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  • 1
    Electronic Resource
    Electronic Resource
    Robust judgement of inter-object distance by an arthropod (2003)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 421 (2003), S. 160-163 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Animals use several strategies for depth vision, reflecting the constraints imposed by body size, the structure of the visual system and the visual geometry of the environment. Arthropods in particular have restricted depth perception, because they are small and possess closely set, ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature01247
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  • 2
    Electronic Resource
    Electronic Resource
    Automatic tracking of complex objects under natural conditions (1995)
    Springer
    Biological cybernetics 73 (1995), S. 415-423 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract We deal with the problem of tracking freely flying insects that have been filmed under natural conditions. Although this appears to be an easy task for human observers it proves to be quite difficult to implement in computer vision systems. The main goal of our project was to automatize the reconstruction of animal flightpaths in a single-frame video film analysis. In addition to standard image-processing tools we employed a number of physical constraints as well as general knowledge to produce a system with acceptable performance. In this article we describe basic algorithms and techniques that provide a pragmatic solution in a specific case but that could in principle be applied to a large class of related problems. Our system copes with up to 5 degrees of freedom and a number of other variables such as brightness, illumination, object shape, occlusion and light reflection. We discuss the performance of a first implementation as well as remaining problems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00201476
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  • 3
    Electronic Resource
    Electronic Resource
    Automatic tracking of complex objects under natural conditions (1995)
    Springer
    Biological cybernetics 73 (1995), S. 415-423 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract.  We deal with the problem of tracking freely flying insects that have been filmed under natural conditions. Although this appears to be an easy task for human observers it proves to be quite difficult to implement in computer vision systems. The main goal of our project was to automatize the reconstruction of animal flight-paths in a single-frame video film analysis. In addition to standard image-processing tools we employed a number of physical constraints as well as general knowledge to produce a system with acceptable performance. In this article we describe basic algorithms and techniques that provide a pragmatic solution in a specific case but that could in principle be applied to a large class of related problems. Our system copes with up to 5 degrees of freedom and a number of other variables such as brightness, illumination, object shape, occlusion and light reflection. We discuss the performance of a first implementation as well as remaining problems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004220050197
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  • 4
    Electronic Resource
    Electronic Resource
    Sexual dimorphism in the visual system of flies: The compound eyes and neural superposition in bibionidae (Diptera) (1983)
    Springer
    Journal of comparative physiology 150 (1983), S. 379-393 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Micro-optical and neuro-anatomical techniques were used to study the retinal organisation of the compound eyes and the receptor terminals in the lamina in Bibionidae (Diptera). 2. Male bibionids have divided compound eyes (Fig. 1). The dorsal eyes have larger facets and longer rhabdomeres than the ventral eyes and the eyes of females (Table 1). Groups of six peripheral retinula cells in six next-but-one ommatidia have parallel optical axes and their terminals in the lamina are shown to pass to next-but-one cartridges (Fig. 6, 7). 3. The retinal organisation of ventral eyes and the eyes of females differs from the one seen in the dorsal eyes of males (Figs. 2, 3). InBibio marci, the rhabdomeres in ventral and female eyes are arranged with the same radial symmetry as in the dorsal eyes, but interrhabdomere angles are smaller than would be expected for ideal neural superposition eyes (Fig. 5d). 4. In the ventral and female eyes ofDilophus febrilis, peripheral rhabdomeres are arranged in a horse-shoe like fashion around the central rhabdomeres (Fig. 2). Groups of four peripheral rhabdomeres in four neighbouring ommatidia have parallel visual axes (Fig. 5b). 5. The terminals of peripheral retinula cells in the ventral and female eye lamina pass to neighbouring and to next-but-one cartridges (Fig. 6). Long visual fibres, originating from the central retinula cells form en passant terminals in the ventral and female lamina. 6. It is shown that in eyes with open rhabdoms where the visual axes are not parallel, neural superposition reduces the amount of overlap between the visual fields of lamina cartridges provided the interrhabdomere angles are larger than 0.876 times the interommatidial angles (Fig. 8). 7. It is suggested that compared with the ventral and female eyes, the dorsal eyes of males are designed to increase the distance at which a small object can be detected against a homogeneous background (Fig. 9).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00605027
