Laser scanning is widely recognized as the fastest, most comprehensive way to digitize a crime scene or crash scene for documentation, analysis and presentation. Technology advances have made laser scanners increasingly accessible to public safety agencies regardless of budget constraints, but some agencies continue to advocate for professional-grade models. What is the justification for investing in a durable, high-performance instrument when other laser scanners appear to be good enough for the job?
Accidents Happen
The Omaha Police Department uses several laser scanners, including a rugged Leica ScanStation PS50 that provides long-distance scanning with survey-grade accuracy (via true dual-axis compensation) and is designed to withstand challenging environmental conditions. When the agency was called to the scene of a homicide investigation in December 2019, crime scene investigators brought the PS50 as a standard operating procedure for scene documentation. Heavy rain and temperatures in the upper 30s would make capturing the outdoor part of the scene uncomfortable for the laser scanner operator but wouldn’t affect the performance of the scanner.
As the laser scanner operator transitioned between the indoor and outdoor scene, he put the laser scanner on the utility drawer deck in the back of the police vehicle, a Chevy Tahoe. In his haste, he neglected to follow agency protocol, which required the scanner to be anchored or placed in a protective case.
Soon after, a colleague moved the Tahoe to accommodate other emergency vehicles. The unsecured laser scanner tipped over to lean against the back lift gate. Unaware that the scanner was in the vehicle, the colleague opened the lift gate. The scanner fell out and hit the concrete pavement 5.5 feet below.
Reliability Matters
With the housing cracked, the scanner’s weatherproof rating was compromised, so investigators took the P50 out of service and replaced it temporarily with their backup ScanStation C10.
At the next opportunity, the agency performed two-face testing on the instrument, which involves measuring a single target first in front-face mode and subsequently in back-face mode to identify potential misalignments. “We used NIST-traceable targets at distances of 25 feet, 50 feet and 150 feet to perform the test,” explains Omaha PD Forensic Manager William Henningsen, who also serves as a trainer and consultant with Collision Forensic Solutions. “The pole measured well within tolerance, and the delta differences on the two-face measurements were .002′ or less (1/32″). Most deltas were 0.”
The exterior housing of the ScanStation PS50 showed evidence of damage from being dropped 5.5 feet onto concrete pavement, but the scanner continued to perform flawlessly.Sending a laser scanner in for repair is always an inconvenience, but in this case it would have required the department to cancel a scheduled training. Henningsen contacted Dietmar Stadelman and Mark Kolman in Leica Geosystems’ HDS Support, and they advised that as long as the two-face checks were acceptable and the scanner firmware was operating properly, the agency could postpone the repair and proceed with training. The laser scanner was used continuously in a five-day training course and never failed a NIST pole performance check throughout the training.
“After I got over the initial shock of the dropped laser scanner and how it occurred, I was impressed that the unit still functioned properly,” Henningsen says. “A low cost of repair was further evidence of the reliability of the instrument.”
Can you digitize your scene with a laser scanner that isn’t built for durability? Absolutely. But what happens if you drop it?
From easy-to-use entry-level laser scanners, to ultra-high-speed scanners with in-field registration, to high-performance survey-grade scanners and even handheld mobile mapping systems, laser scanners now exist for every agency at every stage of digital workflow adoption. Just make sure you understand all the benefits and drawbacks of the technology before you make your investment.
To talk to a public safety expert and explore which digital scene documentation solutions are right for your agency, please contact us.
Related: Why Your Agency Should Aim for a Fully Digital Scene Mapping Workflow