External forces guided fluid surface and volume reconstruction from monocular video

We propose a novel method to reconstruct fluid's volume movement and surface details from just a monocular video for the first time. Although many monocular video-based reconstruction methods have been developed, the reconstructed results are merely one layer of geometry surface and lack physically correct volume particles' attribute and movement. To reconstruct 3D fluid volume, we define two kinds of particles, the target particles and the fluid particles. The target particles are extracted from the height field of water surface which is recovered by Shape from Shading (SFS) method. The fluid particles represent the discrete form of the 3D fluid volume and conform to the flow hydrodynamic properties. The target particles are used to guide the physical simulation of fluid particles based on the Smoothed Particle Hydrodynamics (SPH) model. To formulate this guidance, a new external force scheme is designed based on distance and relative motion between target particles and fluid particles. Additionally, in order to integrate and maintain geometric and physical features simultaneously, we adopt a two-scale decomposition strategy for the height field, and only apply the low frequency coarse-scale component to estimate the volumetric motion of liquid, while serve high frequency fine-scale component as noise to preserve fluid surface details in the stage of rendering. Our experimental results compare favorably to the state-of-the-art in terms of global fluid volume motion features and fluid surface details and demonstrate our approach can achieve desirable and pleasing effects.