Single-camera photogrammetry using a mobile phone for low-cost documentation of corpses.

Photogrammetry is a technique for studying and defining objects' shape, dimension, and position in a three-dimensional space using measurements obtained from two-dimensional photographs. It has gained popularity following the development of computer graphics technologies and has been applied to various branches of medicine. In this study, the authors present a method for low-cost photorealistic documentation of corpses during autopsy using single-camera photogrammetry with a mobile phone. Besides representing the body by demonstrating the injured and non-injured body parts as control, evidencing the body parts on a 3D reconstruction allows easy explanation to nonmedical experts such as lawyers.

Contactless Size Reference in Forensic Photography-Design and Verification of the Novel FreeRef-1 System.

In photographs of evidence in forensic investigations, physical size references (e.g., rulers or stickers) are often placed next to a trace to allow us to take measurements from photos. However, this is laborious and introduces contamination risks. The FreeRef-1 system is a contactless size reference system that allows us to take forensic photographs without having to be close to the evidence, and allows photographing under large angles without losing accuracy. The FreeRef-1 system performance was assessed using technical verification tests, inter-observer checks and user tests with forensic professionals. The results show that the measurements taken with photos using the FreeRef-1 system were at least as accurate as those taken using conventional techniques. Furthermore, with the FreeRef-1 system, even photographs taken under strongly oblique angles provided accurate measurements. The results suggest that the FreeRef-1 system will facilitate photographing evidence even in hard-to-reach places, such as under tables and on walls and ceilings, while increasing the accuracy and speed.

Beneath cover-up tattoos: possibilities and limitations of various photographic techniques.

BACKGROUND: The goal of this study was to investigate the usefulness of various photographic techniques in visualizing previous tattoos under cover-up tattoos. MATERIAL AND METHODS: Ten volunteers with 11 known cover-up tattoos were examined using different photographic techniques: A Canon EOS 6D full-frame digital single-lens reflex camera used in conjunction with a SB600 off-camera flash system and an extension cord; and a Leica M8 digital imaging system camera in conjunction with two different infrared filters (715 nm and 850 nm) and a Metz CL-45 handle-mount flash. A Lumatec Superlite 400 forensic light source was used along with the Canon EOS 6D as a third system. RESULTS: The best results for black cover-up tattoos were achieved with the full-frame digital single-lens reflex camera in conjunction with the off-camera flash system and, for colored cover-up tattoos, with IR-photography at a wavelength of 850 nm. The Lumatec Superlite 400 light source did not provide better results for conventional photography than those obtained with flash lighting. DISCUSSION: In nine out of eleven cover-up tattoos, the previous tattoos could, at least, be partially visualized. The quality of the visualization depended on the color, pattern, density, and quality of the cover-up tattoo as well as on the photographic technique. None of the examined photographic techniques could satisfactorily image the previous tattoo if the cover-up tattoo was large and black, especially not if it was densely inked. CONCLUSION: Depending on the color of the cover-up tattoo, a full-frame digital single-lens reflex camera in conjunction with a SB600 off-camera flash system (for black cover-ups) or infrared photography with flash lighting and an 850 nm filter (for colored cover-ups) proved to be the best of the investigated techniques to visualize a previous tattoo under a cover-up tattoo.

Detection of painted-over traces of blood and seminal fluid.

Dealing with a refurbished crime scene is a special challenge for forensic investigators. In such cases, a crime scene may not have only been cleaned in order to erase all traces but the walls of an indoor crime scene could also be painted over in order to mask traces of the crime. So far, very few publications have shown that painted-over traces of blood and seminal fluid can be detected using a forensic light source or infrared photography. To date, there have been no systematically executed research studies including guidelines on which settings to use depending on the color of the wall. Moreover, no comparative study has addressed the question of whether it is better to use infrared photography or a forensic light source to visualize painted-over bloodstains. The present study covers the aforementioned gaps and shows that painted-over bloodstains are most easily visualized by infrared photography, while traces of seminal fluid are most easily visualized at 440 nm in combination with a yellow filter-both independent of the color of the wall paint.

Estimating the postmortem interval of human skeletal remains by analyzing their fluorescence at 365 and 490 nm.

