Accuracy and Repeatability of Trajectory Rod Measurement Using Laser Scanners

Three-dimensional (3D) technologies contribute greatly to bullet trajectory analysis and shooting reconstruction. There are few papers which address the errors associated with utilizing laser scanning for bullet trajectory documentation. This study examined the accuracy and precision of laser scanning for documenting trajectory rods in drywall for angles between 25 degrees and 90 degrees. The inherent error range of 0.02 degrees-2.10 degrees was noted while the overall error for laser scanning ranged between 0.04 degrees and 1.98 degrees. The inter- and intraobserver errors for trajectory rod placement and virtual trajectory marking showed that the range of variation for rod placement was between 0.1 degrees-1 degrees in drywall and 0.05 degrees-0.5 degrees in plywood. Virtual trajectory marking accuracy tests showed that 75% of data values were below 0.91 degrees and 0.61 degrees on azimuth and vertical angles, respectively. In conclusion, many contributing factors affect bullet trajectory analysis, and the use of 3D technologies can aid in reduction of errors associated with documentation.