## 1 Introduction: The Significance and Aims of Forensic Facial Soft Tissue Reconstruction
In addition to the classical methods, modern techniques such as DNA analysis or the radiocarbon method are used to determine the age at death or the lifespan of the individual. In addition to the creation of the biological profile mentioned at the beginning, the reconstruction methods that have been established over the years form an essential basis for any facial soft tissue reconstruction. The three most prominent methods that initially relied on manual 3D modeling of soft tissues directly onto the skull are the Russian, American, and Manchester methods. The first is the Russian method, also known as the Gerasimov method, which is based on a purely muscular reconstruction of the face, taking into account the individual facial muscles and muscle attachments to the bone structures [11; 12]. The second method is the American method of [PERSON] and [PERSON], which is based on the knowledge and application of cranimetric reference markers, so-called anatomical soft tissue markers, which are characteristic of the age, sex, and ethnic group of the person whose face is to be reconstructed [13]. Anatomical soft tissue markings are applied to specific areas of the skull, and the spaces between them are filled in to accentuate the facial features [12; 14; 15]. The final method is the British or Manchester method of [PERSON] combines the Russian and American techniques to create a successful method of facial reconstruction [2; 16; 17]. In recent years, digital methods have become increasingly important compared to manual FSTR [18; 19; 20; 21]. This is not only due to time-saving and high flexibility but also to the possibility of optimizing individual steps of the reconstruction process through automation. Digital facial reconstruction methods can fundamentally be divided into two categories: 2D and 3D techniques. In 2D reconstruction, one common approach is digital drawing, in which a forensic artist, often in collaboration with an anthropologist, sketches the facial features directly onto an image of the skull [22]. This technique follows similar principles to traditional manual methods, such as the application of average soft tissue thicknesses and anatomical guidelines for feature placement [22]. Another 2D technique is superimposition, where an algorithm reconstructs the face by overlaying skull images with portrait photo databases to find the best visual match [23]. In contrast, 3D digital reconstructions include both the virtual implementation of traditional methods, such as the American, Russian, or Manchester approaches, using computer-aided design (CAD) software [24] and more advanced techniques involving the approximation of facial soft tissues through 3D morphing based on large anatomical databases [25; 26]. A detailed comparison of both classical and digital methods of forensic facial soft tissue reconstruction, including their methodological foundations, advantages, and limitations, is provided in Table 1.  
However, in order to be able to carry out a computer-aided reconstruction in a virtual environment, and for ethical reasons also for manual reconstructions, the remains, in particular the skull, must first be digitized or replicated. Various methods, such as photogrammetry, laser scanning, imaging techniques, and 3D printing techniques, can be used for this purpose [26; 27; 28; 29; 30; 31]. Photogrammetric methods, in particular, are becoming increasingly important for the production of digitized data alongside imaging techniques such as CT scans [32; 33; 34; 35]. A large number of commercial and open-source software applications are available for processing the captured data in the form of image and video recordings or sectional images for CT scans [36; 37; 34; 38]. Another digitization option is laser scanners, which are also widely used depending on the objects to be digitized [39; 40; 41; 42]. Depending on the evidence and the underlying technology, different methods can be used to create high-quality digital copies of remains, which form the basis for computer-aided reconstructions.