Modified Phong BRDF (phong)
This plugin implements the modified Phong reflectance model as described in  and . This heuristic model is mainly included for historical reasons—its use in new scenes is discouraged, since significantly more realistic models have been developed since 1975.
If possible, it is recommended to switch to a BRDF that is based on microfacet theory and includes knowledge about the material’s index of refraction. In Mitsuba, two good alternatives to phong are the plugins roughconductor and roughplastic (depending on the material type).
When using this plugin, note that the diffuse and specular reflectance components should add up to a value less than or equal to one (for each color channel). Otherwise, they will automatically be scaled appropriately to ensure energy conservation.
Parameter Type Description
- exponent : float or texture
- Specifies the Phong exponent (Default: 30).
- specular Reflectance : spectrum or texture
- Specifies the weight of the specular reflectance component. (Default: 0.2)
- diffuse Reflectance : spectrum or texture
- Specifies the weight of the diffuse reflectance component (Default: 0.5)