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Dissertations / Theses on the topic 'Optic flow'

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Published: 4 June 2021
Last updated: 25 May 2024

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1

Cheng, Chuen-kei Joseph, and 鄭傳基. "Path perception from optic flow." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B4961759X.

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Perceiving the path we are travelling on is important for successful navigation. Relative motion between the world and the observer generates optical flow on the retinae (retinal flow). Gibson (1950) pointed out that when travelling on a straight path with no eye, head, or body rotation, retinal flow is radial and the stationary point indicates the instantaneous direction of travelling, or heading, of the observer. The straight path can then be recovered as it coincides with heading. Nevertheless, it is rarely the case that people travel with no rotation. Instead, they normally look at different points of interest when they are navigating. The result of changing one's gaze or rotating one's head is the addition of a rotational component, which is a laminar flow, to the flow field. The rotational component shifts the stationary point from heading and makes heading perception difficult. Extensive research has been conducted on how the human visual system removes the rotational component of the retinal flow and how extra-retinal information, such as efferent copies of eye muscle commands, may contribute to this process. The paths on which people travel are not always straight, but often curved. When a path is curved, it no longer coincides with heading. In this case, heading is the tangent of the path. Researchers have proposed theories to explain how curved paths are perceived. Each of them requires different visual information and gaze conditions (e.g., fixating on a target or gazing along the heading direction). They can be categorized by whether or not path perception depends on heading perception. The goal of this thesis is to systematically examine different theories of path perception and determine how humans perceive curved paths. Study 1 examined different path perception theories by comparing human path perception performance in various gaze conditions and with the availability of various optic flow information. Study 2 investigated whether path perception depends on heading perception. Study 3 examined the contribution of reference objects to path perception. Study 4 investigated how extra-retinal informationcontribute to path perception. The experiments that I present here show that (a) when there is no extra-retinal information, path perception is accurate only when one's gaze is along heading such that the rotation in the flow field is equal to path rotation; (b) when one's gaze is not along heading such that the rotation in the flow field is not equal to path rotation, path perception is inaccurate. Adding more visual information, such as acceleration, dense flow field, and/ or reference objects does not improve the accuracy; (c) eye movement signals support accurate path perception only in the natural case of self-motion in which body orientation is aligned with heading such that eye movement signals help to stabilize heading in the body-centric coordinate system.
published_or_final_version
Psychology
Doctoral
Doctor of Philosophy
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2

Frenz, Harald. "Distance perception derived from optic flow." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=970154836.

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3

Bowns, Linda. "Three dimensional structure from optic flow." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315035.

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4

Herlihey, Tracey A. "Optic flow, egocentric direction and walking." Thesis, Cardiff University, 2010. http://orca.cf.ac.uk/54390/.

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This research explored two aspects of visually guided walking (1) what is the role of optic flow in the recalibration of misperceived direction while walking, and (2) how does a change in perceived direction map onto a change in walking direction. Data from five studies investigating adaptation to displaced direction (by prism glasses) suggested the following. First, optic flow is important in the recalibration of perceived direction. Further, processing optic flow is attentionally demanding, such that when cognitive load is increased, recalibration decreases. The results also demonstrated that the timecourse of recalibration changed as a function of the presence, or absence, of optic flow. With regards to the relationship between egocentric direction and walking direction, we demonstrated that a change in visual straight ahead could be mapped onto a change in target-heading error. We found that this relationship held when we unpacked the data according to the direction of displacement to which observers were exposed. The important relationship between visually perceived direction and walking direction was also highlighted in a patient study, using patients whose perception of direction was endogenously shifted after a right hemisphere stroke. Taken together, the results of this thesis help to highlight the role of optic flow in the recalibration of perceived direction, and the role of perceived direction in the visual guidance of walking. It is argued that optic flow promotes rapid recalibration of visual direction, and that change in perceived visual straight ahead can be mapped onto a changed in walking direction.
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5

Persiani, Michela <1984&gt. "Influence of optic flow on postural control." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/7009/1/Persiani_Michela_tesi.pdf.

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The study of optic flow on postural control may explain how self-motion perception contributes to postural stability in young males and females and how such function changes in the old falls risk population. Study I: The aim was to examine the optic flow effect on postural control in young people (n=24), using stabilometry and surface-electromyography. Subjects viewed expansion and contraction optic flow stimuli which were presented full field, in the foveral or in the peripheral visual field. Results showed that optic flow stimulation causes an asymmetry in postural balance and a different lateralization of postural control in men and women. Gender differences evoked by optic flow were found both in the muscle activity and in the prevalent direction of oscillation. The COP spatial variability was reduced during the view of peripheral stimuli which evoked a clustered prevalent direction of oscillation, while foveal and random stimuli induced non-distributed directions. Study II was aimed at investigating the age-related mechanisms of postural stability during the view of optic flow stimuli in young (n=17) and old (n=19) people, using stabilometry and kinematic. Results showed that old people showed a greater effort to maintain posture during the view of optic flow stimuli than the young. Elderly seems to use the head stabilization on trunk strategy. Visual stimuli evoke an excitatory input on postural muscles, but the stimulus structure produces different postural effects. Peripheral optic flow stabilizes postural sway, while random and foveal stimuli provoke larger sway variability similar to those evoked in baseline. Postural control uses different mechanisms within each leg to produce the appropriate postural response to interact with extrapersonal environment. Ageing reduce the effortlessness to stabilize posture during optic flow, suggesting a neuronal processing decline associated with difficulty integrating multi-sensory information of self-motion perception and increasing risk of falls.
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6

Persiani, Michela <1984&gt. "Influence of optic flow on postural control." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/7009/.

