17-03-2014, 09:20 PM
ABSTRACT
With the increasing power of mobile CPUs and GPUs, it is becoming
tractable to integrate all the components of an interactive,
immersive virtual reality system onto a small mobile device. We
present a demonstration of a head-mounted display system integrated
onto an iPhone-based platform. In building this demonstration
we tackled two main problems. First, how to integrate the userinterface,
utilizing the phone itself as an unseen touch interface.
Second, how to integrate multiple inertial measuring units to facilitate
user interaction. The resulting system indicates the practicality
of mobile virtual reality systems based on smartphones.
Keywords: Mobile virtual reality, head-mounted display, 3D user
interaction, selection tasks.
Index Terms: H.5.1 [Information Interfaces and Presentation]:
Multimedia Information System—Artificial, augmented and virtual
realities
1 INTRODUCTION
The very rapid increase in the power of mobile CPUs and GPUs
has meant that while until recently, immersive virtual reality (VR)
systems were powered by dedicated rendering computers, it is now
feasible to ask whether we can integrate such systems on mobile
devices. Mobility of a VR system has some attractive advantages,
such as no tethering to base stations and easy deployment in novel
situations. If the VR systems can be built with consumer components,
then it reduces the need for specialist hardware.
In this paper, we present an interactive VR system integrated on
to a modern smartphone, an iPhone 4S. Such devices come with
many of the components that are required for an immersive VR: a
mobile GPU capable of rendering high definition imagery, external
video and audio output and an inertial measuring unit (IMU) for
estimating pose. We needed to add another tracker and a headmounted
display system; both were readily available components.
e-mail: A.Steed[at]ucl.ac.uk
†email: S.Julier[at]ucl.ac.uk
Our prototype makes two main technical contributions. First, because
we are driving an external head-mounted display (HMD), the
smartphone itself can also act as an interaction device. We can thus
use it as a hand-held (but unseen) controller that can be used to effect
interaction within the virtual environment. Second, because the
smartphone is hand-held, the HMD is tracked by an external sensor,
which is also an IMU. A pair of IMUs will not be registered into
the same coordinate frame without some external reference. We
take advantage of the fact that both devices can be independently
registered against the local gravity vector. Through two simple interaction
techniques, raising the hand to the face and a clutch, we
can allow the user to realign the two IMUs.