augmentation techniques to artificially increase the size of the training dataset and provide more diverse examples for the model to learn from.

Transfer Learning: Utilize transfer learning approaches to leverage knowledge from the pre-trained diffusion model while adapting it to the specific requirements of the novel view synthesis task.

What other types of generative models, beyond GANs and diffusion models, could be integrated into the GD2-NeRF framework to further improve the quality and consistency of the synthesized novel views

In addition to GANs and diffusion models, other generative models that could be integrated into the GD2-NeRF framework to enhance the quality and consistency of synthesized novel views include:

Variational Autoencoders (VAEs): VAEs can capture the underlying distribution of the data and generate novel views with controlled latent variables, providing a different approach to generative modeling.

Flow-based Models: Flow-based models offer advantages in terms of invertibility and exact likelihood estimation, which can contribute to more accurate and realistic novel view synthesis.

Autoregressive Models: Autoregressive models, such as PixelCNN, can generate high-quality images by modeling the conditional distribution of each pixel given previous pixels, offering fine-grained control over the generation process.

By incorporating a diverse range of generative models into the GD2-NeRF framework, it can benefit from the strengths and capabilities of each model to further improve the synthesis of novel views with enhanced quality and consistency.