7 research outputs found
Automatic landmark annotation and dense correspondence registration for 3D human facial images
Dense surface registration of three-dimensional (3D) human facial images
holds great potential for studies of human trait diversity, disease genetics,
and forensics. Non-rigid registration is particularly useful for establishing
dense anatomical correspondences between faces. Here we describe a novel
non-rigid registration method for fully automatic 3D facial image mapping. This
method comprises two steps: first, seventeen facial landmarks are automatically
annotated, mainly via PCA-based feature recognition following 3D-to-2D data
transformation. Second, an efficient thin-plate spline (TPS) protocol is used
to establish the dense anatomical correspondence between facial images, under
the guidance of the predefined landmarks. We demonstrate that this method is
robust and highly accurate, even for different ethnicities. The average face is
calculated for individuals of Han Chinese and Uyghur origins. While fully
automatic and computationally efficient, this method enables high-throughput
analysis of human facial feature variation.Comment: 33 pages, 6 figures, 1 tabl
Own-race and other-race face recognition problems without visual expertise problems in dyslexic readers
Post-print (lokagerð höfundar)Both intact and deficient neural processing of faces has been found in dyslexic readers. Similarly, behavioral studies have shown both normal and abnormal face processing in developmental dyslexia. We tested whether dyslexic adults are impaired in tests of own-race and other-race face recognition. As both face and word recognition rely considerably on visual expertise, we wished to investigate whether face recognition problems of dyslexic readers might stem from difficulties with experience-driven expert visual processing. We utilized the finding that people tend to be worse at discriminating other-race faces compared to own-race faces, the so-called other-race effect, thought to reflect greater experience with own-race faces. If visual expertise is compromised in dyslexic readers, so that their visual system is not effectively shaped by experience, then they might show a diminished other-race effect. Matched dyslexic and typical readers completed two tests of own- and other-race face recognition. The results show that dyslexic readers have problems with recognizing faces, and these difficulties are not fully accounted for by general problems with attention or memory. However, recognition is compromised for both own- and other-race faces, and the strength of the other-race effect does not differ between dyslexic and typical readers. There was individual variability in both groups, and an exploratory analysis revealed that while dyslexic readers with no university education showed deficits in face recognition, the dyslexic participants with higher education did not. We conclude that dyslexic readers as a group have face recognition problems. These are potentially modulated by educational level but compromised visual expertise cannot demonstrably account for the face recognition problems associated with dyslexia. We discuss the implications of these findings for theoretical accounts of dyslexia and for theories of word and face recognition.This work was supported by The Icelandic Research Fund (Grant No. 174013-051) and the University of Iceland Research Fund.Accepted peer-reviewed manuscrip
3D Shape Descriptor-Based Facial Landmark Detection: A Machine Learning Approach
Facial landmark detection on 3D human faces has had numerous applications in the literature
such as establishing point-to-point correspondence between 3D face models which is itself a
key step for a wide range of applications like 3D face detection and authentication, matching,
reconstruction, and retrieval, to name a few.
Two groups of approaches, namely knowledge-driven and data-driven approaches, have been
employed for facial landmarking in the literature. Knowledge-driven techniques are the
traditional approaches that have been widely used to locate landmarks on human faces. In
these approaches, a user with sucient knowledge and experience usually denes features to
be extracted as the landmarks. Data-driven techniques, on the other hand, take advantage
of machine learning algorithms to detect prominent features on 3D face models. Besides
the key advantages, each category of these techniques has limitations that prevent it from
generating the most reliable results.
In this work we propose to combine the strengths of the two approaches to detect facial
landmarks in a more ecient and precise way. The suggested approach consists of two phases.
First, some salient features of the faces are extracted using expert systems. Afterwards,
these points are used as the initial control points in the well-known Thin Plate Spline (TPS)
technique to deform the input face towards a reference face model. Second, by exploring and
utilizing multiple machine learning algorithms another group of landmarks are extracted.
The data-driven landmark detection step is performed in a supervised manner providing an
information-rich set of training data in which a set of local descriptors are computed and used
to train the algorithm. We then, use the detected landmarks for establishing point-to-point
correspondence between the 3D human faces mainly using an improved version of Iterative
Closest Point (ICP) algorithms. Furthermore, we propose to use the detected landmarks for
3D face matching applications
Three Dimensional (3D) Forensic Facial Reconstruction in an Egyptian Population using Computed Tomography Scanned Skulls and Average Facial Templates: A Study Examining Subjective and Objective Assessment Methods of 3D Forensic Facial Reconstructions
PhDForensic facial reconstruction can assist identification by reconstructing a face of the
unknown person with the aim of its recognition by his/her family or friends. In the facial
reconstruction approach adopted in this study, a 3D average face template was digitally
warped onto a 3D scanned skull image. This study was carried out entirely on an Egyptian
population, and was the first of its kind.
Aims:
This study aimed to demonstrate that 3D facial reconstructions using the novel
methodology described could show significant resemblance to the faces corresponding to
the persons in question when they were alive. Moreover, using techniques previously
validated for facial reconstruction, the aim was to compare them to the method developed,
and to assess approaches used to determine the accuracy of 3D facial reconstructions.
Methods:
Initially, a pilot study was conducted using a database of laser scanned skulls and faces.
The faces were reconstructed using an average facial template generated by merging a
number of faces of similar population, sex, and age. The applicability, as well as the main
components of the facial reconstruction method, the single and average facial templates,
and the facial soft tissue thickness measurements, were investigated. Furthermore, in the
main study, the faces of computed tomography (CT) scanned heads of an Egyptian
population were reconstructed using average facial templates. The accuracy of the
reconstructed faces was assessed subjectively by face pool, and face resemblance tests,
and objectively by measuring the surface distances between the real and reconstructed
faces. In addition, a number of novel subjective and objective assessment methods were
developed. These included assessment of individual facial regions using subjective
resemblance scores, and objective surface distance comparisons. A new objective method,
craniofacial anthropometry, was developed by taking and comparing direct measurements
from the skull, and comparing the measurements from the real and reconstructed faces.
The studied cases were ranked according to all subjective, and objective, tests, and
statistically correlated.
Results and Conclusions:
The average facial templates showed a higher identification rate than the single face
templates. The approach of facial reconstruction used in this thesis showed a comparable
accuracy to many other facial reconstruction methods, yet was superior in terms of its
applicability, transferability, and ease of use. In the face pool tests, the younger assessors
were able to correctly identify the reconstructed faces better than older assessors.
Furthermore, the identification rate by the forensic anthropology experts was higher than
the non-experts. The former group showed the highest agreement between the observers
in giving the resemblance scores. Although there was a significant rank correlation
between the subjective and objective assessment tests, the subjective tests are influenced
by the assessors’ subjective characteristics (e.g., age, professional experience), thus
making objective assessment more reliable. However, in situations where subjective tests
are used, it is better to use the face resemblance tests and consult forensic anthropologists.
Also, Craniofacial Anthropometry, particularly the craniofacial angles, can successfully
indicate the accuracy of the facial reconstructions. Importantly, this study shows that
certain facial regions, particularly the cheek and the jaw, are more reliable than other
areas in the subjective and objective assessment of the facial reconstructionEgyptian Ministry of Higher Education and the Egyptian Cultural Affairs and the Mission Sector, as well as the
Egyptian cultural Counsellor and the staff of the Egyptian Cultural Centre and Educational Bureau in London, UK