XTrack: Multimodal Training Boosts RGB-X Video Object Trackers

TL;DR

XTrack introduces a multimodal training approach for RGB-X video object tracking that leverages cross-modal knowledge sharing during training to improve inference performance, achieving a +3% precision gain over state-of-the-art methods.

Contribution

The paper proposes a novel mixture-of-experts framework with a modality classifier to facilitate cross-modal knowledge sharing during training, enhancing RGB-X tracker performance.

Findings

Achieved +3% precision improvement over SOTA.

Effective knowledge transfer between modalities during training.

Beneficial even with limited paired multimodal data.

Abstract

Multimodal sensing has proven valuable for visual tracking, as different sensor types offer unique strengths in handling one specific challenging scene where object appearance varies. While a generalist model capable of leveraging all modalities would be ideal, development is hindered by data sparsity, typically in practice, only one modality is available at a time. Therefore, it is crucial to ensure and achieve that knowledge gained from multimodal sensing -- such as identifying relevant features and regions -- is effectively shared, even when certain modalities are unavailable at inference. We venture with a simple assumption: similar samples across different modalities have more knowledge to share than otherwise. To implement this, we employ a ``weak" classifier tasked with distinguishing between modalities. More specifically, if the classifier ``fails" to accurately identify the modality of the given sample, this signals an opportunity for cross-modal knowledge sharing. Intuitively, knowledge transfer is facilitated whenever a sample from one modality is sufficiently close and aligned with another. Technically, we achieve this by routing samples from one modality to the expert of the others, within a mixture-of-experts framework designed for multimodal video object tracking. During the inference, the expert of the respective modality is chosen, which we show to benefit from the multimodal knowledge available during training, thanks to the proposed method. Through the exhaustive experiments that use only paired RGB-E, RGB-D, and RGB-T during training, we showcase the benefit of the proposed method for RGB-X tracker during inference, with an average +3\% precision improvement over the current SOTA. Our source code is publicly available at https://github.com/supertyd/XTrack/tree/main.