Timing Accuracy in Motion Extrapolation: Reverse Effects of Target Size and Visible Extent of Motion at Low and High Speeds

Perception ◽  
10.1068/p3397 ◽  
2003 ◽  
Vol 32 (6) ◽  
pp. 699-706 ◽  
Author(s):  
Alexander Sokolov ◽  
Marina Pavlova
Keyword(s):  
Absolute Error ◽  
Human Vision ◽  
Target Size ◽  
Motion Processing ◽  
Timing Accuracy ◽  
Low Speed ◽  
Motion Extrapolation ◽  
High Speeds ◽  
Processing Mechanisms ◽  
Scaling Algorithms

By varying target size, speed, and extent of visible motion we examined the timing accuracy in motion extrapolation. Small or large targets (0.2 or 0.8 deg) moved at either 2.5, 5, or 10 deg s−1 across a horizontal path (2.5 or 10 deg) and then vanished behind an occluder. Observers responded when they judged that the target had reached a randomly specified position between 0 and 12 deg. With higher speeds, the timing accuracy (the reverse of absolute error) was better for small than for large targets, and for long than for short visible extents. With low speed, these effects were reversed. In addition, while long visible extents yielded a greater accuracy at high than at low speeds, for short extents the accuracy was much better with the low speed. The findings suggest that, when extrapolating motion with targets and visible extents of different sizes, the visual system implements different scaling algorithms depending on target speed. At higher speeds, processing of visible and occluded motion is likely to share a common scaling mechanism based on velocity transposition. Reverse effects for target size and extent of visible motion at low and high speeds converge with the assumption of two distinct speed-tuned motion-processing mechanisms in human vision.

CFD-BASED SIMULATION OF THE FLOW AROUND A SHIP IN OBLIQUE MOTION AT LOW SPEED

2021 ◽  
Vol 158 (A4) ◽  
Author(s):  
J Chen ◽  
Z J Zou ◽  
M Chen ◽  
H M Wang
Keyword(s):  
Verification And Validation ◽  
Hydrodynamic Performance ◽  
Dynamic Positioning ◽  
Drift Angle ◽  
Low Speed ◽  
Safety Issues ◽  
High Speeds ◽  
Ship Maneuverability ◽  
Ship Speed ◽  
Ship Flows

Ships tend to maneuver in oblique motion at low speed in situations such as turning in a harbor, or during offloading, dynamic positioning and mooring processes. The maneuverability criteria proposed by IMO are valid for ships sailing with relatively high speeds and small drift angles, which are inadequate to predict ship maneuverability in low speed condition. Hydrodynamic performance of ships maneuvering at low speed is needed to know for safety issues. A CFD-based method is employed to predict the flow around an Esso Osaka bare hull model in oblique motion at low speed, where the drift angle varies from 0° to 180°. The URANS method with the SST k-ω model is used for simulating ship flows with drift angles 0°~30° and 150°~180°, and DES method for simulating ship flows with drift angles 40°~150°. Verification and validation studies are conducted for drift angles of 0° and 70°. The vortex structures at typical drift angles of 0°, 30°, 50°, 70°, 90° and 180° are analyzed. The effects of drift angle and ship speed are demonstrated.

scholarly journals A comparison of monkey and human motion processing mechanisms

2010 ◽  
Vol 50 (21) ◽  
pp. 2137-2141 ◽  
Author(s):  
Catherine Lynn ◽  
William Curran
Keyword(s):  
Human Motion ◽  
Motion Processing ◽  
Processing Mechanisms

scholarly journals What does the Ternus display tell us about motion processing in human vision?

2010 ◽  
Vol 1 (3) ◽  
pp. 156-156
Author(s):  
N. E. Scott-Samuel ◽  
R. F. Hess
Keyword(s):  
Human Vision ◽  
Motion Processing ◽  
Ternus Display

Evidence for Good Recovery of Lengths of Real Objects Seen with Natural Stereo Viewing

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 51-51
Author(s):  
J P Frisby ◽  
D Buckley ◽  
P A Duke
Keyword(s):  
Weber Fraction ◽  
Poor Performance ◽  
Absolute Error ◽  
Binocular Viewing ◽  
Human Vision ◽  
Size Constancy ◽  
Good Recovery ◽  
Scene Structure ◽  
Real Objects ◽  
Matching Performance

How good is human size constancy for real objects seen with natural stereo viewing, which minimises the opportunity for monocular size cues to play a role? This question has attracted renewed interest in recent years, arising mainly from the work of Todd and his colleagues. They have argued, initially from experiments in which stereograms were used, but more recently from studies based on real scenes, that poor performance on length judgment tasks suggests that human vision is weak at computing metric representations. At ECVP '95, we described several experiments demonstrating quite good performance on the task of matching the lengths of two stationary real objects, gnarled wooden sticks, under binocular viewing with head held fixed (1995 Perception24 Supplement, 129). We now report extensions to that work aimed at checking whether this good performance is maintained over three viewing distances (79, 158, and 355 cm), and when test and matching sticks are of different thicknesses. Matching performance was measured with a variety of indices: reliability, accuracy, Weber fraction, and absolute error. Relatively poor performance was observed when the sticks were viewed monocularly at the near and far distances but binocular viewing produced good performance at all distances. These results suggest that stereo can support good representations of metric scene structure when length judgments of natural objects are required under (quasi-)natural viewing. The implications of these results for theories of structure-from-stereo are discussed, and reasons are suggested why our results might differ from those of Todd and his colleagues.

