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TECHNIQUES IN FACIAL RECONSTRUCTION: A FORENSIC ANTHROPOLOGICAL PERSPECTIVE BY: ISHAAN DEEPAK JOSHI
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TECHNIQUES IN FACIAL
RECONSTRUCTION: A FORENSIC ANTHROPOLOGICAL PERSPECTIVE
AUTHORED BY: ISHAAN DEEPAK JOSHI
NALSAR University of Law and MIT-WPU
Faculty of Law
Email: ishaanjoshi2k@gmail.com
Phone no: +91 9158636644
Abstract
The process of identifying human
remains involves considering several elements, with the face being recognised
as a distinctive characteristic that can be utilised for accurate
identification. The face assumes a
crucial function in authentication when DNA or biometric analyses are not
feasible. Porter & Doran note that fingerprints are a more dependable means
of identification, however facial images assist non-experts in making
identifications by matching the suspect in issue with their portrait or sketch.
The objective of forensic facial reconstruction is to utilise a skull in order
to develop a visage that can be employed for the identification of the
individual to whom the skull pertains.
An effective forensic facial reconstruction will yield a countenance
that can be readily and properly recognised as belonging to the individual
whose skull it originated from. The importance of facial reconstruction
procedures in forensic work has led to the creation of many methods for facial
reconstruction. This research aims to elucidate the fundamental principles of
forensic facial reconstruction and conduct a thorough evaluation of its
practical utility. This analysis will evaluate several widely-used techniques
for facial reconstruction, emphasising their inherent advantages and
disadvantages.
Forensic
Principles in Facial Reconstruction
Face
reconstruction is the method of creating facial features, typically for
individuals whose identity is unknown, based on their skull structure. The
underlying principle of this procedure is the concept that the structure of the
skull is closely linked to the external appearance of the face. However,
establishing this association is challenging due to the uneven distribution of
soft tissues over the skeletal structure.[1] Hence,
the contentiousness around the precision of facial reconstruction techniques
arises, with certain scholars casting scepticism on the technologies' capacity
to faithfully replicate a visage that can be readily and accurately identified
as the intended person.[2] Furthermore, the skull lacks any distinctive
features including as birthmarks, scars, or moles that can serve as
identifying markers for an individual.
Clement & Murray concede
that the process of fully rebuilding a face from a skull devoid of any flesh is
exceedingly challenging due to the limited knowledge of the precise connections
between the bony structure and the soft tissues. The link between the
cranium and the facial features is intricate due to the existence of adipose
tissue, muscular tissue, and connective tissue. Stephan &
Simpson state that when determining the depths of facial soft tissue, no
specific anatomical component of the face provides discriminative information.[3]
Furthermore, facial approximation
algorithms lack the capability to ascertain attributes such as facial colours
and textures based on the skull.[4] Hence,
accurately determining the skin depth just from the exposed skull remains
unattainable, even when considering a substantial dataset encompassing a
diverse range of individuals.
Despite the challenges associated
with producing precise anatomical reconstruction of the visage, forensic facial
building has been effective in establishing leads or initial identifications in
numerous forensic instances. According to Wilkinson, forensic facial
reconstruction is employed by the police in cases when they lack a suspect for
identification purposes. The face is widely regarded as the most
influential area of the body when it comes to assisting with identifying
endeavours. Oxenham asserts that the face possesses very distinctive configurations,
making facial reconstruction methods highly valuable for identifying purposes.
Facial reconstruction serves the
purpose of not only determining the identity of the skull's owner, but also
plays a crucial role in eliminating potential suspects. Anthropologists
utilise forensic facial reconstruction to replicate the facial appearances of
early humans and hominids. This tool aids anthropologists in their examination
of the evolutionary transitions from hominids to modern humans. Recent
technological advancements have empowered anthropologists to utilise several
methodologies that have facilitated more precise identification.
