Wednesday, November 28, 2012

Alien Tutorial

I've mentioned the alien tutorial a few times but I haven't actually written properly about it, so I'll do that now.

In order to grasp the techniques involved with modelling, UV mapping, binding, rigging and finally animating a biped model, we spent a number of weeks following a tutorial along with our tutor to create an alien character, with the intention of creating an animated character turntable of him/it in Unity.

Sadly I haven't taken many screenshots during the process, but you can see here that we made a control rig for the body and also one to control basic facial expressions. We've learnt, in more depth, about a wide range of tools in Maya, including the joint tool, weight painting tool, contraints and control/joint hierarchies and making the controls themselves from NURBS shapes and curves.

I've really enjoyed the whole tutorial as I've been keen to learn more about creating characters in more technical detail, as it's possibly the main area of animation I'm interested in.

A few key ideas I've learnt through this that I will take forward into future projects include:

- When modelling, it is vital to pay close attention to the topology and edge flow of the character you're creating. Generally you want your edges to follow the shape of the geometry and show how it will move, and not be all over the place, as it'll be crucial when it comes to animating. You also want to model using exclusively square shapes (in my model there are a few accidental triangles, but as it's very simple it doesn't effect it too much. I will be careful of this on more detailed projects).

This is of particular importance in the face, as illustrated below. Compare the topology around the eyes and mouth:

The "good" edge flow almost mimics the muscle structure of a real face, so that when the character pulls faces the rest of the face will move in a realistic way.

- When building the skeleton using the joint tool, limbs such as the arms and legs should be kept straight and posed far away from each other (like a T-pose). This is so that when it comes to weight painting it's easier to control the influence that a joint has on surrounding joints - if the arms are placed close to the sides, for instance, you will get influence from the arm joints effecting the torso, and a lot of time will be spent making sure there is no influence in these unwanted places. 

- On the arms, an extra joint should be added to the forearm which allows the forearm to rotate slightly when the wrist does, which is more realistic (otherwise the wrist rotates too sharply and can collapse inwards). 

- Set Driven Keys (SDK's) are custom attributes that are added to allow easy manipulation of more in-depth movement without having to move the joints themselves. Generally to create these you:
- Add a custom attribute to the controller of the area (e.g. the hand controller)
- Group the joints that you want effected together in the Outliner
- Edit the group's pivot point to reflect which direction the joints should move
- Open the Set Driven Keys window within the attribute editor
- In the window, load the driver of the attribute (the control), and the joints effecting the driven attribute 
- Set the custom attribute to 0, and place the joints in the position you want, and hit the Key button
- Set the custom attribute to 10, place the joints in the position you want, and hit the Key button.
These attributes are very useful for controlling hands and feet where there might be a lot of joints and intricate movement . 


Here's the final turnaround for my alien, which showcases my model and his walk cycle (I decided for no real reason to give him a swagger), idle animation and jump animation. I wanted to edit them further using the animation graph, but I couldn't figure out which parts to edit - they could all use some further tweaking as the movements look a bit "floaty", but until I get my head around the graph editor, I'll have to leave it as it is.

Unity Web Player | WebPlayer

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