Best practices in Craniofacial Superimposition

  1. Use the real skull to confirm correct fit of the mandible with the cranium.

  2. Use the real cranium and mandible to articulate the dentition and establish centric occlusion.

  3. Reproduce the position of the mandible as displayed in the AM photograph.

  4. Locate and mark landmarks on the skull before scanning.

  5. Use multiple (more than one) AM photos or frames taken from video with the candidate in different poses, as far as they provide new information, e.g. more anatomical information provided by additional viewpoints.

  6. Use AM photographs of good quality. For optimal examination, of full frontal images the resolution of the face image should be at least 180 pixels corresponding to the width of the head, or roughly 90 pixels between the pupils of the eyes. (ISO International Standard ISO/IEC JTC 1/SC 37 N506).

  7. Avoid images with obscuring objects. e.g. spectacles and beards.

  8. During the growth period of children’s lives, always use the most recent AM photos. For adults, use the most informative photos.

  9. Perform CFS using original AM images, avoiding as much as possible image manipulation.

  10. Throughout the entire CFS process, be careful to preserve the aspect ratio of the photograph.

  11. Keep all the information contained within the original image (do not use cropped images which introduces error).

  12. Extract, as much as possible, information from the photograph (both digital information included in the Exif file and visual information) to infer original photographic conditions (e.g. approximate distance from the camera to the subject’s head, camera model, focal length, etc.).

  13. Analyze and describe separately both the skull and the face in the photograph(s) to be compared. This will include (general morphology, specific dimensions, and any special, potentially individualizing, characteristics) prior to superimposition.

  14. When multiple candidates are available, sort AM photos to be compared by reference to the existing description of the skull and prioritize them in a sequence of most to least likely to correspond.

  15. Use as many criteria as possible in order to study the relationship between the face and the skull.

  16. Consider the discriminative “power” of each anatomical criterion.

  17. Give an appropriate “weight” to each criterion according to the degree of uncertainty related to it, which will depend also on the AM view.