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  • 5
    Electronic Resource
    Electronic Resource
    Homing in fiddler crabs (Uca lactea annulipes and Uca vomeris : Ocypodidae) (1998)
    Springer
    Journal of comparative physiology 183 (1998), S. 367-377 
    Details
    ISSN: 1432-1351
    Keywords: Key words Fiddler crabs ; Uca lactea annulipes ; Uca vomeris ; Homing ; Path integration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Fiddler crabs emerge from burrows on intertidal sand- and mudflats to feed during low tide. In the species studied here (Uca lactea annulipes, Uca vomeris) a crab normally wanders no more than about 1 m away from its burrow and, when frightened, dashes back along a straight line to take cover. Feeding crabs tend to move sideways, without changing orientation, along paths radiating from the burrow. When they move along circumferential paths they adjust their orientation so that one side continues to point towards the burrow. The crabs do not need to see the burrow in order to stay aligned with the home vector, and they are not misled by a dummy hole close to their own burrow unless they have come to within about 10 cm of it. The home runs of crabs end within a few centimeters of a burrow that is covered with a sheet of sandpaper and then give way to search runs, centred upon a position slightly short of the burrow location. Feeding crabs can be displaced on sandpapers and their subsequent home runs end at a position where the burrow would be, had there been no displacement. Landmarks close to the burrow do not influence the home runs of displaced crabs. Crabs that are rotated on a sheet of sandpaper, counter-turn to keep their original orientation constant. Fiddler crabs thus employ path integration with external compass information and close range visual guidance for homing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050263
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  • 6
    Electronic Resource
    Electronic Resource
    Sexual dimorphism in the visual system of flies: The free flight behaviour of male bibionidae (Diptera) (1983)
    Springer
    Journal of comparative physiology 150 (1983), S. 395-412 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. The free flight behaviour of swarming male Bibionidae (Diptera) has been filmed in the field with two cameras simultaneously at 50 frames/s. A method is described which allows the reconstruction of the three-dimensional trajectories of flies from the two films. 2. Males track other flies and dummy targets from below and from downwind (Figs. 5–8; 10a). They keep pointing into the wind and control flight direction and their position relative to the target by way of translational movements (forward, side-ways and vertical movements) (Fig. 9; Fig. 16b–d). Angular tracking is minimal, there is evidence, however, that the flies roll and pitch. 3. When interacting with a target, the flies keep the target's image close to and within the zone of binocular vision of their dorsal compound eyes (Figs. 3; 10c). There is some evidence that the flies' sideways acceleration is determined by the error angle velocity with a delay of 90 ms (Fig. 12). Underneath the target the flies perform sideways oscillations at 3–5 Hz (Fig. 13). 4. The flies repeatedly home in on and retreat from a target. At close range (0–20 cm) their vertical and forward velocity is linearily related to the target distance (Figs. 14a, 15a). Switches from ascending to descending flight occur whenever the target is lost from the visual field of the dorsal eyes. 5. Both forward and vertical velocity are to some extent dependent on the altitude of the target above the horizon of the fly (Figs. 14b, 15b). 6. Rotational body movements in response to rotating striped patterns can only be elicited by stimulating the ventral eyes, the dorsal eyes do not mediate the optomotor response (Fig. 17). 7. In bibionids, male-specific visually guided behaviour is mediated through the dorsal eyes only. The visual tasks of swarming males are discussed. The complex behaviour seen in males interacting with a dummy target might reflect their need to distinguish other males in a swarm from females and to keep the surrounding airspace clear of unwanted targets.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00605028
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  • 7
    Electronic Resource
    Electronic Resource
    Tactile localisation: the function of active antennal movements in the crayfishCherax destructor (1985)
    Springer
    Journal of comparative physiology 157 (1985), S. 607-617 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Video recordings and single frame analysis were used to study the function of the second antennae of crayfish (Cherax destructor) as a sensory system in freely behaving animals. 2. Walking crayfish move their antennae back and forth through horizontal angles of 100° and more, relative to the body long axis (Fig. 1). At rest, animals tend to hold their antennae at angular positions between 20 and 50°. Movements of the two antennae are largely independent of each other. Before and during a turn of the body the ipsilateral antenna is moved into the direction of the turn (Figs. 1, 2). Solid objects are explored by repeatedly moving the antennae towards and across them. 3. Both seeing and blinded crayfish can locate stationary objects following antennal contact (Figs. 2, 3). On antennal contact with a small novel object, a moving animal withdraws its antenna and attacks the object. 4. When the antenna of a blinded crayfish is lightly touched with a brush the animal turns and attacks the point of stimulation (Fig. 4). The direction taken and the distance covered during an attack can be correlated with: 1. the angle at which the antenna is held at the moment of contact and 2. the distance along the antennal flagellum at which the stimulus is applied (Figs. 5, 7). 5. From behavioural evidence we conclude that crayfish use information about the angular position of their antennae and about the position of stimulated mechanoreceptors along the antennal flagellum to locate objects in their environment. We suggest ways in which an active tactile system — like the crayfish's antennae — could supply animals with information about the three-dimensional layout of their environment (Fig. 8).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01351355
