Illustrative Stream Surfaces

Abstract

Stream surfaces are an intuitive approach to represent 3D vector fields. In many cases, however, they are challenging objects to visualize and to understand, due to a high degree of self-occlusion. Despite the need for adequate rendering methods, little work has been done so far in this important research area. In this paper, we present an illustrative rendering strategy for stream surfaces. In our approach, we apply various rendering techniques, which are inspired by the traditional flow illustrations drawn by Dallmann and Abraham \& Shaw in the early 1980s. Among these techniques are contour lines and halftoning to show the overall surface shape. Flow direction as well as singularities on the stream surface are depicted by illustrative surface streamlines. ;To go beyond reproducing static text book images, we provide several interaction features, such as movable cuts and slabs allowing an interactive exploration of the flow and insights into subjacent structures, e.g., the inner windings of vortex breakdown bubbles. These methods take only the parameterized stream surface as input, require no further preprocessing, and can be freely combined by the user. We explain the design, GPU-implementation, and combination of the different illustrative rendering and interaction methods and demonstrate the potential of our approach by applying it to stream surfaces from various flow simulations. ;

Poisson-based tools for flow visualization

“…Different levels of the tumbling flow in the measured BUBBLECHAMBER data set of a bioreactor can be visualized using circular seeding curves on an orthogonal surface located at the turnover point of the flow. The simulated DELTAWING data set of the flow at a triangularly-shaped airplane is known to contain two dominant vortical structures [14,5,17,31]. Flow-orthogonal surfaces can be used to seed integrated quantities like stream lines near the assumed locations of the vortices for their concrete visualization.…”

“…This means that the local gradient transformations of each triangle of the mesh are given by T j = R(a j , γ(n j , v j )) (see Section 3). The deformed mesh that optimally approximates these modified gradients (in least-squares sense) is then reconstructed by solving (5). In Section 8 we show that our method for computing orthogonal surfaces achieves higher flux rates compared to APAP [32] surfaces.…”

Interactive Virtual Probing of 4D MRI Blood-Flow

“…Various illustrative renditions of pathsurfaces were presented in recent work [2,10]. Similar to Hummel et al [10], we apply a stripe pattern to enhance the surface shape.…”

“…Garth et al [7] have described a generic hardware-accelerated approach for generating pathsurfaces, while Bürger et al [3] presented a real-time technique for the generation of streak surfaces. Recently, Born et al [2] and Hummel et al [10] introduced distinct illustrative visualization styles for integral surfaces. In particular, Hummel et al [10] proposed to enhance perception of the surface shape by stripe patterns.…”

Parallel stream surface computation for large data sets

“…Garth et al [9], Hummel et al [13], and Born et al [2] recently investigated advanced rendering techniques including nonphotorealistic rendering and better texture mapping to achieve improved visual depictions of stream surfaces (cf. Figure 3).…”