In order to rig the penguins from Caminandes 3, I used the current prototype of BlenRig 5 auto-rigging system. Thanks to its re-targeting feature, I was able to get the first penguin moving pretty easily.
Getting the body moving
The first thing I did, was to bring the BlenRig Armature and BlenRig Mesh Deform cage into the scene.
Note: the final version of the BlenRig addon will do this with a single click.
After that, I set the rig to ''Re-proportion'' mode and moved the controllers to fit the rig into the character's anatomy.
Not only did I adjust the body controllers, but I also set the facial controllers to the correct position.
After the rig was in place I just baked both, the armature and the mesh deform cage, into their new shape with the baking operators.
For those who may not know this, mesh deform, or harmonic coordinates deformation, is a method which uses a low resolution mesh to drive the deformation of another mesh. You can think of it as a kind of customized lattice deformation. By using this technique, you can use a 500 polygons mesh to deform a 15k polygons mesh in a much more organic way than if you used simple armature deformation.
So, the next step was to wrap the mesh deform cage around the penguin model. I just went into Edit Mode and started moving vertices around until the character mesh was inside of the mesh deform cage.
After adding the mesh deform modifier to the model and binding it, the character was already deforming pretty well. Notice that no extra effort was required here, as the mesh deform cage that comes with BlenRig is already weighted and working with the BlenRig armature.
##Getting the face working
After doing some tweaks here and there, I got the body working as we needed and moving like a real penguin. These tweaks included tweaking some IK parameters in the leg bones (as penguins' legs bend the other way around) and adding a bone driven smooth modifier to soften the deformation in certain places.
The idea was to do these rigs as fast as possible, because animation had to start soon. Therefore, there was no time for doing detailed weight painting or shapekeys on the face, instead I tried to automate the process as much as I could.
First, I had to do some technical tweaks to the facial rig, because the beak of the character didn't work well with the humanoid mouth that the rig had. After some small hierarchy changes I was able to start skinning the face.
Note: The idea with the BlenRig project is to initially release it with a humanoid rig, but in time I'll start adding more presets, including quadrupeds, birds and different facial setups.
For weight painting the face I used the automatic bone weights assignment feature. Of course, the result was not perfect, but after some extra painting I got everything working they way I needed.
BlenRig features a bone based facial rig that is intended to behave as organically as possible, therefore, It delivers fully functional expressions out of the box.
Nevertheless, the user can have control over how the face deforms in key positions. This customization functionality is based on some very specific actions, which can be edited to achieve the desired deformation.
In other words, the user can fine tune how the face reacts to certain poses such as the ''U vowel'', mouth widening or eyelid blinking, by moving a grid of control points.
In the case of the penguins I barely had to do any tweaking to these actions, as the default expressions of the rig delivered a really nice result.
Ideally, after you finish editing the facial actions you would need to start creating a bunch of corrective shapekeys, so that the character's skin behaves exactly as you want. Nevertheless, as time was running out I decided to go in a different direction, and I used the ''Corrective Smooth'' modifier to help me out.
In case you don't know what it is, the ''Corrective Smooth'' modifier stabilizes deformation, trying to always keep the model as similar as possible to its original shape. It is a very fast and optimized modifier that won't have a big impact on performance and it will smooth out wrong looking deformations.
The only consideration you must have when using this modifier is that you should use it only in places that don't fold too much, otherwise, you could get some vertices bouncing around if faces collapse too much. Therefore, this comes in handy in areas like the face, in which you know you won't find any joint twisting or rolling over itself.
You can see the difference between the deformation before and after I added the ''Corrective Smooth'' modifier in the images below.
So, that's more or less how the penguins from Caminandes 3 were rigged! You can find the blend files of penguins and the beta version of the BlenRig addon here.
Note that the addon doesn't include rig creation yet and it is intended to be used only with the current character rigs.
Stay tuned for more info about the upcoming release of BlenRig 5 in the Blender Cloud!