Unidentified Skull Research Articles

Deep learning approach for forensic facial reconstruction depends on unidentified skull

Facial reconstruction, or facial approximation, is an essential problem in a criminal investigation involving reconstructing a victim's face from his skull to determine the victim's identification at a crime scene. Facial approximation plays a crucial part when there is a lack of clues with investigators. Investigators utilize facial approximation to guess the victims' identities. This research attempted to use computer-aided face reconstruction rather than traditional approaches. Traditional methods of face reconstruction include the use of clay or gypsum. Traditional procedures necessitate forensic professionals to rebuild the victim's face. This research uses the convolution neural network skull part with sift (CNNSPS) model is employed to reconstruct facial features from a skull image utilizing public datasets CelebAMask-HQ and MUG500+. The proposed algorithm was tested on unidentified skull databases, and celebrity faces were used. The genuine datasets are not available, which is the key issue in this research.

ТАТЬЯНА СЕРГЕЕВНА БАЛУЕВА, УЧЕНЫЙ, СОРАТНИК, ДРУГ

The article elucidates the contribution of an outstanding Russian anthropol-ogist Tatiana Sergeevna Balueva to the development of skull-based facial recon-struction technique and other fields of anthropological science. The pioneer of the scientific approach to face reconstruction based on the underlying bone struc-tures was a famous anthropologist Mikhail Gerasimov who founded the school of anthropological reconstruction in Moscow where in 1950 a laboratory under his guidance was organized in the Institute of Ethnography of the USSR Academy of Sciences. After Gerasimov, the laboratory was guided by his direct student Gali-na Lebedinskaya who also made a significant contribution to the development of skull-based facial reconstruction technique. In 1996, Tatiana Balueva, who had worked under the guidance of Lebedinskaya for along time, succeeded her as the Head of the laboratory.Dr. Balueva, who passed unexpectedly in 2012, left her mark in various fields of anthropology. She led numerous expeditions to remote areas of Siberia. The material collected there became the basis for her dissertation and numerous publications. The anthropological analysis of the data on indigenous peoples of the North-East of Russia shed light on the complex processes of formation of the population of this region.Under her leadership, the Laboratory of Anthropological Reconstruction developed a special program of investigation of the relationship between facial features and the underlying bony framework; its implementation produced a sig-nificant pool of statistical data. The years of research under Balueva’s direction resulted in the program of craniofacial correspondence that significantly clarifies the reconstruction of appearance and allows receiving the lifetime skull-based anthropological description of a face, so-called “physical description on a skull”. During T.S. Balueva’s tenure as the Head of the laboratory the unique collection of sculptural portraits considerably replenished with the works made taking into account improvements of a method.T.S. Balueva authored 64 sculptural reconstructions, over 300 graphic re-constructions, and close to 200 forensic examinations on unidentified skulls. She received international recognition as an expert in craniofacial reconstruction and identification. The list of the main sculptural reconstructions of T.S. Balueva is provided in the appendix.

Morphometric analysis of the foramen magnum in the Peruvian population.

The foramen magnum, as an anatomical structure, holds clinical and functional significance due to its strategic location in the craniovertebral transition. A detailed understanding of its dimensions and shapes is crucial for better comprehension of related pathologies and for enhancing neurosurgical techniques within a specific population. The objective is to measure precise morphometric reference points of the foramen magnum in individuals of Peruvian ancestry, aiming to establish specific anatomical patterns and potential variations within this population. The study was conducted on 17 unidentified skulls donated to the NeuroZone3D Research Center, utilizing an inelastic and soft measuring tape as the tool. Our report considered direct anthropometric measurement techniques with data collection performed by a single researcher. Distinct morphometric characteristics were observed in the foramen magnum of the Peruvian population compared to other studies. The average measurements of the skull base revealed a foramen magnum with a mean length of 33.80 mm and a width of 28.70 mm, along with right condyles measuring 25 mm in length and 14.10 mm in width, and left condyles measuring 23.80 mm in length and 13.90 mm in width. The morphometric analysis of the foramen magnum in the Peruvian population provides valuable insights into specific anatomical features within this ethnic group. These findings could have significant implications across various medical and surgical disciplines, from interpreting diagnostic images to designing more precise therapeutic interventions tailored to this population.

