Radial Basis Functions for 3D Nonlinear Soft-Tissue Warping

Facial reconstruction is important in several scientific areas, especially in forensic science and ar- chaeology. In both areas the basis of all work is a skull find of a dead person which should be recon- structed. This helps with the identification of a skeleton from an open case of death or the compar- ison of facial features between modern and ancient human beings. In this paper a new method for forensic facial soft-tissue reconstruction is presented. It is based on a nonlinear warping technique using radial basis functions known as thin-plate splines extended to 3D space. To minimize the amount of errors a regularized thin-plate spline version was implemented. As for the manual facial reconstruction procedure the forensic expert has to attach soft tissue on a skull find. However, since the conventional, manual 4-step approach of i) examination of the skull, ii) development of a recon- struction plan, iii) practical sculpturing and iv) mask design is very time consuming, multi-modality elastic matching of 3D MRI soft tissue onto the 3D CT image of a skull find is proposed.