  Working with organs and extracted tissue blocks is an essential task in
surgery and anatomy environments. To prepare specimens from human donors for
analysis, wet-bench workers must dissect human tissue and collect metadata for
downstream analysis, including information about the spatial origin of tissue.
The Registration User Interface (RUI) was developed to allow stakeholders in
the Human Biomolecular Atlas Program (HuBMAP) to register tissue blocks, i.e.,
to record the size, position, and orientation of human tissue data with regard
to reference organs. In this paper, we compare three setups for registering one
3D tissue block object to another 3D reference organ (target) object. The first
setup is a 2D Desktop implementation featuring a traditional screen, mouse, and
keyboard interface. The remaining setups are both virtual reality (VR) versions
of the RUI: VR Tabletop, where users sit at a physical desk which is replicated
in virtual space; VR Standup, where users stand upright while performing their
tasks. We then ran a user study for these three setups involving 42 human
subjects completing 14 increasingly difficult and then 30 identical tasks in
sequence and reporting position accuracy, rotation accuracy, completion time,
and satisfaction. While VR Tabletop and VR Standup users are about three times
as fast and about a third more accurate in terms of rotation than 2D Desktop
users (for the sequence of 30 identical tasks), there are no significant
differences between the three setups for position accuracy when normalized by
the height of the virtual kidney across setups.