Two-dimensional facial approximation: facial composite and digital 3D facial approximation techniques applied on cone-beam tomography

This study aimed to demonstrate two protocols of Two-Dimensional Facial Approximation (2DFA) created with resources of the techniques of Facial Composite and Digital Three-Dimensional Facial Approximation. Both protocols were based on craniometric parameters and their facial correspondence obtained from a Cone-Beam computed tomography of a human skull. After this, this protocols were confronted with a photograph of the target subject. Said techniques, when compared with the photograph of the subject, demonstrated compatibilities and incompatibilities. With the obtained results, it is concluded that the two techniques can to be useful in the process of human facial recognition. Further research on the two protocols is suggested in order to assist the work of forensic professionals in the recognition of unidentified human skulls.

Lateral cephalometric assessment of facial soft tissue thickness for craniofacial reconstruction in an Indian population-A retrospective study

Facial soft tissue thickness (FSTT) is a pertinent tool for forensic anthropologists to aid in facial reconstruction, a process that combines both art and science to recreate a recognizable face from an unidentified skull. The facial profile, together with the age and gender of a person is related to FSTT, which is required for accurate facial reconstruction and recognition. These FSTT data are anthropological and differ in various ethnic groups. Until now, no study exists in which the FSTT of the population of Haryana has been measured. Thus, this study aimed to assemble data by deriving mean FSTT in males and females of Haryana origin using lateral cephalograms. Lateral cephalograms of 150 subjects were collected and retrospectively categorized into three skeletal classes (based on convex, straight, or concave facial profile). FSTT was determined at different fixed anatomical landmarks on the lateral cephalograms using the adobe software. There was no significant difference in the FSTT among males and females. Significant differences in FSTT among various anatomical landmarks were present among the different skeletal classes. This research provides valuable data for forensic facial reconstruction and identification of young adults in the study population.

Research Progress and Prospect of Facial Reconstruction in Forensic Science

Facial reconstruction is a way to recover facial morphology by restoring soft tissues based on unidentified skulls using the knowledge of anatomy, anthropology, aesthetics, and computer science. It is applied in forensic science, oral plastic surgery and archeology, and especially plays an important role in the identification of the origin of the unknown corpses in forensic science. Facial reconstruction is the supplementary means of identification when other approaches （such as DNA comparison, imaging matching, dental records comparison, etc.） cannot identify individual identity. Facial soft tissue thickness （FSTT） is the basis of facial reconstruction and with the development of imaging and computer science, the techniques for measuring FSTT are improving rapidly and many related researches have appeared. This paper summarizes the application of facial reconstruction in forensic science, the accuracy of different methods and the research progress of this field to provide reference to this field.

A computerized craniofacial reconstruction method for an unidentified skull based on statistical shape models

Craniofacial reconstruction (CFR) has been widely used to produce the facial appearance of an unidentified skull in the realm of forensic science. Many studies have indicated that the computerized CFR approach is fast, flexible, consistent and objective in comparison to the traditional manual CFR approach. This paper presents a computerized CFR system called CFRTools, which features a CFR method based on a statistical shape model (SSM) of living human head models. Given an unidentified skull, a geometrically-similar template skull is chosen as a template, and a non-registration method is used to improve the accuracy of the construction of dense corresponding vertices through the alignment of the template and the unidentified skull. Generalized Procrustes analysis (GPA) and principal component analysis (PCA) are carried out to construct the skull and face SSMs. The sex of the unidentified skull is then predicted based on skull SSM and centroid size, rather than geometric measurements based on anatomical landmarks. Furthermore, a craniofacial morphological relationship which is learnt from the principal component (PC) scores of the skull and face dataset is used to produce a possible reconstructed face. Finally, multiple possible reconstructed faces for the same skull can further be recreated based on adjusting the PC coefficients. The experimental results show that the average rate of sex classification is 97.14% and the reconstructed face of the unidentified skull can be produced. In addition, experts’ understanding and experience can be harnessed in production of face variations for the same skull, which can further be used as a reference for portraiture creation.

