## 2 Materials and Methods
### Initial Design of the Device  
As part of the prototype design, the internal and external parameters of the device can be calibrated using OpenCV 4.7.0 libraries. The device itself does not require the use of external reference elements, e.g., reference points. Concurrently, the device necessitates that its position in space and its relative position to the object remain constant during the process of digitization. The calibration of the device is performed freely in space, using cv2.calibrateCamera and cv2.stereoCalibrate libraries for calibrating the camera (internal parameters) and the external parameters of the device, respectively. Given the potential for disparate settings for indoor and outdoor parameters, it is imperative to ascertain the correct parameters for digitizing nearby objects. The parameters that are suitable for digitizing nearby objects differ from those that are suitable for digitizing larger objects in a room. A notable example is the working range of optical sensors, where certain sensors may not function optimally at close distances. The design of the ESP32-CAM devices incorporates modularity and adaptability, facilitating the seamless swapping of optical sensors, modification of camera spacing, and adjustment of camera rotation. This functionality is illustrated in Figure 3.  
The device's design utilizes the active SfS stereovision principle, thereby eliminating the necessity for external reference elements. Consequently, the 3D surface digitization process was conceptualized around a laser pattern, ensuring sufficient coverage of the digitized surface area of an object. To this end, a laser source holder was incorporated into the initial design, enabling its rotation around its own axis. This laser holder is attached to the main device holder by a mechanism, whereby it is attached to the guide while the walls are supported against the main holder. The main holder has been designed with shaped elements that protrude regularly around the circumference of the device; these elements are 60 in number and are regularly spaced within a rotation angle of 6\({}^{\circ}\). Within the laser source holder, four shaped elements are designed to project circumferentially, exhibiting a regular  
Figure 3: CAD view of the initial device design. rotation angle of 90\({}^{\circ}\). The friction between these protruding elements enables precise control over the laser beam rotation angle, set at 6\({}^{\circ}\). In the initial proposal, ESP32-CAM devices, manufactured and sourced by AI Thinker in Shenzen, China, are utilized for the execution of stereo pair camera imaging. The utilization of ESP32-CAM facilitates the concurrent operation of two or more cameras, thereby leveraging the comprehensive functionality of the devices. The integration of a PC or laptop facilitates seamless operation, enhancing the user experience. The ESP32-CAM devices establish a wireless connection with the computer via WiFi, eliminating the requirement for a physical cable connection. This feature enhances the device's portability, facilitating its use in confined or inaccessible locations. The ESP32-CAM devices require a 5 V power supply, consuming no more than 1.5 W during operation. Additionally, the ESP32-CAM facilitates the swift and straightforward replacement of optical sensors, employing optical sensors with a lengthier flex cable connection, thereby reducing the necessary device dimensions. The fabrication of the physical models and parts of the prototype device was carried out using Fused Filament Fabrication (FFF) technology. The ESP32-CAM technology, developed by Ai-Thinker, employs a System on Chip (SoC) integration approach, encompassing all the essential electronic system circuitry necessary for utilizing the optical sensor within a unified integrated circuit.