A User Study of the Just Noticeable Difference in Animation Level of Detail Set in a Game Environment

Abstract: Background. A previous study on performance benefits of joint reduction for animations was made by the authors of this thesis. The results of the study showed that a reduction in joint count is highly beneficial for performance. What that study left out was the perception of Level of Detail (LoD) of animations, and what the Just Noticeable Difference (JND) of a percentage decrease on the joint count would be. Thus motivating a study on peoples’ perception of animation quality. Objectives. The aim is to study the perception of LoD of animations in a game-like environment whilst doing a simple search-and-click task. Aiming to find the JND between animations with a different number of joints while the players are set with a task that does not involve interacting with the characters performing the animation. Methods. A psychophysical experiment was performed using a game implementation in Unity. Unity was chosen because it has easy access to develop scripts and a game environment. Furthermore, it has a marketplace where already made content can be downloaded and reused, which made the user study much easier to create. Results. A total of 85.71% did not see any difference between the different qualities used for the animations. The 14.29% that saw a difference in the animations all saw the difference between the lowest and the one next to the lowest quality animation. Conclusions. Three out of 21 participants were able to see a difference in the lowest animation quality, whilst no one saw any difference in the other qualities. Thus, people were not able to see a density reduction of up to 62.26% fewer joints for the chosen animation. Due to the low number of positive detections in the quality change of the animations, the JND could not be reliably computed.