On the conspicuity of 3-D fiducial markers in 2-D projected environments

Fiducial markers are used with head-mounted eye trackers to facilitate eye movement data aggregation for quantitative analysis. However, use of these markers may be problematic in some situations (e.g., natural tasks) as the markers may be visually distracting. To date, we are aware of no study that has examined the conspicuity of such markers to determine how much (if any) effort should be expended into concealing them from view. This paper presents a study that examines Tobii's infra-red (IR) markers' conspicuity in a 2-D projected environment. Results indicate that even when these 3-D markers are superimposed on a canvas on which the 2-D environment is projected, and no effort is taken to hide them (i.e., by minimizing contrast with the background), the presence of markers does not significantly alter the number or duration of fixations on the location of the markers when a specific task is given.