Speed Scanning: Tactical Positioning of the Laser Scanner (When It Has To Be Right – AND FAST!)
Here’s the setting…a man is lying dead in the street. Expended cartridge cases are strewn about…9mm, 40 cal, maybe more… Miscellaneous items of UNKNOWN VALUE are spread up and down the block…or around the parking lot…or at various places around the park…wherever it is that you are working. Thunder rumbles in the distance. No, this is not the beginning of the next great mystery thriller…okay, so it may be that also…but what it is, is the beginning of MANY, MANY crime scenes that are worked across the country, every single day.
Leica ScanStation 3D Laser Scanners serve one primary function: to scientifically and accurately depict spatial relationships in three-dimensions of objects or areas scanned. Yes, most laser scanners today have a camera onboard as well to colorize the points for a more “realistic” view of the scanned area, but photos are not needed for valid scan data. When time is of the essence, leaving the camera off just may be your best bet!
The Leica ScanStation, for example, will scan in the dark and in virtually any weather conditions, and the results (without the accompanying photo set) can be rendered as an intensity map (rainbow coloring) or a grayscale rendering of the scene, each presenting a measured value for the reflectance of the objects scanned (see below).
Of course the third in this series of the Kansas City Liberty Memorial (World War I Memorial and Museum) is using the “Colors From Scanner” view applying the photo colors (“multi-image”) to the captured point clouds. This is done primarily for aesthetics and is included here for comparison.
I can be pretty obsessive when it comes to aesthetics…I love coverage and try and fill-in as much background with my scans as possible. HOWEVER…when time is of the essence, sometimes you just have to MOVE!
To experiment on the topic, I undertook the task of scanning the Platte County R-III High School football stadium with my Leica ScanStation PS40. Special thanks to Riverside Police Sergeant and Platte County High School School Resource Office for facilitating the scans.
Here is a snapshot showing the results of my scanning, with the location of each of my ScanStations depicted by that familiar yellow triangle.
So, my stats ended up as follows for the day: 22 Scans Completed in….yes, drum roll please…
1 hour, 3 minutes, and 5 seconds.
That was a running clockand while I was on a tripod dolly for the first 17 scans, the last 5, I left the scanner in place on the tribrach, and carried the scanner by hand for each move down the field. TOUCHDOWN, the crowd goes wild!
Of the data collected, 17 of the 22 separate ScanWorlds were at 12.5mm at 10m (52 sec/scan) resolution followed by five scans moving down the crest of the football field at 6.3mm at 10m (1 min 42 sec/scan), all captured using speed scanning, or tactical scanning techniques.
Level the Instrument
Hit Standard Set-up
Move to the Next Position
This process of speed scanning and tactical movements around my scene allowed for an average scan time of under 3 minutes per position. For the whole 1,394,000,000 points that were collected, it was less than 368,295 points per second including moving the scanner from position to position.
One of the reasons that I could use such low resolution (low for the instrument…12.5mm at 10m really isn’t that bad!) was because my moves were not greatly spaced (see the video below).
The above “Fly-Through” animation was made in Leica’s Cyclone software suite.
Gathering over 1 billion points (1,394,000,000 to be exact) from 22 different positions just over one hour….that should be enough to impress anyone.
However, this was simply a demonstration of a REAL WORLD problem. But…how about a translation into the REAL WORLD?
On April 13th, 2014, I worked what would be one of the most unsettling crime scenes of my career. That is in fact me, bundled up above.
What would become known simply as the Jewish Community Center Shooting was actually a triple murder occurring at two different locations with several additional victims who survived the event. Those taken included Dr. William Corporon and his grandson Reat Underwood at the Jewish Community Center (JCC) in Overland Park, KS followed by Terri LaManno at the Village Shalom living community, also in Overland Park.
The suspect was taken into custody shortly after the second shooting event. Frazier Glenn Miller was a neo-Nazi who set out that day with hate in his heart and took the lives of three innocent people who were simply going about their everyday lives. Miller, who represented himself at trial, was found guilty on all counts against him, and he was ultimately sentenced to death. Survivors of the event and family of those lost have strove to make the community stronger from this hateful tragedy.
At the crime scene, a struggle ensued, as our CSI team prepared to do battle with mother nature. We fought intermittent storms that were heavy with reports of potential tornadic activity. I reported in a LinkedIn post on weather resilience and that was a HUGE factor at the JCC scene as we deployed our Leica ScanStation C10 (also known as the PS10). But the other factor here was speed.
The below images have been created using aerial shots of the JCC taken subsequent and independent of the investigation at that site. These are not court exhibits nor do they represent the evidence or exhibits used in the case against Frazier Glenn Cross. These images were created solely to depict the concept of tactical scanning at a crime scene.
The above image is the Jewish Community Center site itself. Now let’s say that we had evidence…marked below with yellow-highlights and the red letter “E”… spread throughout four primary zones at the site:
A booming storm was my concern, so quickly scanning through this crime scene was my goal. Like I said earlier, I am a stickler for coverage. But as the storms rolled in, the temperature dropped, and eventually even the sleet began to fall…my goal became singular: speed scanning to fully capture my pertinent scene.
On Day #1, I scanned from nine (9) positions to ensure full coverage of all of the evidence, relevant vehicles, and damaged areas from the shooting event. The scan positions are represented by the yellow triangles below (the locations depicted below are approximated and this is not translated directly from the evidence or the scan data).
By the end of Day #1, the outdoor evidence had been addressed and the scene was secured and guarded for the night. The CSI team returned on Day #2 to do a follow-up search and collect additional data from the site, both outside in the parking lot and inside the JCC White Theater, where many of the impacts had landed as a result of the shooting event.
I collected a total of twenty-nine (29) scans from the JCC. The nine (9) from Day #1, and then with bright, sunny skies, and mild temperatures, an additional 20 (20) scans from both the scene in general including indoors at the White Theater:
I scanned areas that were at the fringe of our known crime scene and a little beyond. I knew that every inch of this site had been searched, and given the gravity of the event, that it would be viewed in 3-D over and over again, as answers were sought. Even when you have a suspect in-custody and confessing, the search for answers doesn’t end. This data would be used for scene reconstruction, depictions of witness views, and in the creation of powerful court exhibits that would help Johnson County (KS) District Attorney Steve Howe to successfully present this complex crime scene.
3D laser scanning need not be a huge time-drain at your crime scene. If the weather agrees and a scene’s complexity leads to a lengthy scan day, so be it. But if time is of the essence, then float like a butterfly and sting like a bee…stick and move…or actually, scan and move, scan and move.
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