Week 2 Overheads
Egocentric and Geocentric Coordinates
Egocentric
Geocentric
- Centred on some point in the environment
Combinations
Egocentric Example
- Scorpion prey localization
Parallax
Locust
TBLs
Looming
Flies landing on walls
Insect Odometers
Burkhalter (1972)
- Step counting?
- 15 m critical...visual cues?
Optic Flow
Retinal image
Speed
Elevation
Retinal Image Size
Size of objects on retina
Distance estimation
Apparent size
Developmental factor?
- Retinal image size vs. motion parallax
Range Lines
Digger wasps
- Two or more landmarks
- Intersecting lines
Piloting
Geometric relations between landmarks
Hoverflies
- 3-D spatial representations
- Memory of landmarks
- Orientation of landmarks
- Visual update mechanisms
Take this link to a picture of an early man-made hoverfly.
Route Fidelity
Saves on landmark memorization
Central place foragers
e.g., Formica rufa
- Individual workers only search a single quadrant
- Rosengren (1971) and Rosengren & Forteliu (1986)
Collett, Dillmann, Giger, & Wehner (1992)
- Side landmark was passed on
Path Integration
Change in velocity over time
- Distance = (speed)(time)
- change in latitude = cos(COURSE)(distance)
- change in longitude = sin(COURSE)(distance)
Need
- Distance and angular change information
Celestial Cues for Orientation
Polarized light
- Different patterns
- Triangle: sun, observer, point observed
- Polarization perpendicular to triangle
Invertebrate eyes
- Evolved to detect polarized light
- Microvilli tubes
- Dorsal rim of compound eyes
- Ocelli
Rule needed
Honeybee Waggle Dance
Identifies food source
Figure eight form
Straight line component
Waggle dance rules
- Use sun as cellestial cue
- Pick further from the sun
- Pick to the right of the sun
Time Sense
Endogenous and exogenous clocks
Bees
- Endogenous clock constant
- Exogenous clock depends on celestial cues
Renner (1960)
- Long Island, NY hive
- Fly hive to Davis, CA
- Three hour 15 minute time difference
- Foraged 9:45 - 12:15
- Exogenous clock gradually adjusts
Sun's Movement
Compensate for change in solar angle across time
- To move in a straight line
- Sun's anglular velocity = 15 degrees/hr
- Sun's azimuth velocity variable
Renner (1960)
- Bees: average suns azimuth velocity across time
- 15 degrees/hr
- No: produces morning and afternoon errors
Wehner & Lanfranconi (1981)
- Cataglyphis: do not average suns azimuth velocity
- Memorize suns position to landmarks
Gould (1980)
- Bees: extrapolate suns azimuth velocity
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