Previously, we (Havig, Aleva, Reis, Moore, and McIntire, 2007) presented a taxonomy for the development of three-dimensional
(3D) displays. We proposed three levels of metrics: objective (in which physical measurements are made of
the display), subjective (Likert-type rating scales to show preferences of the display), and subjective-objective
(performance metrics in which one shows how the 3D display may be more or less useful than a 2D display or a
different 3D display). We concluded that for each level of metric, drawing practical comparisons among currently
disparate 3D displays is difficult. In this paper we attempt to define more clearly the objective metrics for 3D displays.
We set out to collect and measure physical attributes of several 3D displays and compare the results. We discuss our
findings in terms of both difficulties in making the measurements in the first place, due to the physical set-up of the
display, to issues in comparing the results we found and comparing how similar (or dissimilar) two 3D displays may or
may not be. We conclude by discussing the next steps in creating objective metrics for three-dimensional displays as
well as a proposed way ahead for the other two levels of metrics based on our findings.