When a small frontoparallel surface (a test strip) is surrounded by a larger slanted surface (an inducer), the test strip is perceived as slanted in the direction opposite to the inducer. This has been called the depth-contrast effect, but we call it the slant-contrast effect. In nearly all demonstrations of this effect, the inducer's slant is specified by stereoscopic signals; and other signal...

An optimal linear system for integrating visual cues to 3D surface geometry weights cues in inverse proportion to their uncertainty. The problem of integrating texture and stereo information for judgments of planar surface slant provides a strong test of optimality in human perception. Since the accuracy of slant from texture judgments changes by an order of magnitude from low to high slants, o...

Although it is known that high-level spatial attention affects adaptation for a variety of stimulus features (including binocular disparity), the influence of voluntary attentional control-and the associated awareness-on adaptation has remained unexplored. We developed an ambiguous surface slant adaptation stimulus with conflicting monocular and binocular slant signals that instigated two mutua...

Eye movements introduce retinal motion to the image and so affect motion cues to depth. For instance, the slant of a plane moving at right-angles to the observer is specified by translation and a component of relative motion such as shear. To a close approximation, the translation disappears from the image when the eye tracks the surface accurately with a pursuit eye movement. However, both tra...

A vertical test probe is misperceived as slanted in the opposite direction to an inducer when disparity specifies the inducer slant while monocular cues specify a frontoparallel surface (slant-contrast). In reversed cue conditions with vertical axis slant the test probe is misperceived as slanted in the same direction as the inducer (reversed slant-contrast). We found reliable slant-contrast an...

We measured stereoscopic slant detection thresholds for surfaces slanting about a horizontal or a vertical axis. For random-dot covered surfaces, 1.25 deg of slant was required to detect slant about a horizontal axis, whereas 2.1 deg of slant was required to detect slant about a vertical axis. This anisotropy could be due to the fact that orientation disparities, which contain information about...

In this work, we firstly introduce notions of principal directed curves and donor which are associated a Frenet curve in the dual Lorentzian space D 3 1 D13 . We give some relations between curvature torsion curve. show that general helix is plane obtain equation by using position vector Then circle $\mathbb{D}^{2}$ or hyperbola $\mathbb{D}_{1}^{2}$ slant $\mathbb{D}_{1}^{3}$ helix, respectivel...

The contribution of slant and tilt to the detection of differences in local surface orientation was examined for structure-from-motion (SFM) displays of a complex sinusoidal surface. Observers judged whether an elliptical SFM gauge figure appeared to be lying on the surface or intersecting it. The gauge figure orientation either matched the local surface orientation or differed from it in slant...

Observers viewed large dichoptic patterns undergoing smooth temporal modulations or step changes in simulated slant or inclination under various conditions of disparity-perspective cue conflict and concordance. After presentation of each test surface, subjects adjusted a comparison surface to match the perceived slant or inclination of the test surface. Addition of conflicting perspective to di...