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TheRealMJP / TheRealMJP.github.io

Backing repo for my blog
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SG Series Part 4: Specular Lighting From an SG Light Source #13

Open utterances-bot opened 10 months ago

utterances-bot commented 10 months ago

SG Series Part 4: Specular Lighting From an SG Light Source

https://therealmjp.github.io/posts/sg-series-part-4-specular-lighting-from-an-sg-light-source/

alakhag commented 10 months ago

The normalization of NDF causes NDF to be greater than 1. This will eventually cause Specular BRDF to be greater than 1 for some m. Do you define a maximum cap of 1 in this case? Because my understanding is that Specular BRDF should be less than or equal to 1.

TheRealMJP commented 10 months ago

Hey @alakhag, a well-defined BRDF integrates to 1 if you were to sum up all outgoing lighting over all view directions on the hemisphere. This does not mean that the NDF must be <= 1 for any combination of N and H, nor does it mean that result of the specular BRDF must be <= 1 for any given combination of L/N/V vectors. It just means that the total amount of energy being reflected in all directions must be less than or equal to the incoming energy.