Using iWitnessPRO for homicide scenes

Police investigators often face challenges in obtaining accurate measurements when documenting crime scenes. In many cases, it is unfeasible or nearly impossible to map the crime scene with a total station theodolite. Baseline tape measurements are often inaccurate for 3D data, as well as even 2D mapping tasks. Laser scanning technology is a method that works, but costs tens of thousands of dollars and is not economically feasible for most crime scene investigators. Close-range photogrammetry has proven to be a fast, accurate and a low-cost method of 3D crime scene mapping.

iWitnessPRO was used to "3D map" a staged burglary. The purpose of the project was to measure/diagram the room contents, including the position of the burglar (simulated to be knocked unconscious.)

The room was divided into two separate image-based measurement networks, where approximately 150 digital images were used to create the 3D model. A quantity of 48 coded targets and 4 spinner codes were also used. Processing of the 2 networks was accomplished by simply clicking the "R++" button within iWitnessPRO to automatically processed the 3D points. Lines between 3D points as well as facet form polylines were also created.

In addition to measuring the room, a CAD symbol for an exercise bike was also created using iWitnessPRO. The result was DXF exported into RHINO (CAD software) and the symbol was created from the iWitnessPRO 3D wireframe. The newly created exercise bike symbol from RHINO, was then DWG exported into the Crime Zone (CAD Zone's diagramming software.)

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The two iWitnessPRO DXF files were transformed into the same coordinate system using the programs "Transformation To Control" feature and then imported into the Crime Zone. Crime Zone was used to finalize the diagramming work.

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Click to enlarge (CAD diagram)

The Results
iWitnessPRO mapped the entire room with high accuracy in this the crime-scene example.

iWitnessPRO is an important tool in forensic mapping applications for police and accident reconstructionists. It is the best in the field of close-range photogrammetry and is superior to other measurement and mapping technologies at a fraction of the cost.

To watch a two minute video of the iWitnessPRO room mapping and conversion to CAD, click here.

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