Differentiable particle-based simulation can produce physically plausible motion, but target-driven volumetric shape morphing remains underconstrained: physics-only mass matching captures coarse global structure yet struggles with fine geometric detail, while naive image-space coupling destabilizes elastic dynamics. We present PhysMorph-GS, a render-guided morphing framework that couples material point method simulation with differentiable 3D Gaussian splatting. The key idea is to inject visual supervision through the deformation gradient $\mathbf{F}$ rather than particle positions, so render gradients act as control-space guidance while trajectories remain governed by physics. We further introduce phased Chamfer-guided plasticity that delays rest-state migration until coarse structure has formed; in practice, rendering is evaluated on a surface-focused particle subset for efficiency and gradient concentration. Relative to a physics-only baseline, our method reduces silhouette error by 25.8\%, 10.8\%, and 49.9\% on representative examples, with the largest gains on models with thin features. These results suggest that the main challenge in render-guided differentiable morphing is not simply adding stronger image losses, but injecting visual guidance in a way that remains compatible with elastic simulation. We further observe that plasticity-driven rest-state migration drives different sources toward a shared target-determined attractor, distinguishing physics-based morphing from interpolation between registered shape pairs.

翻译：可微粒子仿真能够生成物理上合理的运动，但目标驱动的体积几何形变仍面临约束不足的问题：仅基于物理的质量匹配可捕获粗略全局结构却难以处理精细几何细节，而天真的图像空间耦合会破坏弹性动力学稳定性。我们提出PhysMorph-GS——一种将物质点法仿真与可微三维高斯泼溅相结合的渲染引导形变框架。其关键思想是通过变形梯度张量$\mathbf{F}$而非粒子位置注入视觉监督，使得渲染梯度作为控制空间引导，而轨迹仍受物理规律支配。我们进一步引入分阶段Chamfer引导塑性，推迟参考构型迁移直至粗结构形成；实践中，仅对表面聚焦的粒子子集执行渲染评估以提高效率并集中梯度。与纯物理基线相比，本方法在典型示例上将轮廓误差分别降低25.8%、10.8%和49.9%，其中对含薄壁特征的模型提升最为显著。这些结果表明，渲染引导可微形变的主要挑战并非简单施加更强的图像损失，而是以与弹性仿真兼容的方式注入视觉引导。我们进一步观察到，塑性驱动的参考构型迁移驱使不同源朝向共享的目标确定吸引子，这区分了基于物理的形变与注册形状对间的插值。