Showing papers on "Eye tracking published in 1996"

Mindless reading revisited: eye movements during reading and scanning are different.

Abstract: In an extension of a study by Vitu, O’Regan, Inhoff, and Topolski (1995), we compared global and local characteristics of eye movements during (1) reading, (2) the scanning of transformed text (in which each letter was replaced with a z), and (3) visual search. Additionally, we examined eye behavior with respect to specific target words of high or low frequency. Globally, the reading condition led to shorter fixations, longer saccades, and less frequent skipping of target strings than did scanning transformed text. Locally, the manipulation of word frequency affected fixation durations on the target word during reading, but not during visual search or z-string scanning. There were also more refixations on target words in reading than in scanning. Contrary to Vitu et al.’s (1995) findings, our results show that eye movements are not guided by a global strategy and local tactics, but by immediate processing demands.

Integrating Information Across Saccadic Eye Movements

Abstract: 1. Address correspor\\dence to Paul Bloom, Department of Psychology, University of Arizona, Tucson, AZ 85721; e-mail: blooni@u. arizona.edu. 2. Not all object individuation is plausibly viewed as emerging from an innate object module. In particular, the identification of objects in a static scene draws on a person's prior experience with the objects and on sensitivity to cues such as discontinuities in color and texture. These are the same factors that apply for the individuation of nonobject entities such as parts, suggesting that the procedures for nonobject individuation can sometimes extend to objects as well. Note, however, that although infants are sensitive to object properties such as spatiotemporal continuity, the ability to exploit these other types of cues is not present early in development (for discussion, see Baillargeon &c Hanko-Summers, 1990; Spelke, Breinlinger, )acobson, & Phillips, 1993). This developmental dissociation suggests that although the two modes of individuation might sometimes apply to the same entities (objects), they are nonetheless distinct.

Eye movement control in reading and visual search: Effects of word frequency.

Abstract: Eye movements were recorded as subjects either read text or searched through texts for a target word. In the reading task, there was a robust word frequency effect wherein readers looked longer at low-frequency words than at high-frequency words. However, there was no frequency effect in the search task. The results suggest that decisions to move the eyes during reading are made on a different basis than they are during visual search. Implications for current models of eye movement control in reading are discussed.

Gaze-directed adaptive rendering for interacting with virtual space

Abstract: This paper presents a new method of rendering for interaction with 3D virtual space with the use of gaze detection devices In this method, hierarchical geometric models of graphic objects are constructed prior to the rendering process The rendering process first calculates the visual acuity, which represents the importance of a graphic object for a human operator, from the gaze position of the operator Second, the process selects a level from the set of hierachical geometric models depending on the value of visual acuity That is, a simpler level of detail is selected where the visual acuity is lower, and a more complicated level is used where it is higher Then, the selected graphic models are rendered on the display This paper examines three visual characteristics to calculate the visual acuity: the central/peripheral vision, the kinetic vision, and the fusional vision The actual implementation and our testbed system are described, as well as the details of the visual acuity model

Head-mounted display

Abstract: A head-mounted display for displaying an image that matches a viewer's head movement has a head tracker for detecting the viewer's head movement, an eye tracker for detecting the viewer's eye movement, and an adaptive filter for adaptively filtering the output of the head tracker in accordance with the output of the head tracker and the output of the eye tracker, and when tracker, and when the viewer is watching a particular object in the displayed image, the adaptive filter is set as a low-pass filter, and this and the output gain of the head tracker is lowered; in other cases, the adaptive filter is set as an all-pass filter, and this prevents minute shaking of the head from being reflected on the displayed image, while retaining image display response to head motion, and furthermore, this serves to keep the particular object from being shifted outside the field of view.

