In this tutorial, we learn more about emissive shaders or surfaces by applying it to hair! 🙂 Of course the shader settings are general and can be applied to anything. Hair is used here, together with the Sci-fi girl image below, to provide a fun example.

Emissive Hair in Daz Studio Iray

1. Picking the Right Type of Hair

The first step, is to pick the right type of hair. I want something that is long and dynamic, with lots of movement morphs. The hair should be infused with energy, so much so that it emits light. A great example of this is SWAM’s Laguna-Naoko Hair.

It is long, with many separate strands, and some great movement morphs. It was created for a mermaid theme, so the many moving strands that make it look good in underwater scenes also make it especially suitable for light emitting hair.

In addition, Laguna-Naoko Hair comes with a variety of interesting and colorful textures, which make for a striking emissive surface. In our Sci-Fi girl example, we used the Electric Blue material setting. There are also fun colorful textures (see below) that produce very striking light effects.

Laguna-Naoko Hair comes with a variety of interesting and colorful textures, which make for a striking emissive surface.

2. Iray Emissive Surface Shader Settings

Now that we have settled upon a hair, comes the interesting part of playing with the Iray emissive shader settings.

For Laguna-Naoko Hair, I pick all of the hair strand layers. The only surface I leave-out is the base cap surface.

1. Pick the hair surfaces that we want to make emissive. In this case, I pick all of the hair strand layers. The only surface I leave-out is the base cap surface.

I set Emission Color to white and set the image map to the same one as my Base Color map.
2. I scroll down the shader parameters until I get to Emission Color. I set Emission Color to white and set the image map to the same one as my Base Color map.
3. Notice that as soon as we set Emission Color to something other than black, a new set of parameters become available to us including Emission Temperature, Two Sided Light, Emission Profile, Luminance, and Luminance Units. Here are some short descriptions from Daz as to what each of these parameters mean.
4. Emission Temperature allows us to set the color temperature of our light emitting surface(s). Different temperatures will tint out light differently (see below). In this example, I do not want any tinting, so I set Emission Temperature to 6000K.

 



Color Temperature Scale for our Iray emissive surface. From http://www.atlantalightbulbs.com/color-temperature-scale/
5. We leave Two Sided Light to the On position because we want our hair to emit light from both sides.
6. Emission Profile controls the shape of the light. We do not need to use it for emissive hair, but this Daz forum thread has a good discussion of it.
7. Luminance controls the strength or intensity of our light. In this case, we set Luminance Units to kcd/m^2 so that we can use smaller values in our Luminance setting.

3. Render Emissive Surface Light Layers

To get the glow and lighting effects that I want, I create three different light layers for my emissive Iray hair:

1. Low hair emission – I set luminance to 100 and render a light layer with just the hair (below-left).

2. Volumetric light – I leave luminance at 100, activate my volumetric container/prop, and render a volumetric light layer for my emissive hair (below-middle).

3. Strong hair emission – I set luminance to 3000 so that my light emitting hair will have a strong effect in lighting my figure’s body. However, at such a strong luminance setting, the hair itself becomes too bright. In this case, I only want the body lighting without the overly bright hair. I achieve this by setting Cutout Opacity to 0.0001 (below-right).

To get the glow and lighting effects that I want, I create three different light layers for my emissive Iray hair.

4. Putting it All Together in Photoshop

Here, we follow our usual 3 stage post-work process.

Stage 1 – Combining Lights

We combine our IBL, key, fill, and back lights in the usual way. In addition, we include the Low hair emission and Strong hair emission light layers we generated above. For the Strong hair emission layer, I mask out the hair cap.

Below, we show the image with just our usual lights (left). To the right, we have added in our two hair light layers. Now, it looks more like our hair is emitting light.

Left – Image with just our usual lights. Right – We have added in our two hair light layers.

Stage 2 – Post-Work Effects (Glow, Contrast, & More)

In this stage, we further emphasize our Iray emissive hair by adding glow. To do this, we create a separate glow layer just for our hair.

Adjust our glow according to taste.

