Photogrammetry vs CT Scan: Evaluation of Accuracy of a Low-Cost Three-Dimensional Acquisition Method for Forensic Facial Approximation

Photogrammetry is a three-dimensional acquisition method potentially applicable to the forensic field. This possibility requires the verification of its accuracy. In this study, 3D volumes of skulls are generated to compare the photogrammetry versus the CT scan. In order to provide eligible material to the photogrammetric software, photographs were captured at a distance of 30 cm from the skull placed on a support 1 m in height and illuminated with diffused laboratory ceiling artificial light. A Nikon Coolpix P7100 camera was used. Photographs capture common elements with the previous and the next photograph so as to allow the photogrammetric software to recognize these common points between photographs and create a 3D puzzle. The Zephyr Lite (3DFlow©) software was employed to register the 3D volume. CT-based skulls are taken as a metric reference. The photogrammetry-based skulls are then enlarged according to the measurements of some landmarks or Zygion and Zygion, the distance between end of nasal and base of nasal pyramid for frontal projection, and minimum breadth of the mandibular ramus for the right lateral projection. The accuracy of the photogrammetry is compared to that of the CT scan by measuring the 3D volumes of the skulls studied. Specific landmarks are used as reference points for the measures in both frontal and lateral views. Bland–Altman graph shows homogeneity. The mean difference (1.28 mm) indicates that the measurements taken on the photogrammetry-based skull tend to slightly overestimate compared with the measurements taken on the CT-based skull.     

Forensic Terrestrial Photogrammetry from a Single Image

Abstract:  Forensic terrestrial photogrammetry is one of the most valuable and low-cost resources of spatial data available today. Due to the ephemeral crime scene characteristics, these photographs can often capture information that is never to be seen again. This paper presents a novelty approach for the documentation, analysis, and visualization of crime scenes for which only a single perspective image is available. The photogrammetric process consists of a few well-known steps in close-range photogrammetry: features extraction, vanishing points computation, camera self-calibration, 3D metric reconstruction, dimensional analysis, and interactive visualization. Likewise, the method incorporates a quality control of the different steps accomplished sequentially. As a result, several cases of study are presented in the experimental results section in order to test their viability. The full approach can be applied easily through the free software, sv3DVision, which has been evaluated by a number of police officers, forensic scientists, and forensic educators satisfactorily.     

Development of equipment for the standardization of skull photographs in personal identifications by photographic superimposition

The technique of photographic superimposition of postmortem specimens (dried skull or head) positioned identically to the orientation in an antemortem smiling photograph is now a recognized method for personal identification of human remains. Previous methods used to produce the postmortem photographs were problematic as orientation of the specimen could not be easily adjusted and positions were not reproducible. The objective of this paper is to describe the design and method of use of purpose-constructed equipment intended to alleviate these problems. The equipment comprises a skull-holding jig based conceptually on the Royal Berkshire Hospital halo frame. This is mounted on a pan-and-tilt device, incorporating calibrated measurement scales, enabling independent movements in each of the Cartesian coordinates. A camera is attached to an adjustable mount running on twin parallel rails allowing the camera-to-specimen distance to be varied. The equipment has proven to be straightforward in use and offers considerable advantages over previously described methods for producing postmortem photographs.     

Photogrammetric Documentation of Regions of Interest at Autopsy—A Pilot Study

In this pilot study, the authors tested whether photogrammetry can replace or supplement physical measurements made during autopsies and, based on such measurements, whether virtual computer models may be applicable in forensic reconstructions. Photogrammetric and physical measurements of markers denoting wounds on five volunteers were compared. Virtual models of the volunteers were made, and the precision of the markers' locations on the models was tested. Twelve of 13 mean differences between photogrammetric and physical measurements were below 1 cm, which indicates that the photogrammetric method has a high accuracy. The precision of the markers' location on the models was somewhat less, although the method is still promising and potentially superior to the current procedures used for reconstructions. The possibility to measure any distance on a body, even after the autopsy is concluded and the corpse is no longer available, is one of the biggest benefits of photogrammetry.     

Pig-mentation: postmortem iris color change in the eyes of Sus scrofa

Experienced forensic pathologists and examiners may be familiar with the phenomenon of postmortem iris color change; however, only Knight, Simpson's forensic medicine, Arnold, London, 1997; Ref. 1 and Saukko and Knight, Knight's forensic pathology, 3rd ed., Arnold, London, 2004; Ref. 2 have referred to it in the literature, and to date, there have been no published scientific research studies on this taphonomic artifact. A controlled experiment was conducted of postmortem changes to isolated Sus scrofa eyes. The eyes (n = 137) were separated into three groups and each sample was observed for 3-day postmortem at a different temperature. In addition, a Sus scrofa head was obtained to observe postmortem changes of eyes in situ. All isolated blue eyes in the experiment, at room temperature and higher, changed to brown/black within 48 h. The in situ blue eye, at room temperature, turned brown/black within 72 h. If iris color consistently changes postmortem in humans, then this taphonomic artifact must be incorporated into victim identification protocol, including disaster victim identification software, and autopsy reports to prevent inaccurate victim identification and inappropriate exclusion from the identification process.     

