Creating Human face in 3DSMAX using NURMS.

This is how your scene will look at some stage.

Thin gray or dark blue lines show the initial 3D sketch.

Red lines you see over the surface is kind of low polygonal model, which serves as NURMS control mesh. It is slightly different form typical low-poly in that it is not suited for visualization itself. It only can be used as rough model representation.

NURMS behaves much like NURBS power 3 with that difference that NURMS can be of arbitrary topology with no UVЦquadratic restriction.

Note that control mesh vertices lay somewhat outside the actual surface, if the surface is convex, and inside the surface if the surface is concave.

This surface behavior is different form 3DSMAX Bezier Patch surfaces, in which surface must cross each vertex.

Please see УAdditional information about the subdivision algorithmФ below.

3D sketching.

Draw profile and front view curves first.

These two curves can stay С2DТ.

Draw as many curves in 3D as you need.

Choosing the correct curves is the main thing at this time.

Created curves should give you a sense of volume in perspective or user view-ports, not only correct shapes in front and side view-ports.

Align curves, so the curves that should intersect lay as close to each other as possible at the СintersectionТ point.

Use mirror modifier or the mirror tool to create symmetrical curves.

If you use mirror tool, do not forget to turn СinstanceТ option on, so the symmetric object will last symmetric after modifying original object.

I recommend doing all the modeling around the center of the world coordinate system.

Allow yourself as much time as you can at this stage and create a perfect shape.

This will save you a lot of time creating actual geometry.

Setting up symmetrical objects

Create a Box object; convert it to editable mesh.

Delete all the polygons but one.

Use the transform type-in to center your object along the symmetry axis.

Enter sub-object mode, select the polygon and move it to the side.

Mirror your object using Instance option.

It is important to see the both symmetric sides while editing.

You can then edit either of the two objects and see the other side reflect the changes immediately.

Setting up NURMS

Apply the Mesh Smooth modifier.

Set Mesh Smooth type to NURMS.

Apply To Whole Mesh should be checked.

It is useful to set Iterations value to something smaller then in Render Values to improve interactivity while editing.

Turn the Show End Result radio button on while in Editable Mesh sub-object mode.

Extending surface with edge cloning

Select either of the objects, enter edge sub-object mode. Select the side edge and shift-drag. (Shift-dragging means that you keep a shift button pressed on the keyboard while dragging something with the mouse.)

This is how you create polygons by shift-dragging the edge selection.

Select several boundary edges.

Shift-and-Drag to Create several polygons at once.

Modifying topology with Welding

Delete a polygon. Select a vertex.

Enter Weld Target mode in Vertex sub object mode.

Drag the vertex over another. Release the mouse button. Vertex should weld.

Creating Elements with polygon cloning

Element of mesh is a group of polygons that are connected by their adges or built on same vertices.

You can create elements in your mesh by shift-cloning polygons.

Shift drag a polygon, release the mouse and answer Clone To Element when asked.

Fitting surface to the sketch

Now you are ready to start modeling, using your 3D sketch as a guide. Start with any part of the face.I am starting with the lips.

To make seamless connection between mirrored geometry, you can provide a polygon stripe in the middle.Polygons in this stripe should always be perpendicular to the plane of symmetry.Connection will be seamless even without final welding sides together.If you want to attach and weld the objects together when finished, you should not do it with instances.To attach the sides, do the following:Delete one side. Delete the Mesh Smooth modifier that is applied over the Edit Mesh or the Editable Mesh in the stack. Mirror with the СCopyТ option, not the СInstanceТ, then attach and weld with the weld selected option.

Correct Topology

Control mesh is not treated as just triangles, but as polygons.

For example, each quadratic polygon (quad) actually consists of two triangles in 3DSMAX. There is one invisible edge in each quad.

NURMS makes sense of topology.

Try to make build your mesh of quadratic polygons if possible. Use other types of polygons with care.

Here is an example of СgoodТ topology.

Incorrect topology

Geometry of the control mesh is the same, but topology is different.

Some edges made visible in this example.

Additional information about the subdivision algorithm

Generally, surface does not have to pass through the control vertices, but you can achieve this by placing three vertices to a line (vertices A, B, C on the picture). In this case surface near these vertices will behave somewhat like a Bezier spline, vertex A will serve as a knot, and B and C Ц as the Bezier handles.

This behavior appears on the boundary surface edges, to use this feature with other vertices, you should line up all the 8 vertices around the СknotТ vertex to a plane.

Surface will also intersect all Corner vertices (vertex D). Vertex B serves as a Bezier handle for knot D.

This feature of the subdivision algorithm can be very useful to get more precise control over the surface shape.