  This paper introduces holographic cross-device interaction, a new class of
remote cross-device interactions between local physical devices and
holographically rendered remote devices. Cross-device interactions have enabled
a rich set of interactions with device ecologies. Most existing research
focuses on co-located settings (meaning when users and devices are in the same
physical space) to achieve these rich interactions and affordances. In
contrast, holographic cross-device interaction allows remote interactions
between devices at distant locations by providing a rich visual affordance
through real-time holographic rendering of the device's motion, content, and
interactions on mixed reality head-mounted displays. This maintains the
advantages of having a physical device, such as precise input through touch and
pen interaction. Through holographic rendering, not only can remote devices
interact as if they are co-located, but they can also be virtually augmented to
further enrich interactions, going beyond what is possible with existing
cross-device systems. To demonstrate this concept, we developed HoloDevice, a
prototype system for holographic cross-device interaction using the Microsoft
Hololens 2 augmented reality headset. Our contribution is threefold. First, we
introduce the concept of holographic cross-device interaction. Second, we
present a design space containing three unique benefits, which include: (1)
spatial visualization of interaction and motion, (2) rich visual affordances
for intermediate transition, and (3) dynamic and fluid configuration. Last we
discuss a set of implementation demonstrations and use-case scenarios that
further explore the space.
