**5. Development of multi-sensor system**

Based on previous measurements we decided to use active stereo sensor RealSense D415 as a key element of our imaging system. The scanning accuracy is comparable to other sensor technologies and it is absolutely sufficient for given medical use. On the other hand, active stereo pair does not suffer mutual interference in parallel mode of scanning. From the previous results, we can determine the optimal distance of head from the sensors and this distance is approximately 0.5 m. This distance is respected in a physical model of the sensor stand. For mounting 3 sensors in the fixed position, we use the constructed stand, shown in **Figure 6a**. The spatial configuration schema is shown in **Figure 6b**.

The distance *d* is set approximately to 0.5 m. In our application, the frontal side of the object (the face) is the most important for scanning, so the layout needs to be set to obtain a high fill rate in this area. For future automated processing of captured 3D models and their normalization, the patient must sit in a normalized position. To avoid covering the important parts of the head we had to replace physical head fixation by software assistance tool mentioned later. This assistance algorithm places the head to the center of frontal sensor because the features obtained from this view (facial view) are the most important.

**Figure 6.** *(a) Adjustable sensor stand. (b) Layout of sensor positions (top view).*
