I gotta ask a stupid question here, but what's negative black when it's at home. I would have guessed 'white' :P
A surface normal is white/1 when directly facing the light ray (light ray is opposite the surface normal), 0/black when perpendicular to the light ray, and -1/(also black) when facing away (the light ray is the same as the surface normal). Per uses 'sub-black' as an artist-friendly way of representing a negative number value... 'sub black' doesn't exist, of course, because we define colors in terms of visible light, not mathematics/code (well, I do, but in general language we don't...), but it is probably the simplest way of describing this mathematical phenomena without math that I've seen (this being the first time I've seen it described that way).
And re Per said about black diffuse- if your diffuse is black, it will not get any diffuse lighting... which no surface has, AFAIK, except ones which are very highly reflective and don't diffuse any light (it is all reflected). The only time you would use black on a diffuse, maybe, is when you don't have self-shadowing and you have a very occluded area, like some parts inside of the mouth, but even then maybe not.
And one more thing- the original diffuse and specular lighting won't look right in any dynamic situation, regardless of its orientation in the world lying on a table. You simply do not want to bake that information in, and saying 'well first see if it looks good baked and then adjust it' is the complete opposite of what you should be doing- which is to use the most pure/least baked, and then once your lighting solution is known, you can bake stuff in as needed and see whether it helps.
For both my diffuse and spec i use the same AO/LM. What i do here is just create a layer group above both my diffuse and spec layers in my psd. The reasoning for this has always seemed pretty sound to me, the less diffuse light something is getting, the less specular reflection you're likely to get as well.
So would i used an AO bake as the base for my spec? No, but i would use the same AO bake i have on my diffuse, multiplied on my spec. Generally its good to use your diffuse as a base for your specular, and identify which areas will need more/less reflectivity depending on material type, conditions, wear, etc and make adjustments accordingly.
This is how I do it too. It also makes it easier for making sure your diffuse and spec map's AO fixes are consistent - I tend to lay down a bunch of base colors before I start cleaning up my AO, as until I have the base colors down I don't really know which details need to be enhanced or not.
Also to be the guy who contradicts Perna, I use pure black all the time in vents and holes and really deep crevices - it may not look 100% correct when you put a light right next to that black hole, but a light is never going to be that close to the hole, and it reads better as pure black than not in everything but that edge case. This is for third person weaponry, though, not first person, so there are some different rules - getting those shapes to pop and read more clearly is much more important on a third person weapon than a first person weapon, where more subtlety can be appreciated.
No if you are trying to do something like fake a hole, it make sense to use pure black in your diffuse and spec in that case, anything else will ruin the illusion. The problem comes when you're using pure black in your shading, for parts of the model that you do want to have lighting.
One might argue that light from above is unnecessary to bake as even the simplest engine can do that in realtime... I would never make that claim, though, so don't even think of writing me hate messages and start arguing with me, as I am completely without opinion and preference on the subject.
It's nothing to do with the content of your opinion (for me at least, I cant speak for anyone else), only the matter-of-"fact" way you presented it, as if there was no alternative. I may have gotten the wrong message though.
I also like where the thread is going, discussion/passionate debate about art subects is what forums like this are for, right?
Haha ok been messing around with that BRDF max viewport shader to get an idea of what this'll look like ingame and have been fiddling about with the specular maps. I also darkened the polymer. Problem is the shader only allows one omni :shifty:
Warning: Picture is pretty hooge :poly124:
E: And a random little quick knife with the same shader just a different BRDF texture. It's on a 1024X128, 230 verts
Replies
A surface normal is white/1 when directly facing the light ray (light ray is opposite the surface normal), 0/black when perpendicular to the light ray, and -1/(also black) when facing away (the light ray is the same as the surface normal). Per uses 'sub-black' as an artist-friendly way of representing a negative number value... 'sub black' doesn't exist, of course, because we define colors in terms of visible light, not mathematics/code (well, I do, but in general language we don't...), but it is probably the simplest way of describing this mathematical phenomena without math that I've seen (this being the first time I've seen it described that way).
And re Per said about black diffuse- if your diffuse is black, it will not get any diffuse lighting... which no surface has, AFAIK, except ones which are very highly reflective and don't diffuse any light (it is all reflected). The only time you would use black on a diffuse, maybe, is when you don't have self-shadowing and you have a very occluded area, like some parts inside of the mouth, but even then maybe not.
And one more thing- the original diffuse and specular lighting won't look right in any dynamic situation, regardless of its orientation in the world lying on a table. You simply do not want to bake that information in, and saying 'well first see if it looks good baked and then adjust it' is the complete opposite of what you should be doing- which is to use the most pure/least baked, and then once your lighting solution is known, you can bake stuff in as needed and see whether it helps.
This is how I do it too. It also makes it easier for making sure your diffuse and spec map's AO fixes are consistent - I tend to lay down a bunch of base colors before I start cleaning up my AO, as until I have the base colors down I don't really know which details need to be enhanced or not.
Also to be the guy who contradicts Perna, I use pure black all the time in vents and holes and really deep crevices - it may not look 100% correct when you put a light right next to that black hole, but a light is never going to be that close to the hole, and it reads better as pure black than not in everything but that edge case. This is for third person weaponry, though, not first person, so there are some different rules - getting those shapes to pop and read more clearly is much more important on a third person weapon than a first person weapon, where more subtlety can be appreciated.
lol
It's nothing to do with the content of your opinion (for me at least, I cant speak for anyone else), only the matter-of-"fact" way you presented it, as if there was no alternative. I may have gotten the wrong message though.
I also like where the thread is going, discussion/passionate debate about art subects is what forums like this are for, right?
Warning: Picture is pretty hooge :poly124:
E: And a random little quick knife with the same shader just a different BRDF texture. It's on a 1024X128, 230 verts