Compressing Explicit Voxel Grid Representations: Fast NeRFs Become Also Small

NeRFs have revolutionized the world of per-scene radiance field reconstruction because of their intrinsic compactness. One of the main limitations of NeRFs is their slow rendering speed, both at training and inference time. Recent research addressing this issue focuses on optimisation of an explicit voxel grid (EVG) that represents the scene, which can be paired with neural networks to learn radiance fields. This approach significantly enhances the speed both at train and inference time, but at the cost of large memory occupation. In this work we propose Re:NeRF, an approach specifically designed for targeting EVG-NeRFs compressibility, which aims to reduce memory storage of NeRF models while maintaining comparable performance. We benchmark our approach with three different EVG-NeRF architectures on three popular benchmarks, showing Re:NeRF's broad usability and effectiveness.