The Interaction of Oculomotor Cues and Stimulus Size in Stereoscopic Depth Constancy

Perception ◽  
1991 ◽  
Vol 20 (6) ◽  
pp. 733-754 ◽  
Author(s):  
Thomas S Collett ◽  
Urs Schwarz ◽  
Erik C Sobel
Keyword(s):  
Angular Size ◽  
Natural World ◽  
Angular Width ◽  
Viewing Distance ◽  
Image Size ◽  
Planar Surfaces ◽  
Wide Range ◽  
Close Range ◽  
Simulated Surface ◽  
Depth Constancy

In the natural world, observers perceive an object to have a relatively fixed size and depth over a wide range of distances. Retinal image size and binocular disparity are to some extent scaled with distance to give observers a measure of size constancy. The angle of convergence of the two eyes and their accommodative states are one source of scaling information, but even at close range this must be supplemented by other cues. We have investigated how angular size and oculomotor state interact in the perception of size and depth at different distances. Computer-generated images of planar and stereoscopically simulated 3-D surfaces covered with an irregular blobby texture were viewed on a computer monitor. The monitor rested on a movable sled running on rails within a darkened tunnel. An observer looking into the tunnel could see nothing but the simulated surface so that oculomotor signals provided the major potential cues to the distance of the image. Observers estimated the height of the surface, their distance from it, or the stereoscopically simulated depth within it over viewing distances which ranged from 45 cm to 130 cm. The angular width of the images lay between 2 deg and 10 deg. Estimates of the magnitude of a constant simulated depth dropped with increasing viewing distance when surfaces were of constant angular size. But with surfaces of constant physical size, estimates were more nearly independent of viewing distance. At any one distance, depths appeared to be greater, the smaller the angular size of the image. With most observers, the influence of angular size on perceived depth grew with increasing viewing distance. These findings suggest that there are two components to scaling. One is independent of angular size and related to viewing distance. The second component is related to angular size, and the weighting accorded to it grows with viewing distance. Control experiments indicate that in the tunnel, oculomotor state provides the principal cue to viewing distance. Thus, the contribution of oculomotor signals to depth scaling is gradually supplanted by other cues as viewing distance grows. Binocular estimates of the heights and distances of planar surfaces of different sizes revealed that angular size and viewing distance interact in a similar way to determine perceived size and perceived distance.

An Object-Based Image Reducing Approach

2014 ◽  
Vol 1044-1045 ◽  
pp. 1049-1052 ◽  
Author(s):  
Chin Chen Chang ◽  
I Ta Lee ◽  
Tsung Ta Ke ◽  
Wen Kai Tai
Keyword(s):  
Visual Saliency ◽  
Saliency Map ◽  
Input Image ◽  
Image Size ◽  
Target Image ◽  
Feature Maps ◽  
Object Based ◽  
Wide Range

Common methods for reducing image size include scaling and cropping. However, these two approaches have some quality problems for reduced images. In this paper, we propose an image reducing algorithm by separating the main objects and the background. First, we extract two feature maps, namely, an enhanced visual saliency map and an improved gradient map from an input image. After that, we integrate these two feature maps to an importance map. Finally, we generate the target image using the importance map. The proposed approach can obtain desired results for a wide range of images.

Product Review: High Dynamic Range Displays

2007 ◽  
Vol 16 (1) ◽  
pp. 119-122 ◽  
Author(s):  
Patrick Ledda
Keyword(s):  
Dynamic Range ◽  
Liquid Crystal Display ◽  
Contrast Ratio ◽  
Luminance Level ◽  
High Dynamic Range ◽  
Natural World ◽  
Adaptation Level ◽  
Wide Range ◽  
High Dynamic ◽  
3D Software

