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Bureau of Criminal Apprehension

Crime scene diagramming

The BCA Crime Scene Team employs 3D scanning equipment for the diagramming of crime scenes. The scanners rotate horizontally and simultaneously have a lens that rotates vertically while projecting a laser. The laser meets target surfaces and reflects back to the scanner to create data points. Each data point collected has a three dimensional coordinate value of its location relative to the scanner location. The scanners are also equipped with on-board HDR cameras for photographing the scene from the perspective of the scanner. The photographs taken by the scanner are used to provide appropriate color assignments to the data points. This equipment is unaffected by lighting conditions at a scene, therefore is capable of being used in complete darkness and brightness of full daylight.

The scanners are able to collect up to 2 million data points per second and forms a collection of data points called a point cloud.  The scanners have the ability for automated point cloud data transfer to a specialized filed-based software application that is used to view and register scan data on scene. This allows the data to be bundled appropriately prior to post-scene processing, which results in a scene diagram that is a complete 3D representation of the scene. Each point within the diagram can be used to extrapolate distance and angle measurements. 

Picture showing linked scans of areas at a crime scene

 

Picture showing measurements obtained from the 3D scanner used by the Crime Scene Team

 

A scientist using a 3D scanner outside at a crime scene