Humans perceive and act within a visual world. This has become important even in
disciplines which are prima facie not concerned with vision and eye tracking is now used
in a broad range of domains. However, the world we are in is not two-dimensional, as
many experiments may convince us to believe. It is convenient to use stimuli in 2D or
21/2D and in most cases absolutely appropriate; but it is often technically motivated and
To overcome these technical limitations we contribute results of an evaluation of different
approaches to calculate the depth of a fixation based on the divergence of the eyes
by testing them on different devices and within real and virtual scenarios.