Screen Space Directional Occlusion (SSDO)
- Improvement over SSAO
- Consider (more) actual indirect illumination
- Some information of indirect lighting is already known!
SSDO exploits the rendered direction illumination not from an RSM, but from the camera.
- (Similar to path tracing)
- At shading point $p$, shoot a random ray
- If it doesn not hit an obstacle, direct illumination
- If it hits one, indirect illumination
与 SSAO 刚好相反（source of indirect illumination）
- AO: consider indirect illumination from far away objects
- DO: consider indirect illumination from close objects
Similar to HBAO, teest sampels' depths in a hemisphere: