To solve the problem that the motion capture data has a large number of data redundancy,this paper proposes
a key frame extraction method based on inter-frame pitch. In order to compress,storage,reconstruct and further reuse motion data,key-frame is needed to be extracted which represents the content of the motion. Quaternion is introduced to represent the difference between two rotations. The distance between two frames is defined by the total rotation differences and first frame is regarded as the first key frame. Then,calculate the difference between the current frame and the last key frame continuously. The frame is eliminated when the difference is smaller than the set threshold or the opposite is reserved for the new key frame. Spherical linear interpolation is used to reconstruct the sequence. To express the characteristics of human motion,the joint velocity is introduced. Reconstruction error is defined by the human body posture error of position and the motion speed error between the original frame and the reconstructed frame. Experimental resultdemonstrates that the original motion capture can be compressed in a high ratio and gives a good visual summary erformance.
传统的超声测距方法基于单频脉冲飞行时间,原理简单、应用灵活,但由于声波易受空气衰减以及电路噪声影响,其测量精度较低,多频连续波相位检测法可以达到较高的精度,但其受限于连续声波发射,应用范围较小。为兼顾测量精度与应用范围,提出一种采用多频超声脉冲发射的方法,利用各频段声波之间的固有时间差值,结合飞行时间法精确估计超声脉冲的到达时间,再通过温度补偿测量现场的声速,即可得到精确的被测距离。该方法能够拓展超声测距的应用范围,简化硬件设计,经实验验证,在3 m 范围内,测量精度可以达到0. 3 mm左右。