IVT

class eyefeatures.preprocessing.fixation_extraction.IVT(x, y, t, threshold, min_duration, distance='euc', pk=None, eps=1e-10)

Bases: BaseFixationPreprocessor

Velocity Threshold Identification.

Complexity: O(n).

Parameters:

• x (str)

• y (str)

• t (str)

• threshold (float)

• min_duration (float)

• distance (str)

• pk (list[str])

• eps (float)

Algorithm

Gazes that have velocity below threshold are considered to be fixations, since high velocities are attributes of saccades. If \(d\) is some metric in \(\mathbb{R}^2\) and \(a\) is fixation-classification decision function, then, for a single fixation:

\[a(i) = \left[\frac{d((x_i, y_i), (x_{i + 1}, y_{i + 1}))}{t_{i + 1} - t_i} \leq T\right]\]