Core Insights - The article introduces Light-X, the world's first 4D video generation framework that allows for dual control of camera movement and lighting in single-view videos, enabling users to re-direct and adjust lighting conditions post-capture [2][32] - Light-X addresses the challenge of simultaneously controlling both camera trajectory and lighting, which has not been effectively solved in previous research [7][32] Research Background - The visual experience in the real world is composed of geometry, motion, and lighting, while single-view videos are merely 2D projections of this complex four-dimensional space [5] - The ability to control camera position and lighting conditions after filming can significantly enhance applications in film production, virtual shooting, and AR/VR content generation [5] Methodology - Light-X's core approach involves decoupling camera control from lighting control, then integrating them within a diffusion model to achieve dual controllability in single-view videos [10][32] - The framework constructs two branches from the input video: one for dynamic point clouds (camera control) and another for re-lighting point clouds (lighting control), successfully decoupling these factors during modeling [11] Data Construction - Light-X requires paired geometric alignment, multi-lighting, and multi-view training data, which is scarce in the real world. To address this, Light-Syn was developed to automatically synthesize training data from single-view videos [15][32] - The data pipeline incorporates various video sources to ensure the model learns realistic motion structures and adapts to diverse lighting styles [19] Experimental Results - Light-X was evaluated on two core tasks: joint control of camera and lighting, and video re-lighting, outperforming existing methods in image quality, video smoothness, and user preference [25][32] - In the joint control task, Light-X achieved a FID score of 101.06, significantly better than previous methods, demonstrating superior image quality and user satisfaction [27] Ablation Studies - Ablation studies indicate that multi-source data is crucial for enhancing new view quality, motion stability, and lighting diversity, while fine-grained lighting cues and global lighting control improve consistency and stability [30][32] Conclusion - Light-X represents a significant advancement in video generation technology, enabling simultaneous control of camera movement and lighting, with extensive experimental validation showing its superiority over existing methods [32]