Investigation of Temporal Integration by Video Sampling

Perception ◽  
1973 ◽  
Vol 2 (4) ◽  
pp. 441-490 ◽  
Author(s):  
R Williams
Keyword(s):  
Information Integration ◽  
Temporal Integration ◽  
Recognition Task ◽  
Theoretical Models ◽  
Stereoscopic Depth ◽  
Critical Duration ◽  
Integration Time ◽  
Binocular Fusion ◽  
Central Process ◽  
Time Critical

The results from the preliminary set of experiments in which a new video sampling apparatus was used are reported. With the aid of this apparatus experiments were carried out to measure the maximum visual temporal integration time (critical duration) at various background intensities (0·034–34 cd m−2). The aim was to determine to what extent this phenomenon is attributable to either ‘central’ or ‘peripheral’ events. The extended integration period found for the number recognition task is interpreted as evidence of a ‘central’ process; to follow the argument further, an attempt was made to demonstrate information integration using a rotating form in a similar identification–discrimination situation. Monocular, binocular, and dichoptic arrangements were employed, and the amount of dichoptic summation of form information, achieved by both normal and strabismic subjects without stereoscopic depth perception, was used to test two theoretical models of binocular fusion. In addition, stereoscopic depth was generated with uncorrected sampling of the left and right images, which may be due to the action of a ‘fusion hierarchy’. Signal detection theory is suggested as a possible solution to the problem of expectation effects in identification-threshold experiments.

Temporal Integration and the Masking Effect of Spatiotemporal Noise

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 216-216 ◽  
Author(s):  
H T Kukkonen ◽  
J Rovamo
Keyword(s):  
Spectral Density ◽  
Exposure Duration ◽  
Temporal Integration ◽  
Detection Threshold ◽  
Critical Duration ◽  
Masking Effect ◽  
Integration Time ◽  
Detection Thresholds ◽  
Spatial Noise ◽  
Spatiotemporal Noise

In computer-generated spatiotemporal noise every stimulus frame contains a new static noise sample. The spectral density of white spatiotemporal noise is calculated by multiplying the squared rms contrast of noise by the product of the noise check area and the exposure duration of each noise check. When the exposure duration of each noise check is gradually increased, the spectral density of spatiotemporal noise increases, reaching its maximum when noise becomes static. In static spatial noise both stimulus and noise checks have the same duration. The signal-to-noise ratio is known to be constant at detection threshold. Detection thresholds should thus increase in proportion to the spectral density of spatiotemporal noise, which increases with the duration of the noise checks. We measured detection thresholds for stationary cosine gratings embedded in spatiotemporal noise. The exposure duration of the noise checks was increased from one frame duration to the total exposure duration of the stimulus grating. Noise was thus gradually transformed from spatiotemporal to static spatial noise. The contrast energy threshold increased in proportion to the spectral density of spatiotemporal noise up to a noise check duration found to be equal to the integration time for the stimulus grating without noise. After this, energy thresholds remained constant in spite of the increase in the spectral density of spatiotemporal noise. This suggests that the masking effect of spatiotemporal noise increases with the duration of noise checks up to the critical duration marking the saturation of the temporal integration of the signal.

scholarly journals Effect of Interocular Delay on Disparity-Selective V1 Neurons: Relationship to Stereoacuity and the Pulfrich Effect

2005 ◽  
Vol 94 (2) ◽  
pp. 1541-1553 ◽  
Author(s):  
Jenny C. A. Read ◽  
Bruce G. Cumming
Keyword(s):  
Stereo Matching ◽  
Striate Cortex ◽  
Temporal Integration ◽  
Gaussian Function ◽  
Great Majority ◽  
Integration Time ◽  
V1 Neurons ◽  
Temporal Properties ◽  
Pulfrich Effect ◽  
Behaving Monkeys

