The 3D Advantage

Laser scanning as a method for crime and crash scene documentation is continuing its rapid adoption among law enforcement agencies who want to capture as much evidence as possible and to make court presentations tighter. The trend is occurring both throughout the United States and internationally. Although a scanner’s price tag is higher than those of other mapping tools, the completeness of scene depiction and abundant scope of evidence it captures seem well worth the investment. Many agencies don’t hesitate to adopt scanning because they know a solid crime investigation depends on thorough collection and analysis of different kinds of evidence, such as bloodstains, bullet trajectories, DNA, tire tracks, fingerprints, shoe prints and crushed vehicles, among others. 

 

But scanning goes way beyond just sweeping a scene and producing millions of evidence data points. What really makes scanning so compelling is its ability to produce a 3D model of a crash scene showing the complete scene exactly as it looked once a collision occurred and vehicles came to rest. Today, point cloud software is used in conjunction with the 3D laser. The scanner measures a large number of points on the surface of a crash scene, then outputs a point cloud as a data file. The point cloud represents the set of points that the scanner has measured. 

 

When an activated scanner glides across a scene, it produces a complete dome scan that would measure skid marks, gouge marks, a complete surrounding of the scene so no return visits to the crash scene would be needed. 

 

“That has really paid off over the years because a case develops and witnesses come forth, depositions are reviewed, and additional things come up (that might require returning to the crash scene),” said Dave Buerger, director of operations and a former law enforcement officer with Transcon Imaging Solutions, an Anapolis, Md., firm offering expert witness testimony concerning motor vehicle collisions involving litigation and a crash reconstruction consulting service.

 

Transcon Imaging Solutions uses a Leica C-10 ScanStation laser scanner with its point cloud software to create courtroom-ready 2D and 3D diagrams and animations from the “point cloud” of data produced by the 3D laser scanner. The software produces detailed diagrams, and when the scanner’s point cloud and diagramming software are used together, the diagram is displayed along with the point cloud so that the investigator can work in either window. This allows the investigator to move through the 3D environment of the point cloud, placing symbols, drawing lines, arcs and curves. Thus, the diagram is built instantly in a second window based on the exact coordinates of the points selected from the cloud. 

 

Thanks to television’s exaggerated portrayal of forensic evidence on crime shows—the so-called “CSI effect”—juries have come to expect the level of detail and animation offered by laser scanning. But this trend also becomes a two-way street because the scanning technology now allows investigators to both educate and wow juries with gripping perspectives of what drivers saw just before vehicles impacted, along with perspectives of the scene from witnesses. Generally, in courtroom presentations, “The jury is blown away,” according to Glen Reuschling, owner of Transcon Imaging Solutions and a retired Maryland State Trooper. However, he clarified, “There’s always a chance of a challenge of your demonstrative evidence, which comes in the acceptance of evidence.” Still, the laser scanner can capture substantially more evidence points than other technologies and give complete scene detail and from various vantage points. Furthermore, Reuschling added, “A 3D laser is accurate to within centimeters.”

 

The vantage points that scanning can offer can be crucial to a court presentation and to how a jury will decide on a court case. Jason Fries, CEO of 3D-Forensic, a San Francisco, Calif.-based company that performs laser scanning and forensic animation for its clients, believes it’s important that any court presentation of laser scanned scenes should help explain why a crime or crash scene came to be, not just how. In fact, Fries said his firm has used scanning from its infancy, before it was adopted for forensic use. Crash scenes comprise a large share of 3D-Forensic’s work and they take all forms, not just passenger vehicles. For instance, a “unique vehicle,” as Fries calls it, may be a tractor/trailer, earth moving equipment, front loaders or, say, a vehicle for picking up 50 logs and moving them. “When you have to recreate an accident with vehicles of this size, the laser scanner is immensely helpful because we can create a 3D model of it, with line of sight issues to show what a driver could see or could not see,” Fries said. 

 

Another way that Fries sees scanning as helpful is for volumetric scans. For example, Fries recalls a single-car accident where the driver lost control at a high rate of speed (about 100 mph), collided with seven trees, rolled over a few times, yet at the scene there were no witnesses. Two passengers were in their seats at the time of impact, but one was dead, the other survived. At issue? Who was driving? “We were able to laser scan this vehicle which was very badly damaged,” Fries said. “We performed the scan for volumetrics to find out what percentage of the space in the driver’s compartment was gone compared to just before impact. We discovered that the driver’s area lost about 70%of its volume and that the passenger side lost 12 percent of its volume.”  

 

The scanning enabled 3D-Forensic to determine how much vehicle crush occurred in the driver’s compartment compared to the passenger’s compartment. This led the firm to conclude that because of the huge amount of crush in the driver’s compartment that the driver should have more injuries. This helped show That the driver had died. 

 

“Laser scanning shows us how the car got crushed, which may help explain what the vehicle with the two passengers hit, how it struck something else and injuries that may have happened inside the vehicle,” Fries said. The surviving passenger was charged with second-degree murder because the vehicle was registered to him. It also was evidence he wasn’t wearing a seatbelt. 