Hyperostosis frontalis interna as an age-related phenomenon – Differences between males and females and possible use in identification

Hyperostosis frontalis interna (HFI) is a condition manifested by thickening of the inner surface of the frontal bone and it could be useful when dealing with the identification of human remains in various anthropological and forensic investigations. We compared the macroscopic appearance and morphologic (metric) features of the skulls in cases with and without HFI, in both sexes, and wanted to establish whether age determined occurrence of HFI. To achieve this aim, we performed prospective autopsy study, covering ten-year period (2007–2016). Study group consisted of southeast Europe Caucasian subjects, with determined age and sex. The severity of HFI was classified by two forensic pathologists independently, according to the four types (A–D) proposed by Hershkovitz et al. Thicknesses of the frontal and temporal bones, as well as the longitudinal and frontal diameters of the skulls were measured. The sample consisted of 35 males and 112 females with HFI, and 55 males and 202 females without HFI (404 individuals in total). Type B was the most common type of HFI among males (45%) and type C among females (41%). HFI type D was almost four times more common in females than in males (OR = 3.73). Frontal and temporal bones were thicker in all subjects who have HFI. Thickness of the skull was not age-dependent, in the entire sample, or in subjects with HFI, or in the control group (in all the cases Spearman's Rho was <0.3). Age seemed to be a predicting factor for HFI occurrence only in females. Females younger than 55 years have similar risk for HFI occurrence as males. An unidentified skull with the general markers of old age and severe form HFI is most probably from a female decedent.

DEVELOPING A UNIFIED FACIAL TISSUE THICKNESS MODEL FROM NEUROIMAGING DATA FOR SRI LANKA USING STATISTICAL ANALYSIS AND IMAGE PROCESSING TECHNIQUES

Facial soft tissue thickness (FSTT) is essential to forensic anthropologists for facial reconstruction- recreating a recognizable face from an unidentified skull and to plastic surgeons for treatment planning. Together with the age and sex of a person, the facial profile is related to facial soft tissue thickness, which is required for accurate facial reconstruction and recognition. Having such a facial profile in the national level is very important for a country since FSTT changes according to the geographical factors.&#x0D; In this paper we are presenting a review on literature associated with this topic describing the methods used for data collection, measuring FSTT and analyzing those values along with the method we are proposing to be followed in the research we are to conduct in the Sri Lankan context.

Densely calculated facial soft tissue thickness for craniofacial reconstruction in Chinese adults

Craniofacial reconstruction (CFR) is used to recreate a likeness of original facial appearance for an unidentified skull; this technique has been applied in both forensics and archeology. Many CFR techniques rely on the average facial soft tissue thickness (FSTT) of anatomical landmarks, related to ethnicity, age, sex, body mass index (BMI), etc. Previous studies typically employed FSTT at sparsely distributed anatomical landmarks, where different landmark definitions may affect the contrasting results. In the present study, a total of 90,198 one-to-one correspondence skull vertices are established on 171 head CT-scans and the FSTT of each corresponding vertex is calculated (hereafter referred to as densely calculated FSTT) for statistical analysis and CFR. Basic descriptive statistics (i.e., mean and standard deviation) for densely calculated FSTT are reported separately according to sex and age. Results show that 76.12% of overall vertices indicate that the FSTT is greater in males than females, with the exception of vertices around the zygoma, zygomatic arch and mid-lateral orbit. These sex-related significant differences are found at 55.12% of all vertices and the statistically age-related significant differences are depicted between the three age groups at a majority of all vertices (73.31% for males and 63.43% for females). Five non-overlapping categories are given and the descriptive statistics (i.e., mean, standard deviation, local standard deviation and percentage) are reported. Multiple appearances are produced using the densely calculated FSTT of various age and sex groups, and a quantitative assessment is provided to examine how relevant the choice of FSTT is to increasing the accuracy of CFR. In conclusion, this study provides a new perspective in understanding the distribution of FSTT and the construction of a new densely calculated FSTT database for craniofacial reconstruction.