Mechatronic Design of Mobile Robots for Stable Obstacle Crossing at Low and High Speeds

2015 ◽  
pp. 567-630
Author(s):  
Jean-Christophe Fauroux ◽  
Frédéric Chapelle ◽  
Belhassen-Chedli Bouzgarrou ◽  
Philippe Vaslin ◽  
Mohamed Krid ◽  
...  
Keyword(s):  
Mobile Robot ◽  
Mobile Robots ◽  
High Speed ◽  
Legged Locomotion ◽  
Improve Performance ◽  
Obstacle Crossing ◽  
Low Speed ◽  
Pitch Control ◽  
High Speeds ◽  
Hybrid Locomotion

This chapter presents recent mechatronics developments to create original terrestrial mobile robots capable of crossing obstacles and maintaining their stability on irregular grounds. Obstacle crossing is both considered at low and high speeds. The developed robots use wheeled propulsion, efficient on smooth grounds, and improve performance on irregular grounds with additional mobilities, bringing them closer to legged locomotion (hybrid locomotion). Two sections are dedicated to low speed obstacle crossing. Section two presents an original mobile robot combining four actuated wheels with an articulated frame to improve obstacle climbing. Section three extends this work to a new concept of modular poly-robot for agile transport of long payloads. The last two sections deal with high-speed motion. Section four describes new suspensions with four mobilities that maintain pitch stability of vehicles crossing obstacles at high speed. After the shock, section five demonstrates stable pitch control during ballistic phase by accelerating-braking the wheels in flight.

scholarly journals Differential aging of motion processing mechanisms: Evidence against general perceptual decline

2008 ◽  
Vol 48 (10) ◽  
pp. 1254-1261 ◽  
Author(s):  
Jutta Billino ◽  
Frank Bremmer ◽  
Karl R. Gegenfurtner
Keyword(s):  
Motion Processing ◽  
Processing Mechanisms

Motion Extrapolation and Velocity Transposition

Perception ◽  
1997 ◽  
Vol 26 (7) ◽  
pp. 875-889 ◽  
Author(s):  
Alexander N Sokolov ◽  
Walter H Ehrenstein ◽  
Marina A Pavlova ◽  
C Richard Cavonius
Keyword(s):  
Visual System ◽  
Target Size ◽  
Moving Target ◽  
Motion Extrapolation ◽  
Slow Velocity

A study of the effect of the size of a moving target and the extent of its visible motion on motion extrapolation is reported. Targets (a horizontal pair of dots separated by either 0.2 or 0.8 deg) moved across a 10 deg rectilinear path and were then occluded. Observers pressed a key when they thought the leading dot of a hidden target had reached a randomly specified position (0–12 deg from the point of occlusion). In experiment 1, in agreement with velocity-transposition predictions, at moderate (5 deg s−1) and rapid (10 deg s−1) velocities extrapolation times were longer for large targets than for small ones. At slow velocity (2.5 deg s−1) this effect was reversed. In experiment 2 the effect of target size at moderate velocity was found for a short (2.5 deg) visible path. However, the extrapolation time increased with shorter (2.5 deg versus 10 deg) paths. A proposed account of these effects suggests that the visual system performs a spatiotemporal scaling, according to the velocity-transposition principle, not only of visible motion but also of extrapolated motion.

Vection Aftereffects from Expanding/Contracting Stimuli

2010 ◽  
Vol 23 (4) ◽  
pp. 273-294 ◽  
Author(s):  
Takeharu Seno ◽  
Shoji Sunaga ◽  
Hiroyuki Ito
Keyword(s):  
Optic Flow ◽  
Visual Stimuli ◽  
Motion Processing ◽  
Motion Aftereffects ◽  
Processing Mechanisms ◽  
Direction Opposite

AbstractWe presented three types of visual stimuli (blank, static and dynamic random dots) following optic flow stimuli and measured the durations of the motion aftereffects (MAEs) and aftereffects of vection (vection aftereffects, VAEs). The VAEs were induced in the direction opposite to the MAEs. However, the VAEs were not the same as the vection induced by the MAEs because the VAEs were sustained even after the MAEs vanished. In addition, when vection was facilitated or inhibited by the static dot plane in front or in the back of the optic flow, only the VAE strength was modulated, while the MAE was constant between the two conditions. From these results, we conclude that the vection-inducing mechanism shares some neural units with the motion processing mechanisms but has an additional aspect that adapts independently of the motion processing mechanisms.

scholarly journals Monkey and humans exhibit similar motion-processing mechanisms

2010 ◽  
Vol 10 (7) ◽  
pp. 815-815
Author(s):  
W. Curran ◽  
C. Lynn
Keyword(s):  
Motion Processing ◽  
Processing Mechanisms
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