 

Fries used a Leica ScanStation C10 along with MapScenes to capture data and produce 2D line drawings because, he said, “It’s quick, effective and easy.” For 3D views of the crash, Fries also used MapScenes to create a 3D model of the crash reconstruction to perform analysis. 

 

Detective David DeLeeuw, of the Ocean County (N.J.) Sheriff’s Office/Crime Scene Investigation Unit, has been a longtime scanner user and still deploys a Leica ScanStation 2 that was acquired in 2009. In fact, his agency was the first in New Jersey to acquire scanning technology. 

 

While Det. DeLeeuw acknowledges that a total station was the crash reconstruction tool of choice before scanning technology was developed, he prefers scanning as it not only gives more evidence points, but also does not require two operators, can scan a scene without the user having to be directly in the scene itself, and collects scene data in far less time than a total station. But it’s the detail scanning offers that makes this technology so valuable. With A car crash, for example, “The scanner can map sides of a car, vehicle crush, circumference of the wheel, wheel diameter, curvature of bumpers and glass,” Det. DeLeeuw said. If a car hits a telephone pole, the scanner can even capture the actual diameter of the pole. 

 

Another advantage of scanning is that it can help provide perspectives of what people most likely observed in a scene, whether they were directly involved or just witnesses. Since one version can vary from another, scanning the entire scene is crucial to prove or disprove claims of who saw how events unfolded. To analyze claims of what people said they saw during the crash, Det. DeLeeuw uses a feature in Leica Cyclone 3D point cloud processing software—which he uses with his laser scanner—called witness viewpoint. The detective places a camera view anywhere within the scan data, then witness viewpoint allows him to quickly generate the eyewitness’s line of sight. The feature is very powerful because it allows him to debunk or corroborate a claim that a witness saw something or a specific chain of events.

 

The reason scanning has become so popular is that the evidence it can collect is powerful for courtroom presentations. Most courts will accept scanned evidence of crash or crime scenes, aided by an official verdict. In 2013, a U.S. Federal Court issued a Daubert ruling affirming the scientific validity of Leica ScanStation evidence. 

 

Private crash reconstructionists like David Dustin, owner of DJD Dustin Forensics, an Adairsville, Ga.-based consultancy that specializes in 3D accident reconstruction and animations, considers it essential for jurors to understand how laser scanning works and why its evidence is so important. “We count on the CSI effect because it prepares audiences to expect the kinds of presentations we give through scanning,” said Dustin, who uses a FARO X330 scanner for his crime and crash scene documentation. FARO scanners are minimal in size and weight to most other scanners, and operate via integrated touchscreen display. To help a filled courtroom appreciate scanning’s power for one of his cases, Dustin scanned the courtroom ahead of time, before the trial. 

 

“When it came time to present the data, the district attorney asked me to display this scan to the judge and jury and other people in the courtroom,” he said. “As we flew down from the ceiling (via the scanner) and everyone was able to see the room they were sitting in, to see the seats they were sitting in, it was amazing for them. That set the stage, then we proceeded to present the laser scans we had captured for the case.” 

 

Oftentimes, vehicles can become part of a crime in progress, and scanning can be useful when this occurs. Such was the situation when Dustin was asked to scan a scene involving a gang altercation that led to a vehicular homicide. Four gang members and one other person engaged in a fight in front of a convenience store. The single person was beaten by the gang, then his body was left in a street in front of the store, after which it was run over by a car. He died as a result. The case would have been hard for jurors to understand during trial. Dustin scanned the scene, showing distances within parts of it. He inserted characters into the scan to represent parties involved—the decedent and the aggressors. He also took still frames from the surveillance cameras mounted outside the convenience store and placed a virtual camera in the same location as the surveillance cameras. “Then, we placed an overlay from the frames in front of the camera,” Dustin said. “This allowed a fly-through visual representation through the scene to show where the characters were located as the altercation began to where the decedent was eventually lying.”

 

Another scanning offering is the SceneVision-Panorama from 3rdTech, a maker of 2D and 3D graphics and imaging products. The SceneVision-Panorama starts documenting a scene by taking a 360-degree array of photographs using a panoramic tripod head. The company claims on its website that a complete circular view of a scene can be achieved with its system in less than four minutes, and photos of a dozen different panoramas can be done in less than one hour. SceneVision-Panorama includes software that automatically blends the user’s individual photos into a single, smooth, high-resolution, panoramic image. 

 

Joel Salinas, a veteran crash reconstructionist and experienced trainer on 3D laser scanning and point cloud/diagramming software, teaches law enforcement agencies the basic skills for scanning crash scenes. He initially shows students how to scan and build 2D diagrams. If students want to master the 3D level, Salinas advises them to get six months to a year of experience using a scanner and drawing software, then he can teach the students a follow-up advanced class afterward. Salinas specializes in training with Leica laser scanners and MapScenes Forensic CAD desktop forensic mapping software. 

 

Although any technology for crime and crash scene mapping has limitations, law enforcement agencies in both the U.S. and around the world are finding laser scanning to be well worth the financial investment for the massive amount of evidence it can collect and for yielding a complete view of the actual scene whether it’s a crime or crash. This technology combined with comprehensive forensic drawing software makes these highly valued tools able to document scenes quicker than most other tools and whose evidence can be powerful and credible in court presentations.