The PBR Metal/Rough workflow deliberately simplifies some parts of the material creation process to make it easier, faster and more consistent. It’s worth keeping in mind that it was designed for realtime engines with all their constraints, and Superfly, being an offline render engine, has the huge advantage of time. This means that it is possible to build more complex shaders without this workflow, but I think that PBR Metal/Rough is a very useful tool and the underlying principles are worth getting to grips with.

I’ll discuss the maps in order of importance. First, the metallic map tells Poser which areas are metal and which are not - white pixels are metal and black pixels are not-metal. The importance of this distinction is that all metal areas will be set to 100% reflectance, and the reflections will be coloured by the colour map. Not-metal areas will have reflectance set to the specular value and the reflected light will have no colour i.e. be white. The specular value should be set to 0.5, which is 4% reflectance.

Specular in Superfly does not mean the same thing as Firefly. In Superfly it means base reflectance (sometimes called direct reflection or F0). In Firefly specular is a hack used to simulate/fake reflected highlights as real raytraced reflections, especially blurred reflections, are extremely slow to render. As Superfly is much faster it uses raytraced reflections on everything all the time. Specular maps should only be used in Superfly if the effect they will have on reflectance values are properly understood. Simple values are all that are needed here - the detail and definition in the appearance of reflected light i.e. highlights is carried in the roughness map.

On the PBSDF node the specular value can be set from 0-2, which maps to 0-16%. Setting it to 0.5 equals 4% base reflectance, and in the Metal/Rough workflow all not-metal surfaces are set to this value as it is a good average (most surfaces range between 2-8%, with gemstones an outlier at up to 16%).

(In SP, and any other application that understands the Metal/Rough workflow, when a metal map is created this is what the shader is set to automatically - to get direct control of reflectance values a different workflow, Spec/Gloss, which creates a different set of maps, would be used.)

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