3D Analysis Software

The 3D analysis software is used by forensic experts in the office. Once the data from the 3D-scanner has been uploaded to the analysis software in a first step it is prepared for the subsequent analysis step. Different shading variants are calculated which are later used to emphasize marks in the 3D-data.  Optionally, if an impression was larger than the single field of view of the scanner, such as from a tyre, then multiple scans can be “stitched” together with a cloud to cloud registration process (Fig. 5).

wizard

Fig. 5 Wizard guiding the user in the registration process of two scans covering two partially overlapping areas of the same tyre impression

 
In a further step the high resolution colour data is mapped onto the 3D data (Fig. 6).

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heightmap
coloured_3d_data

Fig. 6 Left image showing the pure 3D-data, center image with projected heightmap and right image with projected colour information

 
The integrated 3D measurement and colour data can then be analysed with the software to investigate characteristics of the footwear and tyre impressions. Class characteristics are determined by the user through comparing the impression with images from manufacturers’ or other databases. Individual identification characteristics such as holes and tears can be marked by the user with an annotation tool. Further tools allow the comparison of footwear and tyre impressions with suspects’ shoes and/or vehicle tyres and other crime scenes. Two 3D-scans can be presented in two opposite windows. The user can move and zoom through both scans to identify similarities or differences (Fig. 7).

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shoe_comparison

Fig. 7 An example of 3D analysis software comparison tool

 
There are several possibilities to insert measurable annotations (profiles, 3D polylines), to export and to document analysis results for further reporting purposes.
A workflow and methods have been implemented in the 3D-Forensics system to ensure the integrity and authenticity of the data.
In the present 3D-Forensics/FTI project the last development steps are being supported by an External Expert Tester Group (EETG) composed of 5 police forces and 1 forensic institute. The activities of the EETG are focussed around performance verification and validation.