Houdini 17.0 Nodes VOP nodes

Conserve Energy VOP node

Clamp the reflectivity of a bsdf to 1.

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This node will clamp the reflectivity of a bsdf to 1, to ensure that it will reflect no more light than it receives. Energy conservation is a requirement for physically correct renders, since non-conserving bsdfs may introduce energy into the scene with each bounce leading to blown out illumination when rendering with photon maps or path tracing. The components of the bsdf will be uniformly scaled, resulting in a uniform darkening of each component for bsdfs with a reflectivity greater than 1.

It is possible to produce energy conserving bsdfs without this VOP, but you need to be careful to balance the weights for each type of reflection. For example, if the diffuse albedo is 0.5, you must have no more than an additional 0.5 of additional reflectivity.

Inputs

f

The bsdf for energy conservation.

Outputs

f

The adjusted bsdf, clamped to a reflectivity of 1. bsdfs with a reflectivity lower than 1 will be passed through unmodified.

scale

The multiplier used to scale the bsdf. bsdfs with a reflectivity lower than 1 will produce a scale of 1.

See also

VOP nodes