Vertex Lighting Bake - Thoughts?
polycounter lvl 11
Alright, I'm coming off using Unreal 3 for a while now where it didn't have any vertex lighting, so I never really had to deal with it before; just had to worry about the crappy way U3 imports the normals(or mayas way, can't remember which)
Anyway, new game, new engine, new software(max) and they want to stick a AO bake on all the models which is driving me up the wall. It really adjusts the way it looks in game and my modeling style is not working with this stuff because once applied I get big dark spots and crap all over the place.
Just wondering what are some of your thoughts on it? Is it really necessary for next gen tech, I assume the shader is working on a higher level at this point baking this stuff in is redundant, not to mention the eventual post effects like AO will kind of cover all this stuff without giving me a headache.
Maybe I'm too rigid, I just feel it's unnecessary at this point.
Anyway, new game, new engine, new software(max) and they want to stick a AO bake on all the models which is driving me up the wall. It really adjusts the way it looks in game and my modeling style is not working with this stuff because once applied I get big dark spots and crap all over the place.
Just wondering what are some of your thoughts on it? Is it really necessary for next gen tech, I assume the shader is working on a higher level at this point baking this stuff in is redundant, not to mention the eventual post effects like AO will kind of cover all this stuff without giving me a headache.
Maybe I'm too rigid, I just feel it's unnecessary at this point.
Replies
Not to mention as I see it as interfering with the lighting already going on; I'm just wondering what are teh advantages here? It's cheap? but it's cheap tha tlooks pretty crappy(at least in my case)
http://www.cybergooch.com/tutorials/pages/lighting_rfom4.htm
They baked lighting into bitmaps that were actually normalmaps themselves, so the tiled enviro normalmaps would get directional lighting from the lightmaps. Pretty cool. The vertex color came into play to add color to the lighting, since the lightmaps could only store lighting direction, not actual color.
For regular vertex-color lightmapping/AO, one way to help you figure out where to subdivide your mesh is to bake lighting into a temporary bitmap, assign that to the mesh, then use it as a guide to start subdividing. You can also use Vertex Paint to bake that bitmap into vertex color, to see how you're doing.
Second to that the lights in the map will help by hiding detail at certain angles of your assets ensuring uniformity is not so apparent. Def the right way to go about creating a realistic env, just need to tweak a few settings here and there and be subtle to pull it off well enough to be believable.
Resistence baked their lighting solution into a map, this isn't really what I'm talking about as it's dealing with how they handled lights.
We're using dynamic lighting solution, meaning very little is going to be baked in, which means no light map ala resistence. However, before importing our models we're doing a AO calculation and baking that info into the vertices(which is the assiness I was describing)
But my thoughts as never dealing with that is, what's the point when using dynamic lighting, more advanced shaders and AO post effects? It's not calculating the AO based on the normal map then baking it into the vertices, just the model themselves.
My point was I feel it's extra useless information that is getting in the way of quality in this particular case, but just wanted to know other opinions on where and how other people thought it was useful.
If neither of those, then best bet is for you to simply bake nice full-on AO into your diffuse bitmaps, and not use vertex AO.
What about environment stuff(which is where I am finding the issues) it feels unnecessary, but is this an older technique used in past generation games? (just trying to figure out where this studio got it in their head to use it for everything)
You usually can't bake AO into enviro diffuse maps because they're tiled like crazy, so the idea is why not bake into the verts instead? Gotta add more edge loops, but the increased # of verts is usually not a problem.
Depending on the hardware/engine, vert color can also cause less render passes than lightmaps.
The baking we are doing doesn't solve the problem of light maps, because we're not baking our lighting solution (IE shadows)
I guess it's a really particular use for very particular solutions, so my conversation is kind of pointless, lol
Ah well, thanks for the insight.
You seem to have a concern with baked vertex lighting interfering or fighting against a dynamic lighting solution? I'm not certain how your system is setup, but ours works great together, and i'll tell you a little about why.
First off, Dynamic Lighting & Dynamic Shadowing are different. Calculating AO in realtime is usually not a solution, which is why most engines now a days bake a bunch of shadows in one way or another.
Baking Vertex AO into a model doesn't mean that those shadows are permanent. Vertex AO can be placed in a "Vertex Illumination" Channel and when in-game, effected by dynamic lighting. This means they don't fight each other, because a bright light shone on a model will cause it's Vertex-based AO to disappear.....It means the shadows are baked but still dynamic in how they are drawn.
It's likely that you are using a shadow-solution that is relatively lightweight, so using vertex-baked AO is an easy way to give your scene a lot more depth with a very cheap cost (usually less than a 10% memory increase, it's a per-vertex cost).
Regardless, when setup right I think dynamic lighting & vertex-baked AO can work great together, it's just a matter of getting used to modeling with it in mind.
I don't particularly think that Oblivion is a good looking game, but its worth noting that many people did, and it shipped without any real shadow solution of any kind. Unless you count a hack alpha on the ground underneath trees. All buildings had was a vert bake.
Anyway, relying purely on dynamic shadowing, If that's what your engine is doing for a lighting solution, won't cut it alone. It just won't get you the visual fidelity that lightmaps will. Which is where the extra needed step of baked AO comes in. The instant large areas of your scene are swathed in dynamic shadow, they'll look completely fullbright and utterly lacking form unless you have some AO baked in there underneath.
In a nutshell: baked light maps look awesome, but of course can't fly for a day/night cycle. Dynamic shadows won't look as good as lightmaps, but they can look petty darm good if backed up by some vertex baked ambient occlusion.
Alex
So even if in theory, dark AO information should diseappear in the areas where light is directed to and should never be multiplied with the castshadow either as this would cause 'double shadowing', in practice it gives some depth because cracks accumulate dirt and dirt is often darker than the surface it accumulates onto.
I guess such bakes just need to be subtle especially on characters. Plus, you can always edit them with vertex painting solutions. Most likely to make them a bit fancier than black or grey.
AO baked into your spec map also helps to keep the spec contained and keeps nooks and crannies from shinning, it helps keep the dirt pior is talking about, looking like dirt.
Regarding baking vertex lighting, if you're having issues wit it, you can also light-map meshes with a second UV channel, which is very common with Unreal Engine 3 games.
http://book.hourences.com/tutorialsue3lightmap.htm
There's pros and cons to both.
But as for vertex lighting, here's a tutorial on that, which includes UE2 and UE3.
http://book.hourences.com/tutorialsvertex.htm
Hourence has some great stuff.
I guess it's a matter of adding more verts, and such, but still having troubles, I model things with seperate elements layered on top of each other rather then one continous mesh, maybe it's just the way I am baking it, but it doesn't seem to be working out so well.
I figured game engines were past this shit of merging and attaching meshes together to be continuous, I find it completely inefficent work flow but now it's necessary for a AO vertex light bake; which I still figured was unneccessary due to newgen shaders and post effects.
* Pior: Though after reading your comments what you said makes sense, however what I am seeing on my side does not, so I'll have to look into this. My dark splotches seem to multiply(get darker) in shadow and remain dark in light.... this is why I figured it's fighting it.