Creating a humanoid mouth




I'm writing this tutorial mainly to point out a common mistake made by beginners when modelling the mouth. The problem occurs when modelling the corners of the mouth. Here is an example model by a friend of mine who let me use it in this tutorial.

Fig 04

Fig 04

image 1

Fig 05

Fig 05

image 2
See how all the polygons of the mouth end up in one vertex resulting in a number of problems. First of all a crease will show when smoothing out the mesh due to the high amount of polys all ending up in one point.

A second problem that occurs is when trying to animate a model like this, it lacks flexibility and geometry where the mouth needs to stretch ending up in a crease that is even more visible.

When we look at a real mouth like in the image below

image 3

image 3

when we draw a grid of poly's over the mouth it should look somewhat like this rather then poly's ending up in a corner point.

A other benifit you see here is that there are only quad poly's this will make it easier to create a smooth surface.

Modelling the mouth

Now down to the real work. Actually making the mouth. I've chosen to create this mouth using polymodelling technique in 3dsmax. This technique can be used in most 3d software so you should have no problem following. I will however explain how to model like this using 3dsmax 4.2 and editable poly 2 which can be downloaded from the site. I also use 2 scripts namely, meshtools and cspolytools. Both can be downloaded from I'll show some of their features shortly. If you prefer another technique like boxmodelling, spline modelling or even nurbs just model a simular structure as shown in image 3.









- in the front viewport create a box or any other primitive.
- convert this primitive to an editable poly by rightclicking it and choosing "convert to" -> "convert to editable poly" from the quad.
- Now create 10 new vertices like I did in the example on the left.
- Select the first 4 verts and use the "Makes poly out of the selected verts" function of the csPolytools script as shown below.

If you often use this function as I do I suggest setting a keyboard shortcut for it. I use the "p" key myself to create poly's this way.

- Create all poly's this way until you have half of the upper lip shape finished.
- click "element" in the selection dialog and select the primitive you created in step 1. Delete it as we have no need for it any longer.
- go to perspective view. The poly's may flipped backwards, if so you select the entire mouth element and click "Flip Normals" under Surface properties.
- Exit sub object mode and mirror the mouth so that we have a full mouth to work on. Create an instance so that when we work on one half the other half gets modified in the same way but mirrored.

- create the lower half of the mouth in the same way.

now select all the outer edges as shown in step 1 in the image on the left

- use the transform gizmo to shift pull the edges along the y axis. If you have edit poly 2 installed the edges will have extruded in doing so

- now pull all the verts into a better position as show in step 3

- do the same thing for the inner edges of the mouth

Now we can see that the mouth is rather flat and unatural becuase we were working in front view and never really looked at the side view to shape the mouth more natural.

Lets remedy that.

The meshtools script has two nice functions called grow and shrink selection. I have those set up on the plus and minus keys on my numeric keyboard for ease of use.

Now follow the steps as shown on the left.

- select the corner of the mouth
- grow selection (press plus key)
- grow selection again(press plus key)

- pull the verteces backwards
- shrink the selection (minus key)
- pull the verteces backwards a second time
- shrink the selection (minus key)
- pull the verteces backwards one last time

now the mouth has a more natural shape. If you don't like it just tweak some of those verts until the shape is perfect.

TIP: Modelling with a background photo is perfect for using this technique. You can press Alt-X to make your model transparent so you can see the photo in the back and model on top of it. one final step to complete this model, the
small indent above the upper lip. Lets model that

- first extrude the outer edges once again so we have the entire mouth area modelled.

- select the edges as shown

- use the meshtools connect function to devide these selected edges. a keyboard shortcut will speed up your work.

- select the button two edges as shown

- connect

- tweak until the indent looks good

you can model about anything this way, be it an eye, and ear or even a full squirrel :)

Well that's it for today, I hope you learned something or at least enjoyed my typo's :)

be sure to drop by at my personal artpage at for tons of 3d, 2d and maybe more tutorials. Also visit my studio at a fantasy art and story page I'm sure you'll appreciate.

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