The temporal properties of disparity-sensitive neurons place important temporal constraints on stereo matching. We examined these constraints by measuring the responses of disparity-selective neurons in striate cortex of awake behaving monkeys to random-dot stereograms that contained interocular delays. Disparity selectivity was gradually abolished by increasing interocular delay (when the delay exceeds the integration time, the inputs from the 2 eyes become uncorrelated). The amplitude of the disparity-selective response was a Gaussian function of interocular delay, with a mean of 16 ms (±5 ms, SD). Psychophysical measures of stereoacuity, in both monkey and human observers, showed a closely similar dependency on time, suggesting that temporal integration in V1 neurons is what determines psychophysical matching constraints over time. There was a slight but consistent asymmetry in the neuronal responses, as if the optimum stimulus is one in which the right stimulus leads by about 4 ms. Because all recordings were made in the left hemisphere, this probably reflects nasotemporal differences in conduction times; psychophysical data are compatible with this interpretation. In only a few neurons (5/72), interocular delay caused a change in the preferred disparity. Such tilted disparity/delay profiles have been invoked previously to explain depth perception in the stroboscopic version of the Pulfrich effect (and other variants). However, the great majority of the neurons did not show tilted disparity/delay profiles. This suggests that either the activity of these neurons is ignored when viewing Pulfrich stimuli, or that current theories relating neuronal properties to perception in the Pulfrich effect need to be reevaluated.

Temporal Integration of Alternately Exposed Monocular Images of a Random-Dot Stereogram

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 312-312
Author(s):  
W Pieper
Keyword(s):  
Temporal Integration ◽  
Female Students ◽  
Stereoscopic Vision ◽  
Binocular Fusion ◽  
Cortical Cells ◽  
Fixation Mark ◽  
Interpupillary Distance ◽  
Frequency Threshold ◽  
Random Dot Stereogram ◽  
The Right

J R Ewald and O Gross (1906 Pflügers ArchivCXV 514 – 521) reported that monocular half-images presented alternately can be fused to a stereoscopic percept. The situation is like looking through a fence close to the eyes, with picket and gap widths being identical to the interpupillary distance. Though vision is monocular, an observer moving fast enough parallel to the fence will have stereoscopic vision of the scenery behind it. Little is known about the limits of this integrating mechanism. In two experiments, LCD shutter glasses were used to control the viewing conditions of the anaglyphs of a random-dot stereogram. Binocular fusion was supported by a visible binocular fixation mark and a frame around the display. Subjects were eight male and three female students with normal stereoscopic acuity. They were instructed to press a key as long as they could perceive a global figure portrayed in the stereogram (25 min arc disparity). In experiment 1, monocular exposures to the right and the left eye followed each other without pauses. Psychophysical procedures were used to determine the frequency threshold for stereopsis. A breakdown frequency of 2.5 Hz was found, for descending as well as ascending series. Transferred to the concrete example of a fence, the result corresponds to a pace of 0.32 m s−1, with an interocular distance and a fence measure of 63 mm. In experiment 2, alternating monocular exposures of 100 ms duration were separated by variable pauses. Stereopsis disappeared with 8 ms pauses (ascending), and 17 ms pauses (descending). Results may be attributed to integrating mechanisms of binocular cortical cells, rather than to retinal processes (afterimages).

Color-opponent characteristics revealed in temporal integration time

1987 ◽  
Vol 27 (7) ◽  
pp. 1197-1206 ◽  
Author(s):  
Muneo Mitsuboshi ◽  
Yasuhiro Kawabata ◽  
Thomas S. Aiba
Keyword(s):  
Temporal Integration ◽  
Integration Time

The peripheral auditory characteristics of noctuid moths: responses to the search-phase echolocation calls of bats

1996 ◽  
Vol 199 (4) ◽  
pp. 847-856 ◽  
Author(s):  
D Waters ◽  
G Jones
Keyword(s):  
Short Duration ◽  
High Frequency ◽  
Temporal Structure ◽  
Temporal Integration ◽  
Agrotis Segetum ◽  
Integration Time ◽  
Constant Frequency ◽  
Low Intensity ◽  
Long Duration ◽  
The Central Nervous System

