The Surprising Effectiveness of Diffusion Models for Optical Flow and
  Monocular Depth Estimation
Authors: name: Saurabh Saxena, name: Charles Herrmann, name: Junhwa Hur, name: Abhishek Kar, name: Mohammad Norouzi, name: Deqing Sun, name: David J. Fleet

Denoising diffusion probabilistic models have transformed image generation
with their impressive fidelity and diversity. We show that they also excel in
estimating optical flow and monocular depth, surprisingly, without
task-specific architectures and loss functions that are predominant for these
tasks. Compared to the point estimates of conventional regression-based
methods, diffusion models also enable Monte Carlo inference, e.g., capturing
uncertainty and ambiguity in flow and depth. With self-supervised pre-training,
the combined use of synthetic and real data for supervised training, and
technical innovations (infilling and step-unrolled denoising diffusion
training) to handle noisy-incomplete training data, and a simple form of
coarse-to-fine refinement, one can train state-of-the-art diffusion models for
depth and optical flow estimation. Extensive experiments focus on quantitative
performance against benchmarks, ablations, and the model's ability to capture
uncertainty and multimodality, and impute missing values. Our model, DDVM
(Denoising Diffusion Vision Model), obtains a state-of-the-art relative depth
error of 0.074 on the indoor NYU benchmark and an Fl-all outlier rate of 3.26\%
on the KITTI optical flow benchmark, about 25\% better than the best published
method. For an overview see https://diffusion-vision.github.io.