Methods for
Restoring Facial Structure
The initial endeavours in facial
reconstruction focused on aligning the skulls of renowned individuals with
their corresponding pictures and sculptures. The unidentifiable craniums were
overlaid over the visuals of the presumed possessor to ascertain if they
corresponded. Nevertheless, the
importance of facial reconstruction in the process of reconstructing the
appearance of unidentified individuals has increased. Consequently, researchers
have focused on developing methods to reconstruct the features of unidentified
individuals based on their skulls.[5]
Facial forensic reconstruction
generally utilises the skull to estimate the appearance of the face, although
physical remnants on the skeletal framework also contribute to this
procedure. The presence of soft tissue remnants aids the practitioner in more
accurately estimating the thickness of soft tissue, hence reducing the inherent
inaccuracies associated with the procedures used to measure soft tissue
thickness.
Two-dimensional
Reconstruction
Tissue depth markers are affixed to
the skull being identified to create an outline sketch of skulls from both
frontal and lateral perspectives. Oxenham illustrates that the
primary sutures of the skulls, which are often referred to as anthropological
landmarks, are the main points of interest for attaching these depth
indicators. Artists can create 2-D facial reconstructions using the
photographic prints generated through this process. According to Wilkinson, this technique
enables police artists to rebuild the facial features of decomposing
individuals and accurately determine the identity of the skull's original
owner.
The conventional method of facial
reconstruction in two dimensions was a manual process where facial drawings
were created on overlays and then overlaid onto skull photographs. In the
manual method, the practitioner may sketch the facial muscles on the
preliminary overlay or immediately draw the completed face over the skull
pictures. Caldwell enhanced the 2D technique by suggesting the utilisation of
life-sized anterior and peripheral views of the skull, followed by the
incorporation of tissue depth information based on Krogman's standards.
The conventional two-dimensional
reconstruction technique has made notable progress in recent decades as a
result of the implementation of computer programmes in the
procedure. Computerised 2D facial reconstruction utilises specialised
computer software built exclusively for this task. The software
application is utilised to generate a facial composite based on a photograph of
the cranium. The programme retrieves facial outlines and traits from a
database it maintains, and then incorporates them. The face features are contingent
upon the musculoskeletal structure & its origins.
Mikhail Gerasimov, a well-known
Russian Anthropologist, proposed that accuracy issues may arise when the
investigator neglects to adequately consider the muscular structure and the
interrelationship between the facial form and the unique characteristics of the
cranium. The precision of 2D reconstruction is contingent upon the
expertise of the practitioner. According to Ullrich and Stephan,
Gerasimov's face approximation technique, which considered muscle structure,
reached nearly perfect accuracy of around a hundred percent.[6]
Advantages
Utilising computer software
programmes for 2D reconstruction expedites the process and yields a rapid
approximation. Modifications to the finalised image can also be easily applied
utilising the editing capabilities of the software. This technique does not
necessitate the utilisation of advanced equipment to generate the facial
estimation.[7] Consequently,
it can be utilised by laboratories that do not own contemporary equipment. The
significance of this issue is important, as a scarcity of resources can impede
forensic teams in their execution of facial reconstruction.
Limitations
This facial restoration approach is
equally susceptible to the subjective influence of the reconstructor. According
to Wilkinson, the reconstructor's perceived subjectivity will have a
significant impact on the result of the procedure. The accuracy of 2D
reconstruction using manual techniques relies heavily on the skill and
proficiency of the artist. The
correctness of the reconstruction primarily depends on the individual
reconstructor's level of talent and expertise. The reconstruction practitioner
employing this technique must possess sufficient expertise and a comprehensive
comprehension of facial anatomy & physiology to produce a sufficiently
precise facial reconstruction.
Three-Dimensional
Sculpture
Gatliff Betty created the 3-D
approach based on the research of Krogman. Gatliff identified the significance
of facial asymmetry during her efforts to rebuild the visage of a Native
American male. According to Wilkinson, Gatliff only recreated part of the face
in the particular case and produced a whole face by utilising mirror image
photographs. There exist two distinct strategies for 3-D facial reconstruction:
the American method and the Russian method. In the American approach, the skull
is affixed to a stand and data regarding average tissue thickness is obtained
from several tables that pertain to different age groups, ethnicities, and
genders. The practitioner chooses the most suitable combination of tissue
density parameters and cuts vinyl rubber cylinders to the corresponding
thickness. The pieces are adhered to the
cranium at the precise anatomical locations, and strips of modelling clay are employed
to link these marks together. By performing this process, a rudimentary
topographic representation of the facial surface is generated, and the
remaining exposed areas are filled in order to simulate the appearance of a
face. An artist is then employed to sculpt the facial features, including the
eyes, lips, nose, & ears. According to Wilkinson, the facial traits are
derived from specific information gathered from the skull, which could
potentially indicate the skull's origins.
