## 4 Discussion
### Data Acquisition  
Data acquisition for maxillofacial prostheses can be achieved through advanced medical imaging techniques and surface scanning technologies, each offering distinct advantages [3]. Medical imaging methods such as computed tomography (CT), cone beam computed tomography (CBCT), and magnetic resonance imaging (MRI) produce DICOM-format files that accurately represent patient anatomy, though they lack color and texture information [3,39]. Surface scanners, including laser, structured light, facial, and intraoral scanners, address this limitation by capturing detailed information about skin texture and color, often saving data in formats like PLY (Polygon File Format) or OBJ (geometry definition file format, developed by Wavefront Technologies). Photogrammetry, which reconstructs 3D models from 2D images using algorithms like Structure from Motion (SFM) and bundle adjustment, presents an accessible and radiation-free alternative. It allows for precise data acquisition with minimal patient discomfort, leveraging open-source software and affordable devices such as smartphones [12,40]. Skin texture and color are essential aspects that must be accurately captured from the patient to ensure a realistic and aesthetically pleasing prosthesis. In conventional and partially digital workflows, silicone--a naturally transparent material--is typically mixed and poured into a mold. To achieve intrinsic coloration, the clinician evaluates various shades directly on the patient's skin, blending specific amounts of pigments to match the base skin tone. This mixture is adjusted to simulate the patient's natural background color but is kept slightly lighter and less saturated, as darker and more chromatic detailsare applied later during extrinsic coloration. These procedures necessitate the patient's presence for accurate matching [2]. As an alternative, a spectrophotometer, such as the e-Skin device (Spectromatch Ltd., Bath, UK) can be employed. This tool not only measures the patient's skin color with precision but also provides a recipe for reproducing the exact shade, reducing reliance on manual adjustments [21]. For a fully digital workflow, it is ideal to record the patient's skin tones digitally and transmit these data directly to the 3D printer. [PERSON] et al. [12] used +ID Methodology, which involved smartphone capturing and open-source software. A series of 39 photos were taken from different heights and angles under indirect natural daylight (1000-4000 lux) to ensure consistent lighting and color accuracy. The subject's facial area, including anatomical landmarks, was captured comprehensively, with fiduciary color elements placed in the capture area for reference. The images were processed into a UV map, which wrapped the 3D model's geometry with texture and color data, using the +IDonBlender software add-on. This ensured accurate alignment between the geometry and the texture. The UV map, containing the face's color data, was calibrated using LAB color tools in Adobe Photoshop(r). The fiduciary color element served as a target for standardizing the color space coordinates, ensuring consistency between the captured data and the desired print output. The 3D model, with its calibrated color information, was exported as a VRML (Virtual Reality Modeling Language) file. This format is capable of carrying detailed color, transparency, brightness, and texture data, and is compatible with a CMYKW (Cyan, Magenta, Yellow, Black, White) Stratasys(r) J750 3D printer [12]. For collecting surface, texture, and color details, [PERSON] et al. [31,38] used 3 dMD photogrammetry system which included three cameras positioned in a \"pod\" to capture detailed spatial and color information. The system relied on built-in camera flashes to standardize illumination and reduce variability in color data. The captured data were separated into a monochrome 3D model containing geometric details and a 2D color image representing the surface color information.