Case Study – Use of Laser Scanning in CCTV analysis

The case study below follows on from the Complex Collision Reconstruction case study and illustrates how Advanced Simtech is able to add value through the application of 3D Laser Scanning. In this case a CCTV camera covered a section of a collision scene but the footage offered limited information as there were merely a few low resolution frames that were relevant to the incident. Using a laser scan of the scene, it was possible to take the 2 dimensional CCTV images into a 3D environment and derive useful position data.

Case Study – Fatal RTC Analysis

Customer: UK Police Force

Case Overview

Low quality CCTV captured the final moments of a serious collision in which one occupant was killed and another was ejected from the vehicle relatively unhurt. In the footage it was possible to observe the ejected occupant standing up and walking along the scene.

Objective

As part of our investigation, we aimed to determine the position of the ejected occupant at the moment when he first became visible in the CCTV footage. This would supplement our simulation work by providing an approximate ejection point and therefore aid our understanding of the sequence of events relating to how he was ejected.

Solution/Methodology

A single frame from the CCTV footage is shown below. The ejected occupant has been highlighted.

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A 3D laser scan of the scene had previously been carried out. This scan included the area covered by the CCTV camera.

CCTV_casestudy_6.PNG

Using specialised software, the CCTV still image can be applied to the laser scan by selecting common points between them to create a ‘texture map’.

CCTV_casestudy_3.png

Texture mapped scan:

CCTV_casestudy_4.png

Results

With the CCTV image applied to the scan, it was then possible to identify the post impact position of the ejected occupant in a detailed 3D scene model. This allowed us to confirm that the only opportunity for an occupant to leave the vehicle without being subsequently struck or ran over by it is following the rebound from the tree impact.

CCTV_casestudy_2.PNG

Conclusion

Using the positional data in conjunction with our detailed simulation allowed us to be confident in our prediction for the timing of ejection from the vehicle by providing a further means of correlation for the occupant simulation work.

CCTV_casestudy_1-A.png

Keywords - Laser Scanning, CCTV analysis, Collision Reconstruction, Advanced Simtech, Collision investigation