This document provides an introduction to global illumination techniques for real-time rendering. It summarizes several methods including direct lighting only, reflective shadow maps, virtual point lights, light propagation volumes, and radiance maps. Performance results are given for different resolutions and methods, with virtual point lights at 800x600 resolution and 36 point lights achieving 47 fps. Further optimization of virtual point lights to an array was able to achieve 65 fps. Light propagation volumes were slower at less than 1 fps for an 8x8x8 volume.

1. @agatestudio
Introduction to Global
Illumination
Aryo
Knight
Agate Studio

2. Introduction to Global
Illumination
Agustinus Arya Adhinugraha

3. Direct Lighting Only
800x600 : 1.42045ms – 704fps
-Draw scene depth from light point of view (for shadow purpose).
-Draw deferred into GBuffer(albedo, normal, depth).
-Draw direct shading & shadow.

4. Reflective Shadow Map (RSM)
128x128
Color (left), Screen Position (center), Light Direction (right)
- Draw scene from light point of view, and output color, screen
position, and light direction.

5. Virtual Point Lights (VPL) Position
800x600 36 VPL: 21.2766ms – 47fps
- Select VPL from RSM (CPU)

6. Indirect Lighting Only
- Draw scene and treat each of VPL as common light.

7. Final (Direct + Indirect Lighting)
800x600
36 Draw VPL : 21.2766ms – 47fps
1 Draw 36 VPL : 15.3846ms – 65fps
- Optimized VPL to array of VPL and iterate in fragment shader.

8. Light Propagation Volume (LPV)
800x600 8x8x8 LPV : >1000ms - <1fps
-CryEngine3 method
-Using spherical harmonics coefficients
- Currently CPU Only (time constraint)

9. Radiance Map
800x600 8x8 RM : 2.087ms – 481fps
-Based on LPV, but using 2D texture instead of 3D one.
-Need further research

10. Reference Image
800x600 Blender cycles : 18910ms

11. References
• http://www.vis.uni-
stuttgart.de/~dachsbcn/download/gi/screen_s
pace.pdf
• http://www.vis.uni-
stuttgart.de/~dachsbcn/download/gi/vpl.pdf
• http://www.crytek.com/download/20100301
_lpv.pdf
• http://www.research.scea.com/gdc2003/sphe
rical-harmonic-lighting.pdf