目標導引模型中的循序目標限制式和避碰方法

Abstract

目標導引模型是一種新的電腦動畫製作方法，可用來設計及描述物體的運 動行為。動畫製作者在利用這種技術設計動畫時，只須 物體運動的目標 ，再由電腦根據物體目前的狀態，算出要完成 所需的作用力，代入適當 的物理運動定律，便可自動地產生動畫的中間過程。這使得動畫製作者不 必花時間來描述動畫過程的細節，而產生更逼真的結果在許多目標導引模 型的應用中，常會遭遇到兩種問題：一是如何協助物體依動畫製作者設定 的時間，確實地完成一連串的目標，並使物體在整個運動過程中，速度可 以維持平穩且順暢；一是如何自動地處理物體間可能的碰撞及穿透問題， 但不可因此而阻礙了原先設定目標的完成。 Teleological modeling techniques are emerging as a useful computer animation approach for modeling and designing the behaviors of objects. By using such technique, animators can describe the behaviors of objects with a number of goals that objects must achieve. Thus, the desired motion sequence can be automatically generated according to the designated goals and the well-known physical laws. This technique alleviates the human efforts on planning animated sequences in detail and generates more realistic results. By using teleological modeling techniques to design an animated sequence, animators usually must deal with two problems. One is how to assist an object to exactly achieve a sequence of goals according to a given schedule and to keep the object's velocity stable in the whole motion. Another is how to automatically deal with the possible collision and penetration among objects and the included collision treatment can not impede the fulfillment of the designated goals. In this thesis, the sequential-goal constraints technique is proposed to assist modeled objects to fulfill a sequence of goals. In our approach, the goals are represented by constraints. According to the designated constraints, the proper forces and torques can be derived to drive the objects to meet each constraint exactly at the specified time. The resulting motion sequence of the object is continuous and integral. Furthermore, for providing the teleological model with collision-free actions, a modified electrostatic potential function, incorporated with a damping process, is proposed to construct the composite fields of repulsive force and attractive force. The composite fields ensure that two objects are connected at the specified part while preventing the other parts from possible collision and penetration. This requirement can not be achieved by traditional potential fields.