Evaluating Visual Quality of Secondary Motion Simulation Techniques : A Survey on Stylized 3D Game Character Cloth and Hair

Sammanfattning: Background. Secondary motion is a principle of animation, it is movement that occurs as a result of other movement, such as swinging hair or clothes. In 3D animation, such as in games, it is often simulated instead of animated manually. In game projects with time limitations, it can be interesting to know to what degree these simulations impact the visual quality in order to decide whether they should be prioritized. It is also interesting to know how the results of various methods compare to each other. To simulate in real-time means that physics simulations are running during gameplay. Baked animations on the other hand are simulations that have already been processed and saved as animation data, they are less dynamic but also less performance intensive. Objectives. The aim of this thesis is to evaluate the impact of three sets of animations by conducting a survey where each set is compared. The three sets are: animations that feature real-time simulations, baked simulations and ones without simulation. The goal is to acquire a metric from the comparisons that can give an insight to the visual quality impact of each method. Methods. Three animation sets were created. Then, a survey was conducted using a questionnaire that featured side by side video comparisons of the animation sets. The videos featured a stylized character running, walking, or jumping through an empty environment. Pairwise similarity judgements were done by asking the participants to rate each video compared to each other. The results from the questionnaire were analyzed using a method that is a part of the analytical hierarchy process. The data from each comparison was averaged, put into pairwise comparison matrices, and then used to calculate priority vectors. The level of consistency of the comparisons were also calculated. Results. The priority vectors show the ratios of how each animation set were preferred compared to each other. In the priority vector for all animations combined, the set without simulations ranked at twenty-four percent, the real-time set ranked at thirty-three percent and the baked set ranked the highest at forty-three percent. The comparisons were calculated to have a very high consistency, which strengthens the result. Conclusions. The results show the impact that adding simulated secondary motion has. The simulations appear to improve the visual quality, but the margin is not extreme. The calculated ratios could be used to argue for or against a game project’s prioritization of secondary motion simulations depending on the project’s time constraints and access to preexisting methods of simulation. It should be noted that the format of video comparisons did not showcase all the advantages of each method such as creation accessibility, technical performance or dynamicity. As such, it is uncertain how fair the comparisons of the baked and real-time simulations are in a more general sense. Nevertheless, the results are considered to give at least a partial insight into how these methods compare.