Insights
Evidence preserved in photographs and video can be analyzed using techniques of photogrammetry and videogrammetry. Through scientific analysis, speed, position, size, and other three-dimensional measurements can be derived from photographs and video. Experts in accident reconstruction, officer involved shootings, crime scene analysis, biomechanics, fire origin, premises liability, and other forensic disciplines regularly rely on photogrammetric analysis and video analysis expertise. Our consultants rigorously review and develop these evolving technologies.
The following peer-reviewed, scientific publications demonstrate our expertise in photogrammetry and our commitment to understanding, achieving, and relating photogrammetric analyses with the highest levels of accuracy.
Reverse camera projection is useful for both determining the location of historical evidence, where it is no longer physically in existence, as well as for directing the investigator to evidence still at the site that may otherwise have been overlooked during a site inspection. With the introduction of augmented reality, an entirely digital process of this technique is now possible. This paper, which received an Excellence in Oral Presentation Award from the Society of Automotive Engineers (SAE) in 2019, both presents a digital methodology and provides reference to a publicly available, augmented reality application developed specifically for this process by the authors.
Professional American football games are recorded in digital video with multiple cameras, often at high resolution and high frame rates. The purpose of the study featured in this paper was to evaluate the accuracy of a videogrammetry technique to calculate translational and rotational helmet velocity before, during and after a helmet impact. Given the high quality of video available for NFL games, the biomechanics of on-field concussive head impacts in the NFL can be determined most accurately using videogrammetry.
Photogrammetry and the accuracy of a photogrammetric solution is reliant on the quality of photographs and the accuracy of pixel location within the photographs. A photograph with lens distortion can create inaccuracies because of the curved nature of a camera’s lens. This paper presents two methods for removing lens distortion from photographs that do not have EXIF (Exchangeable image file format) data, such that specific camera and lens information can be determined.
This paper presents a methodology for determining the position and speed of objects such as vehicles, pedestrians, or cyclists that are visible in video footage captured with only one camera. The authors explain the automated process of first tracking pixels in the video footage, and then remapping the 2D coordinates onto three dimensional geometry using projection mapping and photogrammetry techniques.
The appeal of automated photogrammetry software as a tool for collecting dimensional data is the minimal equipment, equipment costs and ease of use for accident reconstruction. This paper evaluates the accuracy and capabilities of four automated photogrammetry based software programs to accurately create 3D point clouds, by comparing the results to 3D scanning.
Nighttime driving environments contain complex lighting conditions such as forward and signal lighting systems of vehicles, street lighting, and retro reflective markers and signage. This paper discusses processes for creating simulated driving environments by utilizing the realistic manner in which cameras capture complex lighting environments, and combining this imagery with projection mapping techniques that result in a photorealistic environment where variables for different driving scenarios can be changed to create a number of driving environments for testing, evaluating, and visual representation.
This paper presents and evaluates the ability to take video footage of an accident scene that contains physical evidence on the roadway and, through photogrammetric and projection mapping processes, create a three-dimensional, scaled accident scene diagram with rectified photographs mapped onto the geometry.
Computer simulation of nighttime lighting in urban environments can be complex due to the many light sources present, including vehicle headlamps. Within a lighting simulation, photometric files are often used to simulate light sources such as street lamps and exterior building lights in nighttime environments. This paper examines the validity of using these same photometric file types for the simulation of vehicle headlamps by comparing the light distribution from actual vehicle headlamps to photometric files of these same headlamps.
Nighttime crashes often involve complex lighting conditions. The visibility of an object at night is largely due to the luminance contrast between the object and its background. This difference depends on many factors, one of which is the amount of illumination produced by a vehicle’s headlamps. This paper focuses on a method for digitally modeling a vehicle headlamp, such that the illumination produced by the headlamps can be evaluated.
This paper, which received the Arch T. Colwell Merit Award, presents an image analysis of a laboratory-based rollover crash test using camera-matching photogrammetry - the science of measuring 3D objects from images. While the photogrammetric method presented can be a useful tool to extract vehicle roll angle data from test video, it requires further exploration if it is to become a robust post-processing tool for general application to crash safety analysis.
Accident reconstruction engineers often use scene surveys to analyze an accident. This paper explores video tracking photogrammetry technology that is currently available for producing 3D survey data from a single camera video source. The analysis reported in this paper compares the 3D survey data derived from video photogrammetry tracking to an actual survey of the same site.
This paper focuses on camera matching, which is adjusting the camera in computer modeling software to match the photograph. Once properly matched, dimensions within the photograph can be gathered. This technique is beneficial in gathering dimensional data from crash scene photographs like the point of impact and the point of rest of crash vehicles. Once the crash scene dimensions are determined, the accident can be reconstructed using the principals of conservation of momentum and energy.
This paper examines crash severity by analyzing various types of accident configurations, vehicle damages, and occupant injuries. Using close-range photogrammetric techniques and creating a computer model, engineers can maneuver the models in three-dimensional space to analyze the severity of the impact.
This paper discusses the use of close-range photogrammetry to determine a vehicle crush and equivalent barrier speed. Utilizing this method, engineers can measure vehicle crush using photographs instead of physically measuring the vehicle. This method is of great value when the vehicle is no longer available and photographs are the only documentation of the accident that may have occurred years earlier.
The biggest challenge for accident reconstructionists who are recreating a crash scene is when they have to rely on only one photograph and the information about the camera that took the photograph is not available. In this paper, the authors present a technique that enables the user to create an accurate accident scene diagram by using a combination of processes called Inverse Camera Projection and Photographic Rectification.
There are several software packages that allow engineers to gather dimensions from photographs through photogrammetric analysis. However, the software is classified as either 2D or 3D photogrammetric software. This paper discusses the application of 2D and 3D in photogrammetry in accident analysis and reconstruction.
Trajectory rods, also referred to as projection rods, have been an accepted tool for documenting bullet paths in intermediate and terminal targets for many years. However, little research exists comparing accuracies of these methods. The study featured in this paper compares six methods for documenting trajectory rods.
In this study, a model-based image matching (MBIM) approach was employed to analyze video footage of 57 concussions which occurred in National Football League (NFL) games. By quantifying the impact velocities and locations associated with concussive impacts in professional American football, the study, which is highlighted in this paper, provides information that may be used to improve upon current helmet testing methodologies.
This paper introduces a method for calculating vehicle speed and uncertainty range in speed from video footage. The method considers uncertainty in two areas; the uncertainty in locating the vehicle’s position and the uncertainty in time interval between them.
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