Lesson 11 Blend Shapes

Sculpting A Surface

How to use the Artisan Tool to sculpt a surface. Practice using the Artisan Tool to sculpt the surface on a sphere.

Make A Test Sphere
- – Create a polygonal sphere.
- – Set it’s construction history in the Channel Box > Inputs > polySphere1 to the following;
  - SubDivision Axis: 60;
  - SubDivision Height: 60;
- – Note: To see the effect the artisan tool has on the sphere better, apply a phong material.
- – RT + CLICK on the sphere, (inside menu popup) Assign New Material > Phong
- – Press 5: Smooth Shade All
Open the Sculpt Polygons Tool
- – Sphere selected: ANIMATION || Mesh > Sculpt Geometry Tool > □
- - Sculpt Geometry Tool Options:
  - – Click [RESET TOOL];
  - – Brush > Radius (U): 0.2;
  - – Sculpt Parameters > Max Displacement: 0.1;
Paint On The Surface
- – click and drag over the sphere. This pushes the geometry in.
- Notice: The cursor changes to an arrow surrounded by a red circle outline.
- Note: This tool works best with a pen tablet.
Change The Artisan Display
- Sculpt Geometry Tool Options:
  - – Turn off Show Wireframe: Display > Show Wireframe (uncheck)
Paint Another Stroke
- – Paint a second stroke across.
- Notice: You can’t see the lines as you paint across the surface.

The Sculpting Tools

Learn to pull, smooth and erase a surface using the Sculpt Geometry Tool.

Pull The Surface
- Sculpt Geometry Tool Options:
  - – Sculpt Parameters > Operation > Pull
- – Rotate to the other side of the sphere.
- – Paint on the surface to pull the geometry.
Smooth Out the Results
- Sculpt Geometry Tool Options:
  - – Select the Smooth Brush: Operation > Smooth
  - – Change Brush size: Brush > Radius (U)
  - – Note: HOLD “b” + scrub left and right to change the brush size.
- – Paint all the strokes to smooth them out.
Erase Some of the Brush Strokes
- Sculpt Geometry Tool Options:
  - – Select the Erase Brush: Operation > Erase
- – Paint along the surface to erase the last deformations to the sphere.
Flood
- Sculpt Geometry Tool Options:
  - – Select the Pull Brush: Operation > Pull
  - – Click on the Flood Button: Sculpt Parameters > Flood
  - – Check Erase Option: Operation > Erase
  - – Click on the Flood Button: Sculpt Parameters > Flood
  - Note: Sphere returns to it’s original shape.

Updating The Reference Surface

As you paint, you’re painting in relation to a reference surface. Maya takes note of your surface and updates after each stroke. So when you paint strokes that overlap, it builds on top of the previous stroke. You can adjust these settings by unchecking reference surface and updating manually.

Change the brush Attribute
- Sculpt Geometry Tool Options:
  - – Select the Pull Brush: Operation > Pull;
  - – Brush > Radius (U) > 0.2;
  - – Sculpt Parameters > Max Displacement > 0.2;
Pull The Surface With Two Strokes
- – Paint on the surface with two strokes that cross.
Change The Reference Update
- Sculpt Geometry Tool Options:
  UnCheck: Sculpt Parameters > Reference Surface > Update On Each Stroke.
Paint More Overlapping Strokes
- – Paint on the surface with a few more strokes.
- Notice: the strokes do not overlap. The strokes are displaced to the Maximum Displacement until you click on [UPDATE]
Update The Reference Layer
- – Click on the update button: Sculpt Parameters > Reference Surface > Update On Each Stroke > [UPDATE]
Paint On The Surface
- – Paint another Stroke over the last set.
- Notice: The overlapping strokes are building on top of each other.
Flood Erase The Object
- Sculpt Geometry Tool Options:
  - – Check Erase Option: Operation > Erase
  - – Click on the Flood Button: Sculpt Parameters > Flood
  - Note: Sphere returns to it’s original shape.

