When a fatal collision occurred between a motorcycle and SUV at a city intersection, we were asked whether obstructed sight lines may have contributed to the incident.

Two surveillance videos which captured the events leading up to the collision were obtained and provided the foundation for the photogrammetry analysis within the accident reconstruction. From the video, it can be observed that there were several vehicles parked at/near the intersection. A box-truck parked near a crosswalk, the vehicle of interest for this case, was scrutinized as a possible obstruction to the approaching motorcycle and SUV operators.

The two videos were synchronized, and the camera locations were established by correlating multiple points on the 2D image plane to their 3D positions in space measured by high density LIDAR scans of the site.

The trajectories of the motorcycle and SUV were also solved by matching points on the 2D image frames to 3D scale models of the vehicles. The stationary vehicles parked along the roadway including the box truck were also analyzed and accurately placed within the scene. With 3D cameras placed at both operators’ positions, simulating their approaching views of the intersections, it was concluded that the presence of the box truck did not further impede the line of sight which already existed from the surrounding vehicles at the intersection.

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Laurence Penn, CFVT and Hugh Borbidge, BSME, Animation Consultants with DJS Associates, Inc., can be reached via email at experts@forensicDJS.com or via phone at 215-659-2010.

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When a tree fell on a roadway, injuring a passer-by, DJS was tasked with analyzing the evidence to provide opinions on the measurements of the tree and extent of its canopy, including proximity to utility lines, prior to the incident.

A video from the scene and photographs of the property were provided for analysis. A scan of the site was performed by DJS field investigators, capturing high density LIDAR measurements. Using LIDAR assisted photogrammetry of the images and data provided from an arborist report, the position and angle of the tree were modeled in 3D. Major branches visible in the photos were also modeled to establish a canopy radius. 

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A pickup operator crossed an active railroad and collided with an oncoming train.

The client, along with the DJS engineers, wanted to know if the vegetation affected the driver’s ability to see the oncoming train.

Utilizing a scene photograph taken at a similar angle to the pickup driver’s approach of the tracks, we were able to electronically prune the tree to show it as it stood during the time of the site inspection, which had occurred two years later, to match the size of the tree at the time of the accident.

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Hugh Borbidge, BSME, Director of Engineering Animations with DJS Associates, Inc., can be reached via email at experts@forensicdjs.com or via phone at 215-659-2010.

https://www.ForensicDJS.com

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When video surveillance recorded an individual's fall in a building lobby, DJS Associates was tasked with analyzing the video to shed light on the circumstances surrounding the fall.

Unfortunately, the building had been renovated since the incident, but this didn't prevent accurate photogrammetry camera-match analysis to be performed using LIDAR data acquired of the site by the DJS Associates reality capture field crew.

Implementing common features still present in the environment prior to and after the renovation, the position, orientation, and field of view of the camera were established. Several scene photos were also camera-matched successfully with the LIDAR data. Of particular interest to the case, an edge of a rug in close proximity to the plaintiff’s fall was obscured in the surveillance camera. Utilizing multiple angles of the camera-matched scene photos, the obstructed area of the rugs could be established and reconstructed in 3D space. An articulated 3D model mannequin, scaled to the height of the plaintiff, was superimposed and animated over the surveillance footage to match his position and posture in space and time.

Under the guidance of a biomechanical expert, the 3D mannequin animation was refined relative to the video evidence. With an unobstructed view of the reconstructed scene, the analysis revealed the plaintiff's footing relative to the positioning of the rug's edge in much more detail than was originally possible from the surveillance video alone.

Laurence R. Penn, CFVT, Senior Forensic Animation / Video Specialist with DJS Associates, Inc., can be reached via email at experts@forensicDJS.com or via phone at 215-659-2010.

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DJS Associates was retained to create visuals of a spinal diskectomy and disk replacement with 3D animation. The intention was to demonstrate the steps outlined in the provided operative reports to better explain the trauma and recovery necessary to recuperate from such an invasive procedure. In order to add value to the animation and provide a faster turn-around, the surgical tools and organs not crucial to the case such as the larynx, trachea and esophagus, were excluded from the animation.

Our 3D engineers and animation specialists worked closely with the client and medical experts to ensure the demonstrative was medically accurate and followed the stated surgical procedures.