3D forensic facial approximation: Implementation protocol in a forensic activity

The primary objective of this paper is to report on the successful implementation of forensic facial approximation in a real case in the forensic context. A three‐dimensional (3D) facial approximation protocol of the skull was performed with free software, applying techniques in a virtual environment that have already been consolidated in the literature. The skull was scanned with the photogrammetry technique, the digital replica was imported in the Blender software (Blender Foundation, Amsterdam) and individualized model sketches of the face were traced with the MakeHuman software (MakeHuman Org) according to the anthropological profile of the victim. The face created was imported in Blender, where it was adapted, modeled, and sculpted on the 3D skull and its soft tissue markers, using an American open‐source application of the technique in the digital environment. The face created in a virtual environment was recognized and legal identification procedures were started, resulting in the more agile delivery of the disappeared body to its next of kin. It is therefore concluded that facial approximation may not be a primary method of human identification, but it can be satisfactorily applied in the forensic field as an individual recognition resource. It has great value in narrowing the search, reducing the number of alleged victims, and leading to identification tests, therefore significantly reducing the number of genetic DNA (deoxyribonucleic acid) tests—which are considered costly for the State or Federation—and consequently reducing the waiting time before delivery of the body to its family.     

An Alternative Method to Using a Mandibulometer

Mandibular length, mandibular angle, and maximum ramus height measurements used during forensic evaluation of skeletal remains require use of a mandibulometer. This study presents a new method of taking these measurements from images, so that practitioners without access to an expensive mandibulometer or those working with 3D models (e.g., CT scans) can collect and utilize these measurements. Ten trials performed on a sample of 45 mandibles were used to compare measurements collected from photographs and images extracted from 3D surface scans to those collected with a mandibulometer, including intra‐ and inter‐observer analyses. All technical error of measurement (TEM) values were less than 2 mm regardless of observer, trial, or method. Relative TEM values were less than 2% for all except mandibular length (2.10%) and ramus height (2.32%) for the right versus left photographs. Results are comparable with mandibulometer error rates, indicating that the proposed method is accurate and reliable.     

Multiple-probe thermography for estimating the postmortem interval: I. Continuous monitoring and data analysis of brain, liver, rectal and environmental temperatures in 117 forensic cases

One hundred seventeen forensic postmortem cases have been studied under controlled conditions. In each case, temperatures of the brain, liver, rectum, and the environment were monitored over a period beginning shortly after death and ending up to 60 h postmortem. The four temperature measurements were recorded every 5 to 10 min using the Microwave Thermography System. Rectal and environmental temperatures were measured by electrical thermocouples while brain and liver temperatures were measured using microwave probes. Data acquisition, analogue-to-digital conversion (ADC), and data processing were provided by a microcomputer. The ADC technique is described and its problems are discussed. The data were then transferred to a mainframe computer for extensive curve-fitting and statistical analysis. The microcomputer-based ADC and data logging and acquisition were found to be accurate, fast, easy to implement, and useful for the field. The postmortem rate of human body cooling was found to be adequately represented by triple-exponential equations.     

The Red Swamp Crayfish Procambarus Clarkii (the Louisiana Crayfish) as a Particular Scavenger on a Human Corpse

An 85-year-old man was found deceased floating in an irrigation ditch 18 days after his disappearance. During crime scene investigation, specimens of the red swamp crayfish Procambarus clarkii were found in proximity of the body. The feeding activity of these nonendemic crayfishes contributed to the formation of specific injuries on the body and in the production of a large substance defects inside the corpse. The aim of this paper was to illustrate the scavenging activity of P. clarkii on a human body and highlight the potential postmortem artefacts caused by this species. This is the first report on a real case of postmortem injuries produced by P. clarkii crayfishes on a submerged human body. So far, crustaceans are not considered useful for the estimation of the minimum postmortem interval. However, the important modifications on the corpses deriving from the activity of these animals should be kept in consideration.     

Video superimposition at the C.A. Pound Laboratory 1987 to 1992.