The study presented here is regarded as a continuation of the experiments of Sterzik et al., who developed a new practical method to distinguish between historical and recent human skeletal remains. Bone cross-sections were illuminated using light with wavelengths of 365 and 490 nm, causing fluorescence. The fluorescence was documented by photography and further analyzed to examine the areal extent of a certain fluorescent color. Contrary to the previous experiments of Sterzik et al., the present study focused on bones with postmortem intervals (PMIs) ≥ 50 years. Therefore, this study fills the gap created by the former study, pointing towards a correlation between the PMI and the areal extent of the fluorescent surface in both tests. The presence of blue and red fluorescent surfaces < 1% indicated a PMI ≥ 50 years. Furthermore, the presence of blue and red fluorescent surfaces > 1% can be regarded as a marker to exclude a PMI ≥ 50 years; in fact, these bones are likely to have a PMI < 30 years.

Visualizing old biological traces on different materials without using chemicals.

During the investigative process that typically follows a criminal act, it may prove necessary to work with and analyze evidence that is not recent but old. This could become necessary, for example, when a crime is discovered some time after it was committed or when a cold case is reopened. Due to this need, the present study focused on the detection and visualization of 2-year-old biological traces. To do so, an alternative light source and different filters were used. The optical behavior of 2-year-old samples of blood, semen, urine, saliva, and sweat located on 19 different materials was documented, analyzed, and compared with the optical behavior of the same samples when they were recent [1].

Searching for biological traces on different materials using a forensic light source and infrared photography.

Because biological traces often play an important role in the investigation process of criminal acts, their detection is essential. As they are not always visible to the human eye, tools like a forensic light source or infrared photography can be used. The intention of the study presented was to give advice how to visualize biological traces best. Which wavelengths and/or filters give the best results for different traces on different fabrics of different colors? Therefore, blood (undiluted and diluted), semen, urine, saliva, and perspiration have been examined on 29 different materials.

Estimating the postmortem interval of human skeletal remains by analyzing their optical behavior.

The aim of this study was to figure out a new practically applicable method to distinguish between historical and recent human skeletal remains. Therefore, the optical behavior of bone cross sections was investigated using the combination of two methods: a modification of an already established test (UV-induced fluorescence) and a new method (490 nm-induced fluorescence). We evaluated the areal extent of fluorescence of 30 bone cross sections with known postmortem interval (PMI) using ultraviolet light and 490 nm light. For analysis, the areal extend of fluorescent surface was determined using photos of the samples and an image editing software. The results prove that there is a correlation between PMI and the areal extent of fluorescent surface in both tests. Furthermore, the combination of both methods is a good indicator to distinguish within the forensic relevant post mortem interval between PMI < 30 years and PMI > 30 years.

Development of a methodology for the standardisation and improvement of 'Smartphone' photography of patterned bruises and other cutaneous injuries.

Human bite-mark analyses can play a prominent role in forensic case investigations, including those involving sexual assault. High-quality photographs routinely secure a link between a bite-mark and an individual's dentition. Access to around the clock forensic photography, however, is often limited, resulting in delay and/or missed opportunities to record valuable evidence. The emergence of Smartphone high-quality photographic technology now provides a previously unimagined opportunity to gather timely forensic photographic evidence. Problems can arise, however, due to the relatively poor quality of the photographs, as a result of many of those taking photographs having received little or no forensic photography training. This study compares unassisted photography with assisted photography, by a specifically developed camera application (App), to provide a standardised method for taking forensic photographs. An App, written in Java, was hosted on the Google Android Operating System, on a Samsung Galaxy SII Smartphone. Twenty-four volunteers participated in a study to photograph a pseudo bite-mark using three methods, (1) unassisted (as a control), (2) assisted by an ABFO No.2 right-angled photographic reference scale and (3) assisted by the App. The App, method (3), was shown to consistently outperform methods (1) and (2), demonstrating greater standardisation and precision (p<0.001). Analysis of the data showed the extent to which acquiring an accurate photograph depends on the image being orthogonal to the camera. It appears likely that the relatively inaccurate photographs acquired by methods (1) and (2), were as a result of deviation from the plane, orthogonal to the bite-mark. Therefore, the App was successful in ensuring that the camera was both orthogonal and at an appropriate distance, relative to the bite-mark. Thus, the App enhanced the abilities of non-experts to acquire more accurate photographs and created the potential to significantly improve the quality of forensic photographs.

Exploring the use of selfies in human identification.

