Facial Approximation Research Articles

Facial soft tissue depth of a contemporary adult Greek population

Facial approximation is a technique that involves constructing the facial muscles and applying a suitable facial soft tissue depth (FSTD) dataset. To date, several FSTD studies have been conducted for varying population groups. This study aims to establish a FSTD dataset of an adult Greek population sample for the first time. The facial depths of subjects were measured on 100 head CT scans of 50 male and 50 female subjects aged from 18 to 99. The 3D head and skull models of subjects were segmented in Amira 6.1 by using histogram method. FSTDs were measured at 22 cranial landmarks (5 mid-sagittal, 17 bilateral). The FSTD dataset was generated by considering the age and sex of subjects. The impact of age and sex on the FSTD was limited. Slight inter-population depth variations were reported. Facial asymmetry calculated between the bilateral landmarks was insignificant for both male and female subjects.

Facial approximation of a skull with signs of tertiary syphilis found in the Skriðuklaustur monastery (Iceland, 15th-16th century AD)

Syphilis is an infectious disease transmitted by the bacterium Treponema pallidum, caused major problems for the old continent after the European discovery of the Americas in 1492 and its export to Europe, although treponemal diseases have accompanied human history since the Middle Pleistocene. The present work presents the facial approximation of a 15th-16th century AD Icelandic female individual with tertiary syphilis, with lesions that reached the bones, causing significant destruction on the surface of the soft tissues. The objective is to address the history of the disease and the potential harm caused by its non-treatment by offering a facial approximation of an ancient severe tertiary-syphilis patient.

The anatomical bases of the 3D digital facial approximation of the Zlatý kůň 1 woman (ca. 43,000 BP)

In 1950 on Mount Zlatý kůň (‘Golden Horse’) in modern-day Czech Republic a system of caves was discovered. During many years of research in this area, human and animal osteological remains have been excavated, among which the most interesting ones were nine fragments of a female skull, now dated to ca. 43,000 yrs BP which are one of the earliest known anatomically modern humans in Eurasia. The aim of this research was to use purely digital techniques to: (1) to reconstruct the skull based on the 3D data of preserved fragments, (2) to approximate the probable appearance of the female it belonged to, and (3) to analyze the calculated shape of the reconstructed mandible and volume of the neurocranium in the context of similarities and differences with other representatives of the genus Homo. Computer techniques used in this research constitute a new, original approach to the problem of 3D analyses and may be useful primarily in bioarchaeological sciences, where metric analyses of the most valuable bone artifacts are often severely limited due to the incompleteness of the material available for research. The digital techniques presented here may also contribute significantly to the field of surgery, with the possibility of being adapted for applications in cranial prosthetics and post-traumatic reconstructive surgery.

3D facial reconstruction and 3D printing of women skull from Bronze age, Slovakia

Facial reconstruction of individuals from historical periods can provide more information about them. The main aim of this study was to create an anthropological facial reconstruction of a Bronze Age skull based on a new soft tissue thickness database created from a sample of the Slovak female population. Using ultrasound, we evaluated 27 facial landmarks on 50 Slovak women, aged 18–30 years with Slovak genealogical history. The Bronze Age skull was anthropologically estimated as a Caucasoid female aged 24–30 years at the time of death. The ultrasound results were analysed and compared with nine European populations. Statistical analysis showed that there is no statistical difference between these populations in the values of facial soft tissue thicknesses. Using CT and Blender software with add-ons, we created a facial approximation of the skull. We 3D printed the virtual model, which can be used for educational and scientific purposes.

3D facial approximation and endocast analysis of the Mummy of Minirdis (Ancient Egypt, ca. 2,300 Before Present)

The present article offers the facial approximation of the mummy of the ancient Egyptian adolescent named Minirdis (ca. 2300 years BP) by means of anatomical analysis of video-images and through a facial approximation protocol implemented on more historical personages. An evaluation of the mummy's endocast is also offered. A potential diagnosis of Sotos syndrome is cautiously considered but its inherent limitations are detailed. Finally, the methodology is presented as a valuable tool both for bio-historical research and for further studies on normal and pathologic morphologies of the cranio-facial district.

