Efficient High-Quality Rendering of Ribbons and Twisted Lines

Abstract

Flat twisting ribbons are often used for visualizing twists along lines in 3D space. Flat ribbons can disappear when looking at them under oblique angles, and they introduce flickering due to aliasing during animations. We demonstrate that this limitation can be overcome by procedurally rendering generalized cylinders with elliptic profiles. By adjusting the length of the cylinder's semi-minor axis, the ribbon thickness can be controlled so that it always remains visible. The proposed rendering approach further enables the visualization of twists via the projection of a line spiralling around the cylinder's center line. In contrast to texture mapping, this keeps the line width fixed, regardless of the strength of the twist, and provides efficient control over the spiralling frequency and coloring between the twisting lines. The proposed rendering approach can be performed efficiently on recent GPUs by exploiting programmable pulling, mesh shaders and hardware-accelerated ray tracing.