A Comparison of Rendering Techniques for Large 3D Line Sets with Transparency

TL;DR

This paper compares various CPU and GPU rendering techniques for large transparent 3D line sets, analyzing their performance, quality, and memory use, and proposes two improvements to enhance rendering speed and quality.

Contribution

It provides a comprehensive comparison of rendering methods for large transparent 3D line sets and introduces two novel improvements for GPU sorting and transparency bucketing.

Findings

GPU sorting significantly improves rendering speed.

Transparency-based bucketing enhances visual quality.

Optimized techniques reduce memory consumption.

Abstract

This paper presents a comprehensive study of interactive rendering techniques for large 3D line sets with transparency. The rendering of transparent lines is widely used for visualizing trajectories of tracer particles in flow fields. Transparency is then used to fade out lines deemed unimportant, based on, for instance, geometric properties or attributes defined along them. Since accurate blending of transparent lines requires rendering the lines in back-to-front or front-to-back order, enforcing this order for 3D line sets with tens or even hundreds of thousands of elements becomes challenging. In this paper, we study CPU and GPU rendering techniques for large transparent 3D line sets. We compare accurate and approximate techniques using optimized implementations and a number of benchmark data sets. We discuss the effects of data size and transparency on quality, performance and memory consumption. Based on our study, we propose two improvements to per-pixel fragment lists and multi-layer alpha blending. The first improves the rendering speed via an improved GPU sorting operation, and the second improves rendering quality via a transparency-based bucketing.