The Neron-Severi group of divisor classes modulo algebraic equivalence on a smooth algebraic surface is often not difficult to calculate, and has classically been studied as one of the fundamental invariants of the surface. A more difficult problem is the determination of those divisor classes which can be represented by effective divisors; these divisor classes form a monoid contained in the N...

26 Reliable estimation of 3D surface orientation is critical for recognizing and interacting with 27 complex 3D objects in our environment. Human observers maximize the reliability of their 28 estimates of surface slant by integrating multiple depth cues. Texture and binocular disparity 29 are two such cues, but they are qualitatively very different. Existing evidence suggests 30 representation...

Existing techniques for obtaining shape from texture estimate tilt and slant via a single computational mechanism. These techniques do not take advantage of the fact that tilt is relatively easy to estimate, and slant can be estimated more easily once tilt is known. This paper introduces the adaptive bisector method, which allows tilt and slant to be calculated separately, and by different comp...

Previous work has demonstrated a difference in human sensitivity to compressive and shearing speed gradients. This raises the possibility that the ability to estimate the slant of a surface may vary with its direction of tilt. No such variance was found here, which may indicate that slant estimation depends upon deformation rather than upon compression or shear.

Reliable estimation of three-dimensional (3D) surface orientation is critical for recognizing and interacting with complex 3D objects in our environment. Human observers maximize the reliability of their estimates of surface slant by integrating multiple depth cues. Texture and binocular disparity are two such cues, but they are qualitatively very different. Existing evidence suggests that repr...

Keywords: Ruled surface Structure function Pitch function Angle function of pitch Weingarten surface Binormal ruled surface a b s t r a c t In this paper, using the elementary method we study ruled surfaces, the simplest foliated submanifolds, in Euclidean 3-space. We define structure functions of the ruled surfaces, the invariants of non-developable ruled surfaces and discuss geometric propert...

For the online control of movement, it is important to respond fast. The extent to which cues are effective in guiding our actions might therefore depend on how quickly they provide new information. We compared the latency to alter a movement when monocular and binocular cues indicated that the surface slant had changed. We found that subjects adjusted their movement in response to three types ...