Hey all,

After following kfox's sweaty skin tutorial here on Renderosity, I ended up with a result I'm mostly satisfied with in Poser 8:

Simply by adjusting the highlight size and the specular value, anything from a light sheen (as here) or a high gloss is possible. So far, so good.

What I'm trying to do now is add actual sweat droplets to the skin. I have a texture set that comes with a bump map with sweat droplets, but I'm puzzled on getting it combined with the material I already have. Using Blender, Color Math, or Math Functions don't work at all or leave the skin way too gray or washed out; I'd like for this to work in any level of light, but especially bright daylight.

What I'm looking for, ideally, is to have the sweat bump map applied to the diffuse map like a makeup or a tattoo (not affecting the skin color), and to have the droplets raised off the skin.

Any suggestions?

Without seeing the sweat texture set my guess would be its only necessary to mod the bump and specular inputs not the diffuse. For example plug the sweat bump map directly into the PoserSurface bump and specular_value inputs and see what it does. If that works ok the next step would be to mix these with the existing bump and spec settings above.

If you could share your results and settings as you go, a lot of people are watching this.

Still, or animated? If it's for a still, load a second figure with the same pose parameters bute use the surfaces to make it invisible. Then you can make you bumps and sweat trail to your hearts content and put them as an alpha channel. Not only will they look more convincing,but if your renderer has the proper settings, they should cast a faint shadow which will add to making them more convincing.

ironsoul posted at 10:27PM Mon, 01 January 2018 - #4321401

Without seeing the sweat texture set my guess would be its only necessary to mod the bump and specular inputs not the diffuse. For example plug the sweat bump map directly into the PoserSurface bump and specular_value inputs and see what it does. If that works ok the next step would be to mix these with the existing bump and spec settings above.

Tried this; here are the results.

The original shader from before:

The same, but with the spec and bump replaced as described:

Increasing the spec value to 1 and decreasing the highlight size:

Changing the light to see if that had any effect:

This is getting there, I think. It just looks more like warts right now.

Joe@HFG posted at 10:46PM Mon, 01 January 2018 - #4321406

Still, or animated? If it's for a still, load a second figure with the same pose parameters bute use the surfaces to make it invisible. Then you can make you bumps and sweat trail to your hearts content and put them as an alpha channel. Not only will they look more convincing,but if your renderer has the proper settings, they should cast a faint shadow which will add to making them more convincing.

This sounds really plausible. I don't think my personal system would be able to handle it, though.

Another possible option: combining the sweat diffuse map with the original one. It has the actual droplets on it like the bump map does, but I don't know if there's a way to mix the two diffuses without changing the original texture's color.

The highlight size is too big and of the wrong spec shading type for the water drops, could use a blend node to change highlight size for just bump parts but think it really needs to be fresnel to get the correct effect and intensity.
To extract the spec from the diffuse map one thought is to convert it to bw using the HSV node and then use the step function from the math node to filter just the higher values which hopefully will be from the reflection/refraction highlights and either blend with the existing spec using the bump map as a mask or plug into the alt spec input.

Thoughts on adding fresnel below, think it's missing the refracted light component. I tried using reflection instead of spec but Firefly ground to a halt.

I tired ironsoul's settings combined with the original shader. Here's what happened:

Unhooking the original shader and just using the new settings rendered virtually identical. Not sure what the grayish bit around the mouth is.

Hmm, strange. The node called bump_map on my screen shot should be your image_map_3, it's black except for the bumps?

Ah, mine's not fully black-and-white. I'll adjust it and try again.

Made a fully black-and-white version of the original bump map in Photoshop and tried the exact same thing as previously:

Getting there, I think. Needs transparency and refraction, somehow. Less severe displacement too, maybe.

Those highlights look a bit bigger and brighter than expected, maybe the lighting but is highlight mask plugged in ok?

No, my spec value was set to 1. I turned redid it and turned it down to 0.3 and it looked close to what you had.

It doesn't look wet or sweaty. And sweat or water drops don't look so isolated in real on faces. This happens only if the skin is covered with certain face creams or oil is on the skin. Sorry, don't want to be rude, but so far I see only a skin disease, glowing acne and not the "next level"...

To me the major problem is how to fake a complex 3D optical effect involving two materials onto a single 2D surface, as you say the distribution needs to be looked at too. Whats missing is caustics, even if we add a second surface using Joe's suggestion Firefly doesn't generate this lighting effect so it has to be faked but that needs to be linked to the light direction. Taking the caustics from the reference diffuse map won't work as a general solution as the baked in spec is not linked to the light direction so may look odd if the lighting differs from the original too much.