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# Ditch the 2D way of forensic investigations, grab the 3D alternative

Jan 10, 2023by, Maheswari C S

Technology

Why should you use 2D images for crime analysis when you can recreate the scene using 3D models?

While investigating a crime, thoroughly analyzing the evidence is crucial for investigators. Let us visualize a scenario where you are trying to understand the location of a crime. You deploy a squad to search the area, simultaneously decoding images taken from that area. Even a granule of evidence is crucial during these situations. Now let us look at an alternative. You capture the necessary data that needs to be investigated and analyze the whole scenario through a three-dimensional approach. Which of these is more feasible? Undeniably, one would choose the latter as it gives a better look at the crime scene, and requires less time and manpower.

The technology behind this 3D alternative is called Structured Light 3D Scanning. Let’s discuss in detail how this works.

Image credit: 3dnatives.com

## What is a Structured Light 3D scanner?

A device which uses projected light patterns and a camera system to measure the three-dimensional shape of an object.

#### What is its mechanism?

Requirements:

• One or two cameras
• Video projector

The video projector projects a narrow band of light onto a part of an object. Projecting patterns with multiple stripes or arbitrary fringes enables the simultaneous collection of a large number of samples. This creates a line of illumination which, when viewed from angles other than the projector’s, seems to be distorted due to the shape of that object. This new pattern would be recorded by the camera in order to allow the scanner to reconstruct the geometric three-dimensional shape of the surface.

Depending on the thickness of the fringes, the scanner can determine the distance of the part of the object from the scanner. For better accuracy, the scanner projects an average of three to ten patterns onto the part of the object. Because the entire object cannot be scanned accurately from just one angle, we can:

• Use a rotary table to move the object or,
• Move the scanner around the object

Every time a 3D model is created of a part, it is automatically accumulated in a software (called the alignment stage), and a 3D mesh is generated.

Checkout our blog “Structured Lighting to create 3D models” to get a detailed idea regarding Structured light 3D scanning technology.

## So how can this help forensics?

• #### 3D Images for better analysis

For decades, forensic experts have used 2D cameras to capture crime scenes. However, even photos of the best quality produced by these cameras lack vital information that can only be produced by understanding the spatial relations between objects at the crime scene. This conventional approach takes a lot of time and relies on incorrect tape measurements and 2D images. Recent developments in 3D scanning combine structured light and 3D imaging technology to produce a 3D image of an object with accurate size and depth. This enables one to examine data for specifics and collect precise geometric information from the crime scene. For example, the trajectory of a bullet or the depth of a cut.

• #### A splash of color makes everything better!

3D scanners provide high-quality colored images with texture. This is significant for forensic pathology to reveal previously unnoticeable information about the crime scene or the victims’ bodies. This widens the spectrum of forensic information for investigators by emphasizing the various states of the body. For instance, the intensity of the injury and its course may be indicated by the degree of coloration of physical signs of trauma, such as bruises and wounds. In general, skin discoloration might indicate a degree of decomposition in the body. Color can function as a timestamp and may be the key to identifying if environmental factors play an important role, such as the location where the body was discovered and the weather conditions at the time of crime.

• #### A new approach for solving the crime

By performing simulations for various crime scenarios, 3D scanning systems enable you to quickly gather essential data for examining crime scenes. Using 3D data for in-depth forensic investigation allows for the reconstructing bits of evidence in a digital setting to visualize various scenarios on your screen. Additionally, when transferred to a more advanced digital setup, the documentation of this data becomes easier. These lifelike virtual replications can be presented as evidence during pre-trial and court proceedings without any risk of damage.

• #### Better understanding of the case

3D images generated by structured light 3D scanners help forensic pathologists who are unfamiliar with a case quickly familiarize themselves with the visual evidence by opening the image files, and perceiving them from different angles instead of spending hours sorting through stacks of photos or swiping through a gallery of disjointed images. This technique enables cold cases to be less hampered as a result of lost, distorted, or decontextualized evidence.

In short, a 3D scanner will not only give a better view of the crime but also help one ascertain when and how an event occurred. One can gather a variety of evidence, such as bloodstain patterns, bullet holes, shoe prints, and especially those that may skip the human eye or the lens of a 2D camera in a matter of minutes. This technology holds the potential to be an innovative 21st century approach to forensics that may be the game changer for investigators.

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Disclaimer: The opinions expressed in this article are those of the author(s) and do not necessarily reflect the positions of Dexlock.