Fernandez Julian M, Farell Bart
Institute for Sensory Research, Syracuse University, Syracuse, NY 13224, USA.
J Vis. 2009 Oct 26;9(11):23.1-20. doi: 10.1167/9.11.23.
Humans can recover 3-D structure from the projected 2D motion field of a rotating object, a phenomenon called structure from motion (SFM). Current models of SFM perception are limited to the case in which objects rotate about a frontoparallel axis. However, as our recent psychophysical studies showed, frontoparallel axes of rotation are not representative of the general case. Here we present the first model to address the problem of SFM perception for the general case of rotations around an arbitrary axis. The SFM computation is cast as a two-stage process. The first stage computes the structure perpendicular to the axis of rotation. The second stage corrects for the slant of the axis of rotation. For cylinders, the computed object shape is invariant with respect to the observer's viewpoint (that is, perceived shape doesn't change with a change in the direction of the axis of rotation). The model uses template matching to estimate global parameters such as the angular speed of rotation, which are then used to compute the local depth structure. The model provides quantitative predictions that agree well with current psychophysical data for both frontoparallel and non-frontoparallel rotations.
人类能够从旋转物体的二维投影运动场中恢复三维结构，这种现象被称为运动结构感知（SFM）。当前的SFM感知模型仅限于物体绕额状轴旋转的情况。然而，正如我们最近的心理物理学研究所表明的，额状旋转轴并不代表一般情况。在此，我们提出了第一个模型，以解决围绕任意轴旋转的一般情况下的SFM感知问题。SFM计算被视为一个两阶段过程。第一阶段计算垂直于旋转轴的结构。第二阶段校正旋转轴的倾斜度。对于圆柱体，计算出的物体形状相对于观察者的视角是不变的（即，感知到的形状不会随着旋转轴方向的变化而改变）。该模型使用模板匹配来估计全局参数，如旋转角速度，然后用这些参数来计算局部深度结构。该模型提供的定量预测与当前关于额状和平行于额状面旋转的心理物理学数据非常吻合。