Sculpting The Penguin

Use the Sculpt tool to create facial expressions for your character. You will duplicate the body of your character in order to use for the blend shape deformer.

Open a Scene
- – Continue with your penguin scene or open the CD file. 10-bigzSkinning_03.ma.
Skin Envelope
- Before making blend shapes, make sure the geometry is in its original position. One way is to turn off the skin’s influence. If polygon isn’t moving with skeleton, make sure the skinCluster > envelope is set to 1.
- – Select the Penguin’s Body;
- – CHANNEL BOX: highlight the skinCluster node;
- – Set Envelope: 0
- This temporarily turns off the skinCluster, removing any influence of the skeleton and placing the geometry back to it’s exact original position. In other words, if you were to rotate the skeleton, the geometry would not move accordingly.
Duplicate the Penguin
- The blend shape deformer requires the original untouched penguin and the penguin duplicates to be deformed.
- – Hide the joints on the stage.
- – Select all of the Penguin’s geometry.
- – Press CRTL + “d” to duplicate the penguin.
- – While the the duplicate is still selected, open up the CHANNEL BOX and select/highlight all the attributes that are greyed/locked out.
- – RMB > Select Unlock Selected.
- – Group the items: CTRL + g
- – Move the new group next to the character.
- – Rename the new group to smile.
- – Duplicate the duplicate and name it the following:
  - sad;
  - browUp;
  - browDown;
- Note: It is good to duplicate the other objects like the eyes, to use them for reference when you model the blend shapes. Never modify the objects other than the one intended for deformation.
- – Select the penguins original body.
- – CHANNEL BOX || select the skinCluster node;
- – Set CHANNEL BOX || skinCluster > Envelope to 1;
Sculpt the Smile Shape
- Use the Artisan to paint and deform the smile geometry.
- – Select the smile geometry
- – POLYGONS || Mesh > Sculpt Geometry Tool > □
- Note: In the previous example, you were painting using the normals of the surface. Normals meaning the surface direction of the object. So in the exercise, pulling and pushing based on the surface’s outward direction. When painting the expressions for each duplicate, you’ll set your Reference Vector to y-axis. This will pull the vectors up.
- – Paint on the models to get a shape similar to the following expressions:
- – Change Brush Size: HOLD “b” + (LMB left or right);
- – Reverse Direction of Brush stroke: HOLD CTRL;
- – Switch to Smooth Brush: HOLD SHFT;

Blend Shape Deformer

Use a Blend Shape Deformer that will blend between your original shape and the duplicate you modified. Blend shape deformers are useful for animating facial expressions in 3D.

Creating a Deformer
- – Select the objects in this order by holding SHFT;
  - smile, sad, browUp, browDown, original penguin.
  - Note: It is important to select the original object last.
- – ANIMATION || Create Deformers > Blend Shape > □
  - Blend Shape Options:
  - – Origin: Local;
  - – Advance (tab) > Deformation Order: Front of Chain;
  - (Front of Chain Option; tells maya that the blend shape deformer is to be inserted before any other deformers, such as the skinCluster.)
  - – [CREATE];
Testing the Deformer
- – Select the original body;
- – In the CHANNEL BOX, you should see a blendShape1 node.
- – Highlight the blendShape1;
- Notice: The attributes are the same names as your duplicate layers like smile, sad, browUp, browDown. In the image it’s labeled as Weight[1], Weight[2], Weight[3]
- – Highlight the smile attribute.
- – MMB + DRAG on the stage to change the value of the attribute.
- – Experiment modifying more than one attribute to see it’s effect.
Tweaking the Blend Shape
- Since the construction history still links to the blend shape with the deformed surface, you can tweak the sculpted geometry as needed.
Delete Targets
- – Select all the duplicated groups used to create blendShapes.
- – Press DELETE
- Note: When you delete the blend shape targets, Maya keeps the blend values instead of referencing the blend shapes. It is important not to delete the history on the model unless you want to get rid of the blend Shapes.

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