Lighting and Fresnel question
polycounter lvl 19
I've been playing around with different lightmass, mesh, and light settings for the last couple days, and I'm not getting an effect that makes sense to me
I have this:
The left and middle pictures are straight shots from udk. The right one is a paintover of where I'd like to end up. And there are two problems.
The first is that there is an odd blue glow to the hair that doesn't belong there based on the lighting angle. It's a single plane that's set to transparency. I discovered that I can fix it by turning on "Use two sided lighting" in mesh properties, but then the model renders without shadows.
Since I just brought this in as a static mesh, I thought I could fix it by exporting the lightmaps, and painting the area the proper color, but UDK won't save any type of file out when dealing with lightmaps (sp?)
Is there any way to fix this issue, or get around it?
The second problem is the rim lighting for the version of the model on the right. I thought the best way to achieve this effect was with a set of fresnel's hooked into the emissive channel of the material.
Is there a way to restrict the fresnel's effect to one side of the body? Or some type of expression to have it's appearance be based on light within the scene?
I feel like I'm twisting the engine to purposes it was never meant for >_>
Is there anyway to accomplish/fix these things?
I have this:
The left and middle pictures are straight shots from udk. The right one is a paintover of where I'd like to end up. And there are two problems.
The first is that there is an odd blue glow to the hair that doesn't belong there based on the lighting angle. It's a single plane that's set to transparency. I discovered that I can fix it by turning on "Use two sided lighting" in mesh properties, but then the model renders without shadows.
Since I just brought this in as a static mesh, I thought I could fix it by exporting the lightmaps, and painting the area the proper color, but UDK won't save any type of file out when dealing with lightmaps (sp?)
Is there any way to fix this issue, or get around it?
The second problem is the rim lighting for the version of the model on the right. I thought the best way to achieve this effect was with a set of fresnel's hooked into the emissive channel of the material.
Is there a way to restrict the fresnel's effect to one side of the body? Or some type of expression to have it's appearance be based on light within the scene?
I feel like I'm twisting the engine to purposes it was never meant for >_>
Is there anyway to accomplish/fix these things?
Replies
EDIT: http://udn.epicgames.com/Three/MaterialsCompendium.html#LightVector
I think the latest version of UDK has a Function called Fresnel under Material Library. Use that, and stick in the Camera slot Light Vector instead. You should then Lerp your base with the color and have the Alpha take in the new Fresnel.
Either that, or just Mutiply the color by the Fresnel and add to to the base.
Note that in either case, you will almost get the same effect, but they will be slightly be different, Add will bend the colors while Lerp will change it linearly.
besides that I see a big difference in the face's specularity, for which you will at least need a specular glossiness map (use it as alpha in a lerp between 1 and, say, 128 - then connect to the spec power input)
great model btw