Use and Misuse of Linear Perspective in the Perceptual Reconstruction of 3-D Perspective View Displays

2002 ◽  
Vol 46 (17) ◽  
pp. 1560-1564 ◽  
Author(s):  
Harvey S. Smallman ◽  
Mark St. John ◽  
Michael B. Cowen
Keyword(s):  
Computational Model ◽  
Real World ◽  
Relative Position ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Linear Perspective ◽  
Perspective View ◽  
Physical Length ◽  
Cardinal Directions ◽  
Dimensions Of Space

Despite the increasing prevalence of three-dimensional (3-D) perspective views of scenes, there remain a number of concerns about their utility, particularly for precise relative position tasks. Here, we empirically measure and then mathematically model the perceptual biases found in participants' perceptual reconstruction of perspective views. Participants reconstructed the length of 10 test posts scattered across a 3-D scene to match the physical length of a reference post. The test posts were all oriented in the X, Y or Z cardinal directions of 3-D space. Four viewing angles from 90 degrees (“2-D”) down to 22.5 degrees (“3-D”) were used. Matches systematically underestimated the compression of distances into the scene (Y) and systematically overestimated the compression of height (Z). A simple computational model is developed to account for the results that posits that linear perspective (that only operates in X) is inappropriately used to scale matching lengths in all three dimensions of space. The model suggests a novel account of the systematic underestimation of egocentric distances in the real world.

scholarly journals Impact of Position and Orientation of RFID Tags on Real Time Asset Tracking in a Supply Chain

2008 ◽  
Vol 3 (1) ◽  
pp. 1-12
Author(s):  
Sidney D’Mello ◽  
Eric Mathews ◽  
Lee McCauley ◽  
James Markham
Keyword(s):  
Supply Chain ◽  
Real World ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Rfid Tags ◽  
Vertical Orientation ◽  
Fine Grained ◽  
Asset Tracking ◽  
Transverse Electromagnetic ◽  
World Environment

We studied the characteristics of four commercially available RFID tags such as their orientation on an asset and their position in a three dimensional real world environment to obtain comprehensive data to substantiate a baseline for the use of RFID technology in a diverse supply chain management setting. Using RFID tags manufactured by four different vendors and a GHz Transverse Electromagnetic (GTEM) cell, in which an approximately constant electromagnetic (EM) field was maintained, we characterized the tags based on horizontal and vertical orientation on a simulated asset. With these baseline characteristics determined, we moved two of the four tags through a real world environment in three dimensions using an industrial robotic system to determine the effect of asset position in relation to the reader on tag readability. Combining the data collected over these two studies, we provide a rich analysis of the feasibility of asset tracking in a real world supply chain, where there would likely be multiple tag types. We offer fine grained analyses of the tag types and make recommendations for diverse supply chain asset tracking.

A Computational Model for the Stereoscopic Optics of a Head-Mounted Display

1992 ◽  
Vol 1 (1) ◽  
pp. 45-62 ◽  
Author(s):  
Warren Robinett ◽  
Jannick P. Rolland
Keyword(s):  
Virtual Reality ◽  
Computational Model ◽  
Relative Position ◽  
Three Dimensional ◽  
Model Parameters ◽  
Head Mounted Display ◽  
Interpupillary Distance ◽  
Modeling Errors ◽  
Physical Geometry ◽  
Physical Objects

For stereoscopic photography or telepresence, orthostereoscopy occurs when the perceived size, shape, and relative position of objects in the three-dimensional scene being viewed match those of the physical objects in front of the camera. In virtual reality, the simulated scene has no physical counterpart, so orthostereoscopy must be defined in this case as constancy, as the head moves around, of the perceived size, shape, and relative positions of the simulated objects. Achieving this constancy requires that the computational model used to generate the graphics matches the physical geometry of the head-mounted display being used. This geometry includes the optics used to image the displays and the placement of the displays with respect to the eyes. The model may fail to match the geometry because model parameters are difficult to measure accurately, or because the model itself is in error. Two common modeling errors are ignoring the distortion caused by the optics and ignoring the variation in interpupillary distance across different users. A computational model for the geometry of a head-mounted display is presented, and the parameters of this model for the VPL EyePhone are calculated.

