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pem · 8th August 2008, 06:30

Hey Tez,

It's a long time since you posted but I thought I'd just pipe up with a few tips.

I've been working on a figure rig in Carrara and discovered a few things:

- a reverse foot rig for the feet is possible, just follow the usual instructions for setting up a reverse foot. I got my instructions from a book, 3D Character setup and looking online.

- mixed IK and FK on an arm rig is possible but there is no blending. IK can be toggled on and off in the modifiers box and you can even stack IK targets, switching from one to the other (first one in the list has priority if both are active) but the switching is always an all or none affair.

- With IK off you can use FK on a chain but keep in mind that the moment in the timeline where you turn IK back on, the chain will jump to the position calculated by the IK. The way around this is to create keyframes for all the bone positions and rotations in the chain and not just the IK target position and rotation at the beginning and end time after setting the start and end positions with IK.

- Although the IK solution figures out position and rotation of the objects in the chain, it does not propogate rotation up the chain: for example, if you have a chain of 3 bones and each can rotate 90 degrees, rotating the IK target 270 degrees will NOT rotate each bone 90 degrees. The end bone will simply stop rotating at 90 and the next bone higher up will not rotate. You can probably get around this using something like Cognito but havent' tried it yet.

- As you have discovered, once you add constraints to a chain, all the rotations are done via constraint values and not actual bone/object rotation values. Worse yet, constraint values are not adjustable via the graph editor.

I am working on an arm rig where I duplicate all the arm bones using target helper objects (THOs) and set all the bones to track the rotations of THOs. This way I can use the graph editor with the rotations of the target helper objects. The trick is to not move them and to not use constraints on the THOs. Something like Driven could be useful but there isn't a version for C6. Cognito can be used, but it requires setting up a duplicate rig controlled by Cognito and then setting all the bones to track the duplicate rig. I've proved it can be done but haven't done it on a proper character rig yet. I figure cognito could be useful for controlling the arm.

As you can see, better rigging tools or at least some basic scripting/linking tools where you can get one object to control another are necessary for better character animation in Carrara. At least, either constraint values have to be editable in the graph editor or a chain with constraints on it uses an object's rotation for position of the objects in the chain and constraints are only used for checking when an object goes out of bounds.

8th August 2008, 06:30	#6 (permalink)
pem Vertex Join Date: Jul 2005 Posts: 29	Hey Tez, It's a long time since you posted but I thought I'd just pipe up with a few tips. I've been working on a figure rig in Carrara and discovered a few things: - a reverse foot rig for the feet is possible, just follow the usual instructions for setting up a reverse foot. I got my instructions from a book, 3D Character setup and looking online. - mixed IK and FK on an arm rig is possible but there is no blending. IK can be toggled on and off in the modifiers box and you can even stack IK targets, switching from one to the other (first one in the list has priority if both are active) but the switching is always an all or none affair. - With IK off you can use FK on a chain but keep in mind that the moment in the timeline where you turn IK back on, the chain will jump to the position calculated by the IK. The way around this is to create keyframes for all the bone positions and rotations in the chain and not just the IK target position and rotation at the beginning and end time after setting the start and end positions with IK. - Although the IK solution figures out position and rotation of the objects in the chain, it does not propogate rotation up the chain: for example, if you have a chain of 3 bones and each can rotate 90 degrees, rotating the IK target 270 degrees will NOT rotate each bone 90 degrees. The end bone will simply stop rotating at 90 and the next bone higher up will not rotate. You can probably get around this using something like Cognito but havent' tried it yet. - As you have discovered, once you add constraints to a chain, all the rotations are done via constraint values and not actual bone/object rotation values. Worse yet, constraint values are not adjustable via the graph editor. I am working on an arm rig where I duplicate all the arm bones using target helper objects (THOs) and set all the bones to track the rotations of THOs. This way I can use the graph editor with the rotations of the target helper objects. The trick is to not move them and to not use constraints on the THOs. Something like Driven could be useful but there isn't a version for C6. Cognito can be used, but it requires setting up a duplicate rig controlled by Cognito and then setting all the bones to track the duplicate rig. I've proved it can be done but haven't done it on a proper character rig yet. I figure cognito could be useful for controlling the arm. As you can see, better rigging tools or at least some basic scripting/linking tools where you can get one object to control another are necessary for better character animation in Carrara. At least, either constraint values have to be editable in the graph editor or a chain with constraints on it uses an object's rotation for position of the objects in the chain and constraints are only used for checking when an object goes out of bounds.