Bump

Shading details can be faked by modifying the surface Normals without actually modifying the shape of the object itself. The surface remains unaffected as can be seen at the plane’s edges in this example. In the areas viewed at a flat angle, the effect is convincing enough to simulate fine scratches, pores or minor irregularities.

By manipulating object surface Normals, the surface shading can be modified. Minor irregularities such as scratches or pores or wood grain can be simulated without affecting the object’s geometry. Since this is merely a shading effect, the shape of the object will not change. The Bump channel uses grayscales to affect the Normals. Brighter areas will be raised and darker areas sunken.

Value

Here you can link a texture or Material Node. Only the brightness values will be used. Therefore grayscale or monochrome structures can be used.

Strength [-∞00..+∞00%]

This setting defines the intensity of the Bump effect. Negative values can be used to invert the brightness defined by the Value setting.

UV Epsilon [0.001..100000%]
3D Epsilon [0.001..100000%]

These settings reflect those of the material’s Bump Map in the Diffuse channel’s Normal Mode (see here).