Registration errors in augmented reality systems

Abstract: Augmented reality (AR) systems combine three-dimensional computer-generated imagery with the view of the real environment in order to make unseen objects visible or to present additional information A critical problem is that the computer-generated objects do not currently remain correctly registered with the real environment--objects aligned from one viewpoint appear misaligned from another and appear to swim about as the viewer moves This registration error is caused by a number of factors, such as system delay, optical distortion, and tracker measurement error, and is difficult to correct with existing technology This dissertation presents a registration error model for AR systems and uses it to gain insight into the nature and severity of the registration error caused by the various error sources My thesis is that a mathematical error model enables the system architect to determine (1) which error sources are the most significant, (2) the sensitivity of the net registration error to each error, (3) the nature of the distortions caused by each type of error, (4) the level of registration accuracy one can expect, and also provides insights on how best to calibrate the system Analysis of a surgery planning application yielded the following main results: (1) Even for moderate head velocities, system delay causes more registration error than all other sources combined; (2) Using the eye's center of rotation as the eyepoint in the computer graphics model reduces the error due to eye rotation to zero for points along the line of gaze This should obviate the need for eye tracking; (3) Tracker error is a significant problem both in head tracking and in system calibration; (4) The World coordinate system should be omitted when possible; (5) Optical distortion is a significant error source, but correcting it computationally in the graphics pipeline often induces delay error larger than the distortion error itself; (6) Knowledge of the nature of the various types of error facilitates identification and correction of errors in the calibration process Although the model was developed for see-through head-mounted displays (STHMDs) for surgical planning, many of the results are applicable to other HMD systems as well

A comparison of two process tracing methods for choice tasks

Abstract: The proliferation of computerized process tracing tools for monitoring information acquisition behavior demands an inquiry into their validity. This research compares information acquisition behavior for choice tasks using Mouselab, a computerized process tracing tool, and Eyegaze, an eye tracking system. In a paired difference experiment using apartment selection tasks and gambles, we found significant differences in information search patterns and subsequent choice behavior contingent upon the process tracing method. Overall, computerized process tracing tools increase the amount of effort needed to acquire information compared with eye tracking equipment. Our results show that subjects adopt information acquisition strategies to cope with the increased effort. These strategies tend to be more rigorous and systematic than those observed with eye tracking equipment. Thus, computerized process tracing tools fundamentally alter the information processing behavior they are believed to track unobtrusively by limiting the ability of the decision maker to adapt their information processing behavior dynamically to the demands of the data. Additional research is needed to explore the magnitude and consequences of these differences.

New technological windows into mind: there is more in eyes and brains for human-computer interaction

Abstract: This is an overview of the recent progress leading towards a full subject-centered paradigm in human-computer interaction. At this new phase in the evolution of computer technologies it will be possible to take into account not just characteristics of average human beings, but create systems sensitive to the actual states of attention and intentions of interacting persons. We discuss some of these methods concentrating on the eye-tracking and brain imaging. The development is based on the use of eye movement data for a control of output devices, for gaze-contingent image processing and for disambiguating verbal as well as nonverbal information.

Self-moved target eye tracking in control and deafferented subjects: roles of arm motor command and proprioception in arm-eye coordination

Abstract: 1. When a visual target is moved by the subject's hand (self-moved target tracking), smooth pursuit (SP) characteristics differ from eye-alone tracking: SP latency is shorter and maximal eye veloci...

Analog VLSI Circuits for Attention-Based, Visual Tracking

Abstract: A one-dimensional visual tracking chip has been implemented using neuromorphic, analog VLSI techniques to model selective visual attention in the control of saccadic and smooth pursuit eye movements. The chip incorporates focal-plane processing to compute image saliency and a winner-take-all circuit to select a feature for tracking. The target position and direction of motion are reported as the target moves across the array. We demonstrate its functionality in a closed-loop system which performs saccadic and smooth pursuit tracking movements using a one-dimensional mechanical eye.

Noncontact video-based eye-gaze detection method allowing large head displacements

Abstract: The noncontact video-based eye-gaze detection method which allows large head displacements was developed The eye was tracked by a two-dimensional camera rotation system The distance between the camera rotation center and the eye was measured by an ultrasonic distance meter A theory using trigonometry was proposed to determine the pupil center position in three-dimensional space At this time, the displacements of the pupil from the camera frame center were considered to precisely determine the coordinates of the eye-gaze point on a computer display The angle of eye's line of sight against the camera axis was determined from the relative positions of the centers of the feature points in the eye image, ie, the glint (corneal reflection) and the pupil The eye-gaze points while a subject fixated visual targets presented on the display were measured at video rate using custom-made image processors Under the small head-movement condition and under the large head-displacements condition, the results showed almost no distortion between the target and eye-gaze positions This indicated that the theory is adequate and the system worked well The average error was approximately 07 deg in visual angle

Visual tracking and target selection for mobile robots

Abstract: This paper describes how tracking and target selection are used in two behavior systems of the XT-1 vision architecture for mobile robots. The first system is concerned with active tracking of moving targets and the second is used for visually controlled spatial navigation. We overview the XT-1 architecture and describe the role of expectation-based template matching for both target tracking and navigation. The subsystems for low-level processing, attentional processing, single feature processing, spatial relations, and place/object-recognition are described and we present a number of behaviors that can make use of the different visual processing stages. The architecture, which is inspired by biology, has been successfully implemented in a number of robots which are also briefly described.