Automated reconstruction: Predictive models based on facial morphology matrices

Forensic Facial Approximation (FFA) has evolved, with techniques advancing to refine the intercorrelation between the soft-tissue facial profile and the underlying skull. FFA has become essential for identifying unknown persons in South Africa, where the high number of migrant and illegal labourers and many unidentified remains make the identification process challenging. However, existing FFA methods are based on American or European standards, rendering them inapplicable in a South African context. We addressed this issue by conducting a study to create prediction models based on the relationships between facial morphology and known factors, such as population affinity, sex, and age, in white South African and French samples. We retrospectively collected 184 adult cone beam computed tomography (CBCT) scans representing 76 white South Africans (29 males and 47 females) and 108 French nationals (54 males and 54 females) to develop predictive statistical models using a projection onto latent structures regression algorithm (PLSR). On training and untrained datasets, the accuracy of the estimated soft-tissue shape of the ears, eyes, nose, and mouth was measured using metric deviations. The predictive models were optimized by integrating additional variables such as sex and age. Based on trained data, the prediction errors for the ears, eyes, nose, and mouth ranged between 1.6 mm and 4.1 mm for white South Africans; for the French group, they ranged between 1.9 mm and 4.2 mm. Prediction errors on non-trained data ranged between 1.6 mm and 4.3 mm for white South Africans, whereas prediction errors ranging between 1.8 mm and 4.3 mm were observed for the French. Ultimately, our study provided promising predictive models. Although the statistical models can be improved, the inherent variability among individuals restricts the accuracy of FFA. The predictive validity of the models was improved by including sex and age variables and considering population affinity. By integrating these factors, more customized and accurate predictive models can be developed, ultimately strengthening the effectiveness of forensic analysis in the South African region.

Facial soft-tissue thickness in children: A study of a CTBC Brazilian sample

As an auxiliary method in the process of human identification, forensic facial approximation (FFA) is an important tool for identifying unknown human bodies whose remains do not present the necessary traceability to any antemortem data collection. Specific characteristics are necessary when addressing children aged between 6 and 10 years, who have little sexual differentiation and a mixed dentition. Due to the chronology of eruption of the permanent second molars in this population, it is not possible to measure facial soft-tissue thickness (FSTT) from specific landmarks such as supra and infra M2. The objective of this research was to report the method for measuring the average FSTT of 32 landmarks adapting the method for adults replacing the landmarks at the upper and lower second molars (Supra M2 and Infra M2) in children up to 10 years of age for a measurement using the deciduous second molars as reference. We found statistical differences for some points, considering the variables of age and sex, but with a maximum difference of 2 mm, which allows the use of a single FSTT table. The deciduous teeth can replace the reference of the thicknesses at the supra and infra M2 landmarks. In addition to the new FSTT data for children in Brazil, we concluded that the proposed adaptation to the deciduous M2 points can be applied to obtain soft-tissue data for 32 facial points.

ADNA, ethnography, and facial approximations of the Teouma Lapita burials (c. 3000BP)

Although ancient DNA (aDNA) cannot predict the facial appearance of skeletal human remains, knowing which extant populations are most closely related to the deceased has proven to be invaluable in rectifying two early facial approximations (popularly known as facial reconstruction) undertaken 15 years ago. These concerned two of the crania excavated from the Lapita burial site at Teouma on the island of Efate, and are associated with the first human arrival in the Vanuatu archipelago approximately 3000 years ago. This experimental revision to incorporate aDNA into both the methods and results has found there are advantages of knowing the genetic affiliation for estimating facial appearance. Specifically, we have found that this knowledge (i) facilitates identifying which of the current statistically valid predictors of the facial features are the most appropriate, (ii) informs the depiction of sexually dimorphic patterns of facial aging, and (iii) guides the portrayal of the subtle facial morphologies that fall outside what is currently provided by statistically validated skull-soft tissue algorithms and inter-relationships.

Morphological Observation of the Alar Region between the Piriform Aperture and the Alar Soft Tissue for Facial Approximation (Reconstruction)

Prediction methods for regions not lined by facial bones are important elements of forensic anthropology, including forensic facial approximation. The alar region can be predicted by measuring the distances from the piriform margin and multiples of the piriform width. However, studies investigating this region are limited, and some only focus on one side of the alar region. Hence, we aimed to measure the bony points/landmarks to predict the alar region.Post-mortem computed tomography images of the samples from 180 Japanese individuals were obtained and analyzed. The images were processed using Osirix (Pixmeo). The coordinates recorded from all samples were calculated, and the values obtained were stratified by sex, laterality, age, body mass index, and cephalic index. The distances between the alar and the five piriform points were measured. The mean, standard deviation, and confidence interval of all samples were calculated, and the sex-related differences were determined. We evaluated the correlation between alares and other boney landmarks and points. Our findings were compared with those of previous studies. We observed significant sex differences (p < 0.01) and asymmetry (p < 0.01) in laterality in this region; hence, asymmetry was assessed based on these results. Compared with the results of previous studies, the obtained measurements were larger than those of a previous Asian study, suggesting that laterality may influence the accuracy of prediction methods for regions not lined by hard tissues.

