  Comparing mobile eye tracking data from multiple participants without
information about areas of interest (AOIs) is challenging because of individual
timing and coordinate systems. We present a technique, the gaze spiral, that
visualizes individual recordings based on image content of the stimulus. The
spiral layout of the slitscan visualization is used to create a compact
representation of scanpaths. The visualization provides an overview of multiple
recordings even for long time spans and helps identify and annotate recurring
patterns within recordings. The gaze spirals can also serve as glyphs that can
be projected to 2D space based on established scanpath metrics in order to
interpret the metrics and identify groups of similar viewing behavior. We
present examples based on two egocentric datasets to demonstrate the
effectiveness of our approach for annotation and comparison tasks. Our examples
show that the technique has the potential to let users compare even long-term
recordings of pervasive scenarios without manual annotation.
