Question about Video Game Lighting.
interpolator
How do you create contrast?
For example, see this Seal:
If you were to break this image down into black and white, where the sun hits the surface is completely white, whereas areas occluded away from light are going to be black.
However, not all values are the same. The water for example, has a different brightness compared to the Seal and even the beach.
Now, I understand in CGI or high film VFX, contrast can be achieved in two ways:
1. Brute forcing lighting calculations
2. Post processing (via photoshop)
Since video games are tied for resources because they have to run in real time, what is the most efficient way to mimic the above?
I'm sorry if this question sounds complex. I've been doing some of my own experiments within Unreal Engine 4 and looked through samples provided by Epic.
But one problem I notice is, I don't want everything to be "lit" the same. I want there to be a range of values in my scene that can be easily distinguished from each other just like a real photo can.
For example, see this Seal:
If you were to break this image down into black and white, where the sun hits the surface is completely white, whereas areas occluded away from light are going to be black.
However, not all values are the same. The water for example, has a different brightness compared to the Seal and even the beach.
Now, I understand in CGI or high film VFX, contrast can be achieved in two ways:
1. Brute forcing lighting calculations
2. Post processing (via photoshop)
Since video games are tied for resources because they have to run in real time, what is the most efficient way to mimic the above?
I'm sorry if this question sounds complex. I've been doing some of my own experiments within Unreal Engine 4 and looked through samples provided by Epic.
But one problem I notice is, I don't want everything to be "lit" the same. I want there to be a range of values in my scene that can be easily distinguished from each other just like a real photo can.
Replies
There are various tone mapping algorithms available depending on the hardware you're running and what effect you want to achieve. Here's a good overview: http://mynameismjp.wordpress.com/2010/04/30/a-closer-look-at-tone-mapping/
Tonal control is achieved through materials and light settings.
Have you seen this PBR thread? There's loads of great info related to getting values for different material types.
Yeah, tone mapping seems to be one of the better solutions for real time. Although one thing that has me worried is the amount of artistic control.
I was reading this tutorial for creating LUT textures but the disappointing thing I learned is you can't make isolated improvements within a scene.
So in my example of the Seal pic, you can't paint over the Seal and then make a separate paint over for the beach. You have to paint over everything.
Is there a way I can find values that that makes the water brighter than the seal? I guess my issue is accurately knowing how to stop each material from absorbing different amounts of lights.
Yeah, I've been following all the PBR threads. PBR is very interesting because it harks upon the idea I want to work with (assigning materials their own properties in how they're affected by light making it easier to determine contrast).
Just curious, are you working on something stylized or realistic?
At the moment, it's all realistic.
I'm currently inspired by this person's work. While I'm not aiming to create something 100% like his, I greatly admire how much control he has over his scene's values (and you can see I even asked him a question about his method).
I'd just try getting the materials right first, then base lighting(really you'd probably only need the dominant directional and maybe an environment probe), then tweak the settings I mentioned above.
According to PBR workflow, diffuse/albedo textures are suppose to have no light information. The best diffuse textures are ones that come from an overcast scenario.
However, the other day I ran into a problem with this. I wanted to have a blue wall in UE4, so I found a photo reference of blue color during an overcast and plugged that value in. When I tried to light it, it gave me a color totatlly different to what my photo reference looked like (I wanted to make the scene sunny).
This kind of frustrates me because I don't know where else to look for PBR values of just color. There are PBR values of wood, bricks, metal but if I wanted to just assign something a single color, I do not if what I'm using is physically correct.
I get that there are base color values of metal but that's not enough for me.
You can further tweak contrast etc with post, but its important to remember that post effects are not lighting. If your lighting doesn't have enough contrast, the first thing you should do is adjust the root cause. Bumping up the contrast in post will of course increase contrast for everything in the scene, not just the lighting, which may not be what you want.
With large, static objects like buildings and things, generally you would have a baked gi/radiosity pass as well, for smaller dynamic objects like characters and other things that move around, you would generally only have the dynamic light/shadows, ambient ibl and possibly a screen space ambient occlusion pass. Though some systems like Geomeric's Enlighten do realtime gi on everything.
When it comes to finding the correct values, there is no easy solution atm really. If you want to be really accurate, you need to take your own reference photos using a cross-polarization photography rig. Few people have access to that sort of thing, so what you'll need to do is try to find values of similar materials and extrapolate and use trial and error until it looks correct.
I scribbled over this photo with values that are 1:1 with an actual photo. I want to aim for this amount of precision when playing with a game engine.
And here are values I did for saturation
Basically, I want full control over my scene's lightness and darkness and saturation.