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### #ActualHodgman

Posted 31 January 2013 - 06:15 PM

IIRC -
Phong was made just with intuition and observation, so it's an 'empirical BRDF'.
Blinn took Phong's work and recreated similar results from a theoretical basis this time, instead of from guesswork and collected data. The framework he used was microfacet theory (which says that only the facets oriented towards the half-vector will produce a visible reflection), so it's a 'microfacet BRDF'. So yes, it's the fact that the BRDF only considers the percentage of the surface that is pointing in the H direction, that makes it a 'microfacet BRDF'.

### #2Hodgman

Posted 31 January 2013 - 06:11 PM

IIRC -
Phong was made just with intuition and observation, so it's an 'empirical BRDF'.
Blinn took Phong's work and recreated similar results from a theoretical basis this time, instead of from guesswork and collected data. The framework he used was microfacet theory (which says that only the facets oriented towards the half-vector will produce a visible reflection), so it's a 'microfacet BRDF'.

### #1Hodgman

Posted 31 January 2013 - 06:09 PM

IIRC -
Phong was made just with intuition and observation, so it's an 'empirical BRDF'.
Blinn took Phong's work and recreated similar results from a theoretical basis this time, instead of from guesswork and collected data. The framework he used was microfacet theory, so it's a 'microfacet BRDF'.

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