• Open our Low hair emission file.
• Apply glow effects on just that layer.
• Adjust our glow according to taste. In this case, I only enabled the Glow 3 layer, but I set it to 100% opacity.
• Now I have a Hair Glow Layer that I can Copy Merged (Shift + Ctrl + C) into my Stage 2 file.

Copy Merged result of my Hair Glow Layer.

In the left image below, we perform our usual Stage 2 operations. The right image has our Hair Glow Layer, the Volumetric Hair Layer (generated in section 3), as well as some added contrast. Note that there is more glow and atmosphere in the image to the right.

Left – Usual Stage 2 operations. Right – Added Hair Glow Layer, the Volumetric Hair Layer (generated in section 3), as well as some contrast.

Finally, we perform our Stage 3 operations as usual, adding detail by running Color Efex Pro 4 from the Nik Collection. We also make a small collision fix. The final result is shown below.

Final Result from our Daz Studio Iray Emissive Hair Tutorial

Creating wet skin involves three key steps-
1. Making the composition fit. If our figure is to have wet skin, then we want our composition to support that.
2. Making the skin properly shiny. Wet skin is more shiny and reflective than dry skin because there is water on the skin’s surface.
3. Adding water drops on top of the skin. In addition to being more shiny, there will also be some drops of water clinging to the skin, and trailing down the skin.

How to Get Wet Skin in Daz Studio Iray

1. Making the composition fit

First, I create my scene in Daz Studio. Since I want to focus on the skin, I want my figure to be fairly large, and to have a good amount of skin visible. In addition, she should be doing something that will result in wet skin. In this image, I decided to create a dynamic scene, featuring Victoria 7 exercising with weights. Hair is NJA Ponytail Hair, which is one of my favorites. Outfit is Heat Up for G3F and G2F.

Below is the first pass of my composition with regular Victoria 7 skin. Lighting is just with an IBL. At this point, the skin does not look very wet.

Woman exercising with weights with regular Victoria 7 skin.

2. Making the skin properly shiny

Next, I want to change certain settings on my Victoria 7 skin to make it more shiny. To do this, I select my Victoria 7 figure, and go into Surfaces > Editor. I select my V7 skins and make the following parameter changes –

• Glossy Layered Weight set to 1.0.
• Glossy Reflectivity set to 0.9.
• Glossy Roughness set to 0.4. This can be set lower if we want to increase the wet effect on skin. Setting it too low though, will make the skin look unrealistically shiny. Therefore, tweak it according to personal taste.
• Top Coat Layering Mode set to Fresnel. Top Coat IOR set to 1.49 and Top Coat Thin Film IOR set to 1.4. Again, Top Coat Roughness can be adjusted according to taste. A lower Roughness value will increase shininess and a higher Roughness value will decrease shininess.

Victoria 7 skin after changing Glossy and Top Coat parameters.

3. Adding water drops on top of the skin

There are multiple ways to achieve this final step. I use a simple technique here, which utilizes the Daz Studio geometry shell.

• First, I select my Victoria 7 figure.
• Next, I go into Create > New Geometry Shell. This creates a shell over our Victoria 7 figure.
• I then select the Geometry Shell and apply the Iray Water shader to it.
• I go to Parameters > Mesh Offset and set the Offset Distance to 0.001.

Victoria7 after adding a geometric shell with surfaces set to the Iray water shader.

In the image above, she looks like she has cellophane wrapped all around her. This looks strange because water on our body does not form an even continuous shell. Instead, we only want certain small parts of the shell to be visible, simulating water droplets.

To do this, I do a search on “water condensation bump”. I download an appropriate black and white water condensation image, and apply that to the Cutout Opacity parameter of my geometry shell. I can then adjust the Horizontal and Vertical Tiles parameter to control how much water there is. I decided to go for the more subtle effect here with water drops that are not overly prominent.

Finally, I also add some mesh lights to further accentuate the shininess of my wet skin and shell.

Added water condensation map to our water geometric shell, so that only small parts of shell are visible. Also added mesh lights to accentuate our wet skin.

Another way to achieve water droplets on skin is to use crafted specular maps. This is what is done in Genesis 8 Wet Body Iray by SimonWM. He also has a variety of shells for the other Genesis figures. More recently, Hellboy released Real Drops Male Edition, which looks superb. Finally, V3Digitimes also has some great wet skin products, including Wet And Tanned Skins For Genesis 8 Female(s).

