Sunday, November 2, 2008

Creating Blend Shape for Head

Target shapes for blend shape

According to the story of the animation, no speaking is required for character, and the anatomic structure has not to be carefully considered as the cartoony style. Beside the blend shape, joints and “On face control” are used together in the head rig, so the amount of the target shapes are relatively small then the ordinary characters. The main factors in creating target shape models are the emotion of character and the eye blinking movement. Some tips and tricks for creating target shape models.

Most of the target shapes are the duplicate of the original head then are modified, take notice of the translation of the target shapes, don’t freeze transformation of target shapes, otherwise the head will translate towards to the target shapes during the morphing.

Using deformer to assist at modification the target shapes, such as soft modification tool and cluster with paint weight, which can change the mesh partially and smoothly. Delete history after the modification, but do not freeze transformation.

Using soft modification tool to make target shapes

Using cluster with paint weight for the target shapes

Blend shape deformer is linearly interpolated form one shape into another, which may not fulfill what you need. Thus, add In-Between Target for existing target object shapes. In the case of the eyelid, I used two more shapes for the in-between target. In the add blend shape target options, the target index is quite confusing to users.

You can actually identify the appropriate value for Target Index is by looking at the order of the target sliders in the Blend Shape Editor (Window > Animation Editors > Blend Shape). Target Index value for the left-most target slider would be 1, the next 2, and so on.

The target index of blend shape deformer

The target shapes should be separated for deformation left and right side of head individually; in order to create asymmetrical facial expression. Yet the target shape cannot be mirrored or flipped by negative scaling since the vertex order will be not changed, you may have to remodel the same shape for the other side. Fortunately, there are tons of free Mel scripts to mirroring or flipping the target shape which can be found in the internet, using those free Mel script to save your time.

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