Crash, Crime Scene Rectification with the Leica BLK3D

Working with prosecutor offices and defense attorneys in Italy and across Europe, I conducted countless hours of forensic mappings of crash, collision, traffic accident and crime scenes. I led investigations and provided reconstruction services.

I understand well the procedures and challenges of working, documenting and measuring a collision or a crime scene, as well as collecting evidence. Based on my close work with different law enforcement agencies and court experts worldwide over the last decades, I understand, that adopting the best technology with an easy and validated methodology can be of a great help to document an event, especially when the evidence collected is a fundamental part of a criminal or civil court hearing.

Many times, on scenes, painstakingly documenting and collecting evidence, for the sake of its comprehension and level of detail, I could have made the task quicker, safer and more efficient with handheld technology. Luckily today, the Leica BLK3D real-time, in-picture 3D measurement solution ensures evidence is holistically collected in the shortest possible time on scene to increase safety.


Simply create deliverable data

The BLK3D documents the scene with pictures. It also allows for extraction of required measurements from images, operating in the shortest time possible while ensuring the safety of the people present on the scene.

The device runs the BLK3D enhanced software capability on an Android platform, and it's possible to measure directly on display in a matter of seconds. After collecting the evidence, you can send a comprehensive report to the supervisor or to the remote office. Just following an easy, intuitive and validated procedure, there is no more need to perform hand measurements, "bending on the road" to extend a tape and exposing the operator to unnecessary risks.

With the BLK3D, every image captured is a complete and precise 3D measurement record. Later, after the scene is cleared and is no longer possible to re-visit, the exact metric information can be extracted from the images that froze the scene in time, all without losing any details.

With the compact, all-in-one photogrammetry tool, you can:

  • Document the scene and evidence with images

The BLK3D combines a calibrated stereo camera, measurement sensors, software, and on-device edge detection capabilities to make in-picture measurements with professional-grade accuracy. Every image captured is a complete and precise 3D measurement record. 

  • Acquire measurements on the collision scenes
    Designed to make your measurements faster and easier, you can measure directly within any picture you can capture with the BLK3D. It will help you fully document your work, including as-built conditions and project progress. 

  • Complete the report with at least a 2D scaled drawing of the accident scene
    Easy as it is, just take images and notes and leave the scene. The technology of the BLK3D, allows you to use the BLK3D handheld device to document the scene with extractable measurements of the required metrics data regarding the crash scene like, objects, landmarks, evidence, vehicles, etc.


Simply create a scaled 2D drawing of the collision scene

There are many ways to deliver a 2D drawing of the incident scene. For instance, the BLK3D includes the laser measurement capability (like Disto™) to acquire point-to-point measurements. With an adaptor, the BLK3D can be used as a kind of "mini total station" to export the data to your CAD-based software.

We all agree that it is crucial to document as many details as possible on the accident scene in the shortest possible time. Due to the technical abilities and time restrictions on site, a point-to-point method can force the investigator to select just some main evidence and points while neglecting others.

Working with the third-part software for the rectification of photographs, PC-Rect, let’s look at how this 2D drawing can be created.

The software allows the user to rectify photographs of surfaces that are close to being planar, such as roadway surfaces at accident scenes. As a result of the rectification, an image view normal to the surface (a plan view for horizontal surfaces) is created. Even when no measurements have been taken at the time of an incident, the reconstructionist can obtain enough dimensional data to rectify photographs.

The unique functionality of the BLK3D allows the user to extract from the device’s photogrammetry measurements of painted lines, markers or other long-lasting roadway features that appear in the original photographs. I've done some test comparing the results of using BLK3D and PC-Rect and some measurements taken using the Leica BLK360 imaging laser scanner. The outcomes are summarized as follow:

  • No significant errors
    According to the conditions and methodology of this experiment, in the test scenario, results have shown no significant errors between distances readable from the BLK3D and distances readable from the BLK360 using the Leica JetStream Viewer.

  • Matching accuracy
    The same grade of accuracy applies to the measurement taken on the PC-Rect image (view normal to the surface) as a result of the rectification, a process using the BLK3D and PC-RECT software.

  • Acceptable accuracy
    The experiment has also shown an acceptable grade of accuracy for what concerns the evidence, the details, and the dimensional data on the 2D scaled image delivered from PC-RECT.

Accident investigation and incident reconstruction are made easy without sacrificing accuracy using the BLK3D. With a worldwide validated accident investigation software, like PC- Rect, this field is prime for exploration.

For the test results and more information on accident and collision investigation tools, contact us.


As a longstanding Forensic Expert, and the first ACTAR (Accreditation Commission for Traffic Accident Reconstructionists) specialist accredited in Europe with a focus on crime and crash scene forensic mapping and traffic accident reconstruction, Ivan Macella (BEng., ACTAR) is the forensic business development manager for Hexagon’s Geosystems division in Europe.