Search results for "CAMOUFLAGE"
showing 10 items of 24 documents
The biology of color
2017
In living color Animals live in a colorful world, but we rarely stop to think about how this color is produced and perceived, or how it evolved. Cuthill et al. review how color is used for social signals between individual animals and how it affects interactions with parasites, predators, and the physical environment. New approaches are elucidating aspects of animal coloration, from the requirements for complex cognition and perception mechanisms to the evolutionary dynamics surrounding its development and diversification. Science , this issue p. eaan0221
Fake Landscapes
2016
L'articolo affronta i risvolti architettonici del camuffamento strategico effettuato per scopi militari durante la Seconda Guerra Mondiale. Si tratta di una pratica particolare messa in atto soprattutto in California nascondendo con enormi teloni dipinti interi edifici o capannoni facendolo apparire come altre cose e quindi evitando il riconoscimento da parte dei bombardieri. Si trattava quindi di fatto di ampie operazioni di land art o di un ambito dove l'architettura del paesaggio incontra la scenografia. Camouflage was a strategic technique used during the Second World War mainly in California but aslo elsewhere. It consisted in a massive operation on the landscape. The essay analyses it…
Visual Behaviour Based Bio-Inspired Polarization Techniques in Computer Vision and Robotics
2012
For long time, it was thought that the sensing of polarization by animals is invariably related to their behavior, such as navigation and orientation. Recently, it was found that polarization can be part of a high-level visual perception, permitting a wide area of vision applications. Polarization vision can be used for most tasks of color vision including object recognition, contrast enhancement, camouflage breaking, and signal detection and discrimination. The polarization based visual behavior found in the animal kingdom is briefly covered. Then, the authors go in depth with the bio-inspired applications based on polarization in computer vision and robotics. The aim is to have a comprehe…
Intensity-invariant nonlinear filtering for detection in camouflage.
2005
We introduce a method based on an orthonormal vector space basis representation to detect camouflaged targets in natural environments. The method is intensity invariant so that camouflaged targets are detected independently of the illumination conditions. The detection technique does not require one to know the exact camouflage pattern, but only the class of patterns (e.g., foliage, netting, woods). We use nonlinear filtering and the calculation of several correlations. The nonlinearity of the filtering process also allows high discrimination against false targets. Several experiments confirm the target detectability where strong camouflage might delude even human viewers.
Selection for cryptic coloration in a visually heterogeneous habitat.
2001
We studied selection by predators for cryptic prey coloration in a visually heterogeneous habitat that consists of two microhabitats. It has been suggested that the probability of escaping detection in such habitats might be optimized by maximizing crypsis in one of the microhabitats. However, a recent model indicates that a coloration that compromises the requirements of different microhabitats might sometimes be the optimal solution. To experimentally study these hypotheses, we allowed great tits (Parus major L.) to search for artificial prey items in two different microhabitats (background boards): small patterned and large patterned. On each board there was one prey item that was either…
Visual conditions and habitat shape the coloration of the Eurasian perch (Perca fluviatilis L.): a trade-off between camouflage and communication?
2009
In theory, selection for effective camouflage (i.e. dull coloration) in fish should be strongest when the conditions for visual predation are most favourable, such as in structurally simple pelagic habitats. By contrast, in more sheltered (e.g. littoral) habitats, selection may favour effective intra-specific communication (i.e. bright coloration) (at the expense of crypsis). Poor transparency, as in highly humic waters, should constrain colour adaptations. We investigated phenotypic variation in body coloration of Eurasian perch (Perca fluviatilis L.) in littoral and pelagic habitats of four humic boreal lakes. Perch from the most transparent lake had the lightest and less coloured belly a…
L’estetica del camuffamento animale. Riflessioni sul mimetismo biologico
2016
This article wants to investigate the logic of mimicry and their communicative function in animal life adopting an aesthetical perspective. The relationship between appearance and not-appearance, between the act of making itself visible and the act of disguising itself, is investigated starting from the morphological thought of the Swiss biologist Adolf Portmann, in a continuous dialogue with great thinkers of past and actual time – Johann Wolfgang Goethe, Hannah Arendt and Roger Caillois – and with the artistic illustrations of the American painter Abbott Thayer, concerned with the laws of color camouflage. This productive relationship among biology, aesthetics and artistic practice allows…
Data from: Gray plumage color is more cryptic than brown in snowy landscapes in a resident color polymorphic bird
2020
Camouflage may promote fitness of given phenotypes in different environments. The tawny owl (Strix aluco) is a colour polymorphic species with a grey and brown morph resident in the Western Palearctic. A strong selection pressure against the brown morph during snowy and cold winters has been documented earlier but the selection mechanisms remain unresolved. Here we hypothesise that selection favors the grey morph because it is better camouflaged against predators and mobbers in snowy conditions compared to the brown one. We conducted an online citizen science experiment where volunteers were asked to locate a grey or a brown tawny owl specimen from pictures taken in snowy and snowless lands…
Visual Discrimination of the 17 Plane Symmetry Groups
2011
Within most of the 17 plane symmetry groups, individual symmetry operations act in multiple, nonequivalent ways. This, and the fact that many groups can be realized on the basis of different unit cells and generating regions, poses difficulties for visual discrimination and identification. Because of inherent confounds, only few of the groups can be studied by traditional experimental methodology. The use of an oddity paradigm and specific tiling patterns that camouflage groups in complex textures are recommended as partial remedy to this impasse. In order to prepare readers for an appreciation of the aforementioned issues and to provide a rationale for their investigation, the reporting of…
Supplementary data for: Improved camouflage through ontogenetic colour change confers reduced detection risk in shore crabs
2019
Many animals change appearance with age but the reasons why are rarely tested. Common shore crabs (Carcinus maenas), for example, are known for their ability to change colour over time. Young crabs show remarkable variation in coloration and it has been suggested that their variable appearance may help them to hide from predators in the habitats they use. However, as crabs grow they become more mobile and adult crabs, in contrast, are known to possess a more uniform coloration. This creates a problem: how to remain hidden in habitats that are variable and very different in appearance? To answer this, we first reared young shore crabs of two shades, pale or dark, on two background types rese…