Parallel Visual Coding in Three Dimensions

Perception ◽  
1994 ◽  
Vol 23 (4) ◽  
pp. 453-470 ◽  
Author(s):  
Glyn W Humphreys ◽  
Nicole Keulers ◽  
Nick Donnelly
Keyword(s):  
Three Dimensional ◽  
Spatial Relations ◽  
Image Features ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Linear Perspective ◽  
Size Difference ◽  
The Real ◽  
Local Background ◽  
Real Size

Evidence from visual-search experiments is discussed that indicates that there is spatially parallel encoding based on three-dimensional (3-D) spatial relations between complex image features. In one paradigm, subjects had to detect an odd part of cube-like figures, formed by grouping of corner junctions. Performance with cube-like figures was unaffected by the number of corner junctions present, though performance was affected when the corners did not configure into a cube. It is suggested from the data that junctions can be grouped to form 3-D shapes in a spatially parallel manner. Further, performance with cube-like figures was more robust to noncollinearity between junctions than was performance when junctions grouped to form two-dimensional planes. In the second paradigm, subjects searched for targets defined by their size. Performance was affected by a size illusion, induced by linear-perspective cues from local background neighbourhoods. Search was made more efficient when the size illusion was consistent with the real size difference between targets and nontargets, and it was made less efficient when the size illusion was inconsistent with the real size difference. This last result occurred even though search was little affected by the display size in a control condition. We suggest that early, parallel visual processes are influenced by 3-D spatial relations between visual elements, that grouping based on 3-D spatial relations is relatively robust to noncollinearity between junctions, and that, at least in some circumstances, 3-D relations dominate those coded in two-dimensions.

Investigation of ordering kinetics in Cu3Au with the tomographic atom probe

1998 ◽  
Vol 13 (6) ◽  
pp. 1502-1510 ◽  
Author(s):  
S. Duval ◽  
S. Chambreland ◽  
A. Loiseau ◽  
D. Blavette
Keyword(s):  
Scaling Law ◽  
Three Dimensional ◽  
Atom Probe ◽  
Three Dimensions ◽  
Competitive Growth ◽  
Experimental Conditions ◽  
Ordering Kinetics ◽  
Tomographic Atom Probe ◽  
Kinetics Of ◽  
Dimensions Of Space

Kinetics of congruent ordering in Cu3Au at 350 °C was investigated by means of a three-dimensional atom probe. This instrument, called a Tomographic Atom Probe (TAP), enables atomic resolution images of a small volume (10 × 10 × 100 nm3) of the material reconstructed in the three dimensions of space. The time evolution of ordered domains at 350 °C shows that a t1/2 law is followed as soon as 5 min. For this aging time, the nucleus diameter is close to 1.7 nm. This scaling law was observed even before domains came into contact (t = 50 min). Competitive growth was observed to start as soon as 5 min. The number density was observed to decrease rapidly up to t = 50 min. A slower decrease was observed when domains begin to impinge. Experimental conditions and requirements as well as advantages of TAP as compared to HREM for the study of ordering are discussed in detail.

Reference Frame Effects on Shape Perception in Two versus Three Dimensions

Perception ◽  
1988 ◽  
Vol 17 (2) ◽  
pp. 147-163 ◽  
Author(s):  
Stephen Palmer ◽  
Edward Simone ◽  
Paul Kube
Keyword(s):  
Reference Frame ◽  
Interference Effect ◽  
Relative Size ◽  
Three Dimensional ◽  
Shape Perception ◽  
Three Dimensions ◽  
Linear Perspective ◽  
Depth Information ◽  
Frame Effect ◽  
Vertical Arrays

