Scene-of-crime analysis by a 3-dimensional optical digitizer: a useful perspective for forensic science

Forensic exploitation of patterned injuries: Promoting structured analysis as an early assessment for comparison process

Practice at our Center shows that approach using 3D surface imaging for morphometric comparison of patterned injuries does not always lead to accurate conclusions. We decided to evaluate whether a selection protocol focused on analysis phase could enable us to form an early assessment of the outcome of a comparison process, and then to select lesions likely to lead to a probative conclusion. 23 blunt objects were used to create 65 patterned injuries on an experimental model simulating human skin. A blinded analysis and a comparison were conducted on photographs and 3D models of the lesions. Statement of analysis phase was consistent with comparison results in most cases, enabling correct identification of the responsible object or at least keeping it as possibly responsible among 2 to 3 objects. Our protocol has been demonstrated to improve ability to exploit patterned injuries from surface imaging, despite certain limiting factors.

Multimodal Imagery in Forensic Incident Scene Documentation

Various imaging modalities are evaluated for use in forensic incident (crime or accident) scene documentation. Particular attention is paid to the precision vs. cost tradeoff, accomplished by judiciously combining various 3D scans and photogrammetric reconstructions from 2D photographs. Assumptions are proposed for two complementary software systems: an event scene pilot assisting the on-site staff in their work securing evidence and facilitating their communication with stationary support staff, and an evidence keeper, managing the voluminous and varied database of accumulated imagery, textual notes and physical evidence inventory.

A multi-resolution approach for an automated fusion of different low-cost 3D sensors

The 3D acquisition of object structures has become a common technique in many fields of work, e.g., industrial quality management, cultural heritage or crime scene documentation. The requirements on the measuring devices are versatile, because spacious scenes have to be imaged with a high level of detail for selected objects. Thus, the used measuring systems are expensive and require an experienced operator. With the rise of low-cost 3D imaging systems, their integration into the digital documentation process is possible. However, common low-cost sensors have the limitation of a trade-off between range and accuracy, providing either a low resolution of single objects or a limited imaging field. Therefore, the use of multiple sensors is desirable. We show the combined use of two low-cost sensors, the Microsoft Kinect and the David laserscanning system, to achieve low-resolved scans of the whole scene and a high level of detail for selected objects, respectively. Afterwards, the high-resolved David objects are automatically assigned to their corresponding Kinect object by the use of surface feature histograms and SVM-classification. The corresponding objects are fitted using an ICP-implementation to produce a multi-resolution map. The applicability is shown for a fictional crime scene and the reconstruction of a ballistic trajectory.