  Abstract data has no natural scale and so interactive data visualizations
must provide techniques to allow the user to choose their viewpoint and scale.
Such techniques are well established in desktop visualization tools. The two
most common techniques are zoom+pan and overview+detail. However, how best to
enable the analyst to navigate and view abstract data at different levels of
scale in immersive environments has not previously been studied. We report the
findings of the first systematic study of immersive navigation techniques for
3D scatterplots. We tested four conditions that represent our best attempt to
adapt standard 2D navigation techniques to data visualization in an immersive
environment while still providing standard immersive navigation techniques
through physical movement and teleportation. We compared room-sized
visualization versus a zooming interface, each with and without an overview. We
find significant differences in participants' response times and accuracy for a
number of standard visual analysis tasks. Both zoom and overview provide
benefits over standard locomotion support alone (i.e., physical movement and
pointer teleportation). However, which variation is superior, depends on the
task. We obtain a more nuanced understanding of the results by analyzing them
in terms of a time-cost model for the different components of navigation:
way-finding, travel, number of travel steps, and context switching.
