NTT Communication Science Laboratories , Kanagawa, Japan.
Proc Biol Sci. 2024 Sep;291(2031):rspb20241490. doi: 10.1098/rspb.2024.1490. Epub 2024 Sep 18.
The visual naturalness of a rendered character's motion is an important factor in computer graphics work, and the rendering of jumping motions is no exception to this. However, the computational mechanism that underlies the observer's judgement of the naturalness of a jumping motion has not yet been fully elucidated. We hypothesized that observers would perceive a jumping motion as more natural when the jump trajectory was consistent with the trajectory of a vertical projectile motion based on Earth's gravity. We asked human participants to evaluate the naturalness of point-light jumping motions whose height and duration were modulated. The results showed that the observers' naturalness rating varied with the modulation ratios of the jump height and duration. Interestingly, the ratings were high even when the height and duration differed from the actual jump. To explain this tendency, we constructed computational models that predicted the theoretical trajectory of a jump based on the projectile motion formula and calculated the errors between the theoretical and observed trajectories. The pattern of the errors correlated closely with the participants' ratings. Our results suggest that observers judge the naturalness of observed jumping motion based on the error between observed and predicted jump trajectories.
被渲染角色动作的视觉自然度是计算机图形学工作中的一个重要因素，跳跃动作的渲染也不例外。然而，观察者判断跳跃动作自然度的计算机制尚未完全阐明。我们假设，当跳跃轨迹与基于地球重力的垂直抛射物体的轨迹一致时，观察者会认为跳跃动作更自然。我们要求人类参与者评估高度和持续时间调制的光点跳跃动作的自然度。结果表明，观察者的自然度评分随跳跃高度和持续时间的调制比而变化。有趣的是，即使高度和持续时间与实际跳跃不同，评分也很高。为了解释这种趋势，我们构建了计算模型，该模型根据抛射体运动公式预测跳跃的理论轨迹，并计算理论轨迹和观察轨迹之间的误差。误差模式与参与者的评分密切相关。我们的结果表明，观察者根据观察到的和预测的跳跃轨迹之间的误差来判断观察到的跳跃动作的自然度。