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The study of optic flow on postural control may explain how self-motion perception contributes to postural stability in young males and females and how such function changes in the old falls risk population. Study I: The aim was to examine the optic flow effect on postural control in young people (n=24), using stabilometry and surface-electromyography. Subjects viewed expansion and contraction optic flow stimuli which were presented full field, in the foveral or in the peripheral visual field. Results showed that optic flow stimulation causes an asymmetry in postural balance and a different lateralization of postural control in men and women. Gender differences evoked by optic flow were found both in the muscle activity and in the prevalent direction of oscillation. The COP spatial variability was reduced during the view of peripheral stimuli which evoked a clustered prevalent direction of oscillation, while foveal and random stimuli induced non-distributed directions. Study II was aimed at investigating the age-related mechanisms of postural stability during the view of optic flow stimuli in young (n=17) and old (n=19) people, using stabilometry and kinematic. Results showed that old people showed a greater effort to maintain posture during the view of optic flow stimuli than the young. Elderly seems to use the head stabilization on trunk strategy. Visual stimuli evoke an excitatory input on postural muscles, but the stimulus structure produces different postural effects. Peripheral optic flow stabilizes postural sway, while random and foveal stimuli provoke larger sway variability similar to those evoked in baseline. Postural control uses different mechanisms within each leg to produce the appropriate postural response to interact with extrapersonal environment. Ageing reduce the effortlessness to stabilize posture during optic flow, suggesting a neuronal processing decline associated with difficulty integrating multi-sensory information of self-motion perception and increasing risk of falls.
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7

Pannell, C. N. "Fibre-optic laser Doppler velocimetry." Thesis, University of Kent, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383370.

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8

Lee, Jongsoo. "Facet model optic flow and rigid body motion." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/53885.

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The dissertation uses the facet model technique to compute the optic flow field directly from a time sequence of image frames. Two techniques, an iterative and a non-iterative one, determine 3D motion parameters and surface structure (relative depth) from the computed optic flow field. Finally we discuss a technique for the image segmentation based on the multi-object motion using both optic flow and its time derivative. The facet model technique computes optic flow locally by solving over-constrained linear equations obtained from a fit over 3D (row, column, and time) neighborhoods in an image sequence. The iterative technique computes motion parameters and surface structure using each to update the other. This technique essentially uses the least square error method on the relationship between optic flow field and rigid body motion. The non-iterative technique computes motion parameters by solving a linear system derived from the relationship between optic flow field and rigid body motion and then computes the relative depth of each pixel using the motion parameters computed. The technique also estimates errors of both the computed motion parameters and the relative depth when the optic flow is perturbed.
Ph. D.
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9

Fraedrich, Eva. "The effects of spatially relevant and irrelevant optic flow." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-145894.

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10

Wertz, Adrian. "Optic flow processing in premotor descending neurons of the fly." Diss., lmu, 2009. http://nbn-resolving.de/urn:nbn:de:bvb:19-99215.

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11

Zikovitz, Daniel C. "Self-motion perception through visual optic flow and vestibular cues." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ39249.pdf.

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12

Dale, Jason Lee. "A real time implementation of a neuromorphic optic flow algorithm." Thesis, University College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400469.

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13

Stephens, Timothy John. "Fibre-optic delivery of high peak power laser pulses for flow measurement." Thesis, Heriot-Watt University, 2003. http://hdl.handle.net/10399/296.

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14

Patel, Hitesh C. "Non-linear 3D modelling of heat flow in magneto-optic multilayered media." Thesis, Keele University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358555.

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15

Kennedy, Joseph D. "Influence of Imposed Optic Flow on Basketball Shooting Performance and Postural Sway." Miami University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=miami1438106132.

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16

Wang, Wei-Chih. "A study of fluid viscosity and flow measurement using fiber-optic transducers /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/5908.

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17

Arvai, Amanda. "Vision-based navigation using multi-rate feedback from optic flow and scene reconstruction." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0013261.

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18

Hernandez, Guillermina Claudia Martinez. "Investigation into the use of optic flow and CMAC network for robot balancing." Thesis, University of Reading, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424115.

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19

Uesaki, Maiko. "Brain Mechanisms Underlying Integration of Optic Flow and Vestibular Cues to Self-motion." Kyoto University, 2018. http://hdl.handle.net/2433/232163.

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Kyoto University (京都大学)
0048
新制・課程博士
博士(文学)
甲第20828号
文博第758号
新制||文||655(附属図書館)
京都大学大学院文学研究科行動文化学専攻
(主査)教授 蘆田 宏, 教授 板倉 昭二, 教授 Anderson James Russell, 准教授 ALTMANN Christian
学位規則第4条第1項該当
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20

Webb, Ian Andrew. "An extension to optic flow analysis for the generation of computer animated images." Master's thesis, University of Cape Town, 1998. http://hdl.handle.net/11427/12526.

