Policie České republiky – Kriminalistický ústav
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Superimposition
Superimposition means that the skull is superimposed over a portrait photography or an X-ray of a suspected person and it serves to confirm or exclude a positive identification.
It can be carried out if:
- the police is trying to identify an unknown body and they have a suspected person (persons) selected,
- there exists a high-quality photograph of the face or an X-ray of the suspected person.
Video Superimposition Method is one of the superimposition methods applied in the Institute of Criminalistics.
Before the video superimposition is started, it is necessary to mark on the skull points for the anthropologic comparison, e.g. outer edges of eye sockets, lower edge of the nasal aperture, important craniometrical points or any abnormalities. The prepared skull is fixed onto a superimposition head with a ball joint allowing its precise positioning.
This positioning must, with its perspective, correspond the perspective of the comparison photo or X-ray. A special software is used to blend the image of the skull with the photo of the person or the X-ray of the head.
During assessment of the superimposition or video superimposition, relations between the skull and face or X-ray of the particular person are evaluated. The assessment process observes all morphological or metrical characteristics including any individual abnormalities on the skull and compares them to the characteristics in the comparison photo/X-ray of the person. Then it is possible to exclude or confirm whether the skull matches the particular person.