The image-based measurement method 2D Continuous Particle Image Velocimetry (2D Continuous PIV) is commonly used for measuring particle velocities in thermal spraying processes due to its basic measurement setup and its large measurement volume compared to methods based on point sensors. The accuracy of such image-based measurement techniques depends on the measurement algorithm, the process environment, such as distributions of particle characteristics, and the error of the imaging system. However, in the case of 2D measuring, accuracy might also depend on the fact that 2D methods measure only two of the three velocity vector components while ignoring the third component. In this paper, the impact of measuring only two of the three velocity vector components on the accuracy of a closed-source 2D Continuous PIV algorithm is investigated. The analysis is based on a virtual measuring instrument that includes optical aberrations of the imaging system and it is shown that this error contribution of measuring only in 2D is within acceptable limits for typical thermal spraying processes.