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  • 8
    Electronic Resource
    Electronic Resource
    A robust procedure for visual stabilisation of hovering flight position in guard bees of Trigona (Tetragonisca) angustula (Apidae, Meliponinae) (1990)
    Springer
    Journal of comparative physiology 167 (1990), S. 569-577 
    Details
    ISSN: 1432-1351
    Keywords: Stingless bees ; Visual orientation ; Hoverng flight ; Flight control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. In the stingless bee, Trigona (Tetragonisca) angustula, hovering guard bees keep their position relative to a moving stripe pattern mounted on the front face of the nest box constant by flying forwards and backwards parallel to the pattern movement (Fig. 2). 2. The response is guided by two cues: (1) image position and motion of the pattern and (2) the retinal position of the nest entrance (Figs. 2–5). 3. Guard bees react to an expanding and contracting pattern by moving away from and towards the nest box (Figs. 6, 7). Bees always fly away from an expanding pattern in a direction that is defined by a line connecting the centre of expansion with the bee's position at the time the movement starts (Fig. 8). 4. A procedure based on Collett's 2nd optomotor rule can explain the ability of the bees to determine visually the direction of compensatory thrust (Fig. 10). The procedure is robust in 3 respects: (1) there will be no thrust generated in response to animal rotations as long as a scene contains contrast elements throughout the visual field; (2) errors in the direction of compensatory thrust are small even if the local direction of image motion alone is taken into account and not its magnitude; (3) only very few pattern elements are needed for the procedure to work.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00190828
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  • 9
    Electronic Resource
    Electronic Resource
    Multisensory control of eye-stalk orientation in space: crabs from different habitats rely on different senses (1989)
    Springer
    Journal of comparative physiology 165 (1989), S. 643-649 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. We recorded compensatory eye stalk movements in response to pitch and roll stimulation of the visual, statocyst, and leg-proprioceptive systems in different species of crabs (Carcinus maenas, Heloecius cordiformis, Pachygrapsus marmoratus) (Fig. 2). 2. The relative contribution of visual, statocyst and leg-proprioceptive inputs to eye stabilization in space varies greatly among different species (Fig. 3). 3. We suggest that for stabilizing the eyes in space, the contribution of various sensory inputs in different species of crabs correspond to the availability of cues in their habitat. Semiterrestrial crabs living in a habitat with well defined and predictable visual geometry stabilize their eye stalks mainly by visual cues. Crabs living on solid substrate make strong use of leg proprioceptive input. Swimming crabs, and other predominantly aquatic crabs, rely mainly on their statocysts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00610996
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  • 10
    Electronic Resource
    Electronic Resource
    Visually controlled station-keeping by hovering guard bees ofTrigona (Tetragonisca) angustula (Apidae, Meliponinae) (1989)
    Springer
    Journal of comparative physiology 165 (1989), S. 711-718 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Guard bees of the stingless beeTrigona (Tetragonisca) angustula typically hover in very stable positions on both sides of and close to the nest entrance; for most of the time they face the flight corridor or the nest entrance (Fig. 2). Individual bees occupy a distinct airspace which they can leave for short excursions but return to afterwards (Fig. 3). When they change their position, they adjust their body-axis orientation to keep the nest entrance within their frontal visual field (Fig. 4). The accuracy of station-keeping decreases with the distance from the nest (Fig. 5). 2. Guard bees stay tightly coupled to the nest when the whole nestbox is oscillated through 20 cm forward and sideways with respect to the direction in which the nest entrance is pointing. They hold their position and distance relative to the nest entrance by flying forward, backward and sideways while keeping the angular orientation of their body long axis constant for most of the time (Figs. 6, 7). They temporarily lag behind the nest movement when they actively change their angular orientation or when the nest moves away from them. After the movement of the nest stops, bees which have lagged behind regain hovering stations close to the nest (Fig. 8).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00611002
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