Opacity optimization for 3D line fields

Abstract

For the visualization of dense line fields, the careful selection of lines to be rendered is a vital aspect. In this paper, we present a global line selection approach that is based on an optimization process. Starting with an initial set of lines that covers the domain, all lines are rendered with a varying opacity, which is subject to the minimization of a bounded-variable least-squares problem. The optimization strives to keep a balance between information presentation and occlusion avoidance. This way, we obtain view-dependent opacities of the line segments, allowing a real-time free navigation while minimizing the danger of missing important structures in the visualization. We compare our technique with existing local and greedy approaches and apply it to data sets in flow visualization, medical imaging, physics, and computer graphics.

PathlinesExplorer - Image-based exploration of large-scale pathline fields

“…Moreover, enhance the quality of the rendered lines by applying some shading techniques as the o;[ne presented by Malloet al [7] or LineAO method by Eichelbaum et al [3]. Also, combine our work with other optimization methods for lines selection, namely, Opacity Optimization method provided by Gnther et al [5].…”

Hierarchical opacity optimization for sets of 3D line fields

“…The recent work by Günther et al [GRT13] suggests that the selection should also be importance-driven in a sense that it always provides a clear view onto the scene parts that are relevant to the user. All this holds equally for the case of unsteady flow fields.…”

“…This work is based on and extends the approach by Gün-ther et al [GRT13], which formulates line selection in the steady case as a global optimization problem with the goal of showing as much information as possible while avoiding occlusion. We briefly review this opacity optimization approach in this section and provide an overview of the novel contribution required for the unsteady case, i.e., visualizing sets of line fields such as pathlines or streaklines.…”

“…It is decoupled from interaction and rendering such that approximately one asynchronously computed solution per second is sufficient for opacity updates in the interactive rendering. For the interactive exploration of line sets, Günther et al [GRT13] report a maximum problem size n < 10, 000 polyline segments; this bound may vary depending on the data (and the desired rate of solves), n ≈ 3, 000 is a typical value. This is not sufficient for the interactive exploration of parametric sets of line fields such as pathlines or streaklines, because these fields consist of many more, possibly time-dependent, lines.…”

“…Since view-dependent line selection is an interactive process, the approach in [GRT13] has to be accelerated to cope with larger amounts of line segments.…”