In the image below, I used Wet Body Geometry Shells by SimonWM. This is what I did –

• I apply the Wet Body geometry shell to a G2F figure (Victoria 6).
• I select all surfaces on the geometry shell and apply the Iray Uber shader.
• I set Glossy Weight to 1.0, Glossy Reflectivity to 1.0, and Glossy Roughness to 0.
• Finally, I can further control the strength of the drops by changing Translucency Weight. A value of 0 has the strongest wet map.

Water Goddess image with stronger Sweat Rolling specular wet body map.

This first image has a stronger wet body look, and uses the specular Sweat Rolling map. For contrast, we also use a more subtle wet body look, and the Water Beads specular map.

Water Goddess image with more subtle Water Beads specular wet body map. Also using more fantasy lighting here.

The image below is the finished product of my water shader experiment. In this tutorial, I talk about the different parameters of the Iray water shader, and what I focused on to create my pin-up render.

Water Shader Tutorial for Daz Studio Iray

1. Water Shader

Barcelona Sunset environment map with zero rotation.

I create the scene as I normally would. Here I am using FWSA Gillian HD and LF Sorbet Swimwear, which fits in very well with a water pin-up scene. The only extra change I made here, is to make her skin appear more wet by increasing Glossy Reflectivity to 0.9, and decreasing Glossy Roughness to 0.4, for all skin surfaces.

Once I am done, I make a plane primitive and apply the Iray water shader to it. When I look at the surface properties of my water plane, there are two key properties – reflection and refraction.

a) Reflection

To get a good reflection on my water, I want to pick a good environment map and rotation angle. I like the Barcelona Rooftops HDR that I got from sIBL Archives, so I use it here, starting with zero rotation. Unfortunately, at this rotation, it is filled with large buildings and palm trees, which is not a very pleasing reflection on my water. Therefore, I adjust the rotation until I get an interesting far-away skyline, that I am happy with (rotation = 270 degrees).

I adjust the rotation of my Environment Map until I get a more open, far-away, skyline that I am happy with.

b) Refraction

Slight change of the camera angle so we can see more of the refracted foot.

Another important aspect of the Iray water shader is refraction. Light travels at a different speed in air than in water. Therefore, when light enters water, it gets bent (at the point of crossing), thereby allowing us to see more of the leg that is submerged. Without refraction, her foot would not be visible.

Submerged objects always appear to be shallower than they are because the light from them changes angle at the surface, bending downward toward the water.
~~[HyperPhysics]

Create a Ground Plane by duplicating my water plane.

However, because all we have is our water plane and there is no ground plane, her foot looks like it is not standing on anything. To fix this, I duplicate my water plane by going into Edit > Duplicate > Duplicate Node(s). This creates a duplicate plane which I call ‘Ground Plane’. Next, I apply the Concrete Iray shader to my ground plane, and then move it down so that my pin-up girl is standing on it.

Notice that there is now a shadow under her foot, and there are also interesting patterns on the water due to refraction of the ground plane.

I add a ground plane so that the pin-up girl’s refracted foot, under the water, is standing on a solid surface.

c) Waves

You will notice, that there is wind in our render that is blowing out our pin-up girl’s hair. This wind will also create waves/ripples on our water. To add waves to our currently flat water plane, we add in an appropriate normal map. We can do a search for “water normal map” or we can get a normal map from one of our existing environments.

Load my water normal map into the Normal Map parameter of my water plane.

Next, I edit my water plane surface, and load in my water normal map. I can increase the number of Horizontal and Vertical Tiles in my shader parameter, if I want to make my water be more wavy. Finally, I can also color my water plane, for example make my water appear more blue, by changing the Base Color parameter of my water plane.

Added waves on my water plane by loading in an appropriate water normal map.

2. Water Thin & Water Dispersive

The Water Thin Iray shader is just like the Water shader except that it has the Thin Walled parameter turned on. This just means that the water shader is only applied to the surface of the object, instead of the entire volume of the object.

Thin Walled – This property sets the volumetric effects of the surface. Compare a bubble (on) to a marble (off) for example.
~~[Daz Documentation Center]

When Thin Walled is Off, the bubbles look like droplets of water.

