Temporal-Spatial Tubelet Embedding for Cloud-Robust MSI Reconstruction using MSI-SAR Fusion: A Multi-Head Self-Attention Video Vision Transformer Approach
Yiqun Wang, Lujun Li, Meiru Yue, Radu State
TL;DR
The paper tackles cloud-induced data gaps in time-series multispectral imagery by introducing a ViViT-based framework that uses temporal-spatial tubelet embeddings with a constrained temporal span (t=2) to preserve local spectral dynamics. It fuses MSI with SAR data to achieve all-weather reconstruction and employs a three-component architecture (3D tubelet embedding, joint-temporal-spatial MHSA, and linear patch decoding) optimized with a multi-scale MSE+SAM loss. On Traill County data, the proposed SMTS-ViViT approach consistently outperforms MSI-only and standard SAR-MSI baselines across MSE, SAM, PSNR, and SSIM, with SAR fusion yielding notable gains especially under higher cloud cover. The work demonstrates a practical, robust strategy for agricultural monitoring under cloudy conditions and lays groundwork for flexible cross-temporal analysis with all-weather fusion.
Abstract
Cloud cover in multispectral imagery (MSI) significantly hinders early-season crop mapping by corrupting spectral information. Existing Vision Transformer(ViT)-based time-series reconstruction methods, like SMTS-ViT, often employ coarse temporal embeddings that aggregate entire sequences, causing substantial information loss and reducing reconstruction accuracy. To address these limitations, a Video Vision Transformer (ViViT)-based framework with temporal-spatial fusion embedding for MSI reconstruction in cloud-covered regions is proposed in this study. Non-overlapping tubelets are extracted via 3D convolution with constrained temporal span $(t=2)$, ensuring local temporal coherence while reducing cross-day information degradation. Both MSI-only and SAR-MSI fusion scenarios are considered during the experiments. Comprehensive experiments on 2020 Traill County data demonstrate notable performance improvements: MTS-ViViT achieves a 2.23\% reduction in MSE compared to the MTS-ViT baseline, while SMTS-ViViT achieves a 10.33\% improvement with SAR integration over the SMTS-ViT baseline. The proposed framework effectively enhances spectral reconstruction quality for robust agricultural monitoring.
