1. Field of the Invention
The present invention relates to an image processing apparatus that can represent natural movements of an object having a plurality of joints in a simple manner.
2. Description of the Prior Art
When rendering movements of a human by computer graphics, image processing based on a key frame method or motion dynamics is usually performed. The key frame method is a method for expressing a motion using critical frames and their interpolated data, but it takes considerable time to determine the motion using the key frames. On the other hand, the method based on motion dynamics is capable of providing a fairly natural representation of movements, but the computation time required for processing by a computer is enormous.
In view of this situation, a method capable of simplifying the image processing is proposed in "A Method of Expressing Movements of a Multiarticular Object and A Computer Graphics Apparatus for Implementing the Same," (Japanese Patent Examined Publication No.4-71078). This method measures the movement of a multiarticular object (a human being) and attempts to express the movement by a one-dimensional joint angle function.
In this prior art, however, since the joint angle is expressed in one dimension, movements can be expressed only in a two-dimensional plane; furthermore, since no consideration is given to the orientation of a part between joints, motions such as twisting cannot be presented.
The above prior art also achieves reductions in processing time and data amount by expressing one-dimensional joint angles in the form of a function by using a prescribed function. The prior art, however, has had the problem that it cannot present movements responsive to the situation, for example, the movements of a human being trying to catch a ball with a hand.