3D Scanning Technology for Faster Autopsy Documentation
Written by Janujah Sivanandan & Eugene Liscio   


Figure 1—Artec Eva being used to scan a live subject.

 

Originally published: Fall 2017 Issue (Volume 15, Number 3)
View the Digital Edition here

In assisting law enforcement agencies and courts, forensic pathologists play crucial roles in gathering and examining materials that are used to build criminal cases. Utilizing the best tools available for documentation of autopsies is critical to any investigation. A recent study at the University of Toronto in Mississauga, Canada sought to compare photographs and manual measurements with a three-dimensional scanner in the documentation of injuries and bullet trajectories during an autopsy.

Forensic pathologists typically document autopsies with the aid of photography, paired with manual measurements using rulers and tape measures. Over decades, little has changed in imaging autopsies: cameras remain the go-to device. However, as the research underlines, the images cameras generate—regardless of their resolution, technical specifications, and overall visual quality—lack crucial data that only spatial relations between objects can offer.

“A limitation to the traditional approach is that multiple photographs are necessary to give the viewer a sufficient understanding of the location and size of the injury relative to the entire body,” the authors explained in the paper that was published in the January 2017 issue of the Journal of the Association for Crime Scene Reconstruction.

The necessity of geometric information to criminal investigation explains the reliance of pathologists on rulers and tape measures as a panacea to a problem that current 3D scanning technology can easily address. According to the study, “The 3D model of a body presents injuries in a manner that is not only spatially and logically easier to comprehend, but allows viewers to have a clearer understanding of the location and size of injuries relative to other areas of the body.”

A 3D scanner that captures accurate color is also a tremendous benefit to forensic pathologists. High-quality color capture can reveal much beyond the identity of the victim vis-à-vis body modifications. In fact, color can shed light on the varying condition of the body, providing investigators with a richer spectrum of forensic data. For example, the degree of coloring of bodily trauma, including bruises and wounds, may convey the severity of the injury and its progression. More generally, skin discoloration can reflect the body’s stage of decomposition. Add environmental factors to the picture, like the setting of the body’s discovery and weather, and color can act as a timestamp which could be the key piece in the puzzle.

Putting 3D scanning technology to the test

The objective of the experiment was to compare conventional forensic methods to 3D imaging technology. For their experiment, the researchers chose the Artec Eva structured-light 3D scanner to compare accuracy, speed, and ease of use to current documentation methods. Structured-light scanning technology projects a pattern onto a surface, and the deformation data is analyzed and used to reconstruct the shape of the surface. The result is a “point-and-shoot” 3D scanner that enables users to walk around the object being scanned, and point the scanner where needed to create a complete capture.

For this experiment, a live participant was given 11 two-dimensional temporary tattoos on various regions of their body: around the head and neck area, and on both arms and legs. Four 0.25-in. 3D markers in the form of stickers were placed around each tattoo to define the length and width boundaries, as well as one on the nose, one on each elbow, and one on each knee for location measurements.


Figure 2—An example of a two-dimensional tattoo applied to the participant’s skin, along with four three-dimensional markers surrounding it.

The experiment consisted of two tests performed and observed under uniform conditions: one for photography with manual measurements, and the other with the structured-light 3D scanner. The test was also repeated with a FARO Edge ScanArm, a 3D scanner that uses laser technology with a repeatability range between 0.024 and 0.064 mm. This device was used to create reference measurements, as it is more accurate than both manual and Artec Eva methods. The study notes, “[The Edge ScanArm] scanner is less suitable on its own than the Eva for autopsy use because it does not capture color, which is a cruicial detail in injury documentation.”

In the first test, the participant was asked to lie down. To gather measurements, a tape measure was used to record the length and width of each injury, along with the distance to various points on the body (such as the head, soles of the feet, or established landmarks such as the nose or elbow). Close-up and mid-range photos were taken of each injury with a scale, along with full-body photographs.

