Stream Bubbles for Flow Visualization

Abstract:

This paper introduces a new relatively inexpensive technique -- Stream bubbles for 3D flow visualization. The physical analogy to this technique are bubbles (air, carbon-dioxide, oil, etc.) that can be observed in nature with interesting shapes and varying speeds. A stream bubble is defined by 8 control vertices to produce a smooth surface representation. There are different ways of representing these surfaces including NURBS and subdivision surfaces. Its internal shape changes over time and shows twisting and stretching, as well as expansion and contraction along the flow. Upon encountering an obstacle, it will automatically erode and/or split in an intuitively simple geometric way. For highly divergent and vortical fields, stream bubbles can also break apart based on the aspect ratio of the bounding volume. When two or more stream bubbles meet, no explicit merge operation is needed since the surfaces will simply intersect each other to form a composite surface. Bubbles may be of different sizes. Large bubbles give a coarse global view of the flow structure, while smaller bubbles give a more accurate depiction of the local flow structure. In addition, our interface provides a good view of the flow structure by allowing users to interactively move and resize different stream bubbles together with an animated or step-by-step playback facility.