Viewing Geometry and Stereoscopic Vision

PI：Banks，Martin拟议的研究将调查我们通过双目视觉看到三维的方法。本文的研究主要集中在两个方面：1）人类视觉系统如何解决双目视觉中的“匹配问题”; 2）视觉系统如何根据双目视觉的深度信息表征物体表面的形状和方向。我们仍然不完全理解这个问题是如何解决的。匹配问题可以简单地表述为：对于左眼中的每一个图像点，视觉系统必须在另一只眼睛中找到合适的点来与之匹配。对于N个可能的点，理论上可能的匹配数量是N4，因此对于大的N，匹配过程可能变得计算上难以管理。视觉系统可以通过使用所谓的核线约束来大量减少可能的匹配数量。对于一只眼睛中的图像点，其匹配必须位于另一只眼睛中相应的核线上。通过使用极线约束，匹配问题可以减少到一维搜索。然而，当眼睛的位置改变时（例如，从远到近的注视），相应的核线的位置和取向在视网膜上改变。因此，为了实现核线约束，视觉系统必须考虑眼睛的位置。我们已经开发了一个实验程序，将使我们能够确定视觉系统是否使用核线约束，如果是这样的话，系统使用什么信号来计算当眼睛移动时核线应该如何移动，我们还将研究表面形状在视觉系统中表示的方法。表面形状的一个重要线索是到达双眼的水平差异模式，但这些差异本身不能产生形状的真实估计。还必须使用诸如垂直视差或眼睛位置信号的其他信号。我们已经表明，在以前的补助金期间，眼睛的聚散度的变化可以导致一个引人注目的变化，即使在视网膜的差异是完全恒定的感知形状。我们还知道，长时间观察曲面会导致随后观察到的平面出现相反方向的弯曲。像这样的后效被称为“视差后效”，因为所提供的解释仅指视差编码。在拟议的研究中，我们将检查曲率后效。通过独立地操纵眼位信号和视网膜视差，我们可以确定后效是由视觉编码机制（这是流行的理论）中的适应引起的，还是由更高层次的形状编码机制中的适应引起的。初步的测量表明，后一种假设是一个更好的预测数据。我们还将确定所涉及的各种信号（例如，眼肌肉信号和垂直视差）的加权在不同的观看条件下。拟议的工作将产生更好地了解这些方面的双目视觉，因此，可能会产生洞察力的改善视觉辅助，如双目显微镜，头部和头盔安装的显示器，和其他现实的显示。

PI: Banks, MartinThe proposed research will investigate the means by which we see 3-dimensionally via binocular vision. The research will focus on two issues: 1) how the human visual system solves the "matching problem" in binocular vision and 2) how the visual system represents surface shape and orientation from binocular depth cues.The matching problem in binocular vision has been actively researched for decades. We still do not fully understand how the problem is solved. The matching problem is simply stated in the following way: For every image point in the left eye, the visual system must find the appropriate point in the other eye to match with it. With N possible points, the number of theoretically possible matches is N4 so with large N the matching process can become computationally unmanageable. The visual system can massively reduce the number of possible matches by using what is termed the epipolar constraint. For an image point in one eye, its match must lie on the corresponding epipolar line in the other eye. By using the epipolar constraint, the matching problem can be reduced to a one-dimensional search. However, when the eyes' positions change (e.g., fixating from far to near), the positions and orientations of corresponding epipolar lines change on the retina. Thus, to implement the epipolar constraint, the visual system must take the eyes' positions into account. We have developed an experimental procedure that will allow us to determine whether the visual system uses the epipolar constraint and, if so, what signals the system uses in order to calculate how epipolar lines ought to move when the eyes move.We will also examine the means by which surface shape is represented in the visual system. An important cue to surface shape is the pattern of horizontal disparities arriving at the two eyes, but those disparities by themselves cannot yield a veridical estimate of shape. Other signals such as vertical disparities or eye-position signals must be used as well. We have shown in the previous grant period that changes in the eyes' vergence can cause a compelling change in perceived shape even when the retinal disparities are completely constant. We also know that prolonged viewing of a curved surface causes a subsequently viewed flat surface to appear curved in the opposite direction. Aftereffects like this have been called "disparity aftereffects" because the explanations offered refer to disparity encoding alone. In the proposed research, we will examine the curvature aftereffect. By manipulating eye-position signals and retinal disparities independently, we can determine whether the aftereffect is caused by adaptation among disparity-encoding mechanisms (which is the prevailing theory) or whether it is caused by adaptation in higher-level, shape-encoding mechanisms. Preliminary measurements suggest that the latter hypothesis is a better predictor of the data. We will also determine how the various signals involved (e.g., eye-muscle signals and vertical disparities) are weighted under different viewing conditions.The proposed work will yield a better understanding of these aspects of binocular vision and, consequently, may yield insights into improvements in visual aids such as binocular microscopes, head- and helmet-mounted displays, and other realistic displays.