Modelling an alien

( page 7)

Seven: Making the jaw

The first step in creating the jaw is to decide how it will be made. Options include sweeping profiles along two rails curves, moulding a primitive or patching several surfaces together. We begin though by drawing curves that roughly define its shape. Here is the outer edge curve which is drawn in side view then edited in perspective to get the right shape.

The inner curve is created the same way, here viewed in Component Edit mode so you can see the CVs. We can now either create curves between the two 'rails' and make a series of surface patches using the Boundary surface tool or create a profile curve and sweep it along the rails.

We decide on a Birail Sweep for simplicity so the profile curves are created next. In order for sweeps to work the endpoints of the curves must be attached to the rails. Maya's excellent snapping makes this easy. By holding down the [C] key you can snap any selected CVs to another curve.

The Birail 3+ tool allows you to use any number of profile curves. This makes it easy to define exactly the shape of the sweep at the most critical points. Here is the first part of the jaw completed.

That's the outside done, and the inner surface is created in a similar way but using three simpler profiles. To join the two halves we use Maya's Global Stitch tool. This welds the two surfaces together and creates continuity between them for a smooth join.

The Jaw is instanced and mirrored in z to create the other side for checking. The jaw doesn't meet at the chin, but we can fix that by editing the curves. With all the jaw curves selected groups of CVs are marqueed and moved. However, this has caused the outer surface to disappear. Not to worry, this would occur if one of the profile curves loses contact with the ls, a likely occurrence when moving CVs.

A quick check reveals the offending curve which is quickly reattached. The surface pops back into existence thanks to the Construction History. Once all the edits are done a tube like those on the head is added to the jaw using a trim and a surface to surface blend.

The gums are next added to the model. They are created from curves extracted from the lower jaw and the band extrusion. Profiles are swept along the extracted curves ensuring a snug fit between jaw and gums. Then the extruded objects are instanced, mirrored and the CVs are tweaked to sut bulges where the teeth attach.

A palette is created for the inside of the mouth by lofting between a curve drawn along the world z axis and an Isoparm of the band extrude object. The shape of the curvature of the palette is controlled by moving the CVs of the z axis curve in y. The palette is mirrored to the other side and stitched to the original.