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GA 3324 : Character Modeling This course covers advanced modeling techniques for building 3 dimensional characters. Students wil explore techniques of character modeling to include various approaches to figure construction.

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Week 2: Heads: Modeling Facial Features

WEEKLY TABLE OF CONTENTS
1-Building the Head- Tutorials/Overview
2-Using Image Planes- Tutorials
3-Understanding the Facial Anatomy
4-Specific Facial Shapes
5-Tools and Concepts for Execution

BUILDING THE HEAD TUTORIALS:
BOX MODELING METHOD:


EDGE-EXTRUSION MODELING METHOD:

OR READ THIS:

Using Image Planes to fine-tune your reference:

Always good to get a front, side, and 3/4 view to work with. It can often be hard
to find an exact front, so you can do as you see in the image below... copy the
left side into a mirror version for the right in Photoshop.

We will use these photos to suppliment the 3d skull used in week one,
since if you were to use the skull alone, you would just get the same
person over and over again.

Here is a Written Tutorial on inserting image planes..... Click on image:

HOW TO IMPORT IMAGE PLANES FOR YOUR CHARACTER MODELING PROJECT:

Overall, we can use roughly the same topology to create multiple "looks" for the same face.
In the image below, only minor gridflow changes are made, but the face can take on an entirely
different character, just from these little vertex moves:


Here is another image showing even different features,
this time using an Asian female facial shape:

Here is yet another example:

As we build our topology, our number 1 goal is going to be to try and make the gridflow of the Polygons
match the direction of flow of the underlying muscles as much as possible. Key emphais should be
placed on the muscles shown and labeled below. Note how you can see the same structures in all 4 images:
1-The ecorche NURBS template built off of a skeleton
2-An actual Muscle Diagram
3-Loops drawn in Photoshop on a photo of a Human Head
4-A finalized polygon model.

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Lets start exploring the shapes of these individual features:

Mouth

With the mouth, there are several major features that we must take into account. The largest muscle in the face is the orbicularis oris which constricts the opening and closing of the lips. The buccinator muscle can be found at both corners of the mouth sometimes slightly overlapping or overhanging these corners based on age. During chewing it cooperates with the masitcatory muscles in the cheeks and jaw, and is also used in sucking movements, and in "ooo" and "woo" sounds. The philtrum is the vertical indentation in the midline of the upper lip. Also called infranasal depression, it is what seperates the upper lip into it's "M" shape.

Viewed from the front, the lips should be like a gummi-life saver, able to squish and stretch. The Topolgy for this feature should be contained within its own circular edgeloop as we will look at performing facial animation with the mouth later on. The Upper lip is normally thinner than the Lower lip, with the ratio of one to the other usually determining "poutyiness". Towards the edges they get closer and smaller, until the upper lip rotates around the corner and overhangs the lower as it flows into that structure.

From the side, the shape of the lips is very distinct. The upper lip has a ridge which distinguishes where the muscle tissue from the inside of the mouth (the pinker areas) meets the surrounding skin. The lower lip has no such feature and is usually a much more smooth, rounder transition.

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Ears

 

Building an Ear, tutorial 1
Building an Ear, tutorial 2
Building an Ear, tutorial 3 <--Click on Tab "8.Ear"

Building a proper ear can be difficult due to the multile structure contained inside. There are three tutorials listed above, and they should be used for guidance in how to create these structures. While each approaches the ear from a different modeling perspective, they arrive at mainly the same concluding point, which I find valuable to illustrate how the creation of these forms is independant of modeling methodology.

Here however, we will talk much more generally about what these structures are, and how to approach building them. The Numbering below referes to the diagram above.

1. We begin in creating the ear by first establishing a line of gridflow from the jaw line, just under the Tragus (the tiny flap at the front of the ear), over the Lobule which is the skin flap the bottom of your ear. Depending the person, this flap may actually be attached, or remain independant. This edgeflow feature continues, turning upward to define the outer edge of the ear known as the Helix. This size of the helix determines the over all size of the outer ear or Pinna, how much they "stick out", etc... We should also note here that the size of this feature is mainly dependent on age. Since the ears continue to steadily grow throughout life, by old age they can seem large and disproportionate to the rest of the face, especially the Lobule and Helix.
This feature continues to spiral around to the top of the ear which is known as The Crest of the Helix, eventually flowing inward to become the Auditory Canal, the feature which allows sound to to enter the the Inner ear. This edgeflow pattern is crucial and should look like a spiral, mimicing the way that sound will spiral into the ear.

2. The second direction of gridflow again starts out over the jawline, and here crosses over the lower edge of the Crest of the Helix, and then directly into the Auditory Canal.

3. The Third feature for the ear that is determined by different gridflow comes from the top of the head. It enters the ear on the posterior side of the Crest of the Helix, flowing back up over the crest, and into the anterior side of the Pinna. When it crosses over to the front, we use these verticies to form the Antihelix which flows back down against the the helix, splitting off at the ear lobe, and into the auditory canal. Notice a theme so far? Every structure flows into the audiotoy canal!

4. The final main structure that we see is gridflow originating from the back of the head which crosses the Helix behind the ear, travels across the Antihelix, then flows directly into the auditory canal.

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Nose

The nose can very distincly define who your character is. Its shape, size, "direction", can all point to signs of gender, age and race. While we shall tread lightly on racial features, anaylze in you character whether or not their nose needs to be small, thin, pointy, wide, upturned, crooked/downturned, bullish, etc... These are all terms that we commonly use, and defining how your character needs to be developed before actually modeling the nose will greatly influence your decisions. In general, Male adult humans have larger noses than Female adult humans in terms of displacement off the cranial structure. While shape may vary depending on racial and other genetic features, age will also cause (just like the ears) the percepition of a larger nose, as the cartilage continues to grow throughout life.

