Personal mobile devices hold a vast amount of private and
sensitive data and can e. g. be used to access services
with associated cost. For security reasons, most mobile
platforms therefore implement automatic device locking
after a period of inactivity. Unlocking them using
approaches like PIN, password or an unlock pattern is both
problematic in terms of usability and potentially insecure,
as it is prone to the shoulder surfing attack: an attacker
watching the display during user authentication. Hence,
face unlock – using biometric face information for
authentication – was developed as a more secure as well
as more usable personal device unlock. Unfortunately, when
using frontal face information only, authentication can
still be circumvented by a photo attack: presenting a
photo/video of the authorized person to the camera. In this
work we present a variant of face unlock which is harder to
circumvent than with using frontal face information only by
using more facial information, available during a 180∘
pan shot around the user’s head. We develop and evaluate
our mobile device pan shot face unlock in four different
stages in order to identify conceptual weaknesses and do
improvements within the next stage. In the first stage we
present a proof-of-concept prototype based on Android,
which uses different Viola and Jones Haar-cascades for face
detection and Eigenfaces for face recognition. We identify
Eigenfaces as being insufficient for usage in a mobile
device unlocking scenario. Therefore, we utilize neural
networks and support vector machines for face recognition
in the next stage, with which we identify using Viola and
Jones based face detection as being insufficient for usage
in a mobile device pan shot unlocking scenario based on
multiple perspectives. Hence, we develop a novel face
detection and segmentation approach based on stereo vision
and range template matching in the next stage, which we
find to deliver promising results and consequently focus on
improving details of the range template generation and
matching within the fourth and last stage. Parallel to
developing and evaluating our approach we build up the
u’smile face database containing grayscale and stereo
vision pan shot test data. Concluding, our results indicate
that a mobile device pan shot face unlock is a viable
approach to unlocking mobile devices and that using range
information might in general be an effective approach for
incorporated face detection and segmentation.
@thesis{Findling_13_PanShotFace, author = {Findling, Rainhard Dieter}, title = {Pan Shot Face Unlock: Towards Unlocking Personal Mobile Devices using Stereo Vision and Biometric Face Information from multiple Perspectives}, month = sep, year = {2013}, note = { {Winner of the OCG Incentive Award FH 2014 and the IFAC Fred Margulies Award 2015}}, institution = {Department of Mobile Computing, School of Informatics, Communication and Media, University of Applied Sciences Upper Austria}, location = {Softwarepark 11, 4232 Hagenberg, Austria}, type = {Master's Thesis} }