iWitness' image-based photogrammetry techinque improves police crash scene mapping at night

The Washington County (WI) Sheriff’s Department (WCSD) carried out a 3D crash scene diagram using a Sony 5MP digital camera and iWitness. The incident involved a single car, triple fatality. The car caught on fire in a ravine after the crash. Due to the crash being at night, WCSD utilized auxiliary lighting for the digital imaging, using long time exposures with their digital camera tripod mounted. The crash scene evidence was later measured in the office using the iWitness close-range photogrammetry software system in combination with thirty digital images acquired at the incident.

The crash scene evidence was spread over an area of 360 feet (approximately 110m). A WCSD detective measured the scene evidence using the easy-to-use, but highly advanced iWitness ‘network stitching’ functionality to link two subset projects together over the scenes 360 foot distance - using nothing more for the task other than evidence markers and the digital camera. The accuracy of all measured objects was slightly better than one-tenth of a foot over the entire scene (which equates to measurement accuracy of 1:4000 of object size). 

Reportedly, the on-scene mapping time was cut by more than 50% using the iWitness photogrammetry approach, while the 3D mapping accuracy is now significantly improved over traditional methods used in the past by the WCSD.

For the iWitness photogrammetry mapping overview of this crash scene incident, please click here. (475kb PDF – requires Acrobat Reader Version 6 or higher).

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