In the natural world, the human eye is confronted with a wide range of colors and luminances. A surface lit by moonlight might have a luminance level of around 10−3 cd/m2, while surfaces lit during a sunny day could reach values larger than 105 cd/m2. A good quality CRT (cathode ray tube) or LCD (liquid crystal display) monitor is only able to achieve a maximum luminance of around 200 to 300 cd/m2 and a contrast ratio of not more than two orders of magnitude. In this context the contrast ratio or dynamic range is defined as the ratio of the highest to the lowest luminance. We call high dynamic range (HDR) images, those images (or scenes) in which the contrast ratio is larger than what a display can reproduce. In practice, any scene that contains some sort of light source and shadows is HDR. The main problem with HDR images is that they cannot be displayed, therefore although methods to create them do exist (by taking multiple photographs at different exposure times or using computer graphics 3D software for example) it is not possible to see both bright and dark areas simultaneously. (See Figure 1.) There is data that suggests that our eyes can see detail at any given adaptation level within a contrast of 10,000:1 between the brightest and darkest regions of a scene. Therefore an ideal display should be able to reproduce this range. In this review, we present two high dynamic range displays developed by Brightside Technologies (formerly Sunnybrook Technologies) which are capable, for the first time, of linearly displaying high contrast images. These displays are of great use for both researchers in the vision/graphics/VR/medical fields as well as professionals in the VFX/gaming/architectural industry.

Cooperation between Species

2017 ◽  
Author(s):  
Raymond Pierotti ◽  
Brandy R. Fogg
Keyword(s):  
Cooperative Behavior ◽  
Natural World ◽  
Western Science ◽  
Ecological Communities ◽  
Cooperative Hunting ◽  
Wide Range

This chapter reviews the study of cooperative behavior between species, with emphasis on examples of cooperative hunting found in a wide range of species. Seen in this context, the idea of cooperative hunting between humans and wolves that evolved into present relationships with dogs does not seem unusual or surprising. The chapter then critiques the proposal that competition between species is more important than cooperation in structuring ecological communities, discussing how this notion leads to a suite of ideas philosophically separating humans from the rest of the natural world. In many ways Western science is unintentionally complicit in such thinking. The chapter concludes by discussing complex cooperation, including long-term relationships between members of different species.

scholarly journals Theoretical study of the properties of X-ray diffraction moiré fringes. II. Illustration of angularly integrated moiré images

2019 ◽  
Vol 75 (4) ◽  
pp. 610-623
Author(s):  
Jun-ichi Yoshimura
Keyword(s):  
Incident Wave ◽  
Angular Width ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
Acta Cryst ◽  
Low Contrast ◽  
X Ray ◽  
Moiré Fringes ◽  
Wide Range ◽  
Fringe Patterns

Using a theory of X-ray diffraction moiré fringes developed in a previous paper, labelled Part I [Yoshimura (2015). Acta Cryst. A71, 368–381], the X-ray moiré images of a silicon bicrystal having a weak curvature strain and an interspacing gap, assumed to be integrated for an incident-wave angular width, are simulation-computed over a wide range of crystal thicknesses and incident-wave angular width, likely under practical experimental conditions. Along with the simulated moiré images, the graphs of characteristic quantities on the moiré images are presented for a full understanding of them. The treated moiré images are all of rotation moiré. Mo Kα1 radiation and the 220 reflection were assumed in the simulation. The results of this simulation show that fringe patterns, which are significantly modified from simple straight fringes of rotation moiré, appear in some ranges of crystal thicknesses and incident-wave angular width, due to a combined effect of Pendellösung oscillation and an added phase difference from the interspacing gap, under the presence of a curvature strain. The moiré fringes which slope to the perpendicular direction to the diffraction vector in spite of the assumed condition of rotation moiré, and fringe patterns where low-contrast bands are produced with a sharp bend of fringes arising along the bands are examples of the modified fringe pattern. This simulation study provides a wide theoretical survey of the type of bicrystal moiré image produced under a particular condition.

scholarly journals Combined Use of Terrestrial Laser Scanning and UAV Photogrammetry in Mapping Alpine Terrain