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Bibliography: leaves 148-151.
This dissertation seeks to develop image based animation methods using the technique of optic flow analysis developed for a moving planar object. Image based rendering is presented as a class of algorithm using two dimensional shortcuts to the problem of three dimensional animation. The optic flow field is used to develop an image based algorithm based on its use as a description of the diffences between consecutive frames of an animation. A Taylor analysis of the optic flow field is the underlying tool used, breaking the field up into a hierarchy of terms. For a moving planar object, we have considerably simplified the second order Taylor terms into a basis of just two independent terms, which can be related closely to a perspective transformation between frames. Perspective transformations capture exactly the optic flow of a moving planar object. Using the simplified decomposition of the flow field for a moving plane, we decompose the frame to frame transformation into a hierarchy of terms of increasing accuracy and cost. Depending on their accuracy we may choose any of these as transformation on an image between frames, instead of rerendering. The errors in the approximation can be tracked via the Taylor series. This dissertation develops the theory and presents an animation algorithm based on optic flow, and then presents the results of various tests of the algorithm in a variety of simple scenes. The results demonstrate the effectiveness of the algorithm and the time saving achieved in animation.
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21

Harju, Mika. "Exfoliation glaucoma : studies on intraocular pressure, optic nerve head morphometry, and ocular blood flow." Helsinki : University of Helsinki, 2001. http://ethesis.helsinki.fi/julkaisut/laa/kliin/vk/harju/.

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22

SANGANZA, WILSON KARE. "THE FIBER-OPTIC BASED UV-VISIBLE DETECTOR FOR CONTINUOUS FREE FLOW ELECTROPHORESIS, UTILIZING FOCUSING ELEMENTS." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1134504515.

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23

Tripp, Lisa Marie. "The induction of the optic flow motion aftereffect in the central versus peripheral visual field." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Fall2009/l_tripp_091009.pdf.

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Thesis (M.S. in psychology)--Washington State University, December 2009.
Title from PDF title page (viewed on Jan. 20, 2010). "Department of Psychology." Includes bibliographical references (p. 24-28).
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24

Hopp, Elisabeth Verfasser], and Alexander [Akademischer Betreuer] [Borst. "Subcellular mapping of dendritic activity in optic flow processing neurons / Elisabeth Hopp. Betreuer: Alexander Borst." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2015. http://d-nb.info/1080122222/34.

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25

Weber, Franz. "System identification of optic-flow processing neurons in the fly: single cell and small circuit models." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-139155.

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26

Busch, Christian [Verfasser], and Alexander [Akademischer Betreuer] Borst. "Control of walking behavior by horizontal optic flow detectors in Drosophila / Christian Busch ; Betreuer: Alexander Borst." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2020. http://d-nb.info/1216039380/34.

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27

Wilkie, Richard M. "Vision and steering." Thesis, University of Reading, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369203.

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28

Dyhr, Jonathan Peter. "Behavioral and Theoretical Evidence that Non-directional Motion Detectors Underlie the Visual Estimation of Speed in Insects." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/195704.

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Insects use an estimate of the angular speed of the visual image across the eye (termed optic flow) for a wide variety of behaviors including flight speed control, visual navigation, depth estimation, grazing landings, and visual odometry. Despite the behavioral importance of visual speed estimation, the neuronal mechanisms by which the brain extracts optic flow information from the retinal image remain unknown. This dissertation investigates the underlying neuronal mechanisms of visual speed estimation via three complementary strategies: the development of neuronally-based computational models, testing of the models in a behavioral simulation framework, and behavioral experiments using bumblebees. Using these methods I demonstrate the sufficiency of two non-directional models of motion detection for reproducing real-world, speed dependent behaviors, propose potential neuronal circuits by which these models may be physiologically implemented, and predict the expected responses of these neurons to a range of visual stimuli.
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29

Redlick, Fara P. "The roles of optic flow and proprioception in the perception of active and passive linear self-motion." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq43401.pdf.

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30

Siu, Wai-fung, and 蕭蔚鋒. "Can optic flow recalibrate the perceived straight ahead in the visual control of steering toward a goal?" Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/196496.

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There has long been a debate on which of the following two strategies we adopt while we are steering towards a stationary target: (1) The optic flow strategy, which suggests that we can find our ways towards our target by the alignment of our visually perceived heading, our instantaneous direction of locomotion, with the target. (2) The perceived direction strategy, in which we move towards a target by aligning our perceived straight ahead with the target. As we typically walk straight forward in our daily lives instead of making crab movements, our heading is usually well aligned with our perceived straight ahead while we are walking and it is difficult to tell which of the two strategies a person adopts when we observe him or her walking in naturalistic settings. There are multiple methods to displace the visual information about heading from our perceived straight ahead during walking, but inconsistent results have been obtained with these different methods – some showed that only the perceived direction strategy is used, while some found signs that both strategies are used simultaneously. Researchers supporting the perceived direction strategy suggested that the deviation of participants’ locomotive paths from that predicted by the perceived direction strategy observed in some experiments could be due to participants’ shifts in their perceived straight ahead driven by the displaced heading paradigm. So far, little work that addresses this concern have been conducted, thus, this thesis is intended to investigate this issue. In experiment I, participants were required to steer in virtual environments under displaced optic flow, with their steering performance as well as their shifts in perceived straight ahead at the end of each trial measured. A shift of the perceived straight ahead was observed, and its magnitude increased in conditions with richer optic flow. However, after taking this shift into account, participants still steered on paths intermediate between that predicted by the two different strategies. In experiment II, we have shown that a long period of steering under displaced heading can drive adaptations in our perceived straight ahead and corresponding changes in our steering behavior. From the results we conclude that optic flow has a profound effect on our perception of perceived straight ahead, and on top of that effect, optic flow also directly influences our guidance of steering towards a target.
published_or_final_version
Psychology
Master
Master of Philosophy
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31

Fraedrich, Eva [Verfasser], and Stefan [Akademischer Betreuer] Glasauer. "The effects of spatially relevant and irrelevant optic flow : an investigation with fMRI / Eva Fraedrich. Betreuer: Stefan Glasauer." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2012. http://d-nb.info/1025046986/34.