Facial soft tissue thickness in a sample of Sudanese adults with different occlusions

Facial soft tissue thickness is essential to orthodontists and plastic surgeons for treatment planning, and to forensic anthropologists for facial reconstruction, a process combining science and art to recreate a recognizable face from an unidentified skull. The facial profile, together with the age and sex of a person, is related to facial soft tissue thickness, which is required for accurate facial reconstruction and recognition. Skeletal occlusions in orthodontics are classified according to the basic human facial profiles: straight, convex, and concave or skeletal class I, II, and III, respectively. In the present study, the facial soft tissue thickness of 233 Sudanese subjects (105 men and 128 women), ranging in age from 18 to 35 years, with different facial profiles at 20 landmarks was measured (10 soft tissue and 10 dentoskeletal).Sexual dimorphism was noted, with males having thicker facial soft tissue at all measured points. The facial soft tissue thickness varied among different occlusions. Individuals with skeletal class II occlusion had the thickest lower lip, and class III individuals had the thickest upper lip. In general, the Sudanese sample had a unique spectrum of measurements, with thick upper and lower lips, compared with African and Caucasoid subjects, pointing to the need for ethnic-specific data.

Evaluation of Skull Base Parameters in Sex Determination Using Anthropometric Measurements among a Sample of Egyptians

Determination of sex is a vital element in forensic and anthropological examination. In certain circumstances, such as in explosions, warfare and other mass disasters, sex prediction may be a difficult task as a result of loss of important body parts. The skull base bones have a high resistance to adverse environmental conditions. Accordingly, this study aimed to investigate the accuracy of different anthropometric measurements of the skull base for sex determination, to establish parameters that can reliably determine the sex of an unidentified skull. Material and methods: Eighty Egyptian adult skulls were subjected for the following anthropometric measurements; palatal measurements; incisive foramen to greater palatine foramen (right and left), right to left greater palatine foramen and incisive foramen to basion, mastoid notch measurements; incisive foramen to mastoid notch (right and left) and right to left mastoid notch and foramen magnum measurements; sagittal and transverse diameters, area and circumference. All measurements were taken using Vernier caliper and the circumference was measured by a flexible tape. Results: The results showed significant sexual difference in all the studied anthropometric measurements. The resulting formula using palatal measurement had the highest accuracy (94.1%), followed by mastoid notch that revealed 90.2% accuracy while the least accuracy was that of foramen magnum (89.2%). All measured parameters of skull base gave an accuracy of 96.1%. It was concluded that the skull base is a good basis for sex determination in adult Egyptians.

Preliminary performance assessment of computer automated facial approximations using computed tomography scans of living individuals

ReFace (Reality Enhancement Facial Approximation by Computational Estimation) is a computer-automated facial approximation application jointly developed by the Federal Bureau of Investigation and GE Global Research. The application derives a statistically based approximation of a face from a unidentified skull using a dataset of ∼400 human head computer tomography (CT) scans of living adult American individuals from four ancestry groups: African, Asian, European and Hispanic (self-identified). To date only one unpublished subjective recognition study has been conducted using ReFace approximations. It indicated that approximations produced by ReFace were recognized above chance rates (10%). This preliminary study assesses: (i) the recognizability of five ReFace approximations; (ii) the recognizability of CT-derived skin surface replicas of the same individuals whose skulls were used to create the ReFace approximations; and (iii) the relationship between recognition performance and resemblance ratings of target individuals. All five skin surface replicas were recognized at rates statistically significant above chance (22–50%). Four of five ReFace approximations were recognized above chance (5–18%), although with statistical significance only at the higher rate. Such results suggest reconsideration of the usefulness of the type of output format utilized in this study, particularly in regard to facial approximations employed as a means of identifying unknown individuals.