2019 ◽  
Vol 11 (18) ◽  
pp. 2154 ◽  
Author(s):  
Ján Šašak ◽  
Michal Gallay ◽  
Ján Kaňuk ◽  
Jaroslav Hofierka ◽  
Jozef Minár
Keyword(s):  
High Resolution ◽  
Point Cloud ◽  
Laser Scanning ◽  
Terrestrial Laser Scanning ◽  
Point Clouds ◽  
Mutual Orientation ◽  
Close Range Photogrammetry ◽  
Combined Use ◽  
Wide Range ◽  
Close Range

Airborne and terrestrial laser scanning and close-range photogrammetry are frequently used for very high-resolution mapping of land surface. These techniques require a good strategy of mapping to provide full visibility of all areas otherwise the resulting data will contain areas with no data (data shadows). Especially, deglaciated rugged alpine terrain with abundant large boulders, vertical rock faces and polished roche-moutones surfaces complicated by poor accessibility for terrestrial mapping are still a challenge. In this paper, we present a novel methodological approach based on a combined use of terrestrial laser scanning (TLS) and close-range photogrammetry from an unmanned aerial vehicle (UAV) for generating a high-resolution point cloud and digital elevation model (DEM) of a complex alpine terrain. The approach is demonstrated using a small study area in the upper part of a deglaciated valley in the Tatry Mountains, Slovakia. The more accurate TLS point cloud was supplemented by the UAV point cloud in areas with insufficient TLS data coverage. The accuracy of the iterative closest point adjustment of the UAV and TLS point clouds was in the order of several centimeters but standard deviation of the mutual orientation of TLS scans was in the order of millimeters. The generated high-resolution DEM was compared to SRTM DEM, TanDEM-X and national DMR3 DEM products confirming an excellent applicability in a wide range of geomorphologic applications.

Fixation Disparity as a Function of Viewing Distance and Prism Load

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 76-76
Author(s):  
W Jaschinski
Keyword(s):  
Binocular Vision ◽  
Temporal Variability ◽  
Angular Size ◽  
Psychophysical Method ◽  
Viewing Distance ◽  
Fixation Disparity ◽  
Average Standard Deviation ◽  
Natural Interaction ◽  
Near Vision ◽  
Constant Distance

In binocular vision, fixation disparity is present when a fixation point falls within Panum's area, but not on corresponding retinal points. To investigate the effect of vergence load, fixation disparity was measured at viewing distances of 20, 30, 40, 60, and 100 cm (while the test subtended a constant angular size) by the psychophysical method of dichoptically presented nonius lines with a central fusion stimulus. As the viewing distance was shortened from 100 to 20 cm, mean fixation disparity changed monotonically from 1 min arc esophoria (ie the eyes converged in front of the target) to 3 min arc exophoria. The average standard deviation of the psychometric function, which is a measure of the temporal variability of vergence, was smallest at 100 cm (when fixation disparity was esophoric) and increased at shorter distances. Fixation disparity was also measured at a constant distance of 40 cm, but with prisms in front of the eyes that induced the same vergence angles as would be induced by viewing distances between 20 and 100 cm. The slope of these conventional ‘fixation disparity curves’ as a function of prism load correlated with the slope of fixation disparity as a function of viewing distance ( r=0.39, p=0.02, n=25). However, testing at different distances, as introduced here, has the advantage of preserving the natural interaction between vergence and accommodation. Since the change of fixation disparity with distance differed reliably among subjects (with a test — retest correlation of 0.65 in 34 subjects with good binocular vision) this measure may be useful for identifying subjects who are prone to near-vision complaints.

Hybrid Image Illusion

2017 ◽  
Author(s):  
Aude Oliva ◽  
Philippe G. Schyns
Keyword(s):  
Visual Illusions ◽  
Viewing Distance ◽  
Image Size ◽  
Single Image ◽  
Double Image ◽  
Spatial Frequencies ◽  
Dual Images

Artists, designers, photographers, and visual scientists are routinely looking for ways to create, out of a single image, the feeling that there is more to see than what meets the eye. Many well-known visual illusions are dual in nature, causing the viewer to experience two different interpretations of the same image. Hybrid images illustrate a double-image illusion, where different images are perceived depending on viewing distance, viewing duration, or image size: one that appears when the image is viewed up-close (displaying high spatial frequencies) and another that appears from afar (showing low spatial frequencies). This method can be used to create compelling dual images in which the observer experiences different percepts when interacting with the image.