William R. Maples practiced many aspects of human identification using simple and relatively inexpensive video superimposition equipment. Identification of skulls by comparison to known photographs was a primary concern. Clear, smiling photographs revealing the spatial relationships of the teeth to one another led to uncomplicated positive identifications. However, without benefit of dentition, how accurate was an identification based on the alignment of soft tissues with the underlying skull? Most importantly, how often would a false positive result when anterior dentition were not available? A study conducted by this author and Dr. Maples used three human heads and 98 profile and full-face photographs. A 0.6% incidence of false match resulted when both views of the face were used. Lateral view and frontal view superimpositions were identified incorrectly in 9.6% and 8.5% of the sample respectively. As a result, multiple photographs from varying angles were requested for superimposition identity cases. Additional applications in laboratory case work were developed for the equipment. Light boxes under the television cameras allowed radiographic comparisons. Video taped comparisons of antemortem and postmortem radiographs were shown to medical examiners and families as proof of identification. Dr. Maples and this author were also involved in several cases in which photographs taken by a surveillance or ATM camera were compared to court ordered photographs of an alleged perpetrator. One case, which went to trial, led to the conviction of a habitual criminal under Florida statute. This individual had a condition known as Stahl's ear, a deformation of the cartilaginous structure. The ear was seen clearly in many of the ATM camera photographs and was aligned easily with the known photographic sample.     

大鼠尸体组织电阻抗的死后变化及与死亡时间的关系

目的探讨躯体组织的电阻抗的死后变化规律，寻找推断死后经过时间的新方法。方法用阻抗测量仪测量大鼠胃壁、腹壁、躯干、胸部、腹部、腹部皮肤、头皮等处不同死后经过时间的电阻抗。结果大鼠躯体组织的电阻抗随着死后经过时间的延长存在规律性变化。这些结果告诉我们，有望通过测量死后人体躯体组织的电阻抗，利用其死后变化规律，推断人体死后经过时间。     

Variability of bodily measures of normally dressed people using PhotoModeler Pro 5

Photogrammetry is used in forensic science to help identify perpetrators from crime scenes by way of surveillance video, but the reproducibility of manually locating hidden body-points such as the joints remains to be established. In this study, we quantified the inter- and intra-observer variability of bodily measures of clothed individuals in two different poses and examined whether body segment lengths could be used to distinguish between people of similar stature. Stature was reproduced within +/-1.5 cm in both the intra- and inter-observer study. Segment lengths were best reproduced when flexion in the joints was present in the intra-observer study, but only the length of the trunk could be used to distinguish between people of similar height. The reproducibility between the two poses was low. Other measures than stature should be used with caution and with the perpetrator and suspect in the same pose. Consistent guidelines for locating body-points should be developed.     

Determination of Vehicle Speed from Recorded Video Using Reverse Projection Photogrammetry and File Metadata

The prevalence of security and in‐car video has increased the number of motor vehicle accidents captured on digital video. However, inconsistencies in how to accurately determine time and distance for vehicle speed has led to examinations with varying results. A potential solution for calculating time intervals is to use frame timing contained within many digital video file's metadata, recorded with 0.000001 sec precision. This paper examines a fatal motor vehicle accident where frame timing information was used with distance measurements from reverse projection photogrammetry to calculate vehicle speed. A margin of error was then calculated based on the accuracy in performing reverse projection photogrammetry distance measurements. The resulting speed calculation was then compared to event data recorder data and found to be within an average of ±1.43538 MPH. Using specific time intervals may lead investigators to more accurate speed calculations, specifically those involving variable frame rate video.     

Radiographic Identification Using Midline Medical Sternotomy Wires,

Forensic anthropologists are regularly asked to assist with the identification of unknown individuals using comparative medical radiography. This study addressed the use of midline medical sternotomy wires as a means for personal identification. Antemortem and postmortem radiographic comparisons were completed by 46 professional forensic anthropologists and anthropology graduate students familiar with comparative medical radiography as a technique for assessing identification. Participants were asked to make five radiographic matches from a pool of 20 radiographs. Participants also completed an anonymous survey detailing their education level and experience making radiographic comparisons. Participants were 99.5% accurate in matching the radiographs. Sensitivity was 98.7%, and specificity was 99.7%. Logistic regression analysis found no statistically significant differences in the participants' ability to make a correct match. As the high accuracy rates indicate, the shape, size, and various characteristics of the sternotomy wires are individualizing and can confidently be used when assisting with personal identification cases.     

