Nvidia GeForce GTX 980 White Paper page 19

MAXWELL: ENABLING THE NEXT
GeForce GTX 980 Whitepaper FRONTIER IN PC GRAPHICS
Rendering a real-time reflection from a glossy curved surface has been difficult in the past. In order to
render glossy reflections, you would traditionally need to launch hundreds or thousands of scattered
secondary rays for each ray that bounces from the original reflector. It's incredibly challenging to reflect
these lights realistically, especially when you also factor in the material properties of the various light
reflectors. Using our approach, we've replaced the thousands of secondary rays with just a handful of
voxel cones that are traced through the voxel grid.
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