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32

Helde, Kristian. "Exploring a Visual Flow Display to Enhance Spatial Orientation during Flight." Thesis, University of Skövde, Department of Computer Science, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-689.

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The problem of spatial disorientation during flight of aircraft is briefly described, as are definitions of the phenomenon. Traditional countermeasure efforts that are often directed towards changes in the central visual field are reconsidered in favour of presentation of information in the peripheral visual field. It is proposed to use optic flow to support spatial orientation, as well as to omit such information from the central visual field. An experiment was conducted, and results showed that forward visual flow gave very important spatial information. The flow could be cropped to a certain degree in the periphery (horizontally), as well as parts of the central presentation could be omitted without decreasing effects in the experiment. Implications relevant to possible implementations in aircraft are discussed.

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33

Hikosaka, Tomoyuki, Yasunori Hatta, Hidenobu Koide, Akina Yamazaki, Fumihiro Endo, Hitoshi Okubo, Tsutomu Nara, and Katsumi Kato. "Space Charge Behavior in Palm Oil Fatty Acid Ester (PFAE) by Electro-optic Field Measurement." IEEE, 2009. http://hdl.handle.net/2237/14538.

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34

Garratt, Matthew Adam, and m. garratt@adfa edu au. "Biologically Inspired Vision and Control for an Autonomous Flying Vehicle." The Australian National University. Research School of Biological Sciences, 2008. http://thesis.anu.edu.au./public/adt-ANU20090116.154822.

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This thesis makes a number of new contributions to control and sensing for unmanned vehicles. I begin by developing a non-linear simulation of a small unmanned helicopter and then proceed to develop new algorithms for control and sensing using the simulation. The work is field-tested in successful flight trials of biologically inspired vision and neural network control for an unstable rotorcraft. The techniques are more robust and more easily implemented on a small flying vehicle than previously attempted methods.¶ Experiments from biology suggest that the sensing of image motion or optic flow in insects provides a means of determining the range to obstacles and terrain. This biologically inspired approach is applied to control of height in a helicopter, leading to the World’s first optic flow based terrain following controller for an unmanned helicopter in forward flight. Another novel optic flow based controller is developed for the control of velocity in hover. Using the measurements of height from other sensors, optic flow is used to provide a measure of the helicopters lateral and longitudinal velocities relative to the ground plane. Feedback of these velocity measurements enables automated hover with a drift of only a few cm per second, which is sufficient to allow a helicopter to land autonomously in gusty conditions with no absolute measurement of position.¶ New techniques for sensor fusion using Extended Kalman Filtering are developed to estimate attitude and velocity from noisy inertial sensors and optic flow measurements. However, such control and sensor fusion techniques can be computationally intensive, rendering them difficult or impossible to implement on a small unmanned vehicle due to limitations on computing resources. Since neural networks can perform these functions with minimal computing hardware, a new technique of control using neural networks is presented. First a hybrid plant model consisting of exactly known dynamics is combined with a black-box representation of the unknown dynamics. Simulated trajectories are then calculated for the plant using an optimal controller. Finally, a neural network is trained to mimic the optimal controller. Flight test results of control of the heave dynamics of a helicopter confirm the neural network controller’s ability to operate in high disturbance conditions and suggest that the neural network outperforms a PD controller. Sensor fusion and control of the lateral and longitudinal dynamics of the helicopter are also shown to be easily achieved using computationally modest neural networks.
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35

Parks, Matthew Raymond. "Vision-Based Self-Motion Estimation in a Fixed-Wing Aerial Vehicle." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/33855.

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This paper describes a complete algorithm to estimate the motion of a fixed-wing aircraft given a series of digitized flight images. The algorithm was designed for fixed-wing aircraft because carefully procured flight images and corresponding navigation data were available to us for testing. After image pre-processing, optic flow data is determined by automatically finding and tracking good features between pairs of images. The image coordinates of matched features are then processed by a rigid-object linear optic flow-motion estimation algorithm. Input factors are weighed to provide good testing techniques. Error analysis is performed with simulation data keeping these factors in mind to determine the effectiveness of the optic flow algorithm. The output of this program is an estimate of rotation and translation of the imaged environment in relation to the camera, and thereby the airplane. Real flight images from NASA test flights are used to confirm the accuracy of the algorithm. Where possible, the estimated motion parameters are compared with recorded flight instrument data to confirm the correctness of the algorithm. Results show that the algorithm is accurate to within a degree provided that enough optic flow feature points are tracked.


Master of Science
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36

Kramer, Anna [Verfasser], and Herwig [Akademischer Betreuer] Baier. "Optic-flow processing in the pretectum of larval zebrafish as revealed by the FuGIMA method / Anna Kramer ; Betreuer: Herwig Baier." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2019. http://d-nb.info/1200354060/34.

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37

Weber, Franz [Verfasser], and Alexander [Akademischer Betreuer] Borst. "System identification of optic-flow processing neurons in the fly : single cell and small circuit models / Franz Weber. Betreuer: Alexander Borst." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2012. http://d-nb.info/101947923X/34.

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38

Mancuso, Giovanni. "Integration of Head-Centric Optic Flow and Head Rotation signals account for the perception of surface tilt by the active observer." Doctoral thesis, Università degli studi di Trento, 2013. https://hdl.handle.net/11572/368117.

