Hints tips and Scenes - Global Illumination

hint for those who want to render film or print resolution images with GI:

you can safely change many of the channel datatypes of the 'GI_effects' to a more compact form. Select 'GI_effects' from the post image effects list of the select window, open the property window, go to channels tab, find 'Bump normal' from the channel list and change the type from 'Float' to 'Integer'. In most scenes, you can do the same for the 'Distance' channel as well (even WORD may be enough for room interior shots etc.), but don't change the distance channel if you are rendering large scale terrain models.

This reduces memory use almost 50 %, and usually speeds up the rendering. Modern processors convert integers to floats much faster than read floating point data from huge files.

The post image for global illumination is over 10 times deeper than a normal RGB image, and GI also uses doubled resolution to improve antialiasing. Therefore, post image size can easily exceed one gigabyte.
Vesa Meskanen

Animation with GI

Reset the "scaling" of the GI post effect to 1 x 1 and let the stochastic rendering with motion blur set to 9 take care of the anti-aliasing. It gives motion blur for free, and reduces memory use to to one quarter.
Henri Pulla

GI Shader Properties

• GI has reflection / refraction colour control. You can enhance and darken GI illumination visible through reflection rays etc with it.
• GI_Specularity and GI_Spectular_Sharpness channels are back in action. It is for the plastic like GI illumination. Materials like leather, plastic, oil paint etc really need it, but it is also useful for brightening materials like chrome or glass.
• Post effect systems GI_brightness_control effect has two controls. The gamma curve for Diffuse works as before. 'Spectular' scales indirect illuminatino from specular, reflection and refractions.

A note about sharp looking glass: the only way to achieve this is to use high sampling count at level 3. If the glass object is just a flat rectangle, then its the 'raycount2' which should be high. For example - in the test scene with the glass sphere:

• rayCount1=2
• RayCount2=1
• RayCount3=10
• GI Bounces=4
• Recursion depth=4
• Specular blur iterations = minimal value which keeps noise away. The highter RayCount3, the lower blurring is requried.

Vesa Meskanen

GI Scenes

		GI Test Scene This is the standard GI Test scene. Its been through 32 revisions - so I'm not even sure if this is the current one anymore ;) Check the number of threads if your not using a dual. By Bernie den Hertog Click HERE for the zip file (35k). Realsoft 3d v4.5+ only
		GI HDRI It includes a VSL 'pseudo-HDRI' material but I switched the VSL objects off so users can first see the normal illumination sky. It tends to cause extra noise. By Mark Heuymans Click HERE for the zip file (50k). Realsoft 3d v4.5+ only