scholarly journals Countershading enhances camouflage by reducing prey contrast

2020 ◽  
Vol 287 (1927) ◽  
pp. 20200477
Author(s):  
Callum G. Donohue ◽  
Jan M. Hemmi ◽  
Jennifer L. Kelley
Keyword(s):  
Body Shape ◽  
Three Dimensional ◽  
Luminance Contrast ◽  
The Body ◽  
Body Parts ◽  
Live Fish ◽  
Average Luminance ◽  
Fish Predators ◽  
Dimensional Shape ◽  
Three Dimensional Shape

A three-dimensional body shape is problematic for camouflage because overhead lighting produces a luminance gradient across the body's surface. Countershading, a form of patterning where animals are darkest on their uppermost surface, is thought to counteract this luminance gradient and enhance concealment, but the mechanisms of protection remain unclear. Surprisingly, no study has examined how countershading alters prey contrast, or investigated how the presence of a dorsoventral luminance gradient affects detection under controlled viewing conditions. It has also been suggested that the direction of the dorsoventral luminance gradient (darkest or lightest on top) may interfere with predators' abilities to resolve prey's three-dimensional shape, yet this intriguing idea has never been tested. We used live fish predators (western rainbowfish, Melanotaenia australis ) and computer-generated prey images to compare the detectability of uniformly pigmented (i.e. non-countershaded) prey with that of optimally countershaded prey of varying contrasts against the background. Optimally countershaded prey were difficult for predators to detect, and the probability and speed of detection depended on prey luminance contrast with the background. In comparison, non-countershaded prey were always highly detectable, even though their average luminance closely matched the luminance of the background. Our findings suggest that uniformly pigmented three-dimensional prey are highly conspicuous to predators because overhead lighting increases luminance contrast between different body parts or between the body and the background. We found no evidence for the notion that countershading interferes with predator perception of three-dimensional form.

Setpoint regulation of continuum robots using a fixed camera

Robotica ◽  
2007 ◽  
Vol 25 (5) ◽  
pp. 581-586 ◽  
Author(s):  
V. K. Chitrakaran ◽  
A. Behal ◽  
D. M. Dawson ◽  
I. D. Walker
Keyword(s):  
Visual Information ◽  
Robot Manipulator ◽  
Three Dimensional ◽  
The Body ◽  
Reference Image ◽  
Shape Information ◽  
Continuum Robots ◽  
Continuum Robot ◽  
Dimensional Shape ◽  
Three Dimensional Shape

SUMMARYIn this paper, we investigate the problem of measuring the shape of a continuum robot manipulator using visual information from a fixed camera. Specifically, we capture the motion of a set of fictitious planes, each formed by four or more feature points, defined at various strategic locations along the body of the robot. Then, utilizing expressions for the robot forward kinematics as well as the decomposition of a homography relating a reference image of the robot to the actual robot image, we obtain the three-dimensional shape information continuously. We then use this information to demonstrate the development of a kinematic controller to regulate the manipulator end-effector to a constant desired position and orientation.

Understanding EHDA and Protein Stability

2007 ◽  
Author(s):  
Elizabeth M. Nottingham ◽  
Michelle G. Zeles-Hahn ◽  
Corinne S. Lengsfeld
Keyword(s):  
Electrostatic Interactions ◽  
Tertiary Structure ◽  
Therapeutic Proteins ◽  
Three Dimensional ◽  
The Body ◽  
Hydrophilic Interactions ◽  
Dimensional Shape ◽  
Physical Forces ◽  
Three Dimensional Shape ◽  
Secondary And Tertiary Structure

Therapeutic proteins can be difficult to work with due to the fact that each protein has properties and functions that are unique. These exclusive properties are in part due to the proteins three-dimensional shape (secondary and tertiary structure). This shape is determined by bends in the amino acid sequence generated by electrostatic interactions, hydrogen bonds, and hydrophobic-hydrophilic interactions between neighboring amino acids. These bonding interactions are weak and can be severed by chemical or physical forces. Thus, therapeutic proteins can be denatured during manufacture and by methods used to deliver them to the body.

Four Dimensions of Diamond T: Combination Trade Marks of Colours And Shapes

2006 ◽  
Vol 37 (4) ◽  
pp. 583
Author(s):  
Michael McGowan
Keyword(s):  
Three Dimensional ◽  
Trade Mark ◽  
Fourth Dimension ◽  
Trade Marks ◽  
Four Dimensions ◽  
Trade Mark Law ◽  
Dimensional Shape ◽  
Three Dimensional Shape

This article examines the relatively new fields of colour and shape trade marks. It was initially feared by some academics that the new marks would encroach on the realms of patent and copyright.  However, the traditional requirements of trade mark law, such as functionality and descriptiveness, have meant that trade marks in colour and shape are extremely hard to acquire if they do not have factual distinctiveness. As colour and shape trade marks have no special restrictions, it is proposed that the combination trade mark theory and analysis from the Diamond T case should be used as a way to make them more accessible. The combination analysis can be easily applied because every product has a three dimensional shape and a fourth dimension of colour.

Acoustic Analysis of Detailed Three-Dimensional Shape of the Human Nasal Cavity and Paranasal Sinuses

2017 ◽  
Author(s):  
Tatsuya Kitamura ◽  
Hironori Takemoto ◽  
Hisanori Makinae ◽  
Tetsutaro Yamaguchi ◽  
Kotaro Maki
Keyword(s):  
Nasal Cavity ◽  
Paranasal Sinuses ◽  
Acoustic Analysis ◽  
Three Dimensional ◽  
Dimensional Shape ◽  
Three Dimensional Shape

scholarly journals The Effect of Material Properties on the Perceived Shape of Three-Dimensional Objects

i-Perception ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 204166952098231
Author(s):  
Masakazu Ohara ◽  
Juno Kim ◽  
Kowa Koida
Keyword(s):  
Material Properties ◽  
Regional Variation ◽  
Three Dimensional ◽  
Mean Square ◽  
Viewing Condition ◽  
Three Dimensional Objects ◽  
Transparent Objects ◽  
Dimensional Shape ◽  
Local Root ◽  
Three Dimensional Shape

Perceiving the shape of three-dimensional objects is essential for interacting with them in daily life. If objects are constructed from different materials, can the human visual system accurately estimate their three-dimensional shape? We varied the thickness, motion, opacity, and specularity of globally convex objects rendered in a photorealistic environment. These objects were presented under either dynamic or static viewing condition. Observers rated the overall convexity of these objects along the depth axis. Our results show that observers perceived solid transparent objects as flatter than the same objects rendered with opaque reflectance properties. Regional variation in local root-mean-square image contrast was shown to provide information that is predictive of perceived surface convexity.

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