Forensic metrology – the needs of law enforcement and security to capture existing-conditions data – was the focus of a well-attended new track at SPAR 2006. Presentations vividly illuminated how 3D laser scanning technologies, both terrestrial and close-range, are aiding crime scene investigations and accident reconstruction cases. Attendees saw numerous examples of the quality, completeness, speed and safety advantages of high-data-density optical metrology over traditional methods, and heard how evidence gathered with laser scanning has crossed the admissibility threshold in criminal and civil courts in numerous jurisdictions in both the U.S. and Europe.
Carl Adrian, Visual Information Specialist – Examiner, Laboratory Division, from the FBI‘s Special Projects Unit (SPU) in Quantico, VA keynoted the sessions. Duncan Lees, 3D Team Leader with Plowman Craven & Associates, Harpenden, UK; Willem van Spanje, Managing Director of DelftTech BV, Delft, The Netherlands; and Steven Schorr, President of DJS Associates, Abington, PA, and Andrew Durian, Accident Reconstruction Specialist with DJS, also presented. Moderator was Paul Francis, Vice President of Northway-Photomap Inc., Toronto, Canada.
Reconstructing and analyzing human remains
Adrian detailed how, in his role as forensic artist and sculptor, he has exploited close-range laser scanning technology to perform skull reconstructions, superimposing a 2D photograph on the resulting 3D virtual model. For this, he developed a method of scaling the virtual model from the photograph: he has created virtual eyeballs, 25mm in diameter, working from the known dimension that the human iris is 12mm in diameter. From this, the skull can then be scaled, together with the iris in the photograph. The aim of this process is to narrow the possibilities of whom the victim might be.
Lees told how Plowman Craven first utilized custom-built close-range laser scanners to record living humans and objects for the film industry, and subsequently began using this technology in forensic environments. These scanners, which Lees reports can capture tolerances finer than a human hair, can be used to record pathology, disease or trauma present in human remains, to aid forensic pathologists and forensic anthropologists in determining the cause and manner of death.
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Jury impact
Precise 3D measurement can be a high-impact tool for portraying a story to a jury. Adrian described a practice he uses to educate juries as to the size of a location where a crime was committed – he takes a blueprint of the courtroom in which the jury is seated, and graphically superimposes a 3D model of the crime scene (created in Maya) on the 2D courtroom blueprint. The aim is to give the jury a clearer grasp of scale and distances in the crime scene, and of how quickly a perpetrator could have moved through the scene. Adrian first employed this technique in the Exxon Valdez case to communicate the size of the ship to the jury, using the entire multi-story courthouse as a comparison.
Analyzing bullet trajectories and blood spatter
Adrian of the FBI and van Spanje of DelftTech both discussed how 3D laser scan data of bullet trajectories and impact points makes it possible to calculate the position of a firearm at the time of discharge, and to determine the height of the perpetrator. This 3D information may also be combined into the scene model.
Another technique described by DelftTech uses a combination of close-range laser scanning and photogrammetry to provide a new 3D modeling solution for bloodstain pattern analysis. This technique, according to van Spanje, is a revolutionary advance over the conventional method of measuring and recording with strings.
Bomb reconstruction
Close-range scanners with submillimeter accuracy can be used effectively in bomb reconstruction. Adrian reports he wishes he had this technology to use in the Unabomber case, which would have enabled working from recovered bomb fragments to digitally reconstruct the explosive device in 3D. Instead, the fragments were measured by hand, and Tektronix’s TekniCAD 2-1/2-D CAD software was used to produce isometric renderings that enabled the FBI to warn the U.S. Postal Service how to recognize such devices. 3D laser scanning, Adrian notes, could have sped up delivery of this potentially life-saving information.
Urban modeling applications
Urban modeling for forensic purposes was another application described by DelftTech. This involves the combination of 3D laser scanning, photogrammetry, and lens distortion software to create a “4D virtual reality” crime scene management training program. According to van Spanje, this photorealistic graphical modeling technique has been used to train Dutch police, and his firm anticipates its use by German and Swiss police as well. This application, which may be provided from the standpoint of either investigator or instructor, could be utilized for any location and has obvious applications in security training.
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Rapid response
The ability to rapidly capture spatial data in the initial phase of crime scene investigation can revolutionize the way in which senior officers conduct briefings for investigative personnel, observed Lees of Plowman Craven. Further, the point cloud is a rich data set not only for visualizing a scene, but also for rapid-response situations such as hostage settings, where a laser scan of an environment immediately allows police to see what is visible within an area and what is not, and thus to identify viewpoints and position personnel accordingly.
A role to aid law enforcement undertaken by DelftTech, in the event of a crime having been committed and the perpetrator(s) captured on surveillance cameras, is to quantify the suspects’ measurements for the police that same day, within hours of the event.
Scene preservation; investigator safety
For crime scene investigations, the remote survey nature of 3D laser scanning is fundamental to its value – non-invasive documentation can take place from a distance that will not risk contaminating the scene or compromising its integrity.
Safety is a key benefit that laser scanning offers forensic accident investigators who need to record a roadway without closing traffic lanes, for example. The technology can also be more labor-efficient. Schorr and Durian of DJS pointed out that the quality and completeness of data captured by laser scanning means that data collection can proceed even in the event that the forensic engineer – the professional who will analyze the data – is not able to be present at the scene to oversee data gathering, as properly executed scanning will capture tire marks and all other relevant detail.
Forensic track spawns International Association of Forensic & Security Metrology
One outcome of this track was the formation of the International Association of Forensic & Security Metrology (IAFSM). The association will be open to law enforcement people and governmental organizations all over the world. Its first order of business is to set up forensic laser protocols for crime scene investigation, set up IAFSM-certified training, and develop an expert group for laser scanning large crowd events, disasters and terrorist attacks. (We earlier reported the group’s provisional name of “International Association of Forensic Laser Scanning,” which on reflection was decided to be needlessly restrictive.)
Officers of the association include chairman Willem van Spanje (DelftTech) and vice chairman Duncan Lees (Plowman Craven), and founding members include Carl Adrian (FBI) and Daniel Livecchi (U.S. Secret Service). Spar Point Research will work closely with this new organization to provide its support.
The organization’s motto is “To Save Lives” – a goal the IAFSM will support by spearheading the optimum recording techniques necessary at crime scenes. Of course the organization shares the overarching aim of all crime scene investigative personnel – to bring perpetrators to justice, and help provide closure to victims. 3D laser scanning is proving a highly efficient tool to advance these objectives.