The noctuid moths Agrotis segetum and Noctua pronuba show peak auditory sensitivity between 15 and 25 kHz, and a maximum sensitivity of 35 dB SPL. A. segetum shows a temporal integration time of 69 ms. It is predicted that bats using high-frequency and short-duration calls will be acoustically less apparent to these moths. Short-duration frequency-modulated (FM) calls of Plecotus auritus are not significantly less acoustically apparent than those of other FM bats with slightly longer call durations, based on their combined frequency and temporal structure alone. Long-duration, high-frequency, constant-frequency (CF) calls of Rhinolophus hipposideros at 113 kHz are significantly less apparent than those of the FM bats tested. The predicted low call apparency of the 83 kHz CF calls of R. ferrumequinum appears to be counteracted by their long duration. It is proposed that two separate mechanisms are exploited by bats to reduce their call apparency, low intensity in FM bats and high frequency in CF bats. Within the FM bats tested, shorter-duration calls do not significantly reduce the apparency of the call at the peripheral level, though they may limit the amount of information available to the central nervous system.

Two-Pulse Temporal Integration Functions in the Fovea and Peripheral Retina

1987 ◽  
Vol 64 (2) ◽  
pp. 343-354 ◽  
Author(s):  
Michael D. Gottlieb ◽  
Mitchell L. Kietzman
Keyword(s):  
Signal Detection ◽  
Temporal Integration ◽  
Forced Choice ◽  
Critical Duration ◽  
Peripheral Retina ◽  
Light Pulses ◽  
Opal Glass ◽  
Modulator Tube ◽  
Design Integration ◽  
Glass Target

The temporal integration of luminous energy was compared in the fovea and at 7° eccentricity using two-pulse stimuli and two methodologies The two-pulse stimuli consisted of two 1-msec. light pulses separated by intervals of darkness ranging from 1 to 400 msec; they were provided by a glow modulator tube transilluminating a 21.8' opal glass target. In Exp. 1 (equal-performance design), integration functions were generated using a forced-choice staircase procedure to estimate threshold luminance. The data for two Os showed that the critical duration (CD), and thus the period of complete integration, was briefer in the fovea than at 7°. Beyond the CD, integration continued to differ for the two retinal locations. In the fovea, two-pulse stimuli beyond CD evidenced partial integration and at the longest stimulus durations no integration or inhibition. In contrast, at 7° stimuli beyond CD appeared to evidence probability summation. In Exp. 2 (equal-energy design), integration functions were generated by measuring the detectability of two-pulse stimuli of different durations but equal in total luminous energy. A signal-detection procedure yielded measures of both response frequency and signal detectability, P(A). The data for two Os showed that for both measures CD was briefer in the fovea than at 7°. Also, in the fovea, long two-pulse stimuli appeared to show no integration or inhibition. Both experiments then showed a foveal-peripheral difference in two-pulse measures of visual temporal integration, with the fovea evidencing less integration. In addition, the forced-choice and signal-detection procedures showed that these loci differences in integration were independent of the Os' response criterion.

Diphasic and Polyphasic Temporal Modulations Multiply Apparent Spatial Frequency

Perception ◽  
1974 ◽  
Vol 3 (3) ◽  
pp. 323-336 ◽  
Author(s):  
V Virsu ◽  
G Nyman ◽  
P K Lehtiö
Keyword(s):  
Spatial Frequency ◽  
High Frequency ◽  
Light Adaptation ◽  
Second Harmonic ◽  
Temporal Integration ◽  
Low Frequency ◽  
Integration Time ◽  
Sinusoidal Grating ◽  
Spatial Effects ◽  
Spatial Integration

