scholarly journals The perception of shape from shading in a new light

2013 ◽  
Author(s):  
Michael J Proulx
Keyword(s):  
Bayesian Models ◽  
Three Dimensional ◽  
Internal Representation ◽  
Shape From Shading ◽  
Two Dimensional ◽  
Persuasive Power ◽  
Dimensional Shape ◽  
External Light Source ◽  
First Time ◽  
Three Dimensional Shape

How do humans see three-dimensional shape based on two-dimensional shading? Much research has assumed that a ‘light from above’ bias solves the ambiguity of shape from shading. Counter to the ‘light from above’ bias, studies of Bayesian priors have found that such a bias can be swayed by other light cues. Despite the persuasive power of the Bayesian models, many new studies and books cite the original ‘light from above’ findings. Here I present a version of the Bayesian result that can be experienced. The perception of shape-from-shading based was found here to be influenced by an external light source, even when the light was obstructed and did not directly illuminate a two-dimensional stimulus. The results imply that this effect is robust and not low-level in nature. The perception of shape from shading is not necessarily based on a hard-wired internal representation of lighting direction, but rather assesses the direction of lighting in the scene adaptively. Here, for the first time, is an experiential opportunity to see what the Bayesian models have supported all along.

scholarly journals The perception of shape from shading in a new light

2013 ◽  
Author(s):  
Michael J Proulx
Keyword(s):  
Bayesian Models ◽  
Three Dimensional ◽  
Internal Representation ◽  
Shape From Shading ◽  
Two Dimensional ◽  
Persuasive Power ◽  
Dimensional Shape ◽  
External Light Source ◽  
First Time ◽  
Three Dimensional Shape

How do humans see three-dimensional shape based on two-dimensional shading? Much research has assumed that a ‘light from above’ bias solves the ambiguity of shape from shading. Counter to the ‘light from above’ bias, studies of Bayesian priors have found that such a bias can be swayed by other light cues. Despite the persuasive power of the Bayesian models, many new studies and books cite the original ‘light from above’ findings. Here I present a version of the Bayesian result that can be experienced. The perception of shape-from-shading based was found here to be influenced by an external light source, even when the light was obstructed and did not directly illuminate a two-dimensional stimulus. The results imply that this effect is robust and not low-level in nature. The perception of shape from shading is not necessarily based on a hard-wired internal representation of lighting direction, but rather assesses the direction of lighting in the scene adaptively. Here, for the first time, is an experiential opportunity to see what the Bayesian models have supported all along.

Design of a Two-Piece Brassiere Cup From its Data Points Toward its Automation

2020 ◽  
Author(s):  
Kotaro Yoshida ◽  
Hidefumi Wakamatsu ◽  
Eiji Morinaga ◽  
Takahiro Kubo
Keyword(s):  
Three Dimensional ◽  
Developable Surface ◽  
Two Dimensional ◽  
Trial And Error ◽  
Design Efficiency ◽  
Developable Surfaces ◽  
Data Points ◽  
Dimensional Shape ◽  
The Given ◽  
Three Dimensional Shape

Abstract A method to design the two-dimensional shapes of patterns of two piece brassiere cup is proposed when its target three-dimensional shape is given as a cloud of its data points. A brassiere cup consists of several patterns and their shapes are designed by repeatedly making a paper cup model and checking its three-dimensional shape. For improvement of design efficiency of brassieres, such trial and error must be reduced. As a cup model for check is made of paper not cloth, it is assumed that the surface of the model is composed of several developable surfaces. When two lines that consist in the developable surface are given, the surface can be determined. Then, the two-piece brassiere cup can be designed by minimizing the error between the surface and given data points. It was mathematically verified that the developable surface calculated by our propose method can reproduce the given data points which is developable surface.

Are Mechanisms for Perception of Biological Motion Different from Mechanisms for Perception of Nonbiological Motion?

2002 ◽  
Vol 95 (3_suppl) ◽  
pp. 1301-1310 ◽  
Author(s):  
Leo Poom ◽  
Henrik Olsson
Keyword(s):  
Biological Motion ◽  
Three Dimensional ◽  
Constant Time ◽  
Coherent Motion ◽  
Two Dimensional ◽  
Dimensional Shape ◽  
Perception Of Biological Motion ◽  
Three Dimensional Shape ◽  
Over Time ◽  
Unidirectional Motion