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An observer who approaches a planar surface that rotates about the vertical axis (e.g. a flag hinging on a pole) generates the same Optic Flow (OF) that is produced by a planar surface that rotates about an horizontal axis viewed by a static observer. In spite of this ambiguity, perceived surface orientation by the active observer is usually veridical. This result is consistent with an interpretation of the OF that takes into account egomotion signals (1). Here, we suggest an alternative interpretation based on a computational model that ignores linear egomotion signals (2, 3). An implication of our model is that perceived orientation should flip by 90 degrees whenever the OF undergoes a translational motion in a direction orthogonal to the surface axis of rotation. OF translational motion is always present when an observer moves towards or away from a stimulus display, due to the natural rotations and translations of the head. Main conclusion: In the present experiments, we tested our alternative explanation by asking observers to judge surface orientation in three conditions: 1) when a random-dot planar surface is rotated about a stationary axis, 2) when the axis of rotation was tethered to a coordinate system centered on the observer’s head, so as to eliminate the translational components of the OF, and 3) when a translational component was added to the OF produced in 2). The results are consistent with the predictions of our model. Perceived surface orientation (i) was veridical in 1), (ii) was ambiguous in 2), and (iii) underwent a 90 degrees flip with respect to veridical in 3). A similar pattern of results was found when the same OFs, generated by the observer’s movements, were replayed to a static observer. Next steps: This is inconsistent with the idea that extra-retinal information resulting from head movements is used to extract a veridical interpretation of optic flow.
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39

Mancuso, Giovanni. "Integration of Head-Centric Optic Flow and Head Rotation signals account for the perception of surface tilt by the active observer." Doctoral thesis, University of Trento, 2013. http://eprints-phd.biblio.unitn.it/1095/1/thesis.pdf.

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An observer who approaches a planar surface that rotates about the vertical axis (e.g. a flag hinging on a pole) generates the same Optic Flow (OF) that is produced by a planar surface that rotates about an horizontal axis viewed by a static observer. In spite of this ambiguity, perceived surface orientation by the active observer is usually veridical. This result is consistent with an interpretation of the OF that takes into account egomotion signals (1). Here, we suggest an alternative interpretation based on a computational model that ignores linear egomotion signals (2, 3). An implication of our model is that perceived orientation should flip by 90 degrees whenever the OF undergoes a translational motion in a direction orthogonal to the surface axis of rotation. OF translational motion is always present when an observer moves towards or away from a stimulus display, due to the natural rotations and translations of the head. Main conclusion: In the present experiments, we tested our alternative explanation by asking observers to judge surface orientation in three conditions: 1) when a random-dot planar surface is rotated about a stationary axis, 2) when the axis of rotation was tethered to a coordinate system centered on the observer’s head, so as to eliminate the translational components of the OF, and 3) when a translational component was added to the OF produced in 2). The results are consistent with the predictions of our model. Perceived surface orientation (i) was veridical in 1), (ii) was ambiguous in 2), and (iii) underwent a 90 degrees flip with respect to veridical in 3). A similar pattern of results was found when the same OFs, generated by the observer’s movements, were replayed to a static observer. Next steps: This is inconsistent with the idea that extra-retinal information resulting from head movements is used to extract a veridical interpretation of optic flow.
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40

Eriksson, Lars. "Visual Flow Display for Pilot Spatial Orientation." Doctoral thesis, Uppsala universitet, Institutionen för psykologi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-111273.

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Pilot spatial disorientation (SD) is a significant cause of incidents and fatal accidents in aviation. The pilot is susceptible to SD especially in low visibility when the visual system is deprived of information from outside the cockpit. This thesis presents the notion of visual flow displays as enhancement of symbology on flight displays primarily in low visibility for improved support of the pilot’s spatial orientation (SO) and control actions. In Studies I and II, synthetic visual flow of forward ego-motion was presented on displays and postural responses were used as measures of display effectiveness in determining SO. The visual flow significantly affected SO, and although the increased stimulation of the visual periphery from a width of 45° to about 105° increased the effects there was no further effect at a width of about 150° (Studies I and II). Studies I and II also showed that omitting 20°- or 30°-wide central fields of view from the visual flow either reduced or not reduced the effects. Further, although inconclusive, Study II may indicate that horizon symbology in central visual field may enhance the effects of peripheral visual flow. The appropriate integration of peripheral visual flow with the head-up display symbology of the Gripen aircraft was presented. Acceleration in a human centrifuge was used in Study III to investigate the effects of synthetic visual flow on the primarily vestibular-dependent somatogravic illusion of pitch-up. Two experiments revealed a reduced illusion with the visual flow. The results of Experiment 2 showed the visual flow scene not only reduced the illusion compared with a darkness condition but also compared with the visual scene without visual flow. Thus, similar to the main findings of Studies I and II, synthetic visual flow can significantly affect SO and supports the visually dependent SO system in an essential manner.
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41

Elder, John Price. "The Sensory Basis of Rheotaxis in Turbulent Flow." Bowling Green State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1402238282.

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42

Menuchi, Marcos Rodrigo Trindade Pinheiro. "Locomoção visualmente guiada na transposição de obstáculos : efeitos de amostras visuais estáticas e dinâmica /." Rio Claro : [s.n.], 2005. http://hdl.handle.net/11449/87418.

