State Trooper maps a serious collison using a Digital Camera, PM's and iWitness


Using a low-cost, off-the-shelf digital camera, a state trooper imaged this incident in a matter of minutes for measurement with iWitness. The incident involved a two vehicle crash. DCS Inc., photogrammetric markers (PM's) were also used at the accident scene. Other natural features were later marked in the pictures for the photogrammetrical scene diagramming process. The trooper took the pictures in 15 minutes with a hand-held digital camera. The scaled 3D model from iWitness was later exported to CAD, as presented below.


Perspective views in iWitnessTwo persepctive views of police images used in iWitness

The images above are perspective views of a portion of the incident mapped with an Olympus C-5050 (5MP) digital camera and DCS Photogrammetric Markers.

Two persepctive views of police images used in iWitness

The image above is a closer viewing of vehicle final rest. Note how the Markers are used as "additional reference points". The scene evidence (road debris, tire marking, vehicle locations, lane lines, curbing, etc.) are marked as Natural Features in the images for the non contact photogrammetric 3D points, lines and polylines created in iWitness.

At the bottom is the DXF exported results of the iWitness photogrammetry measurements, imported with vehicle symbols inserted in CAD. The iWitness-to-CAD model is illustrated adjacent an aerial view. Project accuracy was better than .1' (2.5cm).

Aerial view (reference only) of roadway and iWitness placed in CADPlan view of iWitness and (aerial view for reference)


Noteworthy is the fact that this incident happened years ago. The digital images were recalled and more feature points, lines and polylines of interest were measured in iWitness two years after the crash actually happened. iWitness offers the flexibility to retrieve 3D-dimensional data long after the crash incident occurs. Using a moderately priced digital camera and iWitness, the combination affords a low-cost, extremely fast and higher level of measurement accuracy compared to other accident reconstruction diagramming tools.


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