We compared the integration of information over space and time for perceiving different configurations of moving dots: a walking person (biological motion), rigid three-dimensional shapes, and unidirectional coherent motion of all dots (translation). No performance differences in judging walking direction and coherent translation direction were obtained in conditions with constant presentation times and varying number of target dots (integration over space). Depending on the speed of the two-dimensional configurations judgments were either worse or better than the judgments of walking direction. The results for conditions with different presentation times (integration over time) show that information about biological motion is integrated over time that increases with increasing gait period, while two-dimensional unidirectional motion is integrated over constant time independent of speed. The effect is not due to the oscillatory nature of the biological motion since information about a rigid three-dimensional shape is summed over a constant time independent of the period of the motion cycle. This could be interpreted as different neural mechanisms mediating the temporal summation for walking direction compared to detecting the orientation of rigid structure, or the direction of two-dimensional unidirectional motion. Since biological motion is characterized by nonrigidity, it is possible that the form itself is integrated over time and not the motion pattern.

Spatial Scale in Stereo and Shape from Shading: Image Input, Mechanisms, and Tasks

Perception ◽  
1997 ◽  
Vol 26 (9) ◽  
pp. 1137-1146 ◽  
Author(s):  
Hanspeter A Mallot
Keyword(s):  
Spatial Scale ◽  
Depth Perception ◽  
Feature Matching ◽  
Three Dimensional ◽  
Shape From Shading ◽  
Probe Experiment ◽  
Dimensional Shape ◽  
Matching Mechanism ◽  
Three Stages ◽  
Three Dimensional Shape

The problem of spatial scale in depth perception can be considered at three stages: image input, mechanisms, and depth descriptors specific for certain tasks. A review is presented of a number of earlier experiments supporting the distinction between a coarse, correlation-based mechanism and a feature-matching mechanism of stereopsis in terms of their respective inputs and outputs. In order to measure the influence of the correlation mechanism on the perception of three-dimensional shape, a shape-probe experiment was designed. For smooth intensity profiles with constant disparity, the results show that perceived shape is largely independent of overall disparity but does make use of shape from shading as well as the assumption that brighter parts are in front (proximity–luminance covariance).

scholarly journals Two-Dimensional Kinetic Shape Dynamics: Verification and Application

2016 ◽  
Vol 2016 ◽  
pp. 1-15
Author(s):  
Ismet Handzic ◽  
Haris Muratagic ◽  
Kyle B. Reed
Keyword(s):  
Equations Of Motion ◽  
Three Dimensional ◽  
Smooth Curve ◽  
Two Dimensional ◽  
Physical Experiments ◽  
Kinematic Behavior ◽  
Force Reaction ◽  
Reaction Forces ◽  
Dimensional Shape ◽  
Three Dimensional Shape

A kinetic shape (KS) is a smooth two- or three-dimensional shape that is defined by its predicted ground reaction forces as it is pressed onto a flat surface. A KS can be applied in any mechanical situation where position-dependent force redirection is required. Although previous work on KSs can predict static force reaction behavior, it does not describe the kinematic behavior of these shapes. In this article, we derive the equations of motion for a rolling two-dimensional KS (or any other smooth curve) and validate the model with physical experiments. The results of the physical experiments showed good agreement with the predicted dynamic KS model. In addition, we have modified these equations of motion to develop and verify the theory of a novel transportation device, the kinetic board, that is powered by an individual shifting their weight on top of a set of KSs.

scholarly journals Dimeric and Trimeric Catenation of Giant Chiral [8+12] Imine Cubes Driven by Weak Supramolecular Interactions

2021 ◽  
Author(s):  
Bahiru Punja Benke ◽  
Tobias Kirschbaum ◽  
Jürgen Graf ◽  
Michael Mastalerz
Keyword(s):  
Driving Forces ◽  
Three Dimensional ◽  
Molecular Switches ◽  
Supramolecular Interactions ◽  
Reaction Conditions ◽  
Π Stacking ◽  
Methoxy Groups ◽  
Dimensional Shape ◽  
First Time ◽  
Three Dimensional Shape

Mechanically interlocked structures, such as catenanes or rotaxanes are fascinating synthetic targets and are the basis of molecular switches and machines. Today, the vast majority of catenated structures are built upon macrocycles and only a very few examples of three?dimensional shape-persistent organic cages forming such structures are reported. However, the catenation in all these cases was based on a thermodynamically favoured π-π stacking under certain reaction conditions. Here, we present our findings that catenane formation can be driven by even less directional dispersion (Keesom) interactions of methoxy-groups during the synthesis of chiral [8+12] imine cubes, giving dimeric and also for the first time trimeric catenated organic cages. To further elucidate the underlying driving forces, twelve differently 1,4-substituted benzene dialdehydes have been reacted with a chiral triamino tribenzotriquinacene under various conditions to study whether monomeric cages or catenated cage dimers are the preferred products.

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