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Orientador: Lilian Teresa Bucken Gobbi
Banca: José Angelo Barela
Banca: Sérgio Teixeira Fonseca
Resumo: Durante a locomoção, ocorre um padrão de movimento visual referido como um campo de fluxo óptico. Para explorar como os ajustamentos locomotores são influenciados por este padrão, um paradigma experimental foi desenvolvido para anular o fluxo óptico durante a locomoção e ultrapassagem de obstáculo. O objetivo deste estudo foi investigar a contribuição de amostragens visuais estáticas e dinâmica na locomoção e ultrapassagem de obstáculos de diferentes alturas. Dez indivíduos (23,4 l 1,28 anos de idade, de ambos os gêneros) foram convidados a andar sobre uma passarela e ultrapassar um de dois obstáculos personalizados (obstáculo alto = altura do joelho e obstáculo baixo = altura do tornozelo) posicionado a 5m do ponto de partida. Diodos emissores de luz foram afixados no 5º metatarso e face lateral do calcâneo em ambos os pés e suas trajetórias foram filmados por quatro filmadoras digitais posicionadas bilateralmente à passarela. Dois blocos de tentativas foram apresentados em função das condições de amostragens visuais. No primeiro bloco, 10 tentativas com amostragem visual dinâmica (iluminação normal) foram apresentadas. No segundo bloco de tentativas, duas condições de amostragens visuais estáticas foram apresentadas de forma aleatória por meio de uma luz estroboscópica (2 flashes/segundo e 4 flashes/segundo). A duração de cada flash não ultrapassou 16ms e forneceu apenas imagens estáticas do ambiente. A altura do obstáculo foi randomizada em cada bloco de tentativas. Cinco tentativas para cada condição foram coletadas, totalizando 30 tentativas por participante. Todas as imagens foram digitalizadas e reconstruídas no plano tri-dimensional. As variáveis dependentes na fase de aproximação (comprimentos dos dois passos anteriores à ultrapassagem) e na fase de ultrapassagem... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: During locomotion, a pattern of visual motion referred as an optic flow field occurs. In order to explore how the locomotor adjustments are influenced by this pattern, an experimental paradigm was developed to remove the optic flow during locomotion and obstacle avoidance. The aim of this study was to investigate the contribution of the static and dynamic visual sampling on the locomotion and obstacle avoidance of different heights. Ten individuals (23.4 l 1.28 years of age, both genders) were invited to walk on a pathway and to avoid one out of two personalized obstacles (high obstacle = knee height and low obstacle = ankle height) positioned 5m from the starting position. Light emitting diodes were fixed on the fifth metatarsal and calcaneus lateral face in both feet and their trajectories were recorded by four digital cameras bilaterally positioned related to the pathway. Two trial blocks were presented depending of the visual sampling conditions. In the first block, 10 trials with visual dynamic sampling (normal light) were presented. In the second trial block, two conditions of the static visual sampling frequencies were presented in an randomized way by means of the stroboscopic light (2 flashes/second or 4 flashes/second). Each flash duration was about 16ms and provided only environmental static images. Obstacle height was randomized for each trial block. Five trials for each experimental condition were collected totalizing 30 trials for each participant. All images were digitalized and reconstructed in the 3D plane. Dependent variables in the approach phase (last two step lengths before crossing) and in the crossing phase (horizontal toe distance to the obstacle prior crossing, obstacle toe clearance and mean horizontal velocity for each foot) were selected. The results revealed differences... (Complete abstract, access undermentioned electronic address)
Mestre
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43

Niehus, Mark T. "An Experimental Study of Temperature Sensor Noise Analysis in Evaluating the Velocity of Single-Phase Air and Water Flows." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1213385038.

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44

Rutkowski, Adam J. "A BIOLOGICALLY-INSPIRED SENSOR FUSION APPROACH TO TRACKING A WIND-BORNE ODOR IN THREE DIMENSIONS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1196447143.

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45

Johnson, Neil G. "Vision-Assisted Control of a Hovering Air Vehicle in an Indoor Setting." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2430.pdf.

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46

Pretto, Paolo. "The perception and production of speed during self-motion: evidence for non-optimal compensation mechanisms." Doctoral thesis, Università degli studi di Padova, 2008. http://hdl.handle.net/11577/3425122.

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The thesis describes a series of studies on the perception of speed of self-motion in realistically simulated environments. We carried out several experiments in order to explore from both the behavioral and the perceptual point of view how visual changes in the environment lead to a misperception of self-speed. More specifically, we investigated the issues of image contrast reduction, gaze direction and field-of-view and their influence on the perceived and produced speed of self-motion. Virtual environments technology was employed to display visual motion for both driving and walking speeds. Given the first results obtained from the implementation of a realistic contrast reduction in a driving simulation we formulate the hypothesis that changes in the perceived and produced speed are due to a non-optimal combination of the retinal angular velocities during self-motion. Indeed, the retinal projection of the environment during forward self-motion consists of expanding optic-flow patterns in which the angular velocities of the objects on the scene vary gradually according to their position and speed relatively to the moving observer. Objects very far away appear as moving slowly in the centre of the field-of-view, while the proximal regions appear as moving faster at the periphery of the visual field. The second part of the thesis is then dedicated to a systematic investigation on how the angular velocities from central and peripheral regions of the field-of-view contribute to the generation of the percept of a unique speed of forward translation. In Chapter 1 we present a brief overview of the principal aspects of visual motion processing. We report some psychophysical and physiological findings that have been produced in the last decades of research, together with some models that try to describe the functional aspects of motion and speed processing. Moreover, we introduce and explain the theme of the visual speed of self-motion. Finally, we describe the technical and methodological tools that have been adopted to implement and execute the experiments of the following chapters. In Chapter 2 experiments are described in which we address the question how image contrast reduction affects the driving behavior. We put particular emphasis to a naturalistic implementation of contrast reduction, namely fog. We show that a realistically simulated fog causes drivers to reduce the driving speed. We provide experimental evidence that this effect has a perceptual origin, due to the increased perceived speed while driving in fog. The behavioral effect of simulated fog is consistent through different experimental setups. Moreover, we show that the effect of an increased perceived speed is enhanced accordingly to the fog density. We hypothesize an explanation for these results based on the fact that the motion signals within the visual field are selectively masked. In fact, the three-dimensional spatial distribution of the exponential fog model used in our experiments reduces mainly the visibility of the lower velocity signals, situated in the distal region of the environment, centrally in the visual field. Furthermore, we compare the effect of simulated fog to the effect of a type of contrast reduction that attenuates the visibility uniformly all over the visual field, independently of the three-dimensional structure of the environment. We demonstrate that the perception of both the driving and walking speed is independent of a spatially uniform contrast reduction and of the region within the visual field in which this reduction is applied (central or peripheral). The experiments of Chapter 3 show that during self-motion the estimation of the self-speed relies on retinal angular velocities that are likely to be combined in a non-optimal solution. We provide evidence that the speed estimate is biased towards the available motion signals from the environment, both in the driving and in the walking speeds domain. When the visibility of the central region of the field-of-view is precluded the perceived speed is higher, and conversely, when the peripheral region is not visible, the perceived speed is lower. This suggests that the speed estimation process takes into account the velocity signals from both central and peripheral areas of the visual field. However, we provide also evidence that the central area is necessary and nearly sufficient to build a correct speed estimate, even in large field-of-view virtual environments. Finally, we report also that the speed estimate depends on the gaze direction and can be impaired when the vertical field-of-view is limited. Summary of the results and general discussion are presented in Chapter 4.
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47

