The advantages and disadvantages on key-frame animation :Based on 3DCG animation work on the subject of free-running

In recent years, key-frame animation is replaced by motion capture system in many areas in making CG animation. However, it still has some indisputable advantages on the performance of traditional animation. For example, we often see some characters stretch their bodies in key-frame animations, but if we want to make this kind of performance through motion capture system, we need to transform the motion data(non key frame) that we captured to key frame data. This means, the motion capture system will take more time to perform traditional animation than key-frame animation. Yet, key-frame animation also has an obvious problem on efficiency, and this problem can only be found by actual practice of making an animation. Therefore, in order to solve this problem, we made an animation at our early stage of study. For this study, we took an extreme sport called free-running as our research target. Free-running has two features: first, continual and quick movements. Second, a wide variety of body positions because of these movements. In animation production，these two features we mentioned above are the most time consuming aspect. We made an animation includes 9 scenes totally and counted the adjusted frames in our animation. By this work, we found 3 factors that will affect the number of key frames: the number of intermediate frames, the creators’ life experience and the sense of timing. All these factors are related with timing. Therefore we considered that the key to solve the problem of efficiency is to appropriately determine the value of timing at initial stage.