For example, cornea surfaces are often set to Water Thin. Another great example of a thin surface object are bubbles. In my first bubble image, I have the Thin Walled parameter set to Off. In this example, my bubbles look more like droplets of water rather than bubbles.

When Thin Walled is On, the bubbles look a lot more like bubbles.

Completed Pink Lady and Bubbles image.

Another very cool aspect of bubbles is that they have chromatic dispersion. These result in the many colors we may see on bubbles, in an oil slick, or in a rainbow.

A bubble film is a sort of sandwich: a layer of soap molecules, a filling of water molecules, and then another layer of soap molecules. When light waves reflecting from one layer of soap molecules meet up with light waves reflecting from the second layer of soap molecules, the two sets of waves interfere. Some waves add together, making certain frequencies or colors of light brighter. Other waves cancel each other, removing a frequency or color from the mixture. The colors that you see are what’s left after the light waves interfere.
~~[Exploratorium]

That is what the Water Dispersive Iray shader addresses. It has an additional parameter called Abbe.

Abbe is a conatant chromatic dispersion. Lower numbers (but greater than 0) give more dispersion on the surface, and the higher the value, the less dispersion. This works on surfaces with volume, not on Thin Walled surfaces.
~~[Daz Documentation Center]

Note that Abbe does not work on Thin Walled surfaces. Therefore, to test this out, I need a double layered bubble (i.e. a bubble that is geometrically represented by both an outer and inner layer). I found such a bubble in the 3D Bubbles product by MindVision G.D.S.

Water Dispersive Iray shader applied to two-sided bubbles. Abbe set to 2.

Chromatic dispersion works here. However, the two sided bubbles look a bit too substantial for bubbles, and ends up looking more like glass. Personally, I like the Thin Walled version best.

Another example image with Thin-Walled bubbles.

3. Under-Water Scene

There are two important aspects in an underwater scene, volumetric or atmospheric effects and caustics. I achieve my underwater atmospheric effect by using AtmoCam for Iray by Marshian. We can also set up our own volumetric cube by following some of the guidelines discussed here (in the Daz3D forum).

In optics, a caustic or caustic network is the envelope of light rays reflected or refracted by a curved surface or object, or the projection of that envelope of rays on another surface.
~~[Wikipedia]

In water, cool caustic patterns are made by the curves of surface waves. To generate these caustic patterns in my underwater scene, it is easiest and most time effective to fake it using a Gobo light.

1. I first did a search for “water caustics texture” and download some patterns that I like.
2. Then, I placed a spotlight up high up in my scene, and point it down at my focus area. I want it high enough so that it casts a bunch of almost parallel rays into my scene.

I invert my caustics image using the Layered Image Editor.
3. Next, I create a plane and apply my water caustics texture to the Cutout Opacity parameter of the plane. White represents opaque and black represents transparent. Therefore, I want my caustics lines to be in black and all the rest to be in white. If necessary, I can invert the image using the Layered Image Editor.
4. Finally I position the plane in front of my light so that it casts the proper shadows onto my underwater floor plane.

Finished underwater mermaid scene with caustics from a Gobo light.

Another way to achieve caustics is to do it for real by setting up an appropriate scene with appropriate shaders, and then letting the Iray renderer physically generate the water caustics pattern. This will take much longer to render, but will create more realistic looking results.

It was a big challenge for me to get Iray to generate caustic patterns in my underwater scene. I was finally only able to do it by using Overcomeon’s underwater caustic test scene.

Remember that the caustic patterns are formed by reflection and refraction off the curved surface of waves, on our water. Therefore, we will need waves on our water plane. In addition, reflection also plays a very important role to bounce off our light rays, thereby increasing the area where the patterns are created. To get caustics in my scene, I needed to place several large planes around my scene to bounce off my sunlight.

Finally, we also want to go to Render Settings > Optimization and turn ON the Caustic Sampler parameter. This will hopefully increase render efficiency of caustics in our scene. Note that this is just an optimization or render efficiency setting.

Finished underwater mermaid scene with real caustics from the Daz Studio Iray renderer.