Pre-processed `TrajSet` of 235 millipede trajectories from a visual-acuity experiment. *Cylindroiulus punctatus* individuals were placed at the centre of a cylindrical arena under bright, downwelling light, with a dark target of varying angular half-width on the arena wall, and their path tracked to test whether they oriented toward the target (object taxis). Eight stimulus conditions are represented: target half-widths of 5, 10, 15, 20, 30, 40, and 50 degrees, plus a featureless control (`arc = 0`, an angular subtense of zero).
Format
A [`TrajSet`] object (44,331 observations) whose data columns include:
- trial_id
Character. Unique trial identifier.
- frame
Integer. Video frame number.
- trans_x, trans_y
Numeric. Unit-circle Cartesian coordinates.
- abs_theta
Numeric. Absolute bearing (radians).
- rel_theta
Numeric. Bearing relative to the target direction.
- rel_x, rel_y
Numeric. Target-relative unit-circle coordinates.
- arc
Ordered factor. Target half-width in degrees (`0` < `5` < `10` < `15` < `20` < `30` < `40` < `50`; 0 = control).
- type
Character. `"control"` or `"stimulus"`.
- individual
Character. Animal identifier.
Source
Behavioural experiment from Kirwan & Nilsson (2019); raw tracks produced with dtrack and normalised with radiatR. A subset of the published dataset.
Details
These tracks are a **subset** of the full experiment; see Kirwan & Nilsson (2019) for the complete dataset and trial counts.
Coordinates are normalised to the unit circle (arena radius = 1) and rotated so the target lies in a common reference direction; `rel_theta`, `rel_x`, and `rel_y` give the target-relative heading and position. The animal identifier is retained in the `individual` column.
The raw dtrack landmark/track text files for every trial are shipped in `inst/extdata/tracks/`, and the trial manifest in `inst/extdata/millipede_trials.csv`, so the full import pipeline can be reproduced with [get_all_object_pos()]. See `data-raw/millipede_example.R`.
References
Kirwan, J. D., & Nilsson, D.-E. (2019). A millipede compound eye mediating low-resolution vision. *Vision Research*, 165, 36–44. doi:10.1016/j.visres.2019.09.003