Table 1.

Features for stranger test.

Feature	Unit	Description
Time until approach	Seconds	Time from start to first approach of stranger
Duration of approach	Seconds	Time from start of the approach to coming in close proximity to stranger
Speed of first approach	Pixels/Seconds	Average speed of first approach
Trajectory length	Pixels	Length of all traveled trajectory
Trajectory length until first approach	Pixels	Length of the trajectory from start to coming to the stranger's proximity
Area	Pixels2	Approximation of the area
		covered by the dog, using convex hull approximation
Intensity of use	Integer	Ratio between the total trajectory and the square root of the area covered by the trajectory
Total contact	Seconds	Time spent in proximity to stranger
Straightness	Decimal	Ratio between the distance from start point S to endpoint F, and trajectory length from S to F
Straightness until first approach	Decimal	Ratio between the distance from start point S to approach point A, and trajectory length from S to A
Contact ratio	Decimal	Percentage of frames in proximity to stranger