Bergen County, NJ Fatal Crash Unit Appreciates CZ Point Cloud

For more than 12 years, the Fatal Accident Investigation Unit (FAIU) of the Bergen County, New Jersey, Prosecutor’s Office used The CAD Zone’s Crime Zone software to document crime and crash scenes. When the agency acquired a Leica ScanStation C-10 laser scanner the investigators tried using the point cloud software that was included with the scanner. They found that they could easily scan a scene, but they struggled with creating courtroom-quality diagrams from the resulting point clouds.

Detective Andrew Rich, a 14 year veteran of the Bergen County FAIU (now retired), evaluated The CAD Zone’s CZ Point Cloud software and he quickly determined it was ideal for creating crime and crash scene diagrams from scanned data. He appreciated the many tools included in CZ Point Cloud that are specifically for generating 2D diagrams – which are critical for most investigations. Only CZ Point Cloud makes it easy to work within a point cloud and accurately select the evidence points you need to build both 2D and 3D diagrams.

Why Scan a Crime or Crash Scene?

Using a laser scanner with CZ Point Cloud software gives crash and crime scene investigators the tools they need to make a dramatic and convincing presentation to jurors in a courtroom. Bergen County’s laser scanner captures millions of points per scan, which results in a highly detailed, 3D model of the scene. Laser scanners accurately record the location of all the points in their range as X-Y-Z coordinates. The resulting “point cloud” is a digital, 3D model of the scene which can contain hundreds of millions of points.

Point Cloud drawing
CZ Point Cloud was used to create an accurate drawing
from this “point cloud.”

Unlike an actual crash or crime scene, the point cloud does not change over time. This is a huge benefit to investigators who may want to look at the scene months, or even years, later. The point cloud gives them a perfect 3D snap shot of the scene at the time it was scanned.

Just having the point cloud model is not enough for most forensic investigations. CZ Point Cloud is a true CAD (Computer Aided Design) application that helps investigators create 2D/3D diagrams and animations from a point cloud. CZ Point Cloud is filled with special tools that make it fast and easy to create accurate drawings of the scene. The user can essentially “connect the dots” in the cloud to create a drawing. These “dots” actually mark the location of all the physical points at the scene, recorded as X,Y,Z coordinates. When using CZ Point Cloud, the original point cloud data is never changed so the integrity of the data points is maintained. The drawing is created over the point cloud so the data points cannot be manipulated.

Real Time Diagramming In a
Point Cloud

In CZ Point Cloud, the 3D point cloud and the 2D diagram are displayed simultaneously in side-by-side windows. The investigator can draw and place symbols in either window and the other window is automatically updated. Detective Rich explains, “I can put the point cloud up on one screen and have the 2D diagram in a Crash Zone window running on the other screen,” Rich said. “I draw by selecting specific X,Y,Z points in the point cloud and watch the diagram being produced in real time on the other screen. It’s a huge time saver!”

When looking at a two-dimensional computer screen, it can be difficult to select the desired point in a 3D point cloud. CAD Zone Point Cloud has several tools that help the user select the correct points. For example, the “Flip Z” feature turns the entire point cloud upside down so you can easily select points on a roadway or draw a building footprint. There is also a tool called “Delta Z” that shows whether a point has been selected that has a large difference in elevation from the previous point. “That’s a big help when selecting points. It’s very important to know what point you’re picking,” says Rich. Because of these unique features, the user can be confident he or she didn’t accidentally select a point on a tree branch or some other overhanging object.

‘Hide’ Tool Gives Clear Perspectives in Diagrams

CZ Point Cloud contains special “Keep,” “Hide,” and “Show” tools that make it easy for investigators to isolate only those data points in the cloud that are critical to their scene. Detective Rich uses the “Hide” tool extensively for hiding unwanted trees and buildings in his diagrams.

If you imagine a satellite image of a road and you want to see the edge or curve of a roadway, it could easily be hidden by trees. A point cloud would provide a similar view because the laser scanner is recording millions of points, including points on the trees. “If I try to look down on that scene and trace the roadway, the trees get in the way,” Rich explains. “The (CZ Point Cloud) ‘Hide’ command allows me to cut out anything above a certain elevation. I can hide the trees so it’s easy to select the points on the roadway,” he added.

Forensic drawings from a point cloud.
The crash scene drawing was created from a point cloud that was captured with a 3D laser scanner.

A Laser Scanner With CZ Point Cloud is a Good Investment

For crash and crime investigators who are regularly mapping scenes, investing in a laser scanner and CZ Point Cloud software is money well spent. Not only is it extremely fast to obtain scans of a scene, the resulting point cloud is a perfect model of the scene. With CZ Point Cloud, the user can use the point cloud to quickly create 2D diagrams, 3D diagrams and animations that are ideal for courtroom presentations. Since the scanned data is an accurate 3D representation of the scene, a point cloud can be opened years later and all evidence points are exactly the same as on the day of the incident.

######################

Andrew Rich is now a principal of Rich Consulting, LLC. Besides providing crash reconstruction and expert witness testimony, Mr. Rich also teaches advanced crash reconstruction classes and lectures throughout the US and at crash reconstruction conferences.