Background:
A police officer of the Hurst, TX Police Department stopped a motorist on an Interstate in the Hurst area. The officer was seated in the driver seat of his cruiser and was rear-ended by a vehicle traveling at highway speed (roughly 65 MPH). The officer sustained injuries, but luckily, his injuries were not life-threatening. The rear of the 2007 Dodge Charger police cruiser was completely crushed.

In October of 2009, DeChant Consulting Services provided an iWitness training workshop to multiple police agencies in the Dallas\ Fort Worth area. One of the attending officers (from Hurst, TX) suggested we map the aforementioned police cruiser for "crush measurement profiling", using the  photogrammetric approach. Attending officers agreed the crushed Charger would make a great training exercise and an opportunity to see the automatic measurement capability of iWitnessPRO. Permission was granted by the Hurst, TX Chief of Police to use the digital imagery, noted below.

Field work:
It took about 10 minutes to setup a qty. of 41 iWitnessPRO coded targets as well as imaging 3 sides of the Charger, for "training" purposes. The drivers side, rear and front portion of the vehicle were imaged for iWitnessPRO measurement. Approximately 20 of the Passive Targets were applied to the crush geometry for automatic measurement in iWitnessPRO.

The 10MP Olympus E-420 camera was set to manual focus, shutter speed of 1/125th sec., and Aperture F20, using the onboard flash. Scale distances of 10' and 5' were used, and seconded as defining the coordinate system. Approximately 40 images were used for measurement in iWitnessPRO.

Computer Work:
It took less than two minutes to automatically process the 3D crush measurements in iWitnessPRO. The work was accomplished on a notebook computer with the group of police officers back at the training facility. iWitnessPRO Facet-Form Polylines were added to define the drivers side and front end for "indexing" the wrecked vehicle to a CAD plan view profile of the exemplar vehicle. The iWitnessPRO DXF result is displayed in The Crash Zone, noted below. If time permitted in our "impromptu survey", we could have mapped an exemplar 2007 Dodge Charger and performed iWitness/ iWitnessPRO project linking and indexed the crush configuration to the exemplar vehicle, all within the iWitnessPRO software system -- as a single DXF export, to CAD. Click here for an example of Network Linking of the iWitness/iWitnessPRO 3D model, exemplar and crush profiles.

Perspective View of iWitnessPRO 3D model

Plan View (with C1 to C6 crush measurements)

Summary:

iWitnessPRO is an affordable image-based photogrammetry software system that is easy to use. It is extremely fast on scene and produces automatic 3D measurement by the "push of one-button". The internal accuracy estimates of the 3D measured points were better than .01" RMS, in this measurement survey.

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