Laurence R. Penn, Senior Forensic Animation/Video Specialist

Laurence R. Penn, Senior Forensic Animation/Video Specialist with DJS Associates, Inc., can be reached via email at experts@forensicDJS.com or via phone at 215-659-2010.

https://www.forensicDJS.com

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DJS was tasked with analyzing surveillance video which captured an unfortunate accident during an indoor recreational volleyball game where a player lost their balance and ran head-first into a padded wall, resulting in a debilitating spinal injury.

A complex task in the best of circumstances, working with video that isn’t from the native surveillance system requires extra levels of scrutiny to make subsequent steps in the analysis process as accurate and resolute as possible.

The video provided in this case was a smartphone recording of a monitor displaying the surveillance video of the accident. A reverse-engineering process is required to stabilize any handshake, remove perspective, and reconstruct the dimensions of the original video frame. Once returned to an acceptable composition that falls within the established norms of digital video standards, the camera view can be calculated in three dimensions relative to high-density LIDAR scan data of the facility.

The plaintiff was then tracked in the 3D environment using a to-scale rigged mannequin to accurately reconstruct the steps and posture recorded in the video. The reconstructed scene can then be viewed by multiple angles to help biomechanical experts and other viewers better understand the circumstances of the event and can even reveal movement previously obstructed by foreground objects.

Laurence R. Penn, CFVT, Senior Forensic Animation/Video Specialist with DJS Associates, Inc., can be reached via email at experts@forensicDJS.com or via phone at 215-659-2010.

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The robot arm was a fun project to show the variety of demonstrative animations the 3D engineers at DJS Associates are able to produce. The robot arm was created and rigged so it rotates along the respective pivot points to maneuver and shoot a basketball through a hoop. It goes through all the motions, while the physics of the 3D software takes care of the basketball dynamics. For example, the trajectory path for the basketball! Shadows and reflections are standard in our animations, but we have gotten “fancier” by adding motion blur and depth of field.

Hugh Borbidge, BSME, Director of Engineering Animations with DJS Associates, Inc., can be reached via email at experts@forensicDJS.com or via phone at 215-659-2010.

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Often, drivers involved in an accident will profess that each had their corresponding green light. Unless there isn a signal malfunction, both cannot be right. Sometimes there are clues to help determine who was at fault.

In the following case, the tractor trailer driver stated that he had the green left turn arrow. The oncoming SUV driver stated that he had the green light and the witness said that they received the green light about 5 seconds after the accident happened.

Utilizing a signal timing plan, witness testimony, and the laws of physics, we can determine who was at fault. Working backwards, the witness statement puts the accident at 5 seconds prior to their light turning green. 5 seconds prior to the witness light turning green. The tractor-trailers light would have been a left yellow arrow. The tractor-trailers light would have been a left green arrow for 12 seconds prior to the left yellow arrow. It takes the tractor-trailer about 14 seconds to travel from the stop bar to the point of impact. These facts check out.

The 3D animation shows this signal timing along with the corresponding vehicle movements. It would not have been possible for the oncoming SUV to have had a green light under this signal timing pattern.

Hugh B. Borbidge, BSME, Director of Engineering Animations with DJS Associates, Inc., can be reached via email at experts@forensicDJS.com or via phone at 215-659-2010.

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We, as vehicle operators, avoid collisions every day. We stop for red lights, brake when a car cuts us off, and slow down if there are children playing close to the roadway. In these avoidance situations, there are three components: Perception, reaction and braking.

Perception is when we first notice a hazard or the need to react to something. Reaction is the time taken to respond to what was perceived. A typical daytime perception/reaction time for a vehicle operator is about 1.5 seconds, meaning that, when you notice a hazard you keep traveling at the same speed for 1.5 seconds before you start applying the brakes. Braking is the minimum time it takes to bring the vehicle to a stop. Every bit of time in this series of events equates to a certain distance traveled. For example:

A vehicle traveling at 25mph travels 55 feet during its perception/reaction time and takes 30 feet to stop for a total of 85 feet in 3.13 seconds.

A vehicle traveling at 45mph travels 99 feet during its perception/reaction time and takes 97 feet to stop for a total of 196 feet in 4.43 seconds.

A vehicle traveling at 65mph travels 143 feet during its perception/reaction time and takes 202 feet to stop for a total of 345 feet in 5.73 seconds.

In summary, the faster you are traveling, the more time and distance is required to bring your vehicle to a stop.

Hugh Borbidge, BSME, Director of Engineering Animations with DJS Associates, Inc., can be reached via email at experts@forensicDJS.com or via phone at 215-659-2010.

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