Del Viva M M, Morrone M C
Istituto di Neurofisiologia del CNR, Pisa, Italy.
Vision Res. 1998 Nov;38(22):3633-53. doi: 10.1016/s0042-6989(98)00022-4.
We have developed a two-stage model of motion perception that identifies moving spatial features and computes their velocity, achieving both high spatial localisation and reliable estimates of velocity. Features are detected in each frame by locating the peaks of the spatial local energy functions, as for stationary images (Morrone MC and Burr DC. Proc R Soc Lond 1988;B235:221-245.). The energy functions are calculated for different scales and orientations, and integrated within a temporal Gaussian window. The velocity of features is determined by the direction of maximal elongation of the energy in space-time, evaluated by calculating the three characteristic curvatures of the energy at each feature point. To circumvent the aperture problem, the energy maps are blurred in space by various amounts, and velocity is computed separately for each spatial blur. The Weber fraction of the local curvatures (curvature contrast) describes the spatio-temporal energy elongation at each feature point, giving a reliability index for each velocity estimate. For each point, the velocity of the spatial blur that yielded the highest curvature contrast was selected, with no further constraints, such as rigidity of motion. Dynamic recruitment of operators of different size allows maximum flexibility of the analysis, allowing it to simulate human visual performance in the detection of noise images, transparent motion, some motion illusions, and second-order motion.
我们开发了一种运动感知的两阶段模型，该模型可识别移动的空间特征并计算其速度，从而实现高空间定位和可靠的速度估计。对于每一帧，通过定位空间局部能量函数的峰值来检测特征，这与处理静止图像时的方法相同（莫罗内·M·C和伯尔·D·C。《英国皇家学会学报》1988年；B235:221 - 245）。能量函数针对不同的尺度和方向进行计算，并在一个时间高斯窗口内进行积分。特征的速度由时空能量最大伸长方向确定，通过计算每个特征点处能量的三个特征曲率来评估。为了规避孔径问题，能量图在空间上进行不同程度的模糊处理，并针对每个空间模糊单独计算速度。局部曲率的韦伯分数（曲率对比度）描述了每个特征点处的时空能量伸长情况，为每个速度估计提供了一个可靠性指标。对于每个点，选择产生最高曲率对比度的空间模糊的速度，且没有进一步的限制，如运动的刚性。动态招募不同大小的算子可使分析具有最大的灵活性，使其能够模拟人类视觉在检测噪声图像、透明运动、一些运动错觉和二阶运动方面的表现。
