In part 1 of this tutorial we saw what conditions were necessary to create catch lights in the eyes of a subject. In part 2 we are going to apply the catch light theory previously explained, to actual Poser scenes.
What Not To Do:
Before we look at the solution that works, it’s worth trying the other approaches that we might think can work, but that actually don’t. First, let’s discuss the spotlight. We see spotlights all the time in theater and movie productions. The reason being, the spot is easy to position and control. Although, with that said the spot doesn’t work for this particular application. In the following figure we see a Poser spot pointed straight at the face of our model. Thankfully she is digital, so there will be no squinting:
If we render the image the result will be disappointing:
We can tell that a spotlight was used: the very sharp shadows, the hard lighting and no reflection in the cornea. This is because a spotlight, in both Poser and Reality, is an infinitesimally small point that generates light in a cone pattern. It has no surface and therefore, can’t be reflected by the cornea. This image gives us the opportunity to see a portrait without reflections in the eyes. It just doesn’t look real.
The second approach is to try to use IBL. That is actually a reasonable idea. Since IBL generates an environment it means that the environment, which emits light, is going to reflect in the cornea. While this is true, it doesn’t necessarily create a good result. The reason being, the whole world around the subject will be reflected, which may cause too much reflection and therefore can remove detail from the iris. The right effect requires balance.
For example, in the following image I have added the “Summi Pool” IBL set provided with Reality. While we see the reflection of the environment in the eye, it doesn’t have that sparkle that we saw in the image from “The Misfits.” Here we can see the difference between illuminating a shot and lighting it, between happenstance and art.
I wanted to show you these examples so that you have no doubt about what works and what doesn’t.
How To Get Great Catch Lights:
First we check that our materials are set in the right way. If we use any of the popular figures, then there’s really not much we have to do. The cornea of Miki, Alyson, Dawn, Victoria 4, Roxie and others is set to be Architectural Glass with the right amount of IOR (Index Of Refraction) set automatically. The only thing that you need to check is that the Transmission texture for the material is set to pure white color and nothing else. This is how your cornea material should be:
Sometimes, when converting a Poser material set by a skin preset, the cornea comes through with an image map in the Transmission channel. That’s because the original material had that same texture. In this case you need to edit the Reality texture and convert it to type color. Once you do that you then need to set the color to pure white. The Transmission channel instructs LuxRender how much light should go through the material. Higher values of brightness for the color, mean greater amount of light. So, pure white means that 100% of light is going through the material. Strictly speaking, that value is unrealistic and you can set it to something like 190,190,190 if you feel that it’s better to stick to pure plausible value, but the visible difference is going to be minuscule. Pure white it is.
Next, we need to have a light surface reflect in the eyes. We create this effect by using the Reality mesh light. This type of light does two things for us:
- it provides a nice soft light that is suitable for portraits
- it provides a surface that will reflect in the eyes of the subject
I scaled the light at a medium size and positioned it like this:
The frontal view of the setup is this:
Basically we want the model to look at the light. The result is quite pleasant:
We can also mix this technique with other lights. For example, we can add the IBL light which provides us with a background, indirect lighting and eye reflections via the mesh light:
We see some extra reflections from the environment and those might not be what we want, from an artistic point of view. From the point of view of physical accuracy, they are exactly right. The goal of this exercise is to show that we can mix lights to obtain a certain effect. In the image above I have increased the gain of the meshlight to 5.8 while leaving the IBL gain set to 1.0. Of course, all this is done using the Linear tonemapper.
So, there you have it. Using this configuration you will get the right catch lights for your subjects every time.