Knowledge about the point of regard is a major key for the analysis of visual attention in areas such as psycholinguistics, psychology, neurobiology, computer science and human factors. Eye tracking is thus an established methodology in these areas, e.g. for investigating search processes, human communication behavior, product design or human-computer interaction. As eye tracking is a process which depends heavily on technology, the progress of gaze use in these scientific areas is tied to the advancements of eye-tracking technology. It is thus not surprising that in the last decades, research was primarily based on 2D stimuli and rather static scenarios, regarding both content and observer. Only with the advancements in mobile and robust eye-tracking systems, the observer is freed to physically interact in a 3D target scenario. Measuring and analyzing the point of regards in 3D space, however, requires additional techniques for data acquisition and scientific visualization. We describe the process for measuring the 3D point of regard and provide our own implementation of this process, which extends recent approaches of combining eye tracking with motion capturing, including holistic estimations of the 3D point of regard. In addition, we present a refined version of 3D attention volumes for representing and visualizing attention in 3D space.