Further Evidence on the Anatomical Placement of the Human Eyeball for Facial Approximation and Craniofacial Superimposition*

Abstract: Recently a small sampled cadaver study (n = 4) suggested that the human eyeballs are placed closer to the orbital roof and lateral orbital wall as first reported in the anatomical literature many years previously. This contrasts with central positioning of the eyeball within the orbit as advocated by the facial approximation literature. Given the limits of such small samples, this study re-examined globe position in nine new cadavers to help clarify which relationship is accurate. The results essentially confirm prior empirical findings except that the mean lateral divergences from the orbit center were found to be larger—the eyeball was found to be “displaced” 1.4 mm superiorly and 2.4 mm laterally. Medians calculated across all 13 cadavers from this study and the above-mentioned recent report refine these measurements to 1.4 and 2.3 mm respectively. Globe projection values were identical to those observed for living individuals (c. 16 mm).     

Anthropological Facial Approximation in Three Dimensions (AFA3D): Computer‐Assisted Estimation of the Facial Morphology Using Geometric Morphometrics

This study presents Anthropological Facial Approximation in Three Dimensions (AFA3D), a new computerized method for estimating face shape based on computed tomography (CT) scans of 500 French individuals. Facial soft tissue depths are estimated based on age, sex, corpulence, and craniometrics, and projected using reference planes to obtain the global facial appearance. Position and shape of the eyes, nose, mouth, and ears are inferred from cranial landmarks through geometric morphometrics. The 100 estimated cutaneous landmarks are then used to warp a generic face to the target facial approximation. A validation by re‐sampling on a subsample demonstrated an average accuracy of c. 4 mm for the overall face. The resulting approximation is an objective probable facial shape, but is also synthetic (i.e., without texture), and therefore needs to be enhanced artistically prior to its use in forensic cases. AFA3D, integrated in the TIVMI software, is available freely for further testing.     

Three-Dimensional Prediction of the Nose for Facial Approximation in a Thai Population

Most of the previous studies about nose prediction were concentrated only some landmarks of the nose. This study aimed to generate prediction equations for ten landmarks of the nose in the midline and alar regions for forensic facial approximation. The six midline landmarks were the sellion, nasion–pronasale posterior, nasion–pronasale anterior, pronasale, nasal drop, and subnasale. The four landmarks of the alar region were the alare, superior alar groove, posterior alar groove, and inferior alar groove. We used the skull landmarks in the nasal, zygomatic, and maxillary bone to predict the landmarks of the nose. Cone-beam computed tomography scans of 108 Thai subjects with normal BMI and age ranging from 21.0 to 50.9 years were obtained in a sitting position. The data were converted into three-dimensional (3-D) images of the skull and face. The Cartesian coordinates of the landmarks of the skull and nose were used to formulate the multiple regression equations. The formulated equations were tested in 24 new subjects. The mean differences in the predicted midline landmarks varied between −0.4 mm and 0.5 mm, whereas those for bilateral landmarks varied between −1.0 mm and 1.4 mm. In conclusion, the prediction equations formulated here will be beneficial for facial approximation of the nose in a Thai population.     

The Validity of Ear Prediction Guidelines Used in Facial Approximation*,†,‡

Abstract: This study examined eight previously published ear prediction methods by Welcker, Gerasimov, Fedosyutkin and Nainys, and Broadbent and Mathews. Computed tomography scans of 78 living adults (n₁) did not support any of these previously published recommendations. Free earlobes were found to accompany protruding supramastoid crests (Pearson’s χ² < 0.05); and ear length [l] and width [w] differed by sex (p < 0.05), correlated with age (r = 0.38[l]; 0.32[w]), and correlated with facial height (r = 0.37[l]; 0.30[w]). New regression equations (for ear length and width) were generated using these variables in several samples and, where possible, cross‐validated using independent data (n₁ = 78, n₂ = 2190, n₃ = 1328, n₄ = 1010, and n₅ = 47). As a result of these analyses, four valid and tested methods for ear prediction were identified, but large degrees of error continue to make accurate prediction of the ear, from the skull, problematic.     