Regardless of genetics, the External naris, or nostrils, will always have two definative traits as seen above. From both the front and side views, we should be able to see into the nostrils, veiwing the lateral cartilage from the side, and the top of the orbicularis oris from the front.

Eyelids/Eyebrows

The Eyelids are yet another structure which demans attention based on genetica features, and is also crucial when it comes to the animation of our characters. The Orbicularis Occuli is the facial muscle, behaving just like the orbicularis oris in the mouth, which allows us to blink, wink, and open our eyes. As such, since this a continuous loop of muscle, our topology must be built accordingly.

The Frontalis Muscle is located just above the orbicularis occuli and is commonly known as the eyebrow muscle. It lifts the eyebrow out of the way and is a muscle of facial animation. It starts on the top of the head and attaches to the eyebrow skin. There is one for each brow. It works with facial expression. It can lift the eyelid in a secondary fashion and can compensate for eyelid muscles to a certain degree. With the aging face, the brow can descend with gravity.

The Corrugator is a small, narrow, pyramidal muscle, beneath the Frontalis and Orbicularis oculi. While this is an important muscle, and distinct from the other two in the eyes, it usually isn't modeled seperately.

The Epicanthic Fold, or epicanthus, is a skin fold of the upper eyelid covering the inner corner of the eye. It is independant of the Upper Eyelid fold and but may at times be present without the upper eyelid fold, espically in individuals of Asiatic descent. In fact most humans of Caucasian or African descent will exhibit the Upper Eyelid fold but not the Epicanthic fold, and as such, this feature can be a main signifier of race.

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Eyeballs

1.	2.
3.	4.

Building an Eyeball, tutorial 1
Building an Eyeball, tutorial 2

The Eyeballs themselves consist of several main parts as witnessed in diagram 3 above. We will discuss 4 main parts here, the Cornea, The Sclera, the Pupil and the Iris.

The Cornea is a thin protective film that encases the eyeball. It can be seen prominently in image 2 above. I have built this shape out of polygon geometry so that it could be easily cylindrically mapped with an panoramic texture sample as reflected color (see image 1). The shape of the Cornea is what produces the shape of the highlights for the entire eye.

Beneath the Cornea lies the the rest of the eyeball. The white area is known as the Sclera and usually is somewhat multi-colored based on underlying feaures. Red and Pink tones will be noticeable based on veins under the outside film of the sclera. The tone of this object also varries by age, with children having a cooler, bluer white, and elderly individuals possesing a more yellowed tone.

The Front of the eye contains 2 more feaures, the Iris and the Pupil. the Iris is the portion of the eye from which we determine "eyecolor". In image 4, you can actually see how I have modeled this feature independantly, seperating it from the NURBS structure that the sclera remains, making sure to set my curvature tolerance to high or highest quality so that I do not get jagged lines between the two at render time. The Iris is a generally flat section, stopping the normal curvature of the eyeball, and actually reversing the curve somewhat and bending inward! The Pupil bulges slightly again, and changes size based on available light in the process we know as dialation.

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Cleaning up Lamina Faces-
Sometimes when modeling you will extrude out a face, but might forget to move it off of that plane. As a result, you get a lamina face, which has no geometry area because it has length but no width and as we all know A=LxW. If we multiply by zero, no matter what we multiply by, we will get zero as a result. This can cause unsettling problems in your model, that will only really be noticed if you are in the face component mode. Lamina faces are circled below. One solution to remove these is to delete the face on either side of the lamina face, then re-extrude or re-append the hole.

New as of Maya 2009 is a new selection tool for selecting faces. One drawback of this function is it doesn't easily let you see your face centers (which helps you identify lamina faces). In Window-->Settings/Preferences-->Preferences, you can access the following options to restore this funtion:

The other solution is to run a Mesh-Cleanup.

You will need to check these 3 options to make it work effectively as they work as redundancy checks:
-Lamina Faces
-Non Manifold Geometry
-Faces with 0 geometry area

Lamina faces are faces which have their edges stuck together. Non-manifold geometry is made from faces which no longer maintain that hallow egg-shell structure. And faces with 0 Geometry area were explained above. Jus thit Apply or Cleanup and you should be good. Check your mesh in Face component mode to be sure.

 

 

Using Soft Deform, and Lattice Controllers
The Soft Deform Tool is a feature that has been around since maya 6.5, but in maya 8.0+ has a color feedback option that allows us to define the region which we need to tweak. As you can see in the first two images below, this tool is excellent for making quick, drastic, major changes to an area of the model .

In the tool settings window, we can adjust the falloff Curve, which will also update color in the 3d viewport. Examine the image below and you can see how the color feedback works in tune with the adjustable falloff curve.

We can also make major changes to our models by using a Lattice Deformer (Animation-->Deform-->Create Lattice). This deformer creates a 3d Matrix around the object, with grid lines determined by the number of divsions in the lattice options window. This lattice works like a simple polygon cube. It has movable verticies in it's component mode that allow us to again make sweeping changes easily; see the second image below.

In addition to creating a lattice around the whole object, we can also use this tool on specific verticies to refine the area. This is ESPECIALLY, ESPECIALLY useful when it comes to animation as these lattices can be used in conjunction with set driven keys to deform parts of your mesh (say, muscle buldges for example) that occur when a part of your underlying skeleton bends.

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