GrinLine Identification Using Digital Imaging and Adobe Photoshop*

Abstract: The purpose of this study was to outline a method by which an antemortem photograph of a victim can be critically compared with a postmortem photograph in an effort to facilitate the identification process. Ten subjects, between 27 and 55 years old provided historical pictures of themselves exhibiting a broad smile showing anterior teeth to some extent (a grin). These photos were termed “antemortem” for the purpose of the study. A digital camera was used to take a current photo of each subject’s grin. These photos represented the “postmortem” images. A single subject’s “postmortem” photo set was randomly selected to be the “unknown victim.” These combined data of the unknown and the 10 antemortem subjects were digitally stored and, using Adobe Photoshop software, the images were sized and oriented for comparative analysis. The goal was to devise a technique that could facilitate the accurate determination of which “antemortem” subject was the “unknown.” The generation of antemortem digital overlays of the teeth visible in a grin and the comparison of those overlays to the images of the postmortem dentition is the foundation of the technique. The comparisons made using the GrinLine Identification Technique may assist medical examiners and coroners in making identifications or exclusions.     

体表损伤与瘢痕的三维测量方法应用评估

目的检验结构光三维扫描法和单相机摄影测量法这两种三维测量方法在法医学体表损伤与瘢痕测量中的准确性和可靠性。方法对比分析直尺法、结构光三维扫描法和单相机摄影测量法对86处尸体损伤的测量结果;对比分析结构光三维扫描法、单相机摄影测量法、Photoshop套索像素法、PDF阅读软件法对13处活体模拟块状瘢痕面积的测量结果,并记录所耗时间;以贴纸的已知规格信息作为标准值,比较直尺法、结构光三维扫描法和单相机摄影测量法的测量准确度,计算均方根误差(root mean square error,RMSE);对不同操作者和同一操作者前后3次测量结果的可重复性进行组内相关系数(intraclass correla⁃tion coefficient,ICC)一致性评价。结果两种三维测量方法与直尺法在尸体损伤上测得的结果差异无统计学意义;结构光三维扫描法、单相机摄影测量法、PDF阅读软件法的测量结果和Photoshop套索像素法相比差异无统计学意义,单相机摄影测量法后处理耗时长于其他方法;直尺法测量长距离组(10~40cm)时结果小于标准值,RMSE值结果为结构光三维扫描法<单相机摄影测量法<直尺法;组内和组间的ICC值均大于0.99。结论结构光三维扫描法和单相机摄影测量法均可应用于法医学体表损伤的记录和测量,前者在测量精度及稳定性上表现更优,后者的数据色彩还原度更好,但后处理耗时较长。     

Anthropological Measurement of the Juvenile Clavicle Using Multi‐Detector Computed Tomography—Affirming Reliability

Currently, there is no standardized protocol for multi‐detector computed tomography (MDCT) measurement of juvenile remains. Using 33 juvenile clavicles, this paper investigates a protocol to allow MDCT measurements, comparable or supplemental with traditional osteometric measurements, to be acquired for application to previously published algorithms. The results illustrate that there is no significant difference between MDCT measurements and those taken by direct osteometric methods. By presenting such a protocol, this paper takes the first steps toward validation of the process of conversion from measurement of dry juvenile bone to MDCT compatibility and allows the forensic world to take a step forward in standardizing the way MDCT is used for forensic practice. This paper assesses the limitations and potential applications of this virtual approach and offers some suggestions for where further work might progress the conversion of these new approaches into legally admissible anthropological techniques of age estimation.     

玻璃体液化学成分规律性改变与死亡时间推断的研究进展

死亡时间（postmortem interval．PMI）的准确推断是法医尸体检验工作中的难题之一,PMI推断对刑事案件的侦察和审判具有重要的意义。人死亡后不同时间眼玻璃体液化学成分的规律性变化,如钾、镁、氨、尿素氮、肌酐和尿酸、次黄嘌呤、乳酸的含量逐渐升高,而钙、钠、酶类、葡萄糖、维生素C的含量逐渐降低,有助于比较准确地进行PMI推断。本文对其在法医学领域的研究进展进行综述。     

Waxing grave about adipocere: soft tissue change in an aquatic context

When postmortem environmental conditions are "just right," according to the "Goldilocks Phenomenon," soft tissues (and associated fatty acids) are converted into and preserved as adipocere. To better understand this conversion process and the development of adipocere three human cadavers were immersed in outside, water-filled pits for over 3 months to observe adipocere formation in an underwater context simulating actual field conditions. Recordings of environmental conditions showed that temperatures were between 21 degrees C and 45 degrees C, a range sufficient for the growth of Clostridium perfringens. Chemical analysis of liquid and tissue samples revealed an increase in palmitic acid and decrease in oleic acid. This study tracked the remarkable gross morphological changes that can occur in human bodies subjected to an aquatic postmortem environment. The results support the "Goldilocks Phenomenon" and substantiate previous findings that the presence of bacteria and water is crucial for adipocere to form.