Validation of the New Interpretation of Gerasimov's Nasal Projection Method for Forensic Facial Approximation Using CT Data,

The most common method to predict nasal projection for forensic facial approximation is Gerasimov's two‐tangent method. Ullrich H, Stephan CN (J Forensic Sci, 2011; 56: 470) argued that the method has not being properly implemented and a revised interpretation was proposed. The aim of this study was to compare the accuracy of both versions using a sample of 66 postmortem cranial CT data. The true nasal tip was defined using pronasale and nasal spine line, as it was not originally specified by Gerasimov. The original guidelines were found to be highly inaccurate with the position of the nasal tip being overestimated by c. 2 cm. Despite the revised interpretation consistently resulting in smaller distance from true nasal tip, the method was not statistically accurate (p > 0.05) in positioning the tip of the nose (absolute distance >5 mm). These results support that Gerasimov's method was not properly performed, and Ullrich H, Stephan CN (J Forensic Sci, 2011; 56: 470) interpretation should be used instead.     

Eyeball Position in Facial Approximation: Accuracy of Methods for Predicting Globe Positioning in Lateral View

This study measured the accuracy of traditional and validated newly proposed methods for globe positioning in lateral view. Eighty lateral head cephalograms of adult subjects from Central Europe were taken, and the actual and predicted dimensions were compared. The anteroposterior eyeball position was estimated as the most accurate method based on the proportion of the orbital height (SEE = 1.9 mm) and was followed by the “tangent to the iris method” showing SEE = 2.4 mm. The traditional “tangent to the cornea method” underestimated the eyeball projection by SEE = 5.8 mm. Concerning the superoinferior eyeball position, the results showed a deviation from a central to a more superior position by 0.3 mm, on average, and the traditional method of central positioning of the globe could not be rejected as inaccurate (SEE = 0.3 mm). Based on regression analyzes or proportionality of the orbital height, the SEE = 2.1 mm.     

Application of Postmortem 3D‐CT Facial Reconstruction for Personal Identification*

Abstract: Postmortem computed tomography (CT) images can show internal findings related to the cause of death, and it can be a useful method for forensic diagnosis. In this study, we scanned a ready‐made box by helical CT on 2‐mm slices in a mobile CT scanner and measured each side of the box to assess whether reconstructed images are useful for superimposition. The mean difference between the actual measurements and the measurements on the three‐dimensional (3D) reconstructed images (3D‐CT images) is 0.9 mm; we regarded it as having no effect on reconstruction for the superimposition method. Furthermore, we could get 3D‐CT images of the skull, which were consistent with the actual skull, indicating that CT images can be applied to superimposition for identification. This study suggested that postmortem CT images can be applied as superimpositions for unidentified cases, and thinner slices or cone beam CT can be a more precise tool.     

Facial Approximation—From Facial Reconstruction Synonym to Face Prediction Paradigm

Facial approximation was first proposed as a synonym for facial reconstruction in 1987 due to dissatisfaction with the connotations the latter label held. Since its debut, facial approximation's identity has morphed as anomalies in face prediction have accumulated. Now underpinned by differences in what problems are thought to count as legitimate, facial approximation can no longer be considered a synonym for, or subclass of, facial reconstruction. Instead, two competing paradigms of face prediction have emerged, namely: facial approximation and facial reconstruction. This paper shines a Kuhnian lens across the discipline of face prediction to comprehensively review these developments and outlines the distinguishing features between the two paradigms.     

Facial Tissue Depths in Children with Cleft Lip and Palate

Cleft lip and palate (CLP) is a craniofacial malformation affecting more than seven million people worldwide that results in defects of the hard palate, teeth, maxilla, nasal spine and floor, and maxillodental asymmetry. CLP facial soft‐tissue depth (FSTD) values have never been published. The purpose of this research is to report CLP FSTD values and compare them to previously published FSTD values for normal children. Thirty‐eight FSTDs were measured on cone beam computed tomography images of CLP children (n = 86; 7–17 years). MANOVA and ANOVA tests determined whether cleft type, age, sex, and bone graft surgical status affect tissue depths. Both cleft type (unilateral/bilateral) and age influence FSTDs. CLP FSTDs exhibit patterns of variation that differ from normal children, particularly around the oronasal regions of the face. These differences should be taken into account when facial reconstructions of children with CLP are created.     

