大型觸控螢幕內三維虛擬物件的旋轉操控模式與手勢型態配對之研究

A Study on the Mapping of Rotation Manipulation for 3D Virtual Objects and Gesture Patterns on Large Touchscreens

觸控螢幕的應用，在現今的社會已達非常普及的程度，有些單位運用大型觸控螢幕來輔助藝術展演與文宣推廣，部分博物館也運用大型觸控螢幕，作為知識宣導與教育的互動媒介，甚至運用動畫技術，展出擬真的三維虛擬物件。然而，在二維的平面觸控螢幕上操控三維物件的動作時，使用者若是對於觸控手勢型態與物件變化的配對方式感到不自然，將會導致績效的降低，甚至影響操作時之愉悅感。因此，本研究之目的即欲探討在數位內容導覽系統中，以不同手勢型態操作大型觸控螢幕時，所對應之三維物件的不同視角翻轉模式及其使用績效。本研究即以製作一款三維擬真生態物種，在大型觸控螢幕上，透過受測者以手勢互動的操作，介紹其細部的外觀，並透過實驗與統計的過程加以分析研究，旨在透過探討水平與垂直拖曳、直線斜角拖曳、弧形或旋轉拖曳與輕推，四種不同手勢型態，對三維物件於三視與透視兩種不同視角模式，在翻轉時的使用績效。以雙因子變異數分析結果顯示：（1）根據耗用時間與點擊次數分析，完成三視圖模式任務皆比透視模式任務容易；（2）經由行為分析的結果發現，當須完成透視模式任務時，使用者直覺上會先以水平或垂直拖曳來操控物件，若無法定位才會嘗試以其他方向拖曳；（3）無論三視模式或透視模式任務，水平垂直拖曳的手勢型態最能讓使用者認知物件翻轉的對應性，也具有較高的使用績效；（4）由於水平或垂直拖曳的手勢往往有些斜度產生，因此容易與直線斜角拖曳混淆。（5）輕推手勢，因與物體旋轉方向較難配對，因此較少使用。本研究建議未來在設計以觸控手勢操縱三維物件旋轉的介面時，針對水平或垂直拖曳動作應加入手勢移動之水平或垂直偏移量的校正程式，以符合一般人操作時之期待。此外，若欲提供弧形或旋轉拖曳之手勢動作，則建議在物體外觀輪廓上增加相對於不同轉軸的圓弧形導引線，或增加不同軸向模式切換的操控介面，以幫助解決二維觸控手勢與三維內容軸向配對不易的問題。

Recently, large touchscreens have been adopted as the interactive devices for exhibition in art galleries or museums. Some contents displayed on these devices may include three dimensional objects manipulated by two dimensional gestures. To facilitate intuitive usage by universal visitors, the nature mapping between 3D content manipulations and 2D gestures is an important issue. To address this issue, the objective of this research is to explore the mapping of rotation manipulation for 3D virtual objects and gesture patterns on large touchscreens. The experiment system was a digital media for ecological education that allowed the users to view and rotate a model of a green turtle with different gestures, such as nudging or dragging on horizontal, vertical, inclined angle, and circular patterns. The tasks of experiments were to rotate the 3D model from the original angle to a designated angle with these gestures. The processes were recorded for detailed analysis. The results of analysis included the following findings. The tasks of rotating models to orthogonal angles were easier than perspective angles. When the task was to rotate the model to perspective angles, participants tended to try the dragging gesture in vertical or horizontal directions first. For all tasks, dragging in vertical or horizontal directions provided more natural mapping between rotation manipulation and gestures than other gestures, such as circular dragging or nudging. In addition, since it was difficult for users to move their fingers in completely horizontal or vertical ways, the confusion of such operations and dragging gestures with inclined angles happened frequently. To overcome the problem of not being able to perform fully horizontal or vertical finger movement, it is necessary to include the algorithm for recognizing the intents of users in the system. The simplest way is to provide calibration with respect to movement using predefined threshold. In addition, if the users would like to perform inclined dragging for the purpose of rotating models with respect to multiple axes, two assistive supports could be offered. First, the system should provide shortcuts for users to change the viewing angles of model orthogonally. Second, circular lines on the bonding sphere of the model should be offered to provide guidance for finger movements with respect to different axes of rotation.