Three experiments are reported in which it is tested whether the Gestalt effect of configural orientation on shape perception operates on two-dimensional (2-D) or three-dimensional (3-D) representations of space. It is known that gravitationally defined squares and diamonds take longer to discriminate in diagonal arrays than in horizontal or vertical arrays. In the first experiment it is shown that this interference effect decreases dramatically in magnitude when pictorial depth information is added so that subjects perceive the target shapes in different depth planes. In the second experiment this difference is shown not to be due to relative size of the target shapes or to occlusion of a background plane. It is also shown, in the final experiment, that this difference is not due to linear perspective information or merely to perception of the target figures in a 3-D scene. The overall pattern of results supports the position that this configural reference frame effect arises primarily when the elements of the configuration are coplanar, and that the principal organization underlying it is the structure of the perceived 3-D environment rather than that of the 2-D image. In all three experiments, however, there is also a small interference effect in the noncoplanar 3-D conditions. This might be due either to some aspect of reference frame selection operating on the 2-D image representation or to the failure of subjects to see depth in the 3-D stimuli on some proportion of the trials.

scholarly journals Second life as technological narrative: Dandellion/@ Kimban: A story of a virtual world

Sociologija ◽  
2010 ◽  
Vol 52 (2) ◽  
pp. 141-166
Author(s):  
Sanja Petkovska
Keyword(s):  
Real World ◽  
Second Life ◽  
Virtual World ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Cultural Elements ◽  
The World ◽  
Historical Periods ◽  
Short Presentation

The spaces of virtual world contain mythological contents from different social and cultural-historical periods, creating a new way of existing and acting of contemporary individual and society, as well as a way to interpret them. The world created in three dimensions called Second Life is crawled both by mythological symbols and postmodern fluidity, generating a special social and psychological sphere. In this survey we will give a short presentation of the Second Life phenomenology, starting with its structure, and then explaining its relation to the real world and to the mode in which traditional cultural elements are presented there. The case study of dandellion/@ Kimban will be used as an illustration of this digital imitation of life given in three-dimensional online role plays and of object modulation.

convergent-beam diffraction from surfaces

1987 ◽  
Vol 45 ◽  
pp. 30-33
Author(s):  
J. A. Eades ◽  
A. E. Smith ◽  
D. F. Lynch
Keyword(s):  
Reciprocal Lattice ◽  
Three Dimensional ◽  
Grazing Incidence ◽  
Three Dimensions ◽  
Plane Figure ◽  
Transmission Electron ◽  
Convergent Beam ◽  
Beam Patterns ◽  
Beam Diffraction

It is quite simple (in the transmission electron microscope) to obtain convergent-beam patterns from the surface of a bulk crystal. The beam is focussed onto the surface at near grazing incidence (figure 1) and if the surface is flat the appropriate pattern is obtained in the diffraction plane (figure 2). Such patterns are potentially valuable for the characterization of surfaces just as normal convergent-beam patterns are valuable for the characterization of crystals.There are, however, several important ways in which reflection diffraction from surfaces differs from the more familiar electron diffraction in transmission.GeometryIn reflection diffraction, because of the surface, it is not possible to describe the specimen as periodic in three dimensions, nor is it possible to associate diffraction with a conventional three-dimensional reciprocal lattice.

Real-World Physical Length Comparison in Virtual Environments

2007 ◽  
Vol 13 (3) ◽  
pp. 19-24
Author(s):  
Chul Hee Jung ◽  
Min-Geun Lee ◽  
Chang Hyuck Im ◽  
이명원
Keyword(s):  
Virtual Environments ◽  
Real World ◽  
Physical Length

Extension of the Spatial PDI Model to Three Dimensions

1997 ◽  
Vol 84 (1) ◽  
pp. 176-178
Author(s):  
Frank O'Brien
Keyword(s):  
Population Density ◽  
Dimensional Space ◽  
Finite Lattice ◽  
Three Dimensional ◽  
Upper Bounds ◽  
Three Dimensions ◽  
Lower And Upper Bounds ◽  
Density Index ◽  
Three Dimensional Space

The author's population density index ( PDI) model is extended to three-dimensional distributions. A derived formula is presented that allows for the calculation of the lower and upper bounds of density in three-dimensional space for any finite lattice.

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