Forensic Facial Approximation: Study of the Nose in Brazilian Subjects

Forensic facial approximation is an auxiliary method for human identification and allows facial recognition. The midface, that includes the nose, is vital for the recognition of a familiar face. The purpose of this study was to set hard tissue parameters to estimate nasal width, to test the method to estimate nasal width of Brazilians, and to analyze the relationship between nasal profile and facial type. A total of 246 computed tomography scans (183 females and 63 males) of adults were analyzed in Horos. Bone tissue measurements and facial type classification were performed on the skull scan. Nasal profile morphology was accessed through the tool 3D surface rendering. There was a difference around 3 mm from real to predicted nose through the method to estimate nasal width in Brazilians. So, the method may be used in forensic practice. Straight nose was associated with long face type.     

Comparison Among Manual Facial Approximations Conducted by Two Methodological Approaches of Face Prediction

This study verified the difference between two methods of forensic facial approximation (FFA) regarding recognition and resemblance rates. Three‐dimensional models of skulls were obtained from computerized tomography (CT) scans of two subjects (targets). Two manual FFAs were performed for each target, by applying two different guidelines for the facial structures (what we called “American method” (AM) and “Combined method” (CM)). Unfamiliar assessors evaluated the sculptures by recognition and resemblance tests. The AM was that which allowed more correct responses of recognition and higher resemblance's scores for the male target (p < 0.001). Regarding guidelines for modeling characteristics of the face, the ones that are practical and easily performed for sculptures, such as the length of the anterior nasal spine multiplied by 3 for nose prediction, may offer better results in terms of resemblance.     

Facial soft tissue depths in craniofacial identification (part II): An analytical review of the published sub-adult data

Prior research indicates that while statistically significant differences exist between subcategories of the adult soft tissue depth data, magnitudes of difference are small and possess little practical meaning when measurement errors and variations between measurement methods are considered. These findings raise questions as to what variables may or may not hold meaning for the sub-adult data. Of primary interest is the effect of age, as these differences have the potential to surpass the magnitude of measurement error. Data from the five studies in the literature on sub-adults which describe values for single integer age groups were pooled and differences across the ages examined. From 1 to 18 years, most soft tissue depth measurements increased by less than 3 mm. These results suggest that dividing the data for children into more than two age groups is unlikely to hold many advantages. Data were therefore split into two groups with the division point corresponding to the mid-point of the observed trends and main data density (0-11 and 12-18 years; division point = 11.5 years). Published sub-adult data for seven further studies which reported broader age groups were pooled with the data above to produce the final tallied soft tissue depth tables. These tables hold the advantages of increased sample sizes (pogonion has greater than 1770 individuals for either age group) and increased levels of certainty (as random and opposing systematic errors specific to each independent study should average out when the data are combined).     

Facial soft tissue depths in craniofacial identification (part I): An analytical review of the published adult data

With the ever increasing production of average soft tissue depth studies, data are becoming increasingly complex, less standardized, and more unwieldy. So far, no overarching review has been attempted to determine: the validity of continued data collection; the usefulness of the existing data subcategorizations; or if a synthesis is possible to produce a manageable soft tissue depth library. While a principal components analysis would provide the best foundation for such an assessment, this type of investigation is not currently possible because of a lack of easily accessible raw data (first, many studies are narrow; second, raw data are infrequently published and/or stored and are not always shared by some authors). This paper provides an alternate means of investigation using an hierarchical approach to review and compare the effects of single variables on published mean values for adults whilst acknowledging measurement errors and within-group variation. The results revealed: (i) no clear secular trends at frequently investigated landmarks; (ii) wide variation in soft tissue depth measures between different measurement techniques irrespective of whether living persons or cadavers were considered; (iii) no clear clustering of non-Caucasoid data far from the Caucasoid means; and (iv) minor differences between males and females. Consequently, the data were pooled across studies using weighted means and standard deviations to cancel out random and opposing study-specific errors, and to produce a single soft tissue depth table with increased sample sizes (e.g., 6786 individuals at pogonion).     

The Use of CT Scans in Estimating Age at Death by Examining the Extent of Ectocranial Suture Closure

We examined the utility of CT scans in the evaluation of degree of ectocranial suture closure. Five cranial points (left and right midcoronal positions, left and right midlambdoidal positions, and the lambda) were evaluated in 231 CT scans using a three‐point scoring system (open, partial closed, and closed). The slice increment and thickness varied between three groups of the scans. The results showed a good correlation between degree of suture closure and increasing age in each group. Young individuals (<40 years) and old individuals (>60 years) could be clearly distinguished from the middle‐aged individuals. ANOVA test revealed no difference between two groups of scans and between left and right sides (p > 0.05). Interobserver agreement was good, especially considering the score by sides. The results of this study create the base for developing a robust and simple method to estimate the age at death using CT scans.     