BACKGROUND AND AIMS: The comparison of post-mortem evidence to ante-mortem data is the usual approach Forensic Odontologists take in managing human identification cases. Although dental charts and radiographs are widely used as ante-mortem dental evidence, photographs, including non-clinical ones such as selfies are not regarded as such. Therefore, photographs are not regularly assessed in identifying the deceased. This cross-sectional study was aimed to investigate the possible contributions of selfies in human identification and to suggest a structured methodology to assess selfie images with the data collected. MATERIAL AND METHODS: An e-survey composed of five open and seven close-ended questions was designed using JISC Online Surveys program (2020) to explore the opinions of practising Forensic Odontologists and related professionals on the use of photographs and selfies in human identification. Responses to the survey were collected and analysed into descriptive charts and statistics. RESULTS: Eighty-two out of 200 professionals completed their responses (40.8% response rate). 73.2% of them acknowledged that selfies could be used as a main or adjunct evidence in dental identification. Experienced participants in selfies assessed dental anatomy (n = 6), dental restorations (n = 6), craniofacial landmarks (n = 5), oral soft tissues (n = 3), and implement the use of photo-editing software (n = 3) when provided with photographs to analyze using the direct comparison technique. CONCLUSION: It may be concluded that selfies could be supplementary dental ante-mortem evidence. The designing of a step-by-step visual analysis of dental characteristics on a selfie photograph could subsequently be incorporated into official Forensic Odontology association guidelines worldwide. Further research in this area should be carried out along with the advancements in technology.

Reflected near-infrared photography: Digging deeper into post-mortem examination.

AIM: This research aims to investigate the utility of the Near Infra-Red (NIR) photographic technique in visualizing forensic evidence in a post-mortem examination. MATERIAL AND METHODS: A total of twenty-six deceased (male: n = 15; female: n = 11) were brought to the Mortuary of King George's Medical University, Chowk, Lucknow, Uttar Pradesh, India (226003), and were used to investigate the applicability of the human visible spectrum (HVS) & near-infrared photography. In the investigation, a modified Nikon D5300 crop-framed digital single-lens reflex camera was used for NIR Photography in combination with a Micro-Nikkor 105 mm, f/2.8, (Nikon Inc., Melville, NY, USA), Hoya R72 (760nm-860nm) infrared filter and a Nikon D5600 crop-framed digital single-lens reflex camera in combination with Nikkor 50mm lens for Human Visible Spectrum (HVS) Photography. RESULTS: The finding of the study reported that the application of the NIR photography would be the best of the investigative techniques for visualization and photo-documentation of forensically relevant post-mortem findings, such as - trace evidences (e.g., blood spots & soil particles on dark clothing), in external findings (e.g., contusion on victim's body) also for internal findings in a road traffic accident (RTA), gunshot, and drowning victim (e.g., mud particles in the trachea of drowning victim & localizing contusion of the scalp in road traffic accident cases). CONCLUSION: Human visible spectrum (HVS) photographs taken with Nikon D5600 provides substantial evidence for documentation purpose, the best results for trace evidence & contusion visualization in Post-mortem examination of the deceased were achieved with the NIR Photography in combination with indirect sunlight & room light as an infrared light source. (At a wavelength of 760nm-860nm).

Forensic photo-documentation in adult sexual assault- what do patients think?

Historically, some forensic practitioners and policy makers have viewed the use of photography in forensic documentation for adult victims of sexual assault as controversial. Some argue that diagrams and verbal descriptions of injury are sufficient, suggesting that sexual assault victims are so traumatised at time of examination that they are not able to provide valid consent, that the imaging process itself is humiliating, and that any decision to have photographs taken might be later regretted. Objectively, a patient capable of consenting to a forensic examination has an equal capacity to consent for forensic imaging, even when this involves sensitive areas of the body, and the process of forensic photography is not inherently problematic. Literature on forensic photography is sparse, particularly from the patient perspective. Our Forensic Medical Unit is in an excellent position to investigate this issue, as it is one of the few services in Australia that routinely offers sexual assault forensic photography, including genital, as part of its standard procedures for injury documentation. Photographs, in adult sexual assault cases, are not routinely taken of normal anatomy nor are they ever taken without patient consent. This study explores the immediate and short-term experiential impacts of forensic photography from the victims' perspective. Capacity to consent was assessed using a trauma informed, evidence-based interviewing tool at the start of their forensic assessment. Participants also completed questionnaires at the conclusion of their examination and on follow-up. Results show that victims not only have the capacity to provide informed consent but also found forensic photography, and the reasons for it, quite acceptable. A majority [80%; n = 87/108] indicated the photographic process had either been not at all or only a little embarrassing. When asked how they felt about having photographs taken, the majority 93.4% [n = 99/106) indicated that as well as having no regrets they were also happy with the way the images had been taken. 4.7% [n = 5] expressed some doubt about whether they had made the right decision. A similar pattern of responses was observed at follow-up which occurred, on average, seven weeks post examination. 72% [n = 26/36] said they did not think about the photographs at all or did so rarely. While 14% [n = 5/36] said they thought about them a fair bit or a lot of the time, most stated they had no concerns regarding the images that had been taken. Given its evidentiary salience and other benefits, such as its potential to promote greater transparency in the provision of forensic opinions and its usefulness in teaching, this study supports the case for the routine use of forensic photography in adult Sexual Assault Units more broadly.