Advantages
The presence of a three-dimensional
representation of the face leads to a heightened level of realism, so aiding in
the process of identification. Stephan & Henneberg have documented
that the utilisation of a 3D model considerably enhances the ability to
identify objects beyond random chance. The employment of the Russian approach,
which involves the development of facial muscles, can greatly enhance accuracy
levels.[8] Utilising
3D sculptures enables the analyst to physically see the texture of the skull,
facilitating the inclusion of crucial skeletal intricacies in the facial
reconstruction procedure. The presence of suitable facial characteristics
greatly aids non-experts in making precise identifications.
Limitations
The reconstructions rely on a limited
number of data points that provide height information. The majority of the
facial features are then constructed using interpolated data, resulting in a
reduction in the precision of the recreated face. If the degree of error is
excessively high, it will be unfeasible to achieve a definitive identification
using the recreated face. Another drawback of this approach is its
time-consuming nature, as well as the necessity for the practitioner to possess
extensive anatomical and forensic expertise in order to achieve a precise
reconstruction.
Three-Dimensional
Computed Tomography Scan
CT scans are invaluable in cases
where utilising the authentic skull of an unidentified individual is not
feasible. The technology of stereolithography utilises CT scans to create an
accurate replica of an individual's skull with great precision. The CT scan
from the skull can be replicated using 3D printing or it can be digitally
altered as a computer model. The modification of the model allows for the
entire computerization of the tissue restoration process. The dowels, serving
as a reference for the reconstruction process, are seamlessly incorporated into
the CT image using software, facilitating effortless editing.
Advantages
The CT-generated 3D scan is devoid of
any geometric aberrations. CT images are useful initial steps in
computer-assisted craniofacial reconstruction. According to Choras, the scan
produces highly precise results, allowing for the identification and
triangulation of equipotential planes.
The CT scan produces undistorted three-dimensional pictures of the skull
due to its non-invasive nature.[9] According
to Choras, it provides as a starting point from which various methods of tissue
restoration can be executed. The practitioner has the ability to adjust the
elevation of the dowels, so effortlessly altering the facial appearance. According
to Clement and Murray, the ability to easily manipulate facial features allows
for a rapid facial reproduction process. CT scan pictures can be stored as data
files, enabling subsequent identification of individuals despite the lack of
the actual skull. This concept holds
great significance in a culture that practises cremation, which involves the
destruction of human remains.
Limitations
Specialised equipment is necessary to
generate the 3D scans using this method. This equipment may be unavailable in
certain laboratories, rendering this procedure inaccessible to certain forensic
practitioners. When rebuilding a face using the acquired scan, averaging
techniques are employed to calculate the dimensions of the tissue. The
extensive dependence on averaging procedures in this technique amplifies the
margin of error in the ultimate reconstruction.
Superimposition
Superimposition is a method that
entails overlaying the skull of the individual with the picture of a person who
is believed to be the bearer of the skull. According to Ishii et al,
PC-assisted craniofacial superimposition is the predominant method employed. The
suspected individual's photograph is overlaid onto an x-ray scan of the skull
to determine if there is a resemblance.
In order to employ this technique, it is necessary to eliminate all
remaining soft tissue from the skull. Implementing this will enhance the
precision of the superimposition approach. When it is undesirable to remove the
soft tissue, CT images might be employed for superimposition, as they closely
resemble actual skulls.
Advantages
Superimposition is highly efficient
in excluding suspects as it can precisely ascertain that the skull doesn't
correspond to a certain individual. The precision of this procedure is
exceptionally high, particularly when high-quality pictures of a suspect are
accessible. This technique can aid in the authentication of human remains even
after the corporeal skeleton has been discarded. Ishii explains that by digitising skull
pictures, it becomes possible to overlay them onto facial photos of potential
suspects at a later time.[10]
Limitations
One significant drawback of this
approach is typically that the forensic squad must possess a roster of
potential culprits to compare with the skull. Therefore, a certain level of
understanding of the identification of the skull is necessary in order to
utilise this procedure. Insufficient understanding renders the utilisation of
this approach in facial reconstruction endeavours unattainable.
