Here’s a tutorial for working with NURBS to create a head.  It covers using the trim tool to create eye holes and then using a blend to attach the eye.

 

IMPORTANT NOTE: Before you do ANY of this, take a picture of your character toy from the SIDE and the FRONT.  Import those images into the corresponding views.  The only reason I didn’t do that here is that I didn’t have immediate access to a digital camera and I wanted to put this page up quickly for y’all!

 

  1. Create a NURBS sphere and model it in the general shape of your character toy’s head.

 

  1. Draw curves that radiate from the mouth (wherever that is on your toy).  Be sure to take the neck into consideration.

 

  1. Split your head model in half and delete the half not seen in the Side view.  How: Select the two isoparms on the half of your model (or create them if they’re not already there).  Then, select Edit NURBS > Detach Curves.  Keep one half and delete the other.
  2. Select your curves and project them on your model.  How: Edit NURBS > Project Curves On Surface.
  3. Select the projected curves and duplicate them.  How: Edit Curves > Duplicate Surface Curves.
  4. At this point, you can either delete everything but the new curves or Hide Unselected Objects.  Delete History on the new curves.
  5. Rebuild the curves so that they all have the same (manageable) number of CVs.  How: Edit Curves > Rebuild Curves and select the little box.  Click “0 to 1” for Parameter Range and enter a number (probably not more than 10) for Number Of Spans.
  6. Loft the curves together.  How: Select each curve in order one by one.  Select Surfaces > Loft.

 

  1. Delete History on your lofted surface.  Group the curves (name the group “head_curves”) and hide them or put them into another layer.
  2. Clean up the model.  Look for overlapping CV’s and spread them out.  Turn on hulls and smooth out the ones that look too jagged.

 

  1. Now you can start to tweak the model to get a better shape.  In the case of my model, the nuzzle or snout is much thinner than the rest of the head.  So, I’m going to use a lattice to achieve this.  How: Select Deform > Create Lattice and select the little box.  Enter the number of Divisions you need for X, Y, and Z.  In my case, I’m using 2 for X and Y, and 3 for Z (since the snout seems to narrow dramatically starting from the middle of the head.  Also I don’t want the neck to be affected).
  2. Go into Component Mode by pressing F8 and then Move, Scale, or Rotate the control points necessary to mold the shape you want.  (To reposition the lattice without affecting your model, select both the lattice and the base in the Outliner) After you’re done, select your model and Delete History.  This will get rid of the lattice.  Note: If you delete the lattice itself, your model will go back to its original shape.  Another note: You don’t have to use the lattice!

 

  1. Continue adjusting the model.  You may need to add isoparms or lattice another area.  Note: Add isoparms sparingly!  Too many will cause problems for you later on… moreso than when working in polygons.  Another note: You can put a lattice a group of CVs and it will only affect those CVs.  Yet another note: I could’ve spent more time developing this model, but I wanted to finish this tutorial for the class.  Please don’t use my model as a quality gauge for yours!!!

 

 

ADDING PARTS - EYES, EARS AND NOSE

 

  1. Draw a curve in the shape of your toy’s eye in the Side view right over the model’s eye area and then scale it up slightly.  Now, project the curve onto the model.

 

  1. Next, create the eye hole.  Select Edit NURBS > Trim Tool.  Select the area you wish to keep (the head) and press Enter.  Now there should be an eye hole.

 

  1. To build the eye itself, use the existing eye curve.  Hold down the right mouse button over your model and select Trim Edge.  Then click on the eye curve.  Duplicate that curve (Edit Curves > Duplicate Surface Curves).
  2. Center the pivot of the curve (Modify > Center Pivot) and scale it down slightly, so that it’s the exact size of your model’s eye (remember we scaled the projected eye curve up slightly).  Duplicate it and move the duplicate (in X, most likely) so that there’s a little distance between the curve and the head.  This will become the eyelid.  Note: if the edge of the eye hole looks jagged, select the model and press 3 for higher resolution.  That should smooth out the edge.
  3. Duplicate that curve and scale it up so that it overlaps the head.  This will be the edge used in the blend.

 

  1. Select the three curves in order.  Select Surfaces > Loft and the little box.  Adjust the lofted surface so that the edges lay flat again the surface of the head.
  2. Now you can Delete History on the loft and delete or hide the curves.  You can also add more isoparms where there are gaps.  This will be beneficial when you apply the blend.  You can also create an eyeball now and fit your eyelids to it.
  3. Select the outer curve of the loft by holding down the right mouse button over the curve and selecting Isoparms.  Duplicate the curve and scale it up.  This will be the outer curve of the blend.
  4. Project that curve onto the head surface. 
  5. Now is a good time to turn on the CVs of your loft so that you will be able to see them even when the loft isn’t selected.  Select the loft and then select Display > NURBS Components > CVs.  ALSO, make sure that your loft is closed and if it’s not, use Edit NURBS > Open/Close Surfaces to close it!
  6. Rebuild that curve so that it has the same number of CVs as the loft curves.  Reposition the projection curve CVs so that they line up with the loft curve CVs.  Make sure that the U and the box next to the U is lined up with those on the loft as well.  This will ensure that both have the same surface direction.  If they don’t, you’ll get a twisting effect when you apply the blend.  Note: If the U is on the inner curve of the loft (the one farthest away from the projection curve), reverse the V surface direction (Edit NURBS > Reverse Surface Direction and select the little box.  Click V)

 

  1. Next, apply a Fillet Blend.  Deselect all objects, then Select Edit NURBS > Surface Fillet > Fillet Blend Tool.  Follow directions from there.

 

  1. After the blend is applied, you’ll need to smooth the transition between it and the loft, especially if there is interpenetration of the two surfaces.  Do this by moving the CVs on the outer curve of the loft.

 

by Jenga Mwendo; July 1, 2002 for 3D Modeling Class at NYU

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