Shape, motion, and optical cues to stiffness of elastic objects
Shape, motion, and optical cues to stiffness of elastic objects
复制标题
DOI：
10.1167/17.1.20
复制
发表时间：
2017-01-01
影响因子：
1.8
通讯作者：
Fleming, Roland W.
中科院分区：
文献类型：
--
作者：
Paulun, Vivian C.;Schmidt, Filipp;Fleming, Roland W.
非刚性材料，如果冻、橡胶或海绵，根据其硬度以不同的方式移动和变形。我们用什么线索来推断僵硬呢？我们模拟了不同硬度和光学外观的立方体(例如，木材、金属、蜡、果冻)受到两种变形：(A)不同程度地向下推入立方体的刚性圆柱体(形状变化，但几乎没有运动：形状主导)；(B)从立方体快速缩回的刚性圆柱体(相同的初始形状，运动的差异：运动主导)。观察者对立方体的表观软度/硬度进行了评级。在形状主导的情况下，评级主要取决于棒子穿透立方体的深度，几乎不受立方体的内在物理性质的影响。相反，在运动占优势的条件下，评级随着立方体的固有硬度而系统地变化，并且受扰动程度的影响较小。我们发现，变形的绝对大小可以很好地预测这两个结果，这表明当被要求判断刚度时，观察者会求助于基于变形量的简单启发式方法。静态、未受干扰的立方体的柔软度等级根据光学特性的不同而有很大和系统的变化。然而，在设置动画时，评级再次受到变形程度的影响，而光学外观的影响可以忽略不计。总而言之，我们的结果表明，要估计硬度，视觉系统强烈依赖于物体对力改变形状的程度的测量。
Nonrigid materials, such as jelly, rubber, or sponge move and deform in distinctive ways depending on their stiffness. Which cues do we use to infer stiffness? We simulated cubes of varying stiffness and optical appearance (e.g., wood, metal, wax, jelly) being subjected to two kinds of deformation: (a) a rigid cylinder pushing downwards into the cube to various extents (shape change, but little motion: shape dominant), (b) a rigid cylinder retracting rapidly from the cube (same initial shapes, differences in motion: motion dominant). Observers rated the apparent softness/hardness of the cubes. In the shape-dominant condition, ratings mainly depended on how deeply the rod penetrated the cube and were almost unaffected by the cube's intrinsic physical properties. In contrast, in the motion-dominant condition, ratings varied systematically with the cube's intrinsic stiffness, and were less influenced by the extent of the perturbation. We find that both results are well predicted by the absolute magnitude of deformation, suggesting that when asked to judge stiffness, observers resort to simple heuristics based on the amount of deformation. Softness ratings for static, unperturbed cubes varied substantially and systematically depending on the optical properties. However, when animated, the ratings were again dominated by the extent of the deformation, and the effect of optical appearance was negligible. Together, our results suggest that to estimate stiffness, the visual system strongly relies on measures of the extent to which an object changes shape in response to forces.