For the measurement of three-dimensional velocity fields in laboratory experiments, Stereoscopic Particle Image Velocimetry (SPIV) is often used. That requires two cameras to scan the flow from two different views. The positions of the cameras play a crucial role in this process, which can be determined via Cam- era Calibration. For the calibration, images of a calibration target must first be captured with both cameras, which defines the world coordinate system using certain markers. Together with the corresponding image coordinates, point pairs are formed, which can be used to perform the calibration. In this work, therefore, a method for detecting a target with circular markers in SPIV experiments is described based on the Laplacian of the Gaussian (LoG) operator. That is augmented with various filtering techniques. To verify the robustness of the method, a series of experiments are performed. In SPIV experiments, Scheimpflug cameras are frequently used to focus on planes that are not perpen- dicular to the cameras’ line of sight. That is accomplished by tilting the image plane. To determine the influence of this rotation on the calibration and in particular on the camera position, a camera model is described after founded research, which includes such rotations. In addition, three different calibration methods are described that can provide results with various accuracy depending on the setup. Using these three methods, both practical and artificial tests are done to deter- mine the impact of the Scheimpflug Model on the calibration. In doing so, the calibrations with this model taken into account provide more accurate results overall. Nevertheless, this rotation in the camera model has no impact on the camera position itself in the artificial tests. The practical experiments, however, indi- cate partially higher deviations. The new calibration technique therefore consists of taking existing methods and modifying their results with adaption to reality. The final comparison between the results of the different methods is fundamental.     «

For the measurement of three-dimensional velocity fields in laboratory experiments, Stereoscopic Particle Image Velocimetry (SPIV) is often used. That requires two cameras to scan the flow from two different views. The positions of the cameras play a crucial role in this process, which can be determined via Cam- era Calibration. For the calibration, images of a calibration target must first be captured with both cameras, which defines the world coordinate system using certain markers. Together w...     »