三個CCD攝影機動作擷取系統之實作

Abstract

由於電腦3D 影像技術的快速進步，已可利用電腦來製作出一個可在3 度虛 擬空間中移動的虛擬人物，然而虛擬人物的動作光靠人工手調來製作如歌手歌 唱、舞蹈等動作，幾乎是不可行的，因為需花費龐大的時間人力成本，且仍無法 非常的接近真實人物的動作。若是透過動作擷取系統(Motion Capture System)(或 稱為動態擷取系統)拍攝真實演員的動作，並將其套用至虛擬人物上，則可以使 虛擬人物的動作有如真實人體的動作一般的靈活。目前國內已有電腦動畫公司購 置來製作人物動畫，購買系統所須花費的成本非常高，因此本研究乃發展一套較 低成本使用三個攝影機與色球辨識的動作擷取系統。 本研究提出的人體3D 動作擷取方法為在環形黑色的布幕背景中，拍攝演員 的動作，演員的身上須穿著黑色衣服，在身上的12 個關節點上放上彩色球。用 3 台CCD 拍攝演員的動作，以解決部份關節點在移動時拍攝不到的問題，並將 拍攝到的關節點的位置，使用本研究提出的修正曲線與計算方法，計算各關節點 三度空間中移動的座標，再利用關節點之間的座標關係產生動作擷取檔– CSM (Character Studio Motion)格式的檔案，以利在3D 軟體上展示，如3ds max 4 軟體， 而Character Studio 是專業製作兩足角色動畫的工具軟體，是屬於3ds max 4 的 Plug-In 軟體。 本研究已製作出只使用3 台PC 與3 台CCD 攝影機，加上自製軟體，可將 所拍攝之演員連續動作套用至3ds max 4 軟體的虛擬人物上，做出和演員相同的 動作。

Because of aggressive virtual characters progressing of 3D image technology, which produce virtual humans, can move in 3D virtual space. But it is impossible to use a mouse to control virtual human to sing songs or dance. It costs a lot of time and doesn’t look like the real human motion. Using the motion capture system to capture a real actor's motion makes a virtual human motion look like a real human motion. Now, some computer animation companies have bought the motion capture system to produce the human animation. But the cost of such motion capture system is very expensive; therefore, we have developed a motion capture system that customers can have at low price. In this study, the method, which captures the human motion in 3D space, uses black fabric to be the background, and the actor has to wear black cloth and then put color balls on 12 body joints. Using three CCD cameras to capture an actor’s motion can solve the missing joints problem when one camera can’t picture the body motion which is partly blocked whiling moving. In this study, we have developed the method to recognize the 12 color balls, to calculate the 12 joints 3D position data by the pictures which are captured by the three CCD cameras, and we have developed the method to calculate the 12 joints 3D position data to CSM (Character Studio Motion) format. So we can demonstrate the 3D virtual human motion on 3D software, such as 3ds max4 software. The method uses 3 personal computers and 3 CCD cameras only, the installed 3D software, and it combines the pictures on the cameras with virtual humans on the 3D software. It imitates the actor’s motion virtually.