By Duke Dutch, Sept. 25, 2014
Investigators can significantly cut documentation time on fatal crash scenes and simultaneously eliminate the challenge of subjective data selection by combining 3D laser scan and total station data. This streamlined workflow, as introduced in a previous article, is a highly accurate and efficient way to document fatal crash scenes and relate the data in court.
Documenting the Scene in Less Than one Hour
First, select your desired locations for scanner targets or reference points. Next, set up the robotic total station and operate as normal—measure and record reference points; measure and map critical skids, scuffs, gouge marks and evidence items. Since you will not be measuring the roadway and physical area, this part of the procedure should take less than 30 minutes.
Next, in one or two setups, laser scan the area to capture all the physical features of the road, the vehicle points of rest, and any other roadway or evidence within line of sight. The combined field time to document the crash scene with both technologies should be less than one hour.
Combining the Data to Create one Work Product
Depending on your preferences, software and experience, you have two ways to combine the data:
Enter the coordinates of the target location reference points from the robotic total station data into the scanner to create an automatic orientation in the field. This creates a single scan world for users who have not upgraded to Leica Cyclone REGISTER 9.0 3D point cloud processing software, which features new auto registration and graphical registration capabilities. This method is advantageous for investigators who are comfortable operating a laser scanner, e.g., crime scene units that have years of scanner experience in assisting accident reconstructionists.
Process both scenes separately—the robotic total station data in CAD and the scan data in Leica Cyclone—and use the two reference points to snap the orientation in a CAD software, such as MapScenes, that handles both cloud and map data. This method is beneficial for accident reconstructionists who have experience with the two-point resection or merge commands. (An image from MapScenes is shown above.)
Advantages of Presenting Combined Data in Court
In the courtroom, the combined final scene documentation allows investigators to describe or testify to the evidence using the individual strengths of the robotic total station and the laser scanner.
Since the critical measurements and evidence were taken using the robot, investigators can testify to standing and viewing those points directly using established methods. The laser scan data shows the physical area, including lane widths, lengths of roadway for time and response, and any possible view obstructions.
The combination of technologies also allows for a very powerful image of the points of rest showing the result of the collision. Rather than having to explain to lawyers or jurors what the 2D or 3D sketches mean, investigators can simply use the free Leica TruView 3D visualization software to walk viewers through the crash scene. The evidence shows what happened. The visual images support the argument.
The capacity to combine laser scan data and robotic total station data for fatal vehicle documentation shows the advantage of manufacturer-standardized data formats and logic that enable multiple technologies and software to work in conjunction and create a much more complete final scene documentation.
For more information on how to improve your crime scene documentation, please contact us.
———————– About the author: Duke Dutch has worked as an instructor for the FBI, HSA and ATF for mapping post-blast scenes for more than 14 years. He also worked as a contractor for the U.S. Navy and for MPRI in the area of mapping of pre- and post-blast facilities as well as for the Earth Radar Project. He has trained hundreds of agencies over the last 20 years on total stations and GPS and RTK, authored numerous papers on automated mapping using robotic and GNSS systems, and is a contributor to the Student Manual on Advanced Post Blast Investigations by the Homeland Security Administration.