Nvidia GeForce GTX 980 White Paper page 16

MAXWELL: ENABLING THE NEXT
GeForce GTX 980 Whitepaper FRONTIER IN PC GRAPHICS
The following picture illustrates this approach applied to a single triangle. In the picture, each cube that
contains a portion of the purple triangle is highlighted in blue.
Figure 7: Voxels touched by a triangle
In VXGI, we store two pieces of key information in each voxel: (a) the fraction of the voxel that contains
an actual object, and (b) for any voxel that contains an object, the properties of light coming from that
object (i.e., bouncing off of it from primary light sources), including direction and intensity.
The first step, as illustrated in the following figure, is the coverage calculation step. In this step, each
triangle needs to be checked from the perspective of each face of the cube, to assess what fraction of
the voxel is covered. The picture on the left shows a traditional rasterized image of a simple scene. The
picture on the right is a visualization of the voxelized result. In this picture, empty voxels are not drawn,
voxels that are fully covered are drawn in red, and voxels that are partially covered are represented by a
shade between blue (minimally covered) and red (fully covered). Note that the interior of each box is
solid red, as expected, while the edges are blue, due to the edge of the triangle intersecting but not fully
covering a voxel.
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