How do we know Pluto and Charon are specular ?

[Hamiltonian]

I see Pluto and Charon have specular maps in the distribution package. I can't really see much effect from them, but maybe that's something to do with my old computer. But my question is, how do we know the specular appearance of Pluto and Charon when we know so little surface detail? Was this calculated in the same way as the surface maps, from changes in eclipse brightness?
Very clever, if so. And is there something special about them that makes their surface shiney?

[t00fri]

I see Pluto and Charon have specular maps in the distribution package. I can't really see much effect from them, but maybe that's something to do with my old computer. But my question is, how do we know the specular appearance of Pluto and Charon when we know so little surface detail? Was this calculated in the same way as the surface maps, from changes in eclipse brightness?
Very clever, if so. And is there something special about them that makes their surface shiney?

Yes, the logics was as you suggested. The reflectivity was assigned from the discussion in the scientific paper on which I based the Pluto & Charon textures.

Bye Fridger

[Hamiltonian]

Thanks!