Investigating the Perceived Quality of Image-Based Impostors

Abstract: The rendering process of a large number of 3D objects is computationally expensive and to achieve a fluent experience for the observer, optimization techniques need to be applied. One such technique for rendering 3D objects is with image-based impostors, which involves replacing a 3D object with a 2D image. This thesis investigates the number of degrees the observer can move in relation to the impostor before updating its representation to still appear as a 3D object. Specifically, the aim of this thesis is to explore what update-rate an impostor of a virtual human should have to be perceived as smooth, and if the distance between the user and impostor has any effect on this update-rate. A user study was conducted with an experiment outline based on previous work by Hamill et al. [1], with the objective to answer if a certain update-rate was considered smooth or jerky. Results display that an update every ~5.9° was considered smooth at a close distance, while an update-rate of ~6.5° was considered smooth when the impostor was far away from the observer. A one- way ANOVA test on the two different distances indicated that the distance did not significantly influence the degree that was considered smooth. This implies that impostors of virtual humans should be used with an update-rate of approximately 6°, regardless of the distance between the observer and the impostor.