Sparse DTU
3 views
Sparse RFF
3 views
Generalizable DTU
unknown scene
Generalizable RFF
known scene
ILSH
ICCV 23 challenge
A recent trend among generalizable novel view synthesis methods is to learn a rendering operator acting over single camera rays. This approach is promising because it removes the need for explicit volumetric rendering, but it effectively treats target images as collections of independent pixels. Here, we propose to learn a global rendering operator acting over all camera rays jointly. We show that the right representation to enable such rendering is a 5-dimensional plane sweep volume consisting of the projection of the input images on a set of planes facing the target camera. Based on this understanding, we introduce our Convolutional Global Latent Renderer (ConvGLR), an efficient convolutional architecture that performs the rendering operation globally in a low-resolution latent space. Experiments on various datasets under sparse and generalizable setups show that our approach consistently outperforms existing methods by significant margins.
Overview of ConvGLR. The 4D grouped PSV $\boldsymbol{X}$ is turned into a latent volumetric representation $\boldsymbol{Y}$, then rendered into a latent novel view $\boldsymbol{Z}$ and finally upsampled into the novel view $\boldsymbol{\tilde{I}}_{\!\ast}$. The dark gray blocks are implemented with 2D convolutions and resblocks.