Novel view synthesis of dynamic scenes is fundamental to achieving photorealistic 4D reconstruction and immersive visual experiences. Recent progress in Gaussian-based representations has significantly improved real-time rendering quality, yet existing methods still struggle to maintain a balance between long-term static and short-term dynamic regions in both representation and optimization. To address this, we present SharpTimeGS, a lifespan-aware 4D Gaussian framework that achieves temporally adaptive modeling of both static and dynamic regions under a unified representation. Specifically, we introduce a learnable lifespan parameter that reformulates temporal visibility from a Gaussian-shaped decay into a flat-top profile, allowing primitives to remain consistently active over their intended duration and avoiding redundant densification. In addition, the learned lifespan modulates each primitives' motion, reducing drift in long-lived static points while retaining unrestricted motion for short-lived dynamic ones. This effectively decouples motion magnitude from temporal duration, improving long-term stability without compromising dynamic fidelity. Moreover, we design a lifespan-velocity-aware densification strategy that mitigates optimization imbalance between static and dynamic regions by allocating more capacity to regions with pronounced motion while keeping static areas compact and stable. Extensive experiments on multiple benchmarks demonstrate that our method achieves state-of-the-art performance while supporting real-time rendering up to 4K resolution at 100 FPS on one RTX 4090.

翻译：动态场景的新视角合成是实现逼真4D重建和沉浸式视觉体验的基础。基于高斯表示的最新进展显著提升了实时渲染质量，但现有方法在表示与优化中仍难以平衡长期静态区域与短期动态区域。为此，我们提出SharpTimeGS——一种寿命感知的4D高斯框架，在统一表示下实现对静态与动态区域的时间自适应建模。具体而言，我们引入可学习的寿命参数，将时间可见性从高斯形衰减重构为平顶分布，使基元在其预期持续时间内保持持续活跃，避免冗余致密化。此外，习得的寿命参数可调制每个基元的运动，减少长寿命静态点的漂移，同时保留短寿命动态点的无约束运动。这有效解耦了运动幅度与时间持续性的关联，在保持动态保真度的同时提升了长期稳定性。进一步，我们设计了一种寿命-速度感知的致密化策略，通过为运动显著区域分配更多容量，同时保持静态区域紧凑稳定，缓解了静态与动态区域间的优化不平衡。在多个基准测试上的大量实验表明，我们的方法实现了最先进的性能，并可在单张RTX 4090显卡上以100 FPS的帧率支持高达4K分辨率的实时渲染。