Forensic facial approximation of an individual with achondroplasia from medieval cemetery in Central Europe

Achondroplasia (ACH, achondroplastic dwarfism) represents the most common form of skeletal dysplasia, occurring in c. 4 out of every 100,000 births. This study presents a computer-based facial approximation of the skull of a male individual living with ACH, who died at 30–45 years of age and was buried in Łekno, Poland between the 9th and 11th centuries AD. For the approximation procedure, soft tissue data from CT scans and ultrasonic measurements performed on living individuals were used. Additionally, an anatomical deformation technique was applied to arrive at the most reliable reconstruction of the achondroplastic individual's appearance. To our knowledge, this is the first facial depiction of a person with achondroplasia, and one of the few showing a head of an individual suffering from a hereditary disease, with dimensions and shape differing from the population average values.

Digital 3D facial approximation of the Petralona skull. Methodological issues and applications

The human face is a highly specialized anatomical entity. Its appearance is a result of evolutionary processes that include biomechanical, physiological, and social influences. The facial approximation is based on the relevance of skeletal and soft tissue anatomy and aims to reconstruct a person's face from the anatomical features of the skull. In forensics, the technique focuses on the estimation of the facial characteristics of unidentified individuals. In archaeological contexts, it has been widely used for the representation of hominins, prehistoric and historic periods individuals. For the facial approximation of the Petralona man, we digitized a cast of the original skull with an Artec Spider 3D scanner of metrological accuracy up to 0.05mm. A digital model of the Mauer mandible (Germany), the holotype of Homo heidelbergensis, was used to virtually complement the skeletal anatomy of the face. Cinema4D (Maxon) was used to place soft tissue depth markers according to standard nomenclature. The digital reconstruction of facial anatomy and skin texture was developed in ZBrush (Pixologic). The facial features were approximated with the use of techniques that are based on anatomical and/or statistical evidence. The facial approximation of the Petralona skull aims to disseminate scientific information and contribute to the public understanding of evolutionary science.

Pharaoh Tutankhamun: a novel 3D digital facial approximation

This article offers a novel and original facial reconstruction of pharaoh Tutankhamun based on data published in the biomedical and Egyptological literature. The reconstruction adopts the Blender 3D software, running the add-on OrtogOnBlender, which allows for a refined presentation of the soft tissues. The present reconstruction is also compared to other approaches produced in the past.

Age and sex dependent differences in midline facial soft tissue thicknesses measured on MRI scans of Northwest Indian subjects: a forensic anthropological study

BackgroundHuman face is complex and intricate structure, with several features that are unique to each individual and can be taken as an identity pass in this mortal world. The facial profile of an individual holds materialistic value and is crucial for human identification. Present study aims to investigate the influence of sex and age of an individual on the soft tissue thicknesses (FSTT) at midline facial landmarks estimated on MRI scans.MethodsFacial soft tissue thickness was estimated at 20 midline landmarks on the MRI scans of 120 (57 male; 63 female) anatomically normal Northwest Indian adult subjects (18–70 + years age-group). Age and sex dependent variations in tissue thicknesses at different landmarks were estimated using statistical software IBM SPSS Statistics 23.ResultsThe results of the study yielded that most of the midline landmarks had higher values in males than in females indicating observable sexual dimorphism in FSTT values in this facial region, statistically significant differences were also noted in soft tissue thickness estimates of different age-groups, showing increasing or decreasing trend with age. The mid-facial landmarks like mid-philtrum, supra-dentale, incisor superius, and labile inferius displayed highly significant p values.ConclusionsPresent study results were in tandem with the findings of previous studies; males and younger age-group individuals were having higher tissue thickness values than the females and older individuals, respectively. The highest soft tissue estimates were obtained for the middle age subjects and the most aged individuals had the least midline soft tissue thickness values. These results can have significant forensic anthropological repercussions in attempting facial approximations on unknown skulls and identification of unknown individuals from still images, photographs or videos.