scholarly journals A review of friction damping modeling and testing

2019 ◽  
Vol 90 (1) ◽  
pp. 107-126 ◽  
Author(s):  
Louis Gagnon ◽  
Marco Morandini ◽  
Gian Luca Ghiringhelli
Keyword(s):  
Internal State ◽  
Experimental Testing ◽  
Analytical Models ◽  
Friction Damper ◽  
Friction Damping ◽  
Friction Dampers ◽  
Modeling Approaches ◽  
Planar Surfaces ◽  
Wide Range ◽  
Friction Models

Abstract This survey provides an insight into the modeling and testing of uniaxial friction dampers. The focus is on attenuating the linear relative movement along planar surfaces for frequencies between 10 Hz and 1 kHz. An overview of the different approaches seen in the literature concerning friction damping is provided. Examples and evaluation of such dampers excited over a wide range of frequencies are presented. The information required to develop models of friction dampers is covered. To that end, different modeling approaches are presented for dry friction. Dynamic friction models with an internal state are covered, and their advantages are described. Other modeling approaches are reported for complete systems with friction dampers. Both numerical and analytical models are covered. Experimental configurations from a selection of authors are also included. Finally, a series of suggestions for the numerical modeling and experimental testing of a friction damper are given.

scholarly journals The Role of the Centre of Projection in the Estimation of Slant from Texture of Planar Surfaces

Perception ◽  
10.1068/p3002 ◽  
2001 ◽  
Vol 30 (2) ◽  
pp. 185-193 ◽  
Author(s):  
Stefaan Tibau ◽  
Bert Willems ◽  
Erik Van Den Bergh ◽  
Johan Wagemans
Keyword(s):  
Estimation Error ◽  
Stimulus Display ◽  
Perspective Projection ◽  
Viewing Distance ◽  
Circular Aperture ◽  
Focal Distance ◽  
Square Grid ◽  
Specific Combination ◽  
Planar Surfaces

Displays were presented consisting of a perspective projection of a regular square grid, made up of vertical and horizontal equally spaced white lines, that was slanted in depth. The surface was viewed monocularly, through a circular aperture. A range of slants was shown (0°, 10°, 20°, 30°, 40°, 50°, or 60°) and the observers' task was to match the slant by means of a mouse-driven probe. The viewing distance (50, 75, or 100 cm) as well as the focal distance (25, 50, 75, 100, or 125 cm) were varied. We expected the estimation error to be smallest when the viewing distance and the focal distance coincided. This was not the case. Instead, subjects seemed to use the perspective deformation of the texture elements in the stimulus display to make a slant estimation, regardless of the specific combination of viewing distance and focal distance.

Ink-Jet as a MEMS Manufacturing Tool

2007 ◽  
Author(s):  
David Wallace ◽  
Donald Hayes ◽  
Ting Chen ◽  
Virang Shah ◽  
Delia Radulescu ◽  
...  
Keyword(s):  
Optical Interconnects ◽  
Medical Diagnostics ◽  
Data Driven ◽  
Mems Packaging ◽  
Nanostructure Materials ◽  
Planar Surfaces ◽  
Wide Range ◽  
Ink Jet ◽  
Color Printing ◽  
Manufacturing Applications

In the last decade, ink-jet has come to be viewed as a precision microdispensing tool, in addition to its huge success in color printing. Today, this tool is being used in a wide range of applications, including electrical & optical interconnects, sensors, medical diagnostics, drug delivery, MEMS packaging, and nanostructure materials deposition. Ink-jet microdispensing is data-driven, non-contact, and is capable of precise deposition of picoliter volumes at high rates, even onto non-planar surfaces. Being data-driven, ink-jet dispensing is highly flexible and can be readily automated into manufacturing lines. This paper will illustrate a few of the applications of ink-jet technology that are either MEMS manufacturing applications, or relevant to potential MEMS manufacturing applications.

Sign in / Sign up

Export Citation Format

Share Document