The absence of high-quality images
hinders the precision of superimposition, as clear pictures are essential for
the procedure. Aulsebrook et al. observes that the majority of individuals
exhibit a smiling expression when being photographed, which poses a challenge
for overlaying the mouth. The illumination in the majority of images is
likewise indistinct, with certain areas of the face being veiled.[11]
Concluding
Remarks
The objective of this study is to
examine forensic facial reconstruction & evaluate various approaches
employed, along with their advantages and disadvantages. The discussion
commenced by emphasising the significance of the face in discerning an
individual's identity.[12] A comprehensive assessment has been
conducted on the primary methods used for facial reconstruction, including 2D
and 3D sculptures, 3D CT scan, & Superimposition. The paper has emphasised
the utilisation of facial reconstruction software to address the limitations of
human techniques. The article highlighted that facial reconstructions do not
precisely replicate the visual representation of the individual. Every forensic
facial reconstruction methodology has inherent limitations, making it
impossible to completely eradicate all issues and achieve a precise depiction
of the subject's face.[13] However,
the approaches can generate a facial representation that closely resembles the
original person, aiding in their identification by others familiar with the skull
bearer.
[1] Porter, G., & Doran, G. (2000). An anatomical and photographic technique for forensic facial identification. Forensic Science International, 114 (1), 97-105.
[2] Oxenham, M. (2008). Forensic Approaches to Death, Disaster and Abuse. Sydney: Australian Academic Press.
[3] Stephan, C.N., & Henneberg, M. (2001). Building faces from dry skulls: are they recognized above chance rates? J Forensic Sci, 46(3), 432–440.
[4] Clement, J.G. & Murray, K.M. (2005). Computer-Graphic Facial Reconstruction. NY: Academic Press.
[5] Wilkinson, C. (2004). Forensic Facial Reconstruction. Cambridge: Cambridge University Press.
[6] Ullrich, H., & Stephan, C. (2011). On Gerasimov’s Plastic Facial Reconstruction Technique: New Insights to Facilitate Repeatability. J Forensic Sci, 56 (2), 470-474.
[7] Damas, S., et al. (2011). Forensic identication by computer-aided craniofacial superimposition: a survey. ACM Computing Surveys, 43(4), 1-31.
[8] Stephan, C.N., & Henneberg, M. (2001). Building faces from dry skulls: are they recognized above chance rates? J Forensic Sci, 46(3), 432–440.
[9] Choras, S.R. (2011). Image Processing & Communications Challenges. Boston: Springer.
[10] Ishii, M. et al. (2011). Application of Superimposition-Based Personal Identification Using Skull Computed Tomography Images. J Forensic Sci, 56 (4), 960-966.
[11] Aulsebrook, W.A., Iscan, M.Y. Slabbert, J.H., & Becker, P. (1995). Superimposition and reconstruction in forensic facial identification: a survey. Forensic Science International, 75 (1), 101 – 120.
[12] Joshi, I.D. (2022) Analysis Of Various Approaches Of Criminal Profiling And Psychological Assessment, Indian Journal of Law and Legal Research. Available at: https://www.ijllr.com/post/analysis-of-various-approaches-of-criminal-profiling-and-psychological-assessment-1
[13] Rosalie, D. (2008). Egyptian Mummies and Modern Science. Cambridge: Cambridge University Press.
Article Information
TECHNIQUES IN FACIAL RECONSTRUCTION: A FORENSIC ANTHROPOLOGICAL PERSPECTIVE BY: ISHAAN DEEPAK JOSHI
Authors: ISHAAN DEEPAK JOSHI
- Journal IJLRA
- ISSN 2582-6433
- Published 2023/10/31
- Issue 7
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International Journal for Legal Research and Analysis
- Abbreviation IJLRA
- ISSN 2582-6433
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