A computational framework for CT-based craniofacial reconstruction

Introduction Estimating the facial outlook from an unidentified skull is a challenging task in forensic investigations. This paper presents the implementation and testing of a fully automatic pipeline for computerized craniofacial reconstruction (CFR). Methods A database of age-, gender- and BMI-annotated full-head 3D cross-sectional CT reference scan images is used. The database is continuously being upgraded with new reference cases. Furthermore, the procedure can be easily extended to include data of different ethnicities when such data become available. Facial and skeletal surfaces are automatically extracted for every image in the database. Reconstruction of the face of an unidentified skull (scanned ‘as is’, not requiring a time-consuming soft tissue removal procedure) is started by warping all skull surfaces in the database to the target skull. The resulting transformations are then applied to the associated facial surfaces resulting in as many warped facial surfaces as individuals in the database. A single consensus facial surface is generated by combining the individual reconstructions taking into account gender, BMI and age matching. By implementing this procedure on a cluster platform, reconstructions can be obtained in less than 10 min, irrespective of the number of reference images, which is considerably shorter than current manual reconstruction procedures. Results Validation was performed using a cross-validation leave-one-out scenario where each image in the database was reconstructed using all other images in the database as reference. The reconstructed and actual facial surfaces are then compared using statistics of intersurface distances. On a database of 72 reference individuals a maximal reconstruction error of 4 mm was obtained.

Computerized craniofacial reconstruction using CT-derived implicit surface representations

In forensic craniofacial reconstruction, facial features of an unknown individual are estimated from an unidentified skull, based on a mixture of experimentally obtained guidelines on the relationship between soft tissues and the underlying skeleton. In this paper, we investigate the possibility of using full 3D cross-sectional CT images for establishing a reference database of densely sampled distances between the external surfaces of the skull and head for automated craniofacial reconstruction. For each CT image in the reference database, the hard tissue (skull) and soft tissue (head) volumes are automatically segmented and transformed into signed distance transform (sDT) images, representing for each voxel in this image the Euclidean distance to the closest point on the skull and head surface, respectively, distances being positive (negative) for voxels inside (outside) the skull/head. Multiple craniofacial reconstructions are obtained by first warping each reference skull sDT maps to the target skull sDT using a B-spline based free form deformation algorithm and subsequently applying these warps to the reference head sDT maps. A single reconstruction of the target head surface is defined as the zero level set of the arithmetic average of all warped reference head sDT maps, but other reconstructions are possible, biasing the result to subject specific attributes (age, BMI, gender). Both qualitative and quantitative tests (measuring the similarity between the 3D reconstructed and corresponding original head surface) on a small ( N = 20) database are presented to proof the validity of the concept.

Craniofacial reconstruction using a combined statistical model of face shape and soft tissue depths: Methodology and validation

