## 5 Discussion and Conclusions  
When a conventional phase-shifting method is employed in measuring dynamic scene, three images can determine the phase. In this method, only one corresponding phase can be determined by each group of three images. It is an average effect in a short period of time during the acquisition of the three images. The accuracy of the measurement result is also affected by motion blur. In consideration of the dynamic object's moving nature, appropriate sampling rate of the employed high-speed camera should be selected to capture as many frames of deformed fringe patterns as possible. Then, to ensure temporal resolution and measuring accuracy, multiple periodic signals are constructed to analyze the phase variation along temporal axis with TFTP. In the proposed method, only one frame of the deformed fringe pattern is required to calculate its corresponding phase distribution and it is only limited by the sampling rate of the employed high-speed camera.  
During the measurement process, when the dynamic object moves both in the horizontal or vertical direction at the same time, the 3D reconstruction can also be retrieved. If it moves much faster, guaranteeing successful reconstruction and improving measurement accuracy can be achieved by having the negative influence reduced. This is done by decreasing the spatial frequency of the projected fringe pattern or accelerating the sampling speed along the temporal axis. If the dynamic object is broken after fracture, the 3D shape of measurement object can also be reconstructed as long as the sampling rate of the employed high-speed camera is fast enough to ensure the phase distribution is continuous along the temporal axis.  
As a novel 3D shape measurement profilometry, TFTP only performs Fourier transform, band-pass filtering, and inverse Fourier transform operations along the temporal axis pixel by pixel and never performs weighted filtering operation in spatial domain. The high-frequency spatial components of the tested isolated dynamic object have been successfully retained. TFTP neither limits to precise phase-shifting techniques, nor does it require strict spatial modulation frequencies. During the whole measurement process for dynamic object, only one 2D wrapped phase is required to be correctly unwrapped in spatial domain, and the whole 3D wrapped phase can be easily unwrapped via temporal axis. This method essentially requires one single deformed fringe pattern to retrieve its corresponding 3D shape of the measured dynamic object, and is only limited by the sampling rate of the employed high-speed camera. This possesses an obvious advantage for high speed measurement of dynamic process. The current recording speed is 300 fps, which can be raised if the marking points on the film are increased or the recording rate of the employed camera is faster.  
Conceptualization and methodology, Q.Z. and Y.L. ([PERSON]); Data curation, H.Z. and Y.L. ([PERSON]); writing--original draft preparation, H.Z.; writing--review and editing, Q.Z. and Y.L. ([PERSON]); funding acquisition, Q.Z. This research was funded by the National Natural Science Foundation of China (under Grant No. 61675141). The authors declare no conflict of interest.