How can you use blend shapes and morph targets for expressive character animation?

1 What are blend shapes and morph targets?

Blend shapes and morph targets are essentially the same thing, but with different names depending on the software you use. They are a type of animation technique that involves creating multiple variants of a 3D model, each with a different shape or pose, and then blending them together to create smooth transitions and variations. For example, you can create blend shapes for different facial expressions, such as smiling, frowning, or blinking, and then animate them to create realistic and emotive characters.

2 How do blend shapes and morph targets work?

Blend shapes and morph targets work by using a base mesh and a set of target meshes. The base mesh is the original 3D model that you want to animate, and the target meshes are the modified versions that you want to blend with. Each target mesh has the same topology and vertex count as the base mesh, but with different positions and orientations of the vertices. You can assign a weight or influence value to each target mesh, which determines how much it affects the final shape of the base mesh. By animating these weights over time, you can create complex and dynamic deformations of the base mesh.

3 How can you create blend shapes and morph targets?

There are different ways to create blend shapes and morph targets, depending on the software you use and the level of detail you want. One common method is to use a sculpting tool, such as ZBrush or Mudbox, to create the target meshes from the base mesh. You can use various brushes and tools to sculpt the details and features of the target meshes, such as wrinkles, muscles, or hair. Another method is to use a rigging tool, such as Maya or Blender, to create the target meshes from the base mesh. You can use bones, joints, or controllers to pose and deform the base mesh, and then duplicate it as a target mesh. You can also use a combination of both methods, such as sculpting the fine details and rigging the broad movements.

4 How can you use blend shapes and morph targets for character animation?

Once you have created your blend shapes and morph targets, you can use them to animate your character in various ways. One way is to use keyframes, which are points in time where you set the values of the weights or influences of the target meshes. You can then use interpolation or curves to create smooth transitions between the keyframes. Another way is to use drivers, which are parameters or attributes that control the values of the weights or influences of the target meshes. You can then use expressions, scripts, or constraints to link the drivers to other elements, such as audio, motion capture, or user input. For example, you can use the volume of a voice recording to drive the blend shape of a mouth opening, or use the position of a joystick to drive the blend shape of an eye direction.

5 What are the benefits and challenges of blend shapes and morph targets?

Blend shapes and morph targets have many benefits and challenges for character animation. Flexibility and versatility are some of the advantages, as you can create any shape or pose you want. Additionally, they are fast and efficient, as they do not require complex calculations or simulations to deform the mesh. They are also easy and intuitive, as you can see the results of your changes in real time and adjust them accordingly. However, blend shapes and morph targets can be tedious and time-consuming, as you have to create many target meshes and adjust their weights or influences manually. Furthermore, they can be difficult and complex, as you have to maintain the consistency and quality of the target meshes and their transitions. Finally, they can be limited and unrealistic, as they do not account for physics, collisions, or secondary effects of the deformations.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?