For the second test, the structured-light 3D scanner was used. The body of the participant was scanned several times. Artec Studio’s geodesic tool helped record measurements of injuries and curvatures. A tape measure was used for straight and manual measurements. A color map was applied to register color. Meanwhile, during the scan, the output on the computer displayed 3D mesh data, or point clouds, which help with adjusting viewing angles and orientations. Notably, they result in meshed surface data which allows for higher resolution. The platform for these scans was Artec Studio software, where the images underwent alignment and fusion for the assembly of the 3D digital replica.


Figure 3—An example of the geodesic tool being used to measure a tattoo on a curved surface of the body.

In addition, the experiment aimed to test the structured-light scanner’s ability to document glossy steel rods for bullet trajectory presentation. Tripods were placed at the sides of the examination table with a mounted steel rod to represent the bullet’s path. Due to their gloss, rods are often hard to capture, especially for structured-light scanners, where the conflicting light sources generate a great deal of noise. Nevertheless, Artec Eva handled the task well.


Figure 4—Screenshot of the bullet trajectory setup in Artec Studio. The green lines circled in red represent the trajectory rods that were successfully scanned by the Artec Eva.

Adding up the benefits

To quantify ease of photography and manual measurements versus 3D scanning, the study utilized a method for calculating efficiency and ease of use. The method constituted a scoring system based on technical difficulty (which could encompass such “hiccups” as software failure that may seriously impede documentation) and the time spent on documentation. The results were immediately evident: While it took exactly 54 minutes and 30 seconds to complete full photographic documentation with manual measurements, the total time for the 3D scanner setup, scanning, and measurements took just 26 minutes and 1 second. A large part of the difference is owed to the speed of up to 16 frames per second with which Artec Eva can replicate complex geometries. Also, the study notes, “the processing time of 85 minutes with the Artec Eva model was not included in the ease-of-use analysis” since this post-processing can be performed after the autopsy itself.

The study concludes that the 3D scanning technology held substantial advantages over current forensic documentation methods. Not only did the scanner record color better than photo cameras, but it could also render rich datasets in 3D without any of the technological complexity. Moreover, the 3D data it generates can reveal and preserve findings more tangibly and efficiently. Of particular note is the apparent “freshness” that the data retains whether now or in posterity. With the new technology, revisiting cold cases is less likely to be hindered by lost, corrupted, or decontextualized data. Forensic pathologists new to a case can simply open the image files, manipulate and examine them from various angles, and acquaint themselves with the visual evidence much more quickly than sifting through piles of pictures or swiping across a gallery of disconnected images. In other words, the difficulty of having to recreate the crime scene is virtually eliminated.


About the Authors

Eugene Liscio is a registered Professional Engineer in the Province of Ontario, Canada and is the owner of AI2-3D, a consulting company that specializes in 3D forensic documentation, analysis, and visualizations. Liscio has testified in court in both the United States and Canada utilizing 3D technologies, and has also provided interactive 3D crime scene reconstructions to aid the jury. He has been called to aid police agencies in Canada and the U.S. and was retained to assist the Ontario Provincial Police in the shooting at the Canadian House of Commons. He is a past-president of the International Association of Forensic and Security Metrology and is an Adjunct Professor at the University of Toronto, where he teaches a 3D Forensic Reconstruction and Mapping course as part of the Forensic Sciences Program. Liscio is actively engaged in research and mentoring students focusing on 3D documentation and analysis techniques.

Janujah Sivanandan specialized in Forensic Biology at the University of Toronto. She was the Marketing Director for University of Toronto Mississauga’s Forensic Society from 2013-2015, helping to promote the Forensic Sciences program at the university. She has presented her forensics-related work at the Toronto Police Service’s Forensic Identification Educational Training Conference. Sivanandan recently completed her Masters in Health Informatics and is now a credentialed trainer for a well-known electronic medical record software program.

 
< Prev   Next >






Crime Scene Revisited

Faces of the victims recovered from the scene of a genocide.

Read more...