Converting Specular from Phong to PBR
Before Lotta/VStitcher 2019 April Edition, the applications used Phong Shader. 2019 April Edition replaces this with Physically Based Rendering (PBR).
The following table summarizes how, using Phong shader and PBR, specular effects are represented.
Specular Effect Parameters  

Phong Shader  PBR 

Note: when specular tint has a value, it inherits its color from the diffuse color. 
Conversion
The following table shows in outline how each of the PBR parameters for specular derive their value.
PBR  Value Derived From Phong Shader 

Specular map  Specular map 
Specular intensity  Formula applied to specular color values 
Specular tint 

Roughness map  Roughness map 
Roughness intensity  Formula applied to specular spread value, provided that value is not equal to zero. If specular spread is equal to zero, roughness intensity is set to zero. 
Diffuse color  Diffuse color 
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