Ganis G, Casco C, Roncato S
Dipartimento di Psicologia Generale, Università di Padova, Italy.
Perception. 1993;22(1):23-34. doi: 10.1068/p220023.
Stroboscopic simulations of three-dimensional rotating rigid structures can be perceived as highly nonrigid. To investigate this nonrigidity effect a sequence of either three (experiment 2 and 3) or thirty six frames (experiment 4) was used, each consisting of a set of dots with location on the horizontal axis corresponding to the parallel projection of a nominally defined helix. Observers were asked to judge the angle of rotation of eighty helices defined by the factorial combination of eight phase (phi) values (ie difference between the sinusoidal path of one dot and its neighbours) and ten different angular displacement values (alpha). When in each static frame the dots can be organized into curved dotted line (small values of phi), the perceived 3-D helices are highly nonrigid. But when shape information is not available in each static frame (high values of phi), the helices are perceived as rigid and rotation judgement is possible providing that alpha < 15 degrees. It appears that at small values of phi observers fail to recover the rigid structure of the helices since the input to the structure from the motion process may be distorted.
三维旋转刚性结构的频闪模拟可能会被视为高度非刚性的。为了研究这种非刚性效应，使用了一系列由三帧（实验2和3）或三十六帧（实验4）组成的序列，每帧都由一组点组成，这些点在水平轴上的位置对应于名义定义螺旋的平行投影。要求观察者判断由八个相位（φ）值（即一个点与其相邻点的正弦路径之间的差异）和十个不同角位移值（α）的因子组合所定义的八十个螺旋的旋转角度。当在每个静态帧中，点可以被组织成曲线虚线（φ值较小）时，所感知到的三维螺旋是高度非刚性的。但是，当每个静态帧中没有形状信息（φ值较大）时，螺旋被视为刚性的，并且只要α<15度，就可以进行旋转判断。似乎在φ值较小时，观察者无法恢复螺旋的刚性结构，因为来自运动过程对该结构的输入可能会被扭曲。
