Blender 2.8 | Cycles Render
The shading normal‘s Z component can be easily used as a ready-to-use procedural mask for ‘covering effects’ like dust, snow, and if baked, also as a base for particle effects like debris and vegetation.
This simple shading flow example the shading normal‘s Z component, that represents how much the surface is facing upwards is separated , mixed (multiplied) with a noise textured and than fed into a ColorRamp Converter node for fine tuning the resulting mask:
This is the full shading flow of the snow effect in the image above:
Maya 2018 | Arnold 5
Arnold’s Ambient Occlusion (dirt) node can be used as a procedural mask to create interesting material effects like in this example of paint that is eroded at the model’s bulging areas to reveal metal beneath it.
In this shader’s case the Ambient Occlusion node is connected to the Mix property of an Arnold Mix shader, that blends between two different Arnold Standard Surface shaders, one simulating the underlying tin metal, and the other simulating the red paint that covers it.
Note that in the Ambient Occlusion node the Invert Normals property is checked, so that the effect will create a mask for the bulges and not for the creases,
And also that the Self Only property is checked so that the node will behave as a fixed object mask disregarding the proximity of other objects.
In this example the output of the Ambient Occlusion node is also process using a Remap Value node to increase it’s contrast so it will define borders between the areas.
After Effects CC 2018
Creating Inside and Outside garbage masks allows better and easier keying because the keying parameters can be focused for the best result at the contours areas.
- Apply the Keylight effect and, sample the screen color and adjust Screen Gain optimize it for the contours area.
- Create an ‘Inside’ garbage mask, name it, and set its mode to ‘None’.
- Create an ‘Outside’ garbage mask, name it, and set its mode to ‘None’.
- In the Keylight effect properties, under ‘Inside Mask’, select the inside mask you created.
- In the Keylight effect properties, under ‘Outside Mask’, select the outside mask you created, and also check Invert if needed.