Mode/Map – Specifies the bump map type.

Bump Map – A height map should be used.
Bump Texture Channel – Some V-Ray textures have a special bump channel output that can be used here. It is most commonly used for Round Edges effect. Edges texture is used as a bump.
Normal Map – RGB normal map should be used with this option. Note that in most cases the normal map bitmap color space should be set to Linear to ensure correct results.

Amount – Multiplier for the bump/normal map.

Delta Scale – Specifies a scale for sampling the bitmap when using bump mapping. The exact value is calculated automatically by V-Ray, but can be scalled here.