WorldCat Identities

Hildreth, Ellen C.

Overview
Works: 7 works in 9 publications in 1 language and 14 library holdings
Roles: Author
Classifications: BF241, 153.754
Publication Timeline
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Most widely held works by Ellen C Hildreth
The measurement of visual motion by Ellen Catherine Hildreth( Book )

3 editions published between 1982 and 1983 in English and held by 5 WorldCat member libraries worldwide

The analysis of visual motion divides naturally into two stages: the first is the measurement of motion, for example, the assignment of direction and magnitude of velocity to elements in the image, on the basis of the changing intensity pattern; the second is the use of motion measurements, for example, to separate the scene into distinct objects, and infer their three-dimensional structure. In this paper, we present a computational study of the measurement of motion. Similar to other visual processes, the motion of elements is not determined uniquely by information in the changing image; additional constraint is required to compute a unique velocity filed. Given this global ambiguity of motion. Local measurements from the changing image, such as those provided by directionally-selective simple cells in primate visual cortex, cannot possibly specify a unique local velocity vector, and in fact, specify only one component of velocity. Computation of the full two-dimensional velocity field requires the integration of local motion measurements, either over an area, or along contours in the image. We will examine possible algorithms for computing motion, based on a range of additional constraints. Finally, we will present implications for the biological computation of motion
Drivers in pursuit of perceptual and virtual targets by Erwin R Boer( )

1 edition published in 1998 in English and held by 3 WorldCat member libraries worldwide

The visual input to steering control by Ellen C Hildreth( Book )

1 edition published in 1996 in English and held by 2 WorldCat member libraries worldwide

Examines what visual information is used to plan steering maneuvers while driving
The computational approach to vision and motor control by Ellen Catherine Hildreth( Book )

1 edition published in 1985 in English and held by 1 WorldCat member library worldwide

The analysis of visual motion: From computational theory to neuronal mechanisms by Ellen C Hildreth( )

1 edition published in 1987 in Undetermined and held by 1 WorldCat member library worldwide

The measurement and use of visual motion is one of the most fundamental abilities of biological vision systems, serving many essential functions. For example, a sudden movement in the scene might indicate an approaching predator or a desirable prey. The rapid expansion of features in the visual field can signal an object about to collide with the observer. Discontinuities in motion often occur at the locations of object boundaries and can be used to carve up the scene into distinct objects. Motion signals provide input to centers controlling eye movements, allowing objects of interest to be tracked through the scene. Relative movement can be used to infer the three-dimensional (3-D) structure and motion of object surfaces, and the movement of the observer relative to the scene, allowing biological systems to navigate quickly and efficiently through the environment. More generally, the analysis of visual motion helps us to maintain continuity of our perception of the constantly changing environment around us
The incremental rigidity scheme for recovering structure from motion: position vs. velocity based formulations by Massachusetts Institute of Technology( Book )

1 edition published in 1985 in English and held by 1 WorldCat member library worldwide

Perceptual studies suggest that the visual system uses the rigidity assumption to recover three dimensional structure from motion. Ullman (1984) recently proposed a computational scheme, the incremental rigidity scheme, which uses the rigidity assumption to recover the structure of rigid and nonrigid objects in motion. The scheme assumes the input to be discrete positions of elements in motion, under orthographic projection. We present formulations of Ullman's method that use velocity information and perspective projection in the recovery of structure. Theoretical and computer analyses show that he velocity based formulations provide a rough estimate of structure quickly, but are not robust over an extended time period. The stable long term recovery of structure requires disparate views of moving objects. Our analysis raises interesting questions regarding the recovery of structure from motion in the human visual system. Keywords: Space perception. (AW)
Recovering three-dimensional structure from motion with surface reconstruction by Massachusetts Institute of Technology( )

1 edition published in 1991 in English and held by 0 WorldCat member libraries worldwide

This paper addresses the computational role that the construction of a complete surface representation may play in the recovery of 3-D structure from motion. We first discuss the need to integrate surface reconstruction with the structure-from-motion process, both on computational and perceptual grounds. We then present a model that combines a feature-based structure-from-motion algorithm with a smooth surface interpolation mechanism. This model allows multiple surfaces to be represented in given viewing direction, incorporates constraints on surface structure from object boundaries, and groups image features on the basis of their 2-D image motion to segregate features onto multiple surfaces. We present the results of computer simulations that relate the behavior of this model to psychophysical observations. In a companion paper, we discuss further perceptual observations regarding the possible role of surface reconstruction in the human recovery of 3-D structure from motion
 
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