Otten, Edward W. "The Influence of Stimulus Complexity and Perception-action Coupling on Postural Sway." Miami University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=miami1218562177.

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48

Vanhoutte, Erik. "Microdrone équipé d'un système visuel inspiré des abeilles." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0431/document.

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De nos jours, l'engouement pour la robotique autonome ne cesse d'augmenter en particulier pour les microdrones. En effet, ces aéronefs de petite taille font l'objet de nombreuses recherches afin de les miniaturiser et de rendre leur navigation plus autonome. Ainsi, cette thèse explore un système de vision parcimonieux dédié à la navigation courte portée au moyen de capteurs visuels auto-adaptatifs innovants composés de seulement 12 pixels aux propriétés optiques inspirées de celles de l'abeille. Deux algorithmes de mesure de flux optique sont ensuite comparés en conditions idéales sur 5 décades d'irradiance et 3 décades de vitesses optiques, puis testés en conditions réelles de vol. L'algorithme le plus robuste et le plus efficace, de par ses très faibles besoins calculatoires, a été embarqué à bord d'un micro quadrirotor pesant environ 400 g et équipé d'un système visuel parcimonieux de 96 pixels stabilisé via une nacelle articulée en roulis et tangage pour compenser les rotations du quadrirotor. Les stratégies de navigation observées chez l'abeille ont ensuite été simulées dans des environnements virtuels (tunnel de longueur 6 m ou 12 m pour une section minimale de 25 ou 50 cm) et la preuve de faisabilité de la détection du flux optique à bord d'un microdrone a été démontrée en conditions réelles de vol en salle expérimentale (vol de 4 m de long à une distance minimale de 50 cm). Couplé à des stratégies de navigation inspirées de l’abeille, ce système visuel innovant dédié à la perception du mouvement permettra dans un futur proche de naviguer dans des environnements encombrés ou exigus
The interest in autonomous robotics is continually expanding, especially in the domain of micro air vehicles. Indeed, much research focuses on these small-size aircraft in order to miniaturize them and to make their navigation more autonomous. This PhD thesis explores a parsimonious vision system dedicated to short range navigation using innovative self-adaptive visual sensors composed of only 12 pixels with optical properties inspired by those of honeybees. Two optic flow measurement algorithms are first compared under ideal conditions over 5 decades of irradiance and 3 decades of optical velocity, then tested under real flight conditions. The most robust and efficient algorithm, due to its very low computing requirements, was embedded on board a micro quadrotor weighing about 400 g and equipped with a parsimonious visual system of 96 pixels stabilized via an articulated gimbal in roll and pitch to compensate the quadrotor rotations. The navigation strategies observed in honeybees were simulated in virtual environments (6 m or 12 m long tunnel for a minimum section of 25 or 50 cm) and the feasibility of the detection of the optic flow on board a micro quadrotor was demonstrated in real flight conditions in experimental room (flight of 4 m long at a minimum distance of 50 cm). Coupled with navigation strategies inspired by the honeybee, this innovative visual system dedicated to the perception of movement will in the near future allow to navigate in cluttered or cramped environments
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49

Menuchi, Marcos Rodrigo Trindade Pinheiro [UNESP]. "Locomoção visualmente guiada na transposição de obstáculos: efeitos de amostras visuais estáticas e dinâmica." Universidade Estadual Paulista (UNESP), 2005. http://hdl.handle.net/11449/87418.

