FOCUS Small Unmanned Aerial System Photogrammetry
An orthographic view (left) allows the reconstructionist to take dimensionally appropriate measurements as compared to a perspective photograph (right).
Animations showing the pre-impact,
impact, and post-impact series of events are a series of images placed together to il- lustrate the story. These animations have limitations and sometimes appear to be amateurish or have a cartoon appear- ance. Using the images and video from the drone, the exact location of the skid, scuff, groove, yaw marks to name a few can be displayed exactly where they appear on the roadway. After this data is analyzed and calculated, the investigator can place or import vehicles over the marks captured and place time sequence intervals where the events occurred.
Whenever a motor vehicle collision is re- constructed, travel the path of the respective collision vehicles to gain a sense of what the operator may or may not have seen and any potential view obstructions of obstacles. The drone can follow the path of the collision vehicles at various altitudes to expand the view, which can provide a greater under- standing of the collision process. The drone data collection software and capabilities of the drone could combine the following procedures in one operation: 1) detailed orthographic mapping and data collection of the scene geometry, includ- ing the roadway and accident vehicles; 2)
Aerial, orthographic images allow the reconstructionist to identify tire track dimensions and chronology. The tread pattern can be compared to databases to identify the make and model of the tire and which vehicle may use it. This image is a magnified view of Figure 4, but it still maintains visual clarity due to the data collection and image processing techniques used.
photogrammetry images used for 3D mod- eling of the scene and vehicle; 3) video of the path of travel of the collision vehicles; 4) still images of the collision scene and vehicle; 5) damage analysis of the collision vehicles at their fi nal rest prior to removal; and 6) animation sequence images. With training and experience, the total
time necessary to process a collision scene and vehicle damage analysis could be as short as 30 minutes plus or minus depend- ing on the complexity of the scene. All of the data necessary to conduct a reconstruc- tion can be collected and verifi ed before the Reconstructionist leaves the scene. The affordability of the drone and corre- sponding software can easily put all of the components of this type of data collection within reach of most any agency. The abil- ity to conduct data collection of this type has only started to grow.
John D. Jarrell, PhD, PE, has a doctorate from Brown University in Biology, Medical Science and Engineering, has his Professional Engineer License (PE), Mechanical Engineering, and may be reached via
johnjarrell@materialsscience.org. Donald L. Mong is a retired Police Traffi c Offi cer with the East Greenwich, R.I. Police Department and Traffi c Accident Reconstruction Instructor and may be reached via dmong@materialsscience. org. Jay Vincelli, MSc is a Forensic Engineer with Materials Science Associates and may be reached via
jvincelli@materialsscience.org. Thomas Mangan is a retired CW5 with the Rhode Island Army National Guard and may be reached via
tmangan@materialsscience.org.
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30 LAW and ORDER I May 2016
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