The effects of heat on the physical and spectral properties of bloodstains at arson scenes.

This study examines the spectral characteristics of blood after being exposed to intense heat within a structural fire. Fire and intense heat have previously been understood to destroy or chemically change bloodstain evidence so that traditional forensic science recovery techniques are rendered ineffectual. Understanding the effects of the denaturation process and physical changes that occur to blood when exposed to heat may develop innovative forensic investigation methods, including the use of reflected infrared photography to enhance the recording of bloodstains. This research revealed that the denaturation of blood, specifically changes to the haemoglobin state from oxyhaemoglobin to methaemoglobin, resulted in the heat affected blood having a more optimal spectral target range within the infrared region when exposed to heat> 200 °C. It was observed both qualitatively and quantitatively using spectrophotometry, that there is a relationship between the appearance, viscosity and infrared absorption properties of blood when exposed to different temperatures as experienced in fire. This result indicated the increased potential for reflected infrared photography to be utilised as an effective tool for crime scene evidence recovery of bloodstains from arson scenes involving fire.

The Application of Photogrammetry in the Autopsy Room: A Basic, Practical Workflow.

Photogrammetry is a technique that uses two-dimensional photographs taken from different angles and positions to determine three-dimensional coordinates and distances. Becoming familiar with the photography technique for photogrammetry purposes is the first step to obtaining high-quality results. Ten human cadavers were studied to develop this protocol. Appropriate equipment settings, measurements, and suitable ambient conditions were determined. Finally, the protocol was tested on one cadaver wherein a full postmortem examination was conducted, allowing accurate 3D modeling and measurements of the human body. This straightforward, step-by-step workflow will help users become familiar with this technique. A thorough description of the necessary steps is reported, including equipment, environment requirements, body placement, how to take photographs, and the minimum suggested number of photographs. Numerous graphics show the protocol's main steps to help users understand and reproduce the entire process. Photogrammetry allows the permanent recording and storage of photographic evidence of conditions that existed at the time of autopsy and accurate measurements of the body. The 3D model can have a powerful effect in court, where the findings can be accurately depicted without elicitation of strong emotion that may influence the judge or jurors. The primary disadvantage of photogrammetry for forensic pathology is its time-consuming nature. However, the widespread use of the photogrammetry technique in postmortem rooms would allow in-depth testing to detect and fix potential pitfalls, making this technique more reproducible and verifiable, increasing its admissibility in courts.

Application of Structured-Light 3-D Scanning to the Documentation of Plastic Fingerprint Impressions: A Quality Comparison with Traditional Photography.

Plastic fingerprint impressions found at crime scenes are often too delicate for collection, leaving photography as the best option for documentation. However, traditional photography techniques can be inadequate in documenting minute 3-D details due to limitations of the camera and lighting conditions. This study investigated the feasibility of applying commercially available structured-light 3-D scanners in the documentation of plastic prints. Attempts were made to develop a procedure to extract curvature features from 3-D scanned fingerprints and flatten the friction ridge features into two-dimensional (2-D) images to allow direct comparison with the traditional photography in the CSIpix® Matcher and NFIQ 2.0 software. Two 3-D scanners were evaluated a Dentsply Sirona inEos X5® and an Artec Space Spider. In this study, 3-D scanners demonstrated robustness as well as efficiency in the collection of plastic fingerprint impressions in select substrates. One of the developed methods utilizing a discrete geometry operator and convexity features outperformed traditional photography, achieving higher software detection scores in minutiae count and match quality, while traditional photography could not always capture enough high-quality minutiae for comparisons, even after digital enhancement.

Technical note: A rapid, non-invasive method for measuring live or preserved insect specimens using digital image analysis.