Principles and guidelines for the design of eye/voice interaction dialogs

Abstract: Pilots and operators of advanced military systems need better ways of interacting with their systems, including more efficient human-machine dialog and better physical interface devices and interaction techniques. The goal of the Eye/Voice Mission Planning Interface (EVMPI) research is to integrate voice recognition and eye-tracking technology with aviation displays in order to reduce the pilot's cognitive and manual workload. In its current state of development, the EVMPI technology allows an operator to gaze on user interface items of interest and issue verbal commands/queries that can be interpreted by the system, thus permitting hands-free operation of cockpit displays. This paper describes the concept for the EVMPI, presents general principles for integrating eye gaze and voice input in the form of human-computer interaction dialogs, and describes the architecture and current implementation of the system.

Vision-based visual/haptic registration for WYSIWYF display

Abstract: We have been working on developing a visual/haptic interface for virtual environments. The authors have previously (1996) proposed a WYSIWYF (What You See Is What You Feel) concept which ensures a correct visual/haptic registration so that what the user can see via a visual interface is consistent with what he/she can feel through a haptic interface. The key components of the WYSIWYF display are (i) vision-based tracking, (ii) video keying, and (iii) physically-based simulation. The first prototype has been built and the proposed concept was demonstrated. It turned out, however, that the original system had a bottleneck in the vision tracking component and the performance was not satisfactory (slow frame rate and large latency). To solve the problem of our first prototype, we have implemented a fast tracker which can track more than 100 markers in video-rate. In this paper, new experimental results are shown followed by the improvements of the vision-based tracking component.

Visual tracking based on cooperation of multiple attention regions

Abstract: This paper describes a method for tracking moving objects with multiple cooperative visual attention regions. Each attention region is tracked using a sum of absolute difference (SAD) correlation technique. The method is based on an implementation of a transputer-based multi-processor vision system with a correlation processor. The vision system provides a large number of attention regions, each of which can be tracked using fast SAD correlation performed in an LSI MEP. We call these regions windows since the region resembles a clipped section of a whole view. On the top of the system, we built a software manager which facilitates program image processing, motion control of a window, and cooperation control of windows. The cooperation is achieved using constraints, which are tree-structured, between windows. Cooperation of multiple attention regions enables one to track route predictable objects, deformable objects, and structured objects in a natural scene. As examples, passing car tracking, human arm tracking, and finger action recognition are shown.

Effect of low alcohol concentrations on visual attention in street traffic

Abstract: There is currently public discussion as to whether the legal limit of blood alcohol concentration of drivers might be reduced from 0.8% to 0.5%. To acquire information concerning this problem, we measured temporal parameters of saccades and analysed the overall eye-movement behaviour with various blood ethanol concentrations. Eye movements were registered with an IR eye tracker and analysed while the subjects followed a randomly moving stimulus on a CRT screen and during presentation of a realistic traffic scene of 4 min duration on a TV screen. Alcohol has a significant effect on latency, velocity and accuracy of saccades, even at low concentrations between 0.4% and 0.6%. Because of the altered "gaze activity", the inflow of visual information is reduced in a state of inebriation. Our results are a further argument for reducing the legal limit of blood alcohol concentration to 0.5%. Language: de

Hybrid eye tracking for computer-aided retinal surgery.

Abstract: We describe initial results of a new hybrid digital and analog design for tracking the retina and controlling the laser beam. The results demonstrate tracking rates which exceed the equivalent of 50 degrees per second in the eye, with automatic lesion pattern creation and robust loss of lock detection. Robotically-assisted laser surgery to treat conditions such as diabetic retinopathy, macular degeneration, and retinal tears can now be realized under clinical conditions with requisite safety using standard video hardware and inexpensive optical components.

On the Visual Input Driving Human Smooth-Pursuit Eye Movements

Abstract: Current computational models of smooth-pursuit eye movements assume that the primary visual input is local retinal-image motion (often referred to as retinal slip). However, we show that humans can pursue object motion with considerable accuracy, even in the presence of conflicting local image motion. This finding indicates that the visual cortical area(s) controlling pursuit must be able to perform a spatio-temporal integration of local image motion into a signal related to object motion. We also provide evidence that the object-motion signal that drives pursuit is related to the signal that supports perception. We conclude that current models of pursuit should be modified to include a visual input that encodes perceived object motion and not merely retinal image motion. Finally, our findings suggest that the measurement of eye movements can be used to monitor visual perception, with particular value in applied settings as this non-intrusive approach would not require interrupting ongoing work or training.

