Laser scanning technology has become a typical way of capturing the necessary evidence points when documenting a crime scene. A point cloud, the end result of the laser scanner’s methodical sweep of the scene, becomes crucial to investigators. This is because the millions of evidence points collected can be integrated with a powerful CAD drawing program that yields revealing details about the crime scene; often unmatched by other technologies. Laser scanning and point clouds make scene documentation efficient, save time, and can be used to build a compelling 3D representation that is detailed, clear and often unchallenged in courtrooms.
The beauty of point clouds is that they provide a complete scan of the scene, so much so that once the scene has been scanned, no return visits to it are needed. This is important because as a case develops and witnesses come forward, depositions are reviewed and new findings may arise. Though returning to the physical crime scene is not an option, the point cloud contains every single evidence point as documented at the time of processing. What’s more, if law enforcement professionals need forensic analysis that is outside of their area of expertise, they can share the point cloud data with experts who can use it to rebuild the scene.
The point cloud greatly aids investigators by enabling them to create courtroom-ready 2D and 3D diagrams and even animations from the point cloud of data points gathered by the laser scanner. Additionally, a 3D laser usually is accurate to within millimeters.
Although Powerful, Scanning Not Widely Used
As superbly thorough as laser scanners have become in collecting evidence and replicating crime scenes, they are not foolproof. Such is the reason that the Omaha, Neb., Police Department Crime Laboratory uses several tools for scene mapping: a robotic total station, a GPS GNSS rover unit and a Leica C10 ScanStation laser scanner for creating a 3D point cloud.
"For many scenes, we’re creating a 3D point cloud, unless we need exceptionally accurate measurements on individual pieces of minute evidence, such as blood spatter or cartridge casings," explains Will Henningsen, a criminalist and shift supervisor with the laboratory. "The laser scanner may not fully document these types of evidence."
For example, he noted the level of scanning needed to document something as small as, say, a .22-rimfire cartridge casing is often prohibitive, so a total station would be used instead.
Although there has been much news and information on laser scanning and point cloud technology, these methods are not yet widely used according to Henningsen, who notes that the most common method of scene documentation, whether a crime or crash scene, is via hand measurements using a tape measure or Rolatape, or a total station. In fact, the Omaha Crime Laboratory is the first in that state to deploy scanning and use of point clouds.
They have been used for about a year.
Diagrams Once Hard To Generat While laser scans and point clouds give amazing detail once plugged into a diagram, agencies that were early adopters of these tools found it difficult to generate the drawings. The reason was that drawing programs were not advanced enough up until, say, 2010, to create a drawing from a point cloud. One company that addressed this challenge, however, was MicroSurvey Software, Inc., whose Map-Scenes Forensic CAD 2013 produces scaled diagrams that are powerful when used for court presentations. The software offers two separate modules for animation and point cloud usage. The point cloud module allows the user to import and visualize the point cloud and provides several tools for building a drawing. The animation module, which works seamlessly with the point cloud module creates animations either within the point cloud or as stand-alone animation.
Software Easy For Users at Any Level
Henningsen’s career has included considerable work wit forensic video, which explains why he feels so strongly about the need for appropriate display technology as part of crime scene representations in a courtroom. The Omaha Crime Laboratory uses MapScenes Forensic CAD along with the point cloud and animation modules.
"What this software does is to allow people (users) to properly demonstrate this data at many different levels," Henningsen says, noting that diagrams can be in 2D or 3D. "This process gives us diagrams that are sound, well documented, and well accepted in court." Point clouds can be demonstrated with animation, cut-away views, and snapshots. MapScenes typically is used with its Evidence Recorder product, which both records evidence points from a scene and allows the user to see his drawing being made at the crime scene so that he has confidence the data is accurate and representative of all relevant scene details.
Courtrooms in Douglas County, where Omaha is located, do not have the capability to digitally display diagrams or laser-scanned point clouds. Thus, Henningsen pursued trying to furnish the courts with equipment to properly display crime scene presentations along with video and other technology. Mobile units armed with 72-inch screens and integrated computers were proposed, but have not been purchased. Instead, the Omaha Police Crime Lab transports its in-house equipment to the courtrooms to offer 2D and 3D views of crime scenes as well as animations to courtroom audiences. Henningsen’s laboratory has a formal contract with nearby city of Bellevue, Neb., to provide these presentations for their crime investigators, and also performs work for federal agencies, including the FBI and OSHA.
Solid Display of Evidence With Software’s Versatile Toolbox Once law enforcement professionals are trained on the use of scanners, point cloud technology, and CAD drawing, these tools become invaluable in the field. Detective Sergeant Pete Thompson with the Kings County, Calif., Sheriff’s Office agrees. Shortly after having such training, he was faced with a homicide scene to be mapped. The homicide victim was found in a car, shot to death. A 3D view of the scene was needed, and the drawing software made it easy to pull up any measurements. Thompson used a Leica ScanStation and then fed the point cloud into his drawing program.
"It was the first time we used the scanner to measure a crime scene," he says. Then he plotted the evidence points using his drawing program, which proved swift and easy. Using the software, Det. Sgt. Thompson was able to insert trajectory rods (for the bullets that had entered the doors and windows) as part of a 3D view of the incident.
"You can bring all of this up on a computer, print it out, and then view in a courtroom," Thompson says. "It shows specific evidence because people lie, but the evidence doesn’t." Also, when 3D views of crime scenes are mapped with a laser scanner and displayed in a CAD drawing program with point cloud processing capability, other capabilities factor in:, such as different types of text, labeling, arrows pointing to evidence, symbols such as grass, trees, curves and elevations and layering to show differing perspectives of the scene.
Prior to using scanning and CAD drawing software with point cloud processing, Thompson says that he and his crime scene reconstruction team had never created full-scale drawings. Now, with these technology aids, "Our drawings are to scale, and you can know how far everything is from another point. This allows us to document more efficiently and professionally," he says.
Technology Education Crucial for Legal Professionals
For years, it was nearly impossible to introduce 3D diagrams and animations as part of court cases, because judges simply wouldn’t allow it. But with the precision and accuracy of laser scanning and point clouds, courts have reversed this stance. Henningsen has helped ensure acceptance of these technologies by demonstrating how they work for those parties involved in court cases. "We involve defense attorneys in the process of preparing a case by showing them how scanning and point cloud-based diagrams work," he says. In fact, Henningsen adds, "We assume they have measurements or points of view that they want included in the point cloud." Henningsen has also launched a public education campaign with all county attorneys throughout Nebraska, public officials in Omaha and defense counsel in pre-trial consultations. "This gives them a chance to ask for inclusions or to raise objections," Henningsen says.
The impact of 3D representations of crime scenes in court is substantial. Typically, a witness needs to make a variety of qualifying statements to make his/her testimony accurate and understood. Precise descriptions of location and direction are commonly confusing to the court. But Henningsen emphasized that scanning and point cloud technology remove this barrier by adding visual context. Technical statements and testimony are bolstered by these technology tools. "This makes it difficult to create doubt about a witness’s statements or the evidence found at the scene," Henningsen says.