The challenge of accurately evaluating the size and shape of the human face has always sparked the interest of both researchers and doctors. The utilization of 3D surface scanning technique to create digitized models of human anatomical parts that can assist with altering the way a huge variety of products are planned and manufactured [1]. One of the fundamental problems which any novel user encounters during 3D laser scanning is the choice of suitable process parameters to obtain the full scan with very few steps. There is always an option associated with input process parameters like angular orientation, relative scanner distance, and the effect of light intensity, which is not always too intuitive but also strongly influences the scan results. The demand for accurate assessment and visualization of the facial bone and other tissues increases due to advancements in dentistry, maxillo-facial and plastic surgery. Face scanning is also examined to evaluate the outcomes of facial plastic surgery [2].
3D Scanning is the technique of detailed analysis of real-world capture to gather data on its specifications related to dimensions appearance. From the past few years, the majority of reports are published on the utilization of 3D scanners in the medical, dental, and healthcare sectors is considerably increased, which might prove helpful for plastic surgery[3–7]. Scanning technology during its infancy period is limited to industrial applications as the scanning of the human face requires a sequence of specific conditions compared to industrial objects[4]. Various studies focused on improving the performance and optimization of process parameters of handheld scanners studying the face of person, including a progression of exceptional circumstances. As the face of living person can't be immobilized, the scanner must feature a brief recording span. Hence a handheld 3D scanner is used for this purpose.
Moreover, a portable handheld scanner can be moved in various directions and enables us to scan from different orientations. A study has been performed to create a laser triangulation 3D scanner whose sole purpose is to solve the limitation of occlusion. It uses two distinct laser colors, namely green and red, along with a charge coupled device camera (CCDC) and helps enhance the reliability of respective system[8]. Several research focused on design of a time-to-digital converter and measurement of time of flight (ToF), in order to utilize same in portable scanners[9].
The dependency of ambient lighting as an essential factor in influencing the quality of the captured signal by Charge Couple Devices (CCD), and the impact of surface roughness the object during measurement was also recorded in few studies. Optimum results are obtained in case of absence or limiting ambient lighting conditions [10]. The research was performed to worked with the diffuse reflections of the object’s surface being scanned and an effective method to restrict the outcome of ambient illumination by implementing the distinct light filters upon the CCD sensors[11]. Moreover, a general solution to use the coating spray for covering the object by matty white layer is also introduced. The effects of other influential factors such as incident angle, distance from the scanner, and object color are also studied on a Computer Numerically Controlled (CNC) laser scanning process [12]. A primary structured light pattern for 3D structured light scanner is implemented in a research, during development, the suggested system's accuracy and resilience were evaluated on artificial items with established surface geometry, followed by assessments on human individuals [13].
Several researches indicated the problems in data acquisition of dark, translucent, and glossy surfaces. Generally, in the case of shining surfaces, noise is eventually added during the measurement, and the points exclusive to the actual surface can also be provoked. In both instances, sensors cannot achieve data locally (lost data), or the scan measurement is adversely affected [14]. These shiny surfaces are covered with coating sprays that help scan the objects' dark, glossy, and translucent surfaces. It was found that for 5–15 micrometers, the respective additional thickness and variation is about 45 micrometers using comparatively thin coating sprays. A low cost scanner with a hemispherical workspace has been designed and implemented with least square minimization approach to realign the parameters for achieving optimized results[15]. Further, a modified particle swarm technique, to optimize the significant morphological parameters in a contactless laser scanning method in various research [16]. Few of them investigate the effectiveness of positioning aids for obtaining 3D data in various clothing postures and configurations, through a superior quality body scanner [17].
The quality of digitized points with the help of 3D laser scanning is evaluated by several criteria, namely density, completeness, noise, and accuracy [18,19]. Several types of research are published regarding the performance of 3D scanners at various surface-to-scanner comparative orientations, and altogether examined scanners in normal position w.r.t the surface as the best condition [20–22].
A handheld, cost-effective 3D laser scanner was used to scan a human face under three significant input factors, i.e., scanning distance, angular orientation, and light intensity. A combination of input factors for twenty experiments has been designed based on face-centered central composite design. Accordingly, twenty CAD models have been retrieved on the twenty combinations of input factors. The accuracy of scan models is investigated through the Frechet Inception Distance (FID) score, which is taken as output. A model has been trained among input and output using a neural network, and further, it is optimized using a genetic algorithm.