Gi = global illumination

Why GI?

Why GI?

What is GI?

Direct lighting Indirect lighting

What is GI?

Only Direct Lighting Direct + Indirect

What is GI?

ON OFF

What is GI?

What is GI?

● Direct lighting – sucks

● Direct + Indirect lighting – cool

What is GI?

8 spp 13 sec

200 spp 5 min

1000 spp 25 min

25k spp 10.3 h

2.4 GHz Intel Core 2 Quad, 1024 x 768, by Kevin Beason

GI in 99 Lines of C++

● Brute force – really heavy

GI in 99 Lines of C++

MotoGP

Hemisphere Lightning

Radiosity Map

Hemisphere Lightning

Hemisphere Lighting

● Fast & simple

● Too simple

Hemisphere Lightning

Mirror's Edge

Lightmaps

Lightmaps

● Only static objects

Lightmaps

Killzone 2

Light Probes

Light Probes

Light Probes

Light Probes

● No dynamic lights

● No self-illumination of dynamic objects

Light Probes

Light Propagation Volumes

Light Propagation Volumes

Light Propagation Volumes

Light Propagation Volumes

No propagation

Light Propagation Volumes

After 4 iterations

Light Propagation Volumes

After 6 iterations

Light Propagation Volumes

After 8 iterations

Light Propagation Volumes

Light Propagation Volumes

Light Propagation Volumes

Light Propagation Volumes

● Dynamic lights

● No indirect shadows

Light Propagation Volumes

Algorithm

● Voxelize the geometry

● Construct sparse voxel octree (SVO)

● Inject direct lighting into the octree

● Propagate radiance

● Gather radiance by cone tracing

Voxel Cone Tracing

Voxel Cone Tracing

Voxelization

Voxel Cone Tracing

Sparse Quad-tree

Voxel Cone Tracing

Sparse Voxel Octree

Voxel Cone Tracing

Voxel Cone Tracing

Light injection

Voxel Cone Tracing

Filtering up

Voxel Cone Tracing

Voxel Cone Tracing

Voxel Cone Tracing

Voxel Cone Tracing

Voxel Cone Tracing

37 ms 32 ms 14 min

Voxel Cone Tracing

● Dynamic lights & objects

● Shadow casting

● Huge amount of memory

Voxel Cone Tracing

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