Fast Point Cloud Processing Speeds Plane Crash Investigation
By Michael Cunningham, Jan. 22, 2015
As a retired NYPD detective, my goal is to see Leica Geosystems’ clients ready to spring into action when the bell rings. That’s why I appreciate opportunities to come alongside them outside of manufacturer training.
One such event was the 3D terrestrial scanning conference held by the Kansas Bureau of investigation in Wichita last May. Many Leica technology users were present, including Crime Scene Supervisor Cory Rodivich, of the Wichita Police Department Crime Laboratory. Since the two-day conference was held in the city known as “The Air Capital of the World,” it was fitting that we visited the Kansas Aviation Museum airfield to scan a plane produced in Wichita—the Boeing B-52 Stratofortress bomber.
That was a practice aviation exercise. We didn’t know that a few months later a Beechcraft King Air 200 would crash into the FlightSafety International Cessna Citation Learning Center at Wichita Mid-Continent Airport, killing the pilot and three people inside the building.
Challenging Scene Requires More Efficient Data Collection Techniques
The Wichita Police Department Crime Laboratory transitioned from total station to Leica ScanStation PS10* in September 2013. When the plane crash occurred in October 2014, the CSIs had built a good deal of scanning experience with 20 scenes under their belt. But they’d always chosen to take the extra time on scene to set targets in exchange for faster and easier registration in the office.
However, this wasn’t a cleared scene. In fact, this incident was still in the response phase and presented serious time, documentation and safety challenges. Responders were everywhere. Fires were flaring. The building, which was in danger of collapse, was surrounded by a 25-foot safety zone. On top of all that, firefighters were discussing partial demolition for recovery efforts.
Rodivich realized their 12- to 15-minute target-based routine wouldn’t provide the efficiency he needed to document this hectic scene. He also knew from our previous discussions that Leica Cyclone 9.0 3D point cloud processing software, launched just weeks earlier, featured new registration capabilities that would enable him to both eliminate targets and register the data with ease. While the crime lab didn’t yet have Cyclone 9.0, the CSIs did have an advanced software training with me in a matter of days. Rodivich decided to go without targets knowing that Leica and I would help him get the data together.
Data Capture in Record Time
At the end of the day, Rodivich and his team captured the entire building in 12 setup positions at approximately six minutes per setup. That’s half the time of their target-based routine, which is significant. They documented so efficiently that, when you look at the scans, you can see noise from the smoke because the scene was still smoldering.
Had they documented the scene by hand, Rodivich said it would have taken eight to 10 hours and the CSIs would have walked away with 100 or so measurements. In contrast, the scanner captured millions of data points and a dozen 360-degree panoramic photographs in less than 90 minutes.
New Cyclone 9.0 Tools Make Targetless Registration Easy
Typically, targetless registration is a tedious and time-consuming procedure, which is one of the reasons Rodivich had always shot targets. But when I arrived for the team’s advanced software training, we were able to put together all 12 scans in less than an hour with Cyclone 9.0. It could have taken three or four hours with prior versions.
Before Cyclone 9.0, targetless registration was only possible through a cloud-to-cloud routine in which users open two scans in separate windows, arrange them side-by-side, and identify common points. When enough points are selected, the scans are stitched together. Then the next one in the batch is opened, and the process is repeated until all the scans have been united. While it seems easy enough to find common points, when you’re looking at point cloud that’s made up of 30 million points and you’re trying to pick out individual points out of each scan that are a near perfect match, it’s challenging, especially for new or infrequent users.
In contrast, Cyclone 9.0 has made targetless registration easy with two new tools which work hand in hand: Automatic Initial Alignment and Visual Alignment. When users select Automatic Initial Alignment, many, if not all, of the scans are automatically aligned and registered upon import. To optimize the process, Leica recommends that users capture at least 20 percent overlap between scans. When the software algorithms find enough common features, it aligns the scans. In this particular case, Cyclone 9.0 automatically aligned most of the 12 scans for us. We just had to finish up with what the computer algorithms couldn’t do.
For that, we used the new Visual Alignment tool. This simplified manual routine brings up a pair of scans in a single window. The scans are displayed from an overhead view and in contrasting colors. One scan is colored orange and locked in a stationary position. Users drag and rotate the second scan, colored blue, over the orange scan until the two are aligned. This new routine is 40 percent faster than cloud-to-cloud registration (which is still available) making it not only much more of an intuitive and visual process but also a big timesaver.
Doubled Efficiency With High Accuracy
Of course, doubled efficiency on scene and in the office means nothing if the data can’t stand up in court. To validate the accuracy of the scanner, Rodivich set a NIST-certified Leica twin-target pole in select scans; this can be used as an interim validation method even though no targets are acquired for registration purposes. A printable Cyclone registration report, which documents accuracy, error statistics and histograms, validates the new Automatic Initial Alignment and Visual Alignment registration procedures—both of which were highly accurate and on par with target-based registration.
No doubt, this tragic multifatality airplane crash presented a number of unusual documentation challenges. But, when the bell rang, Rodivich and his CSI team had the flexibility and support they needed to double their efficiency on the scene and in the office with no compromise to accuracy. As Leica’s public safety group training and services operations manager, I couldn’t ask for a better outcome.
For more information about laser scanner training for public safety professionals, click here.
**Identical to the C10.
About the author: After a 26 year career, Mike Cunningham retired from the New York City Police Department in 2012 as a Detective 1st Grade and the senior ranking Investigator in the Crime Scene Unit. In addition to his many years of CSI experience, he was a forensics instructor for the NYPD and is a Certified Instructor for Department of Homeland Security course “Advanced Forensics for Hazardous Environments” and “Integrated Response to WMD Incidents.” As a contractor for the U.S. State Department, he served as an International Police Instructor for “Forensic Examination of Terrorist Crime Scenes” delivered to U.S. anti-terrorism partner nations. Mike served his country with distinction and professionalism for ten months at Ground Zero in the aftermath of September 11th. He is an IAI Certified Crime Scene Investigator and a New York State Certified Police Instructor.