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Durante a locomoção, ocorre um padrão de movimento visual referido como um campo de fluxo óptico. Para explorar como os ajustamentos locomotores são influenciados por este padrão, um paradigma experimental foi desenvolvido para anular o fluxo óptico durante a locomoção e ultrapassagem de obstáculo. O objetivo deste estudo foi investigar a contribuição de amostragens visuais estáticas e dinâmica na locomoção e ultrapassagem de obstáculos de diferentes alturas. Dez indivíduos (23,4 l 1,28 anos de idade, de ambos os gêneros) foram convidados a andar sobre uma passarela e ultrapassar um de dois obstáculos personalizados (obstáculo alto = altura do joelho e obstáculo baixo = altura do tornozelo) posicionado a 5m do ponto de partida. Diodos emissores de luz foram afixados no 5º metatarso e face lateral do calcâneo em ambos os pés e suas trajetórias foram filmados por quatro filmadoras digitais posicionadas bilateralmente à passarela. Dois blocos de tentativas foram apresentados em função das condições de amostragens visuais. No primeiro bloco, 10 tentativas com amostragem visual dinâmica (iluminação normal) foram apresentadas. No segundo bloco de tentativas, duas condições de amostragens visuais estáticas foram apresentadas de forma aleatória por meio de uma luz estroboscópica (2 flashes/segundo e 4 flashes/segundo). A duração de cada flash não ultrapassou 16ms e forneceu apenas imagens estáticas do ambiente. A altura do obstáculo foi randomizada em cada bloco de tentativas. Cinco tentativas para cada condição foram coletadas, totalizando 30 tentativas por participante. Todas as imagens foram digitalizadas e reconstruídas no plano tri-dimensional. As variáveis dependentes na fase de aproximação (comprimentos dos dois passos anteriores à ultrapassagem) e na fase de ultrapassagem...
During locomotion, a pattern of visual motion referred as an optic flow field occurs. In order to explore how the locomotor adjustments are influenced by this pattern, an experimental paradigm was developed to remove the optic flow during locomotion and obstacle avoidance. The aim of this study was to investigate the contribution of the static and dynamic visual sampling on the locomotion and obstacle avoidance of different heights. Ten individuals (23.4 l 1.28 years of age, both genders) were invited to walk on a pathway and to avoid one out of two personalized obstacles (high obstacle = knee height and low obstacle = ankle height) positioned 5m from the starting position. Light emitting diodes were fixed on the fifth metatarsal and calcaneus lateral face in both feet and their trajectories were recorded by four digital cameras bilaterally positioned related to the pathway. Two trial blocks were presented depending of the visual sampling conditions. In the first block, 10 trials with visual dynamic sampling (normal light) were presented. In the second trial block, two conditions of the static visual sampling frequencies were presented in an randomized way by means of the stroboscopic light (2 flashes/second or 4 flashes/second). Each flash duration was about 16ms and provided only environmental static images. Obstacle height was randomized for each trial block. Five trials for each experimental condition were collected totalizing 30 trials for each participant. All images were digitalized and reconstructed in the 3D plane. Dependent variables in the approach phase (last two step lengths before crossing) and in the crossing phase (horizontal toe distance to the obstacle prior crossing, obstacle toe clearance and mean horizontal velocity for each foot) were selected. The results revealed differences... (Complete abstract, access undermentioned electronic address)
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50

Expert, Fabien. "Un robot volant inspiré des insectes : De la mesure du flux optique aux stratégies de guidage visuel pour un micro hélicoptère." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4116/document.

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Dans ce travail, nous avons premièrement développé et caractérisé des capteurs de flux optique robustes aux changements de conditions lumineuses inspirés par le système visuel de la mouche et mesurant la vitesse angulaire à l'aide de l'algorithme appelé "time of travel". En particulier, nous avons comparé les performances de capteurs mesurant visuellement la vitesse angulaire en intérieur et en extérieur. Les résultats de nos capteurs bio-inspirés ont aussi été comparés avec des capteurs de souris optique. Enfin, une nouvelle implémentation de l'algorithme "time of travel" a été proposée réduisant la charge de calcul de l'unité de traitement.Dans le cadre du projet européen CurvACE (Curved Artificial Compound Eye), nous avons aussi participé au développement du premier oeil composé courbé artificiel capable de mesurer le flux optique à haute vitesse sur une large gamme de lumière ambiante. En particulier, nous avons caractérisé ce capteur et montré sa capacité à mesurer le flux optique à l'aide de plusieurs algorithmes.Finalement, nous avons aussi développé un robot aérien miniature attaché appelé BeeRotor équipé de capteurs et de stratégies de vol imitant les insectes volants et se déplaçant de manière autonome dans un tunnel contrasté. Ce robot peut expliquer comment les abeilles contrôlent leur vitesse et leur position à l'aide du flux optique, tout en démontrant que des solutions alternatives existent aux systèmes couramment utilisés en robotique. Basé seulement sur des boucles de contrôle réagissant à l'environnement, cet hélicoptère a démontré sa capacité à voler de manière autonome dans un environnement complexe et mobile
In this thesis, we first developed and characterized optic flow sensors robust to illuminance changes inspired by the visual system of the fly and computing the angular speed thanks to the "time of travel" scheme. In particular, we have compared the performances of sensors processing the visual angular speed based on a standard retina or an aVLSI retina composed of pixels automatically adapting to the background illuminance in indoor and outdoor environments. The results of such bio-inspired sensors have also been compared with optic mouse sensors which are used nowadays on Micro Aerial Vehicles to process the optic flow but only in outdoor environments. Finally, a new implementation of the "time of travel" scheme has been proposed reducing the computational load of the processing unit.In the framework of the European project CurvACE, we also participated to the design and development of the first curved artificial compound eye including fast motion detection in a very large range of illuminations. In particular, we characterized such sensor showing its ability to extract optic flow using different algorithms.Finally, we also developed a tethered miniature aerial robot equipped with sensors and control strategies mimicking flying insects navigating in a high-roof tunnel. This robot may explain how honeybees control their speed and position thanks to optic flow, while demonstrating alternative solution to classical robotic approach relying on ground-truth and metric sensors. Based only on visuomotor control loops reacting suitably to the environment, this rotorcraft has shown its ability to fly autonomously in complex and unstationary tunnels
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