Skin and overexposure

Steven-V

Hey folks.

I am working on a scene with lots of stuff in it - props, clothing, hair, multiple characters. I am using 3DeLight and AOA Advanced Distant and Ambient lights. I started out with the recommended settings of 150% distant, 100% ambient, although that was a bit bright and I cut it down to about 120%/80%.

For some reason, one character's skin seems to be "brighter" than everyone else's... when the rest of the scene seems to be just fine, even including other people's skin, white clothes, and so on, the one girl's arms, legs, etc are clearly over-exposed. When I turn down the light to make her skin look good, everything else is way too dark.

Now, I can play tricks in most shots by doing things like rendering her separately at a lower light intensity or putting in multiple AOA lights with dim ones flagged to light her and bright ones flagged to light everything else. I can also play tricks like lowering the offending character's diffuse strength to 80% or so and it is better. Although that also makes her look more "dark skinned" than she ought.

BUT...

It seems this should not be a problem. Skin is skin, more or less, right? Two Caucasian characters with very similar skin tones ought to expose similarly, ought they not?

I have played around with things like specular and so forth. I've checked ambient and it's 0% so she is not accidentally "emitting" light or anything like this. I've tried with SSS on and off. And so on.

So I was wondering if maybe there is a setting somewhere that I am missing. Has anyone ever had this happen and figured out a solution to it? If it were just one scene I would play some tricks and be done with it, but I'm going to use her over and over (she is my main character in my webcomic) and I don't want to have to play these games in EVERY SHOT if I can come up with a simple one-and-done solution.

Richard Haseltine

The shaders, and the settings applied, can make a huge difference. Try selecting the SkinFace material (or equivalent) on each figure in turn and look at top-left of the Surfaces pane to see which shader is used.

Steven-V

Ah, hm... yeah they are different. The one over-exposing uses Shader: AOA_Subsurface, whereas the other one not doing that uses Shader: omUberSurface.

So this presumably means the AOA-Subsurface shader is "brighter" somehow and I will need to find a setting somewhere to tone it down... now I just need to figure out where.

scorpio

Try turning down the subsurface scattering, or the diffuse.

Steven-V

I turned SSS off completely and it did not help much.

Turning down the diffuse enough to get rid of the overexposure makes her look black. And not that I have anything against black people but she is not supposed to be black.

scorpio

Which skin are you using and can you post an image showing the problem.

mjc1016

scorpio64dragon said:

Which skin are you using and can you post an image showing the problem.

What scorpio said...at this point being able to see what's going on is going to be helpful.

Steven-V

The character model I'm using that is going to "hot" in terms of exposure is FW Cassie for Teen Josie 6. I've attached an example. This is a battle scene in Urban Sprawl 2. As you can see, the rest of the scene seems to be in reasonable lighting, including the skin of the villain who has grabbed the main character. But the girl's skin is clearly over-exposed (by a lot).

I am guessing there is some setting that will fix this, but so far playing around with it has not given me a good render of this scene. Lowering the lighting makes her look better but everything ELSE look too dark.

DestinysGarden

The Cassie character I just loaded up loads with DAZ Default shader applied. Can you try that one and see if it helps? Also, the specular strength is set to 100% by default and that can certainly cause the blown out highlights that you are seeing. Do you have any of your lights set to specular only? if you have a spec only light at high intensity, it will also create those highlights.

Steven-V

Hey DG,

Thanks for the response. First let me say I love your shaders for fabric, leather, wood, etc.. :)

There are only 2 lights in the shot, AOA advanced ambient and AOA advanced distant. There are no extra speculars.

I think if you apply the regular non-SSS skin you get the DAZ default with Cassie, and I think that is what comes in with the Cassie full figure. I did not use the figure... I applied the Cassie head shape to the Izzy body because I thought Izzy looked a little better for a superhero (she is a little more muscular). I applied the Cassie SSS skin option, which I just tested and it comes in with the AOA shaders. So I think that is why I am getting this happening.

Here is a little test shot with the lighting exactly the same (I think it was AOA Distant 100%, AOA Ambient 75%, but I could be slightly off). The only thing I did was swap out the AOA shaders on the skin for UberSurface. Notice the difference. I changed nothing else. (First one is AOA shaders, second is UberSurface).

So clearly, some combo of my settings and the shader presets is the culprit.

I guess I can fix this by applying the Cassie non-SSS shaders and that will probably solve most of the issue.

DestinysGarden

Thanks for the compliment. Glad you like the shaders.

Yeah, the full figure loads with DZ default. FWArt has a folder for base Mats which uses DAZ defaults, and the SSS folder which is using AoAs shader. If you do apply the UberSurface shader to the skin, (which is definitely what I would do with two figures in close proximity in strong light) you can then copy the parameters from the male figure, since he is already looking like you want him to in the light you are using.
Let us know how it goes.
cheers!

scorpio

You could try turning down the lights a bit more, in the image you posted even the male has a bit of blow out, also perhaps angle the distant light slightly away from the girl.

Steven-V

Although you may be right about the male, the point remains that she is way more overexposed than he is, so regardless of the specific lighting values, for any particular value, she will look like she is in more intense light than everything else in the scene, which she really shouldn't.

As for the angle, sadly I can't change it very much. This is one panel of a webcomic where a long multi-page scene takes place in a very short time (a few minutes) on the same city block. The sun angle should not change very much during that time. If the shadows suddenly start coming from another place the reader would surely notice and wonder why it is morning in the first shot and afternoon in the second but only minutes have passed.

IN the end as DG pointed out, it is clearly the specific shader, as my twin shot above shows that under exactly the same lighting regime, the AOA shader looks much brighter than the UberSurface shader.

404nicg

How handy are you with photo editing software? Sometimes I'll load up the skin's diffuse texture maps into GIMP and play with the brightness/contrast settings to get the desired results and then replace the defaults with the adjusted maps.

Steven-V

I'm pretty good at using PS, but I would be very reluctant to mess with the skin texture files in this case. One reason I chose FW Cassie as the model/texture for the main character of my web comic is because of what beautiful skin she has. The problem in this case is the shader used for the SSS variant of the skin, not the texture itself. Changing the shader to UberSurface has largely fixed the problem, while keeping the lovely skin texture that came with the character unchanged.

But thanks for the advice.