The measurement of insects is an important component of many entomological applications, including forensic evidence, where larvae size is used as a proxy for developmental stage, and hence time since colonization/death. Current methods for measuring insects are confounded by varying preservation techniques, biased and non-standardized measurements, and often a lack of sample size given practical constraints. Towards enhanced accuracy and precision in measuring live insects to help avoid these variables, and that allows for different measurements to be analyzed, we developed a non-invasive, digital method using widely available free analytical software to measure live blow fly larvae. Using crime scene photographic equipment currently standard in investigation protocols, we measured the live length of 282 Phormia regina larvae. Repeated measurements of maggots, for all instars, were performed for several orientations and images. Most accurate measurements were obtained when maggots were oriented in their natural full extension. Killed specimens resulted in greater length measurements (Mean 1.79 ±â€¯1.11 mm) when compared to live length. Herein, we report a technically simple, fast, and accurate measurement technique adapted for field and lab-based measurements, as well as, a simple linear equation for conversion of live length to standard killed length measurements. We propose this method be utilized for the standardization of forensic entomological evidence collection and development model creation.

Detection of latent bloodstains at fire scenes using reflected infrared photography.

Bloodstain evidence is an element of crime scene investigation often found at scenes involving violence. Setting fire to the scene is a method sometimes used by offenders of crime in an attempt to conceal evidence. Fire often produces thick soot as a by-product of the combustion and has the potential to cover bloodstain patterns rendering them latent. There is limited published material offering a method of detecting bloodstains hidden beneath dense soot deposits caused by fire. This project employed a modified digital single-lens reflex (SLR) camera to investigate the application of reflected infrared photography to detect latent bloodstain evidence beneath varying deposited overlaying soot densities. The potential of this technique was examined by photographing blood samples beneath soot from a scaled fire simulation. A qualitative evaluation was completed by comparing images taken of a series of samples using both reflected infrared and standard visible light photography and corroborated with quantitative image analysis to support the findings. Results indicate that infrared photography can reveal latent bloodstains beneath a dense layer of soot in excess of ρ2.3 (550nm) density with substantial clarity. The success of this technique is dependent on specific optical and specimen parameters. These parameters include (i) the reflective properties of the background surface, (ii) the spectral absorption properties of blood and (iii) the ability of infrared wavelengths to transmit through the soot layer. Reflected infrared photography may provide crime scene examiners with a specialised field recording method that is easily executed and non-destructive to assist in visualising and locating latent bloodstain patterns beneath dense layers of soot.

The Effects of High Dynamic Range on Fingerprint Images Processed by Photoshop.

High dynamic range (HDR) imaging is a function that combines five images with different exposures into a single image. This technique may provide fine ridge details of fingerprint images for forensic latent fingerprint examination. Therefore, viewing fingerprints under optimal conditions is of paramount importance. This paper analyzes HDR and non-HDR photos by using the Michelson contrast formula. The Michelson formula will provide a measurement to determine whether better contrast between the background and print can be achieved using the HDR function and if the background color affects the quality of the images. Two hypothesis were tested: (i) the HDR image provides more details of fingerprints with a better tone, greater clarity, and contrast than a normally exposed image regardless of the background color; (ii) the background color does not affect the quality of HDR fingerprint images overall, but the multi-color background may increase the contrast of HDR fingerprint images in some cases.

Forensic photography: Prospect through the lens.

Forensic photography is an indispensable tool in modern forensic odontological protocol which aids in investigative procedures, maintenance of archival data, and to provide evidence that can supplement medico legal issues in court. Proper selection and implementation of the appropriate photography and computer equipment combined with necessary training and correct workflow patterns make incorporating photography into the field of forensics, an easily obtainable goal. The role of the forensic photographer is crucial, as a good skill in photography with updated knowledge of the mechanics and techniques involved is required for proper documentation of evidence. This paper aims to shed light on the various aspects of forensic photography with emphasis on its diverse applications and advancements.

A novel method for the photographic recovery of fingermark impressions from ammunition cases using digital imaging.

The photographic preservation of fingermark impression evidence found on ammunition cases remains problematic due to the cylindrical shape of the deposition substrate preventing complete capture of the impression in a single image. A novel method was developed for the photographic recovery of fingermarks from curved surfaces using digital imaging. The process involves the digital construction of a complete impression image made from several different images captured from multiple camera perspectives. Fingermark impressions deposited onto 9-mm and 0.22-caliber brass cartridge cases and a plastic 12-gauge shotgun shell were tested using various image parameters, including digital stitching method, number of images per 360° rotation of shell, image cropping, and overlap. The results suggest that this method may be successfully used to recover fingermark impression evidence from the surfaces of ammunition cases or other similar cylindrical surfaces.