A geometric morphometric assessment of the hard tissue external auditory meatus and soft tissue ear of South Africans

Research on how to reliably reconstruct the shape of the ear for facial approximations is limited, especially in countries such as South Africa where standard ear casts are still used in manual methods. To improve objectivity, computer aided methods are being developed for facial approximations – which require extensive population specific datasets for facial feature morphology. This study aims to assess variations in the shape of the ear and the underlying external auditory meatus (EAM) through the analysis of cone-beam computed tomography (CBCT) scans of 40 black South Africans (males n = 17; females n = 23) and 76 white South Africans (males n = 29; females n = 47) between the ages of 18 and 90 years. Shape data was collected by placing 19 capulometric landmarks on the 3D reconstructions of the ear and 46 sliding craniometric landmarks along the EAM. Geometric morphometric analysis revealed highly significant variation in ear shape between groups for population affinity (p-value = 0.001), while sex and age were only significant between the white South Africans (p-value < 0.05). Only population affinity significantly influenced shape in the EAM (p-value = 0.001), and both the ear and EAM showed significant levels of symmetry (p-value = 0.007). While an ear will never be exactly recreated, basing facial estimates on the decedent’s biological profile can lead towards the highest possible accuracies. For the ear shape specifically, sex and age will not be a priority when creating predictive models, but population affinity will greatly influence the output.

Simplified Formula for Estimating Nasal Dimensions for 3-Dimensional Facial Reconstruction among Japanese Adults

The eyelids, external nose, and lips play an important role in individual identification and facial recognition; however, they are excluded from tissue marker points, and are reconstructed based on generic methods for 3D facial reconstruction or facial approximation. Therefore, this study focused on nasal dimensions and evaluated whether Krogman’s widely used formula for estimating the dimensions of an external nose, regardless of sex, race, and body physique, can be applied to Japanese adults. A total of 146 postmortem CT images of Japanese adult cadavers (64 males and 82 females, aged 58–105 years old) were retrospectively analyzed. The total nasal projection (TNP) among Japanese adults was estimated using the formula, TNP = 1.9 × the anterior nasal spine projection (ANSP) + the mid-philtrum depth (MPD), which differed significantly from the coefficient (3.0) in the conventional formula, regardless of sex, race, and body physique, and therefore needed modification for Asians. Although there was no positive relationship between the total nasal width (TNW) and the maximum width of the anterior nasal aperture (ANAW), the TNW could be estimated by adding soft tissue that varies by sex and body physique to both sides of the nearly constant ANAW. Therefore, we determined a simple and practical formula to estimate nasal dimensions among Japanese adults for conventional 3D facial reconstruction and manual 3D facial sculpture.

A computerized facial approximation method for Homo sapiens based on facial soft tissue thickness depths and geometric morphometrics.

Facial approximation (FA) provides a promising means of generating the possible facial appearance of a deceased person. It facilitates exploration of the evolutionary forces driving anatomical changes in ancestral humans and can capture public attention. Despite the recent progress made toward improving the performance of FA methods, a limited understanding of detailed quantitative craniofacial relationships between facial bone and soft tissue morphology may hinder their accuracy, and hence subjective experience and artistic interpretation are required. In this study, we explored craniofacial relationships among human populations based upon average facial soft tissue thickness depths (FSTDs) and covariations between hard and soft tissues of the nose and mouth using geometric morphometrics. Furthermore, we proposed a computerized method to assign the learned craniofacial relationships to generate a probable facial appearance of Homo sapiens, reducing human intervention. A smaller resemblance comparison (an average Procrustes distance was 0.0258 and an average Euclidean distance was 1.79 mm) between approximated and actual faces and a greater recognition rate (91.67%) tested by a face pool indicated that average dense FSTDs contributed to raising the accuracy of approximated faces. Results of partial least squares (PLS) analysis showed that nasal and oral hard tissues have an effect on their soft tissues separately. However, relatively weaker RV correlations (<0.4) and greater approximation errors suggested that we need to be cautious about the accuracy of the approximated nose and mouth soft tissue shapes from bony structures. Overall, the proposed method can facilitate investigations of craniofacial relationships and potentially improve the reliability of the approximated faces for use in numerous applications in forensic science, archaeology, and anthropology.

