| Output bent normals? |
Normally, the Dirtmap will directly output the occlusion information so you can
easily use it in the render tree. If you enable this checkbox, it will instead
generate so called "bent normals". A bent normal is a vector that points in the
average unoccluded direction above a point. If you have a completely unoccluded
surface, this will be equal to the surface normal (if you use enough samples), or
the basis vector if it is in use.
The R, G and B components contain the X, Y and Z values of the vector (normalized,
in the [-1, 1] range), while the Alpha component contains the amount of occlusion
that occured.
You can easily use this mode for e.g. sampling the environment
map with another plugin, or outputting the bent normals to disk.
|
| Probe geometry? |
If ON (default), the shader will shoot out rays to gather occlusion information.
You normally will only want to turn this off when making a separate enironment
pass. There, however, you can turn it off (and "Probe environment" on) to get
pure environment information, like in this example:
From left to right:
- Ambient pass: Probe environment ON, probe geometry OFF.
- Occlusion pass: Probe environment OFF, probe geometry ON.
- Final: Simple multiply composite of the two passes.
|
| Probe environment? |
Toggles if the base/dirt colors are output directly, or if they get multiplied
with the environment color first. To get any visible results, you should first
apply some kind of color or texture to the environment slot of the material or
current render pass. If you now set the base color to white and the dirt color
to black, and connect the dirtmap output to the ambient input of a surface
shader node, you get a perfect ambient occlusion effect. Relatively open areas
of the mesh, that aren't occluded, return the unmodified environment color, and
"dirty" areas return black, therefore pulling ambience in those areas towards zero.
Here is an example scene, to illustrate the effect:
From left to right:
- Without any dirtmap
- With standard dirtmap, white base with black dirt
- The same dirtmap, with "Multiply by Environment" checked
As you can see, the "Probe environment" can create an ambient occlusion
effect (the environment map was not shown in the background). You can use
it to quickly get a skylight effect without the need of final gathering.
|
| Invisible to secondary illumination? |
If ON (default), the dirtmap will not do any sampling when hit by any secondary
illumination rays, no matter if GI or Caustic photons, or Final Gather rays.
Use this to greatly speed up Final Gathering in scenes where you are using the
dirtmap. The visual difference is normally not noticable, the speed difference
can be huge.
|
| Near |
Sets the minimum range of a ray. For each ray that gets cast, if the distance
to the first hit is below the Near Falloff distance, full dirt color gets
applied.
|
| Far |
Sets the maximum range of a ray. Every ray that doesn't hit an obstacle in less
than the distance defined by Far Falloff causes full base color to be applied.
|
| Gain |
This controls the falloff that gets applied if a ray hits an object in a
distance between the near and far falloff. At 1, a linear falloff gets applied,
while at 0.5 it is square (effectively reducing dirt density), and at 2 it is
square-root (effectively increasing dirt density). Note that this gets applied
per ray, and therefore might not yield the amount of change you want. To
dramatically increase the dirt strength, either lower the dirt color to a value
with negative luminance, or use a color correct node with negative gamma to
modify the output color.
|