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From NeRF to 3D Gaussians: how do we represent a world?

Edited for the SaJTU websiteOPEN ACCESS READING

Two scene representations, one reading path into neural rendering. Compare implicit radiance fields and explicit 3D Gaussians through the original papers.

Start with the problem

Given several images of a scene, how can we generate an image from a viewpoint that was never photographed? This is a central question in novel-view synthesis. It relates to reconstructing an interactive physical world, but it is not the same task.

Two representative works take different approaches: NeRF: Representing Scenes as Neural Radiance Fields for View Synthesis, presented at ECCV 2020, and 3D Gaussian Splatting for Real-Time Radiance Field Rendering, presented at SIGGRAPH 2023.

NeRF: a scene as a continuous function

NeRF uses a neural network to map spatial positions and viewing directions to volume density and color. Volume rendering converts these predictions into images. Rather than merely storing photographs, the method learns a continuous scene representation that can be queried from different viewpoints.

Follow three mechanisms while reading: coordinate encoding, sampling along camera rays, and the supervision provided by comparing rendered and training images.

3D Gaussian Splatting: an explicit alternative

3D Gaussian Splatting represents a scene as a collection of 3D Gaussians, optimizing their positions, shapes, opacities and appearance. A visibility-aware splatting renderer generates images. The original work targets high-quality real-time novel-view synthesis.

This makes the implicit–explicit comparison concrete. How does the representation affect optimization, memory requirements and rendering? Does comparable image quality imply comparable geometry?

Keep three questions separate

  • Image quality: how closely synthesized images match reference images.
  • Geometric accuracy: whether the representation recovers reliable 3D structure.
  • Physical consistency: whether the scene supports trustworthy dynamics and interaction.

Good novel-view synthesis does not automatically establish the latter two. Check hardware, resolution, datasets and training settings before interpreting performance figures. This guide makes no additional quantitative performance claims.

Original sources

  1. Mildenhall et al. NeRF: Representing Scenes as Neural Radiance Fields for View Synthesis. ECCV 2020. Project, paper and code.
  2. Kerbl et al. 3D Gaussian Splatting for Real-Time Radiance Field Rendering. SIGGRAPH 2023. Project, paper and code.

This page is a guide to public papers, not research produced by this website or a claim of collaboration with their authors.