Techniques for Creating Realistic Eyes for Another Level of Believability
Recreating eyes in a CG environment, whether it's for a human, animal or even some type of mythical creature can be a difficult task. There are some very important principles to keep in mind to ensure the eyes on your character are as believable as possible. This article will cover some key techniques for modeling and texturing realistic eyes that can be applied in any 3D application you're using.
When it comes to the eyes of your character or creature it's something that really can't be overlooked, but often times it is. Sure, there are times when going for three basic colors to create the eye will work, and sometimes this is all a cartoony style character needs.
But more often than not, your character needs more detail in the eyes. So much emotion and personality can come just from the eye, that's why it's important that the eyes on your character are realistic.
Creating believable eyes is vital for capturing and maintaining the audience's attention. Eyes that look unnatural can be a dead giveaway to a CG character, which you almost never want.
Find the Right Reference
As with just about every other task in a 3D production you'll want to find great reference, and when it comes to creating realistic eyes there is no exception.
Before you begin creating the eyes you should search for some reference images online or even just snap some pictures of your own eyes. This is a great way to really study the eye and see all the small details and variety of colors that actually appear on someone's eye.
Another very important detail you should get out of studying the right reference is to understand the anatomy of an eye. The key features you want to keep in mind are the cornea, the iris, the pupil and the sclera.
The cornea of the eye is actually the transparent area of the eye that covers the iris and the pupil. The cornea is actually what helps give the eye its refractive nature.
The iris of the eye is the area of the eye that gives it its unique color. The iris has very intricate details that require the most attention when creating the textures. On a technical level the iris is what controls the diameter of the pupil, but more often than not it just needs to be remembered as the "colored" part of the eye.
The pupil is the hole located in the center of the eye which allows light to enter in. Of course, you as an artist just needs to remember that the pupil is the black area in the center of the eye. One very important thing you need to keep in mind is that not all pupils are shaped circular. For instance, a cat's pupil is typically a vertical split in the eye.
The white area of the eye is referred to as the sclera, which acts as the protective layer of the eye. One thing you need to remember is that there are usually visible blood vessels that appear on the sclera, and if someone has an itchy eye and rubs it or if the person is tired it can increase the blood shot appearance.
Creating the Model
When it comes to modeling the eyeball your first instinct may be to just drop in a simple sphere and rotate it in the correct direction. While this might work for a more stylized eye, if you're trying to create a photorealistic model that can hold up to close scrutiny then this isn't the best route to take.
Upon close examination and research you'll find that the human eye is not perfectly circular, in fact, the iris and pupil area of the eyeball actually protrudes out. When modeling the shape of the eye this is something that should be addressed in order to truly create a realistic eye.
You can see just a very basic example of the rough shape of the eye in the image below. This is exaggerated slightly for clarity, but you can see what you should try and recreate when modeling the eyeball.
By keeping this shape in mind when modeling the eye in a 3D application you should end up with a mesh that resembles the image below. You can see how the iris and pupil area is extruded out slightly to create the protrusion. A good technique to use when modeling the eye is to create a copy of the eye and have this new copy act as the reflective lens on the eye so you can have more control over the look of the cornea.
Texturing the Eye in Photoshop
When you have the model for the eye finished you can unwrap the UVs and create a UV snapshot or a UV stamp depending on your 3D application. Once you do that you can bring the unwrapped UVs into a program like Photoshop where you can begin the actual texturing process.
When texturing the eye it's important to build the detail slowly. Like most other CG tasks you don't want to start out by creating the tiny details, but rather create the most important aspects and build on more and more details from there.
A good starting point is to begin with the iris color; this doesn't need to be perfect but just a base color to block in the shape and color of that area of the eye.
Once you have the Iris color created you can apply a simple Pattern Overlay to the color, something like the cloud pattern. This will give you a nice looking pattern for the eye that mimics some of the intricate details of the Iris.
The next step will be to create the different layers of fibers found on the iris; this is what will really give the iris its unique and realistic appearance. You can do this very simply by dropping in a new white shape into the middle area of the eye and use the smudge tool to begin to pull out the fibers for the iris.
When that is finished you can incorporate different color variations into the iris fibers. Now all that is left is to drop in the pupil and create the sclera portion of the eye, which again is the white area. One thing you need to remember when coloring the sclera is that there should be the small red blood vessels incorporated in to really push the realism.
Creating the Eye Material
Once you're happy with the eye texture you can bring this back into your 3D application and begin creating the material for the eye. This is a very important part of the eye creation that can make or break the believability.
An important thing to keep in mind is that the sclera (white area of the eye) has a level of translucency to it, so your material should utilize subsurface scattering to really help sell this.
One very important aspect of an eyeball is that it should appear wet; this can be achieved by utilizing the separate layer you created for the cornea and fine tuning the reflectivity. You also want to ensure that the areas where the eye meets the eyelids appears wet as well. This can be accomplished by either creating a very thin separate piece of geometry just above the lids, or building this wetness straight into the material of the eye shader.
Creating realistic eyes is not a simple task but with the right techniques and understanding you can create great looking eyes for any character or creature that are believable and will add a whole other level of realism. If you want to learn more watch Creating Realistic Eyes in Photoshop and Maya to get a step-by-step look at how a pro tackles texturing an eye. If you have any questions share them in the comments below!