Understand the physics of the liquid sloshing is crucial to prevent the liquid storage tank instability. This paper proposes a novel videogrammetric method for high-frequency and accurate measurement of the liquid-level response. By using the lightweight floating spheres as independent measurement points and considering the settlement and aggregation of spheres under complex liquid environments, an adaptive block tracking method combined with an arc segmentation strategy is proposed to track spherical targets continuously. Combined with the calibrated stereo camera and the correspondence across different views, the liquid surface can be reconstructed by triangulating and interpolating the multiple tracking targets at any time. The reliability and robustness of the proposed method are demonstrated using the measurements from the total station, laser range finder, and stereo cameras beside the tank in multiple validation tests. In addition, the proposed method has been successfully applied to a large-scale LNG model shaking table test.