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From field to finish: best practices in shooting documentation

Scanned project point cloud with trajectory rods in FARO Zone 3D software.

Multiple perspectives are key to analyzing a shooting incident — FARO Field Application Engineer Noreen Charlton reviews how 3D forensic solutions provide a 360-degree, comprehensive reconstruction of the incident, which can’t be accomplished with just photography alone.

 

Evolving best practices for shooting documentation in forensic investigations

As the number of shooting incidents continues to rise in the United States, proper documentation of these scenes is imperative. Traditionally, photography has played a leading role in scene documentation. The public’s call for more transparency in the aftermath of officer-involved shootings adds an additional level of need for accuracy, thoroughness and compelling visual presentation of what happened.

3D laser scanning is a process in which a laser captures real world information, used in the digital world, for scene documentation and analysis, thus creating an exact measurable copy of even the most complex scenes in forensic analysis software. Photographs have a tremendous amount of value, but they rarely have the same impact as a three-dimensional representation of a scene. Laser scans allow the viewer to visualize the scene in much more detail, providing a complete documentation tool, as it will document everything within its line of sight. In turn, the location is forever digitally preserved for review and analysis.

When a scene is captured in a precise, detailed, photo-realistic 3D view, the investigator has created a foundation for virtual storytelling. The scanner eliminates potential human error within measurements. There are no more fixed perspectives or overlapping photographs to achieve a similar view of an officer, witness or suspect. Scan data provides an aspect of relational space that assists investigators in locating evidence and forensically reconstructing the circumstances of the incident.

Investigators can get the most out of laser scanning by following some practical steps when they use their forensic hardware and software:


Preparing to scan

Before scanning a shooting scene, the bullet holes should be labeled. Typically, this is accomplished by way of identifying different bullet-series. For example, if a bullet entered the exterior wall of a residence and perforated through the interior side of the wall, those bullet holes could be labeled A1 and A2, respectively. These markings ensure that the final trajectory report, produced with software, is consistent with the photographic documentation of the scene. 

Next, the investigator must insert trajectory rods into the bullet holes, keeping in mind shooting reconstruction basics. If necessary, centering cones will assist with stabilizing the rod in larger or irregular holes.

While not required, it is suggested that you use trajectory spheres for measurement repeatability. When trajectory rods are
scanned without spheres, the software user must choose points on the trajectory rod to obtain measurements. These points may differ between users and can introduce small discrepancies between measurements from one user to the next. 

However, the addition of spheres eliminates measurement discrepancies and provides repeatability within the project. Lightweight spheres, affixed to the trajectory rod, ensure that the angle measurements reported in the software are the same every time, regardless of the software user. Repeatability is an essential factor for courtroom testimony and consistency with results.


Documentation with a 3D laser scanner

Given that a 3D laser scanner is a line-of-sight device, you may have to move the scanner into multiple positions to capture all trajectory rods. If necessary, the investigator can scan trajectory rods and move them to a secondary location to not have several prepared at once. When the scanner documents something in a scene, it is forever preserved in its original location. Where photography can be difficult in tight spaces, a handheld laser scanner offers the freedom to scan in some of the most hard-to-reach environments.

Scanner settings can vary, but the use of trajectory spheres will provide the ability to scan from a farther distance and a lower resolution, thus saving time on scene. As bullets begin to perforate different objects and surfaces, they can begin to tumble or deflect. For this reason, you should only scan the trajectory rod for the first entry of a bullet path. The software will allow you to virtually illustrate that bullet through the scene on the same path. This tool helps determine whether something or someone may have been struck by a bullet when comparing it to additional holes or defects on the scene.


Analysis in forensic software

Forensic analysis software, such as FARO® Zone 3D Software, allows the investigator to conduct shooting reconstruction with scan data captured at the scene. The software removes any of the guesswork or potential human error with hand measurements — and provides visual presentations that cannot be achieved from two-dimensional photographs.

Once the scan data is imported into the software, the user can either select the trajectory rods or spheres to begin the analysis process. Once selected, the user will then adjust the impact plane to the surface that was impacted by the bullet. 

The software reports the azimuth (horizontal) and inclination (vertical) angles in several angle conventions and provides the ability to add virtual protractors for visualization of the measurements.

Once a trajectory has been determined, the software provides the ability to virtually extend the cone/rod to determine approximate shooter location. Furthermore, an investigator can choose to continue the bullet path through the scene to determine a potential termination location of a bullet. 

Upon completion of analysis within the software a report can be generated for each trajectory to include its position within the scene and associated measurements.

 

Visual presentations
For years, law enforcement has had to face the “CSI Effect” as it pertains to courtroom testimony. Today, there is a sense of urgency for an agency to be as transparent as possible after an officer-involved incident.

Diagrams, forensic animations, virtual reality and fly-thru videos are some of the many presentations that can be created with 3D laser scan data. These presentations allow viewers to see more and feel as though they have a complete understanding of the events that transpired. This pulled back, analytic perspective is key in a shooting incident. While photography is certainly beneficial, it does not provide the spatial relationships that can be obtained with 3D laser scanning. Scan data can assist in confirming or refuting a statement made about the incident by providing complete 360-degree views with all the elements of the original environment. These perspectives can be visualized by way of screenshots, fly-thru videos or panoramic images.

The scan project of an exterior shooting scene is frequently supplemented with a satellite image. This provides the investigator the ability to present the shooting over long distances which were not captured by a laser scanner. This imagery, along with 3D modeling, can be used to present a scene in a more comprehensive way than ever before.

From start to finish, the data collected and analyzed using 3D laser scanning technology is captured faster, more accurately and more safely than what could be processed using more traditional methods. It provides a fuller, more detailed picture — an objective, visual record of the facts of the incident that viewers can visit again and again.

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