Fast and Effective Visual Tracking Method for Multiple Moving Targets

Abstract: In this paper we describe the tracker that provides the real-time visual feedback using on-board low-cost computers. Instead of using the voluminous and costly special purpose image processor, we exploited conventional processors and reduced processing time using the smart system software and vision software. The proposed tracker is based on the Two Stage Visual Tracking Method (TSVTM) which consists of real-time kernel, image saver, and vision module. A vision task is divided into two stages according to the information available: recognition and tracking itself. In the recognition stage, grayscale images are segmented into a set of regions. Targets are then recognized by their shapes. Once targets are initially located by the recognition stage, tracker itself can easily find and keep tracking targets using the focus-of-attention strategy based on Kalman filter. In order to avoid its inherent large variation of response time due to the difference of computation requirements between both stages, real-time kernel and image saver manage the resources efficiently. The tracker has been implemented on an mobile robot CAIR-2 and exhibited at '93 World Exposition and '95 IJCAI Robot Competition[19, 21].

Motion Portrayal, Eye Tracking, and Emerging Display Technology

Abstract: This paper explores how the temporal characteristics of image capture devices and image display devices interact with eye tracking. A display system with a large pixel count can be exploited only by having a wide viewing angle, such as the 30 degrees of HDTV. Eye tracking – which is insignificant for conventional television – becomes significant in HDTV. A fast-moving element might take as little as two seconds to traverse the width of a screen; for 1920 samples per picture width, this corresponds to 16 pixels per field time at 60 Hz. Artifacts due to temporal effects at the camera, and artifacts due to temporal effects at the display, can be expected to be revealed in HDTV displays. Many emerging displays have pixels that emit a constant amount of light throughout a large fraction of the frame time – they have long duty cycles. We have little experience of motion portrayal on displays having long duty cycles. Computers cannot yet display full-screen motion, and although conventional television can display smooth motion, it is restricted to narrow viewing angles. But it’s clear that wideangle, long duty cycle displays will introduce substantial blur on objects that the eye is tracking, and thus will have poor motion portrayal. Many emerging display technologies, such as plasma display panels (PDPs) and Texas Instruments‘ digital-micromirror devices (DMDs) have pixels that are intrinsically bilevel: At any instant in time, light is either emitted or not at any pixel. Apparent grayscale reproduction can be achieved by pulse-width modulation (PWM). The PWM technique works well when image content is static. But when PWM is combined with eye tracking in scenes with rapid motion, a new class of artifacts is introduced. Digital technologists have long speculated about displays where each pixel is updated independently. It is assumed that if updating is at least as frequent as the arrival of new frames, the display will be free of artifacts. I will prove using several very simple examples that artifacts will be introduced unless the updating process is spatially coherent. 2 MOTION PORTRAYAL, EYE TRACKING, AND EMERGING DISPLAY TECHNOLOGY

Visual Guidance of an AGV

Abstract: Image processing plays an important role in the visual navigation of a mobile robot. A real-time visual tracking system, using an active stereo vision head mounted on a mobile robot, is described in this paper to demonstrate the real-time implementation of a classic stereo method, featuring algorithm simplification for a real application. Disparity information is used directly to guide visual tracking by integrating tracking tightly to its final purpose, to provide control signals for obstacle avoidance by the mobile robot. Using an approach proposed here, the stereo correspondence algorithm can be applied to compute disparity information in real time from stereo images captured from active stereo system with two cameras verging dynamically.

Integration model of eye-gaze, voice and manual response in multimodal user interface

Abstract: This paper reports the utility of eye-gaze, voice and manual response in the design of multimodal user interface. A device- and application-independent user interface model (VisualMan) of 3D object selection and manipulation was developed and validated in a prototype interface based on a 3D cube manipulation task. The multimodal inputs are integrated in the prototype interface based on the priority of modalities and interaction context. The implications of the model for virtual reality interface are discussed and a virtual environment using the multimodal user interface model is proposed.

Eye movement control method for viewing three=dimensional image

Abstract: The method involves visually following a three-dimensional moving object (2). Simultaneously, the position of the viewing angle of the eye is measured and the movement of the eye is determined. The measured eye movement is compared with the object movement. Preferably, the three-dimensional moving image is generated using a three-dimensional computer display (1). The position of the angle of the eye is measured using the reflected images of a light source (3) on the eye surfaces.