Illuminated Lines Revisited

Abstract

For the rendering of vector and tensor fields, several texturebased volumetric rendering methods were presented in recent years. While they have indisputable merits, the classical vertex-based rendering of integral curves has the advantage of better zooming capabilities as it is not bound to a fixed resolution. It has been shown that lighting can improve spatial perception of lines significantly, especially if lines appear in bundles. Although OpenGL does not directly support lighting of lines, fast rendering of illuminated lines can be achieved by using basic texture mapping. This existing technique is based on a maximum principle which gives a good approximation of specular reflection. Diffuse reflection however is essentially limited to bidirectional lights at infinity. We show how the realism can be further increased by improving diffuse reflection. We present simplified expressions for the Phong/Blinn lighting of infinitesimally thin cylindrical tubes. Based on these, we propose a fast rendering technique with diffuse and specular reflection for orthographic and perspective views and for multiple local and infinite lights. The method requires commonly available programmable vertex and fragment shaders and only two-dimensional lookup textures.

Embroidery modeling and rendering in real time

“…When we render the model, we can easily place these details above the fill layer, which is similar to what real embroiderer would normally do for such details. In the third phase, stitches are dynamically lit in real time in surface space by a simple thread thread lighting model [Mallo et al 2005], but modulated with alpha mapping and tangent modifications to simulate curved stitches. Our rendering technique supports high-quality real-time rendering on deformable objects using hardware acceleration.…”

Direct visualization of fiber information by coherence

“…3). The use of illuminated lines [13] emphasizes the three-dimensional structure of the data and improves the perception of the topological relationships among lines, especially when interaction with the data is desired and possible. Furthermore, adding volumetric coherence information as discussed above provides spatial context to the fiber visualization.…”

Segment-based tetrahedral meshing and rendering

“…For isosurface extraction, several GPU based algorithms have been proposed [Kipfer and Westermann 2005] that load the mesh onto the GPU and run fragment shaders to compute the isosurface. For vector field visualization, stream lines are computed and rendered using different rendering modes [Mallo et al 2005]. The rendering of a lot of stream lines usually leads to severe occlusion problems which has only be partially been adressed in literature yet.…”