The effects of diphasic and polyphasic flicker on apparent spatial frequency were studied in several experiments through simultaneous spatial-frequency matches. In diphasic flicker the spatial phase of a sinusoidal grating alternated between two values in a counterphase fashion, and in polyphasic flicker the spatial phases of gratings were varied discretely in time in a variable number of steps. Both forms of flicker increased the apparent spatial frequency at low temporal frequencies, in the same manner as low-frequency monophasic flicker has been found to do. At high temporal frequencies, diphasic flicker doubled the apparent spatial frequency, as reported by Kelly (1966). We found that through high-frequency polyphasic flicker the spatial effect that Kelly mentions can be generalised to spatial frequency multiplication: polyphasic flicker produces not only the apparent second harmonic but also the third and the fourth harmonic, depending on the phase parameters. A numerical analysis showed that the spatial high-frequency effects can be explained through temporal integration of nonlinearly filtered input signals if a value of 200 td(1) is assumed for the nonlinearity constant in [Formula: see text] where B( I) is the brightness, I is the retinal illuminance, K is a scale constant, and I½ is the constant of nonlinearity. A minimum value of 60 ms had to be estimated for integration time. An investigation of the integration time with diphasic flicker indicated that spatial integration time decreases when the level of light adaptation increases, and that the integration time for spatial effects is longer than for flicker fusion. The spatial effects of low-frequency and high-frequency flicker differ in so many respects that different neural processes have to be postulated for their explanation.

Development of Dual-Lifting Technique for Installation of Topside Mega-Modules

2016 ◽  
Author(s):  
Dong Woo Jung ◽  
Hyun Joe Kim ◽  
Hae Sung Ji ◽  
Hyoen Su Jeong ◽  
Mihee Nam ◽  
...  
Keyword(s):  
Production Efficiency ◽  
Oil And Gas ◽  
Ocean Basin ◽  
Structural Safety ◽  
Integration Time ◽  
Project Schedule ◽  
Construction Time ◽  
Mooring Lines ◽  
Central Process ◽  
Operation Conditions

As many deep-sea oil and gas fields are being developed, floating platforms becomes larger with more complicated topsides. However, the construction time is demanded to be shorter to meet the overall project schedule. The use of very large topside modules is one of the effective ways to reduce the integration time and decrease the possibility of fabrication defects. The Ichthys Project’s CPF (Central Process Facility) is currently being constructed at Samsung Heavy Industries (SHI). The CPF will be the world’s largest production semi-submersible platform. The hull is constructed on the Offshore Floating Dock and most of the topside modules are prepared at workshops and integrated by floating cranes on the hull. To maximize production efficiency in terms of reduced integration time and reworks, several topside modules are assembled into a larger module weighing up to 7,400 tonne spanning 150m long. Such large module cannot be handled by a single 8,000 tonne F/C, the largest crane that SHI owns. This fact initiated the idea of dual-lifting with a combination of the two F/Cs (8,000 tonne and 3,600 tonne) which enables lifting, transportation and integration of the mega-modules properly and safely without building a larger capacity F/C. Using different sized F/Cs increases the flexibility of the operation of the F/Cs. To ensure safety during the dual-lifting, the two F/Cs are synchronized to be controlled as a single crane unit. During hoisting, all the measured data such as loads and positions of the hooks, and rotation of the module, are monitored in real time basis and used to hoist the module automatically. All the systems are designed to be redundant. Additional engineering works are performed to check the safety such as 1) structural analysis to investigate the structural safety with out-of-phased motions at boom-tip 2) time-domain analysis and 3) model test in ocean basin with the operation scenarios in real environments to obtain the dynamic load factors and the guidance on the operation limits in terms of wave heights. The two crane barges are moored side-by-side using fenders and mooring lines, and tug operation conditions are planned not only to move but also to push the two barges from sideways to be moored tightly, which minimizes the possibility of relative motions between the two barges. The developed system had been applied to the integration of all the modules successfully weighing from 4600 to 7400 tonne. It is expected to be applied to many other offshore projects to keep the construction schedule on time. This paper will address and share the technical experiences obtained during the dual lifting of the mega-modules for the Ichthys Project’s CPF.

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