Question for Cristophe on Specular

[xxdanbrowne]

So I watched your video on the "big guy" where you demo octane for maya. Really nice work by the way.

My question is related to a sort of running commentary you have with yourself: at a couple of points you mention that you think Specular maps are a pain in the butt and that you think they are now outdated by some kind of layering technique.

I'd like to ask what you mean by way of offering my own opinion:
Specs are really great in games in certain situations: because you're painting in how the specular highlight/glinting effect is, the render engine doesn't need to calculate it. So obviously it increases speed significantly. But... given that in real life the specular highlight moves around on the object you're viewing depending on the viewing angle, the specular map is WRONG for certain viewing angles.

That doesn't matter much if you're careful to constrain the viewing angle or you're running past the view very quickly when chased by a monster or a bunch of enemy guys shooting at you...

However, I don't see any way round having the specular calculated at runtime in the render engine if you're not painting a specular map. The only other thing I can think of is to paint *multiple* specular maps for different viewing angles and calculate the viewing angles and then do some kind of lookup.

So would you mind filling in the gaps as to what you meant by "layering technique"...

Thanks.

[xtrm3d]

hi ,
well my opinion about painting specular map is based on rendering in engine like mental ray , vray and octane

for real time ,
i cannot tell you about what we are doing at naughtydog .. but i can tell you that i do not paint specular map anymore at work ( physical based shader )

anyway ...

the idea about layering material is that .. let say , you paint a car ..

you would have

metal, with paint on top , then some dirt and may be some rust

having all those material layered on top of each other with a mask for each one..

would allow you to quickly be able to do iterations .
example.. more rust ? change the mask value .. and do not have to repaint a specualr map .. since teh value of teh rust material is constant

the car is blue.. but you want red .. ??
just change the paint material color .. without having to repaint a diffuse or spec map ..

i could do more detailed video if needed to illustrate my point .

regards,
christophe

[xxdanbrowne]

Thanks Cristophe I think you have answered my question. Yeah I get what you means about layering. Thanks.

A few months back I posed the question: "True or False: if octane is a physically based renderer then it looks like you shouldn't need a specular map because it will correctly render the specular highlights for the viewing angle?"

I believe if I'm not mistaken that you have just confirmed that. OK Cool.