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Calculation of angles and number of walks.

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posted on 09.08.2012, 01:16 authored by Julien Colomb, Lutz Reiter, Jedrzej Blaszkiewicz, Jan Wessnitzer, Bjoern Brembs

A. The inner circle represents the platform, while the outer circle represents the arena and the light source (to scale). The bars represent the stripes (wide or narrow). Considering the movement from P0 to P1, α0 is the absolute movement angle (similarly α−1 is the absolute movement angle of the movement P−1 to P0). The turning angle γ can be calculated as α0 - α−1, it represents the change in direction at time 0. β is the “stripe deviation” angle, the angle from the movement to a vector going straight toward the middle of the stripe that is in the direction of the movement. In the “ltraj” object, α is assigned to P0, β to P1. Gray areas denote the sectors used to start and end a walk between stripes: a walk is counted for each passage from one gray area to the other. B. Trajectory example, zoomed on the platform size. The disposition of the stripes are at 90 and −90° as in A. Dots represent the position of the fly during the three first minutes of a test with narrow stripes, after down sampling to 10 Hz.