Recognizability of Demographically Altered Computerized Facial Approximations in an Automated Facial Recognition Context for Potential Application in Unidentified Persons Data Repositories.

This study examined the recognizability of demographically altered facial approximations for potential utility in unidentified persons tracking systems. Five computer-generated approximations were generated for each of 26 African male participants using the following demographic parameters: (i) African male (true demographics), (ii) African female, (iii) Caucasian male, (iv) Asian male, and (v) Hispanic male. Overall, 62% of the true demographic facial approximations for the 26 African male participants examined were matched to a corresponding life photo within the top 50 images of a candidate list generated from an automated blind search of an optimally standardized gallery of 6159 photographs. When the African male participants were processed as African females, the identification rate was 50%. In contrast, less congruent identification rates were observed when the African male participants were processed as Caucasian (42%), Asian (35%), and Hispanic (27%) males. The observed results suggest that approximations generated using the opposite sex may be operationally informative if sex is unknown. The performance of approximations generated using alternative ancestry assignments, however, was less congruent with the performance of the true demographic approximation (African male) and may not yield as operationally constructive data as sex-altered approximations.

Ludmila of Bohemia (ca. 860–921): Multidisciplinary considerations on her facial approximation

Ludmila of Bohemia or Saint Ludmila (ca. 860–921) is a popular religious figure from the Czech Republic. In 2021, the reliquary containing part of her skull was scanned and the missing portion of the structure was digitally reconstructed using references from anthropological studies carried out in the late 1990s by Dr. Emanuel Vlček, Ph.D. (1925–2006). From the completed skull, an estimation of facial hard tissue made a forensic facial approximation possible. The present study aims to present the sequence of methodological analysis, the development of new techniques and procedures used in this case that can become tools to facilitate the task of digitally restoring skulls with missing structures that can be applied in archeological and surgical context. The cranial hard tissue from an anonymous donor of a CT-Scan exam was “deformed” to fit onto the remains of the historical skull of Ludmila of Bohemia. The estimated facial proportions were tested by several methods that correlate the proportions of cranial structures. The reconstruction was performed based on several scientific parameters and the resulting structures were also consistent to predictors commonly used in the forensic field. The cranial deformation method provided a hard tissue estimation and gave reference to a facial approximation of a historical figure. Its development and testing may inspire future research to support a wide range of applications that goes from archaeology to medical usage.

Analysis of the hard-tissue menton shape variation in adult South Africans using cone-beam computed tomography (CBCT) scans

: In forensic anthropology, the biological profile is based on human variation and can help in the process of personal identification. In order to better understand shape variation of the mental region, this study analyzed the influence of population affinity and sex on the menton in adult black and white South Africans, using geometric morphometric methods (GMM). : We used cone-beam computed tomography (CBCT) scans of 291 adult dental patients with dentition patterns up to Eichner Index B3, retrospectively collected from the Oral and Dental Hospital, University of Pretoria. We placed eleven standard craniometric landmarks on the menton, mandible, and maxilla of three-dimensional (3D) reconstructions by automatic landmarking and analyzed them by applying GMM. In addition, a subtle shape matrix of seven landmarks was created for a focused analysis of the menton only. Finally, we tested the reproducibility of the landmarks placement with a dispersion analysis. : The landmarks used in this study were reproducible, with an overall dispersion of less than 1 mm. Population affinity significantly influenced menton shape, with P-values = 0.001 in the complete sample and within the sex groups. Differences between sexes for these seven landmarks were also statistically significant (P-values between 0.001 to 0.003) in the complete sample, but not within population groups in isolation. The accuracy for estimation of population affinity by discriminant function analysis was 86.9%. : The use of automatic landmarking improved landmark reproducibility. Population affinity and sexual dimorphism significantly influenced menton shape. However, shape analysis, including all eleven landmarks, was not significantly influenced by sex. This study supports further research focusing on the facial approximations for forensic identification in South Africa.

The 3D digital facial approximation of Saint Anthony of Padua

Anthony of Padua is one of the most popular saints of the Catholic Church, with great veneration in Italy, Portugal and Brazil. The present work sought to approach a little of the history of this religious figure in order to contextualize the recognitions of the body, among which the exhumation of 1981 that allowed the technical analysis and the cranial replica, digitized and used in the project presented here for the approximation of its face, as well as the survey of the endocranial volume, with the use of new technologies and statistical data collected from computed tomography.