  We propose a relighting method for outdoor images. Our method mainly focuses
on predicting cast shadows in arbitrary novel lighting directions from a single
image while also accounting for shading and global effects such the sun light
color and clouds. Previous solutions for this problem rely on reconstructing
occluder geometry, e.g. using multi-view stereo, which requires many images of
the scene. Instead, in this work we make use of a noisy off-the-shelf
single-image depth map estimation as a source of geometry. Whilst this can be a
good guide for some lighting effects, the resulting depth map quality is
insufficient for directly ray-tracing the shadows. Addressing this, we propose
a learned image space ray-marching layer that converts the approximate depth
map into a deep 3D representation that is fused into occlusion queries using a
learned traversal. Our proposed method achieves, for the first time,
state-of-the-art relighting results, with only a single image as input. For
supplementary material visit our project page at:
https://dgriffiths.uk/outcast.

Graphics;Computer Vision and Pattern Recognition;Machine Learning