tips and Scenes - Global Illumination
hint for those who want
to render film or print resolution images
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
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
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.
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.
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:
- GI Bounces=4
- Recursion depth=4
- Specular blur iterations = minimal value
which keeps noise away. The highter RayCount3,
the lower blurring is requried.
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
for the zip file (35k). Realsoft 3d
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
for the zip file (50k). Realsoft 3d