The use of technology in sports has increased in recent years. One of the most influential of these technologies is referee support systems. Team sports such as volleyball require accurate and robust tracking systems that do not affect either the players or the court. This paper introduces the application of intrinsic and extrinsic camera calibration in a 12-camera volleyball referee system. Intrinsic parameters are calculated by using the classic pinhole model and Zhang’s method. To perform extrinsic calibration in real time, the volleyball court is treated as a global calibration artifact. Calibration keypoints are defined as court-line intersections. In addition, a new keypoint detection algorithm is proposed. It enables achievement of an accurate camera pose in regard to the court. With all 12 cameras calibrated in a common coordinate system, a dynamic camera stereo pair creation is possible. Therefore, with known ball 2D image coordinates, the 3D real ball coordinates can be reconstructed and the ball trajectory can be estimated. The performance of the proposed method is tested on a synthetic data set, including 3Ds Max rendering and real data scenarios. The mean camera pose error calculated for data biased with keypoint detection errors is approximately equal to 0.013% of the measurement volume. For the real data experiment with a human hand phantom, it is possible to determine the presence of the human phantom on the basis of the ball reflection attitude.

The electronic, optical and thermoelectric properties of zirconia-based MgZrO₃ oxide have been studied theoretically at a variant pressure up to 25 GPa. Calculations for the formation energy and tolerance factor reveal the thermodynamic and structural stability of MgZrO₃. To tune the indirect band gap from to a direct band gap, the optimized structure of MgZrO₃ has been subjected to external pressure up to 25 GPa. The optical properties have been discussed in the form of dielectric constant and refraction that brief us about the dispersion, polarization, absorption, and transparency of the MgZrO₃. In the end, the thermoelectric parameters have been analyzed at variant pressure against the chemical potential and temperature. The narrow band gap and high absorption in the ultraviolet region increase the demand of the studied oxide for energy harvesting device applications.

We review recently proposed concepts of infrared and terahertz photodetectors based on graphene van der Waals heterostructures and HgTe-CdHgTe quantum well heterostructures and demonstrate their potential.

Magnetoabsorption in far and mid IR ranges in double HgTe/CdHgTe quantum wells with inverted band structure has been studied in high magnetic fields up to 30 T. Numerous intraband and interband transitions have been revealed in the spectra and interpreted within axial 8 × 8 k·p model. Splitting of dominant magnetoabsorption lines resulting from optical transitions from hole-like zero-mode Landau level has been discovered and discussed in terms of a built-in electric field and collective phenomena.

The evolution of microstructured optical fibers with hexagonal array (H-MOFs) of air-holes rooted in the background of undoped silica has led to the realization of an ideal host for encouraging and technologically entitled optical properties. We focus to explore the divergence of radiation into free space from the end-facet of solid-core H-MOFs by using the improved theoretical model. Also, we investigated the wavelength dependence of beam divergence angle for principal core mode of H-MOFs under step-index fiber approximation (SIFA). Experimental results have been included for comparison.