Accelerating Geometry-Based Spherical Harmonics Glyphs Rendering for dMRI Using Modern OpenGL

Diffusion-weighted magnetic resonance imaging is a technique aimed at measuring the displacement of water molecules inside biological tissues. From High Angular Resolution Diffusion Imaging acquisitions, it is possible to reconstruct fiber orientation distribution functions (fODF) describing the apparent quantity of white matter fibers going through a voxel for some arbitrary direction. Because these fODF are signals on the sphere, they are usually represented using a spherical harmonics (SH) basis, and visualized as radially scaled spherical glyphs. In this work, we present a novel GPU-based method for interactive real-time visualization of fODF datasets using modern OpenGL. Our algorithm relies on compute shaders to distribute the deformation of SH glyphs on the GPU, allowing real-time slicing of fODF images. We show that our method offers better performance than CPU-based methods and allows the real-time exploration of large datasets.