Effect of Head Position on Facial Soft Tissue Depth Measurements Obtained Using Computed Tomography

Facial soft tissue depth (FSTD) studies employing clinical computed tomography (CT) data frequently rely on depth measurements from raw 2D orthoslices. However, the position of each patient's head was not standardized in this method, potentially decreasing measurement reliability and accuracy. This study measured FSTDs along the original orthoslice plane and compared these measurements to those standardized by the Frankfurt horizontal (FH). Subadult cranial CT scans (n = 115) were used to measure FSTDs at 18 landmarks. Significant differences were observed between the methods at eight of these landmarks (p < 0.05), demonstrating that high‐quality data are not generated simply by employing modern imaging modalities such as CT. Proper technique is crucial to useful results, and maintaining control over head position during FSTD data collection is important. This is easily and most readily achieved in CT techniques by rotating the head to the FH plane after constructing a 3D rendering of the data.     

A Preliminary Study of the Reliability of Anatomical Facial Landmarks Used in Facial Comparison

Anatomical landmarks are considered the most objective indicators for use in forensic facial comparisons. Therefore, accurately identifying and locating these landmarks is the beginning of reliable facial comparison. This study evaluated the accuracy with which facial landmarks are located and examined their reliability according to type of landmark, head posture, and image quality. Nine operators located a series of landmarks on prepared facial images used to produce comparison images. Then, the average distances between the reciprocal landmarks (ADRL) on the reference and the comparison images were measured as indicators of landmark reliability. We found that a set of landmarks had higher or lower reliability as a function of the head angle and image quality. More reliable landmarks were associated with certain head postures and degrees of image quality. These should be used for facial comparison analysis depending on various head and image conditions.     

Beyond the sphere of the English facial approximation literature: ramifications of German papers on western method concepts

In the English literature, facial approximation methods have been commonly classified into three types: "Russian,"American," or "Combination." These categorizations are based on the protocols used, for example, whether methods use average soft-tissue depths (American methods) or require face muscle construction (Russian methods). However, literature searches outside the usual realm of English publications reveal key papers that demonstrate that the Russian category above has been founded on distorted views. In reality, Russian methods are based on limited face muscle construction, with heavy reliance on modified average soft-tissue depths. A closer inspection of the American method also reveals inconsistencies with the recognized classification scheme. This investigation thus demonstrates that all major methods of facial approximation depend on both face anatomy and average soft-tissue depths, rendering common method classification schemes redundant. The best way forward appears to be for practitioners to describe the methods they use (including the weight each one gives to average soft-tissue depths and deep face tissue construction) without placing them in any categorical classificatory group or giving them an ambiguous name. The state of this situation may need to be reviewed in the future in light of new research results and paradigms.     

Measuring the accuracy of facial approximations: a comparative study of resemblance rating and face array methods

The success of facial approximation is thought to depend, at least in part, upon the "accuracy" of the constructed face. However, methods of accuracy assessment are varied and this range in methods may be responsible for the disparate results reported in the literature. The aim of this study was to determine if the accuracy results of one facial approximation were comparable across two different assessment methods (resemblance ratings and simultaneous face array tests using unfamiliar assessors) and if resemblance ratings co-varied with recognition responses. True-positive recognition performance from the facial approximation was poor (21%) while resemblance scores using the same facial approximation were moderately high (3 out of 5 on a five-point scale). These results are not, therefore, consistent and indicate that either different variables are being evaluated by the methods, or the same variable is being examined but with different weight/calibration. Further resemblance ratings tests of the facial approximation to three foil faces from the face array revealed that resemblance scores were similar irrespective of which face was compared, and did not closely correspond with the degree of recognition performance. This was especially the case for isolated comparisons of single faces to the facial approximation. Collectively, these results indicate that resemblance ratings are: (i) insensitive measures of a facial approximation's accuracy; and (ii) inconsistent with results of unfamiliar simultaneous face-array recognition results. These data suggest that familiar and unfamiliar recognition tests should be given increased weight in contrast to current resemblance rating tests.