Line density control in screen-space via balanced line hierarchies. (December 2016)

• Record Type: Journal Article
• Authors: Kanzler, Mathias; Ferstl, Florian; Westermann, Rüdiger
• Is Part Of: Computers & graphics. Volume 61(2016)
• Page Start: 29
• Page End: 39
• Publication Date: 2016-12
• Subjects: Scientific visualization -- Flow visualization -- Line fields -- Focus + Context -- Line hierarchy; Computer graphics -- Periodicals; 006.6
• DOI: 10.1016/j.cag.2016.08.001
• Languages: English
• ISSNs: 0097-8493

Abstract

Abstract: For the visualization of dense sets of 3D lines, view-dependent approaches have been proposed to avoid the occlusion of important structures. Popular concepts consider global line selection based on line importance and screen-space occupancy, and opacity optimization to resolve locally the occlusion problem. In this work, we present a novel approach to improve the spatial perception and enable the interactive visualization of large 3D line sets. Instead of making lines locally transparent, which affects a lines spatial perception and can obscure spatial relationships, we propose to adapt the line density based on line importance and screen-space occupancy. In contrast to global line selection, however, our adaptation is local and only thins out the lines where significant occlusions occur. To achieve this we present a novel approach based on minimum cost perfect matching to construct an optimal, fully balanced line hierarchy. For determining locally the desired line density, we propose a projection-based screen-space measure considering the variation in line direction, line coverage, importance, and depth. This measure can be computed in an order-independent way and evaluated efficiently on the GPU. Graphical abstract : Abstract : Highlights: Construction of a fully balanced line hierarchy via minimum cost perfect matching. A scalable GPU approach for computing control parameters for line density selection. A scalable embedding of local line density control into the line rendering process.