Forensic facial reconstruction aims at estimating the facial outlook associated with an unidentified skull specimen. Estimation is generally based on tabulated average values of soft tissue thicknesses measured at a sparse set of landmarks on the skull. Traditional ‘plastic’ methods apply modeling clay or plasticine on a cast of the skull, approximating the estimated tissue depths at the landmarks and interpolating in between. Current computerized techniques mimic this landmark interpolation procedure using a single static facial surface template. However, the resulting reconstruction is biased by the specific choice of the template and no face-specific regularization is used during the interpolation process. We reduce the template bias by using a flexible statistical model of a dense set of facial surface points, combined with an associated sparse set of skull-based landmarks. This statistical model is constructed from a facial database of ( N = 118) individuals and limits the reconstructions to statistically plausible outlooks. The actual reconstruction is obtained by fitting the skull-based landmarks of the template model to the corresponding landmarks indicated on a digital copy of the skull to be reconstructed. The fitting process changes the face-specific statistical model parameters in a regularized way and interpolates the remaining landmark fit error using a minimal bending thin-plate spline (TPS)-based deformation. Furthermore, estimated properties of the skull specimen (BMI, age and gender, e.g.) can be incorporated as conditions on the reconstruction by removing property-related shape variation from the statistical model description before the fitting process. The proposed statistical method is validated, both in terms of accuracy and identification success rate, based on leave-one-out cross-validation tests applied on the facial database. Accuracy results are obtained by statistically analyzing the local 3D facial surface differences of the reconstructions and their corresponding ground truth. Identification success rate is obtained by comparing, based on correlation, Euclidean distance matrix (EDM) signatures of the reconstructed and the original 3D facial surfaces in the database. A subjective identification success rate is quantified based on face-pool tests. Finally a qualitative comparison is made between facial reconstructions of a real-case skull, based on two typical static face models and our statistical model, showing the shortcomings of current face models and the improved performance of the statistical model.

Use of hand-held laser scanning in the assessment of craniometry

The intra- and inter-examiner reliability was evaluated for hand-held 3D laser scanning technology when it was combined with localization of landmarks for craniometry. The data from the laser surface scanning were compared with those of conventional direct measuring. Using thirty unidentified skulls requested for individual identification, measurements were taken of the line distances from lambda to 26 landmarks, and also for seven breadth parameters. For the laser surface scanning, two examiners performed replicate measurements with an interval of 1 week. In the conventional direct measuring, the first examiner took replicate measurements with a 1-week interval. To assess intra- and inter-examiner reliabilities, the intraclass correlation coefficient was used. Analysis of variance with repeated measures for each parameter was performed to compare the conventional method with the 3D scanning method. Both the 3D scanning and conventional methods showed excellent intra-examiner reliabilities, and the 3D laser scanning method also showed excellent inter-examiner reliability. A statistical difference between the two examiners was found only in nasal breadth in the 3D laser scanning method. There was no significant difference between the two measuring methods, though the 3D laser scanning method tended to give a slightly lower reading. Collectively, the 3D laser scanning method with point localization is a useful method with excellent reliability, and it can replace the conventional direct measuring method in craniometry.

The Lateral Craniographic Method of Facial Reconstruction

Abstract Fifty-four lateral cephalographs with clear soft tissue profiles of American Caucasians (17 males, ages 14 to 36; 37 females, ages 14 to 34) were traced and measured to establish the ranges and means of midline soft tissue depths and facial angles. With these data it is possible to reconstruct “approximate” profiles over X-ray tracings of unidentified skulls. The lateral craniographic method of facial reconstruction requires four steps: (1) a cephalometric analysis is first made to determine the facial proportions and individual skull type; (2) the mean soft tissue thicknesses and angles are then plotted against the basic midline anthropometric points to establish the average dimensions of the nose, lips, and chin; (3) the points are connected and “harmonized” in accordance with the known anthropological data (sex, age, race); and (4) the profile is finally “humanized” by adding tone, a stylized eye, hair patterns, age lines, and any other features that can be determined from an anatomic examination of the skull. The validity of the method is illustrated with three study cases of living orthodontic patients.

A Method of Matching Skulls with Photographic Portraits Using Landmarks and Measurements of the Dentition

A method of matching and identifying skulls to family snapshots or passport photographs is described. The technique depends on the recovery of teeth, particularly the maxillary anterior teeth, with the skull and the availability of an antemortem photograph showing those teeth. Measurements of the anterior dentition of unidentified skulls are used to determine the magnification factor necessary for the preparation of life-sized transparencies of photographs. Superimposition of dental landmarks in these transparencies leads to correlation of further cranial features, thus enabling a successful positive identification. Suggestions are made for a system of identification based on assessment of visible features of the dentition.