Burt P, Julesz B
Perception. 1980;9(6):671-82. doi: 10.1068/p090671.
It is generally believed that there is an absolute disparity limit for binocular fusion; objects with disparities within this limit, known as Panum's fusional area, will appear fused and single, while objects with disparities outside the limit appear double. It is demonstrated, however, that the disparity gradient, rather than the disparity magnitude, dictates binocular fusion when several objects occur near one another in the visual field. The disparity gradient is defined as the difference between the disparities of neighboring objects divided by their angular separation. If this ratio exceeds a critical value (approximately 1) then fusion does not occur, even though the absolute disparities of the individual objects may be well within the classical Panum's area. This discovery leads to the reinterpretation of several enigmatic phenomena in stereopsis, including Panum's limiting case.
一般认为，双眼融合存在一个绝对视差极限；视差在这个极限范围内的物体，即所谓的潘诺融合区，会呈现为融合且单一的，而视差超出该极限的物体则会出现重影。然而，研究表明，当视野中几个物体彼此靠近时，决定双眼融合的是视差梯度而非视差大小。视差梯度定义为相邻物体视差之差除以它们的角间距。如果这个比值超过一个临界值（约为1），那么即使单个物体的绝对视差可能完全在经典的潘诺区内，融合也不会发生。这一发现导致了对视差感知中几个神秘现象的重新解释，包括潘诺极限情况。
