Disentangling Random and Cyclic Effects in Time-Lapse Sequences

TL;DR

This paper presents a data-driven generative model based on GANs that disentangles random, cyclic, and overall trends in time-lapse sequences, enabling flexible re-rendering and analysis of dynamic scenes.

Contribution

The authors introduce a novel GAN-based approach with Fourier feature conditioning to separate different effects in time-lapse data, improving control and robustness.

Findings

Able to stabilize sequences to highlight specific phenomena

Robust to data defects like occlusions and missing frames

Enables re-rendering with controlled weather and cyclic effects

Abstract

Time-lapse image sequences offer visually compelling insights into dynamic processes that are too slow to observe in real time. However, playing a long time-lapse sequence back as a video often results in distracting flicker due to random effects, such as weather, as well as cyclic effects, such as the day-night cycle. We introduce the problem of disentangling time-lapse sequences in a way that allows separate, after-the-fact control of overall trends, cyclic effects, and random effects in the images, and describe a technique based on data-driven generative models that achieves this goal. This enables us to "re-render" the sequences in ways that would not be possible with the input images alone. For example, we can stabilize a long sequence to focus on plant growth over many months, under selectable, consistent weather. Our approach is based on Generative Adversarial Networks (GAN) that are conditioned with the time coordinate of the time-lapse sequence. Our architecture and training procedure are designed so that the networks learn to model random variations, such as weather, using the GAN's latent space, and to disentangle overall trends and cyclic variations by feeding the conditioning time label to the model using Fourier features with specific frequencies. We show that our models are robust to defects in the training data, enabling us to amend some of the practical difficulties in capturing long time-lapse sequences, such as temporary occlusions, uneven frame spacing, and missing frames.