Photogrammetry and Surveying
Utilizing Scientific Data from Photographs, Video, and Forensic Inspections
The ability to accurately analyze evidence related to an accident or product failure is imperative to the successful outcome of the analysis. Veritech uses state-of-the-art methods in order to gather all information necessary to perform an accident reconstruction. After an accident, evidence remains in two locations: within the vicinity of the accident site and upon the involved vehicles or machinery. Evidence inspections performed by forensic engineers usually occur after responding emergency personnel have left and law enforcement have completed their investigation.
The term photogrammetry is largely unknown aside from its use in certain niche industries, mostly due to the recent advancement in current technology related to it. Photogrammetry can be defined as the scientific extraction of data and measurements from photographs. The process of capturing information from a series of photographs, two-dimensional information, and turning it into a three-dimensional model, is the essence of photogrammetry. While this concept may be difficult to appreciate in theory, in practice the process is very effective at extracting information from photographs, and even digital video. Photogrammetry provides another level of data collection, evidence measurement, and 3D modeling capability that may have not been previously considered possible with standard photographs.
While the science of photogrammetry has been around for many years, employing the process in real-world applications is still very state-of-the-art. Recently developed software packages allow Veritech’s engineers the ability to take advantage of the science of photogrammetry during accident reconstruction and forensic engineering projects. What’s more, Veritech’s usage of photogrammetry is unrivaled in the industry, giving us significant advantage over industry competitors.
Photogrammetry in Accident Reconstruction
Imagine that the only record of an incident was a series of photographs, and no other means of investigation or inspection was done. A common hypothetical example of this would be a series of photographs taken by an individual involved, or witness to, a car accident. Perhaps the photographs show the points of rest of the vehicles involved and some evidence of tire marks within the vicinity of the crash. Upon first glance, these photographs may not hold much relevance to the subject accident. However by utilizing photogrammetry, valuable information related to the accident can be collected. This scenario is common, and Veritech has successfully performed analyses of accidents based upon information provided in standard photographs.
Dashboard mounted video cameras are becoming more and more popular as a component of passenger vehicles. These small video cameras are already largely used by commercial truck fleets, on trains, and even construction equipment due to their recording capabilities in the event that an accident occurs. The science of photogrammetry applies to the use on video recordings, sometimes referred to as “videogrammetry”, in a similar manner to still-frame photographs. With this approach, information can be extracted from a series of video frames that change with time, referred to as a “sequence” of frames. A common example would be to determine speeds of vehicles visible within a video recording based upon their change in position within the video sequence.
Another common approach is to determine the speed of the vehicle in which the dash-mounted camera is installed. Both of these scenarios are accomplished with videogrammetry. Veritech has been an industry leader in photogrammetry since our founding. Our application of videogrammetry has aided in establishing a scientifically backed basis for numerous accident reconstruction and forensic engineering opinions in the work that we perform.
Limitations on the Application of Photogrammetry
While photogrammetry provides a very powerful tool to be used in forensic engineering, it is important to understand the limitations of this science. In many instances, the quality of the photographs taken may affect whether or not information can be extracted using photogrammetry. If the photographs do not properly capture the subject of interest from a sufficient number of angles, the accuracy of the photogrammetric project can be compromised. In other cases, such as if the image has been distorted, photogrammetry may not be the best solution. These issues, as well as others, can be identified beforehand by a trained eye. Veritech would be happy to discuss the details of your photogrammetry project further, and our engineers can assist in determining if your photographs or video can be used with this process.
Site Inspections: What Can Be Inspected?
It is common for reconstructionists to document site-related information such as:
Tire mark evidence,
Roadway gouges and evidence of area of impact (AOI),
Crash related damage debris, and
Visibility studies, obstructions to line of sight and adverse weather conditions
Night time lighting studies
Analysis of traffic control devices, such as traffic lights
Vehicle Inspections: What Can Be Inspected?
The vehicle inspections are similar in scope to the site inspections, and comprise of documenting impact related damage, taking digital measurements, and assessing the overall conditions of the vehicles as they were during the accident. Vehicle inspections often include:
Vehicle condition after accident occurs
Vehicle "black box" downloads
Condition of safety systems: airbags and seatbelts, even roll cages and occupant compartment structure
Vehicle crush measurement and documentation
Braking system assessment
It is important to note that the accident site and vehicle conditions may change with the amount of time after an accident occurred, due to environmental conditions and other external factors. Therefore, it is important for reconstruction engineers to inspect an accident site and perform vehicle inspections as soon as possible after an accident occurs in order to obtain the most accurate data.
Forensic Site Surveying
Veritech’s team of Professional Engineers have the capability to utilize Unmanned Aerial Vehicles (UAV, a.k.a. Drones) for use in aerial imagery, video, photogrammetry, and surveying for dimensionally accurate point cloud generation. Our cutting-edge Drone Technology allows us to develop fully detailed, three-dimensional terrains of accident sites with accuracy that rivals 3D scanners or total station surveys. Additionally, our drone surveys are capable of properly surveying impact related damage on large vehicles, semi tractor-trailers, trains, construction equipment, and other large and difficult to inspect machinery. Our drone surveying capabilities allow us to capture feature-rich surveys of an accident site in a safe and effective manner.
Veritech has the ability and experience in using tripod-mounted total station survey equipment and three-dimensional scanning equipment from manufacturers such as Sokkia, Trimble, Leica, and Faro. These pieces of equipment are used frequently in various stages of building construction, civil engineering, and metrology. More recently, law enforcement agencies have adapted the use of scanners to aid in documenting accident scenes. While these pieces of equipment are useful in some forensic engineering matters, it is important to consider their limitations when used for accident reconstruction. In many situations, these scanners are used simply as an automatic default tool that is not quite appropriate for the task at hand, and can end up costing valuable time, effort, and financial expense when a simpler, more direct, solution is available. Veritech engineers always consider the objective for each project individually and employ the best tool for the job, saving on costs and increasing efficiency.