[Bf-committers] re: Animation Baking Take II -- response to Ton's questions

Roland Hess me at harkyman.com
Sun May 6 16:57:01 CEST 2007

I'll take a shot at answering your questions. Also, I'll see if I can 
get slikdigit to comment/chime in...
> It still confuses me though... the wiki text mixes up end-user  
> expectations and implementation ideas too much. You might separate that  
> more (ignore implementation ideas altogether?).
Right -- that's a brainstorming wiki page there, and could easily be 
divided. It's a "first draft" for comments and modification.
> The wording also confuses me... "key framed motion", what is that? I  
> guess you mean the object Ipo, and not Shape keys? What is a path +  
> speed-ipo, "key framed motion" too? Or what is a lattice with hooks?
By "key framed motion" I mean motion that is generated by directly 
setting Translation keys on objects or bones in the 3D view, which, 
while not the only method or animation is certainly the most commonly 
used when animating hero or foreground characters. Most of this proposal 
is targeted at enhancing hero character animation.

> Another issue I need to know is "why". What do you require baking for,  
> and which situations really? That is crucial information for being able  
> to implement and design features well.
> It is well possible you use this baking feature to solve weak parts of  
> Blender animation design? In that case we better solve other design  
> issues.
The main point of baking animation is for flexibility and work flow. The 
best example is this, a hypothetical project involving some nice 
character animation.

1. Block out gross character motions by keyframing (LocRot) proxies.
2. Swap a character skeleton for the proxy so you can do the character anim.

Up until now, everything is as the normal way you approach a project, 
but the user would like to have the character walk around and do a few 
things in between.

3. Offset bone walkcycling works well only with curves, so to use it, 
you have to bake LocRot keyed motion into a curve.
4. Now, you have a walkcycle using Offset Bone in NLA, with a wave, and 
then the character stopping and stooping to pick something up, added as 
NLA strips. Also, you would like to vary certain aspects of the walk 
along the length of the path, like exact foot positioning, etc.
5. There's no good way to accomplish this, now. But, if you can bake, 
you bake the entire NLA into a single Action.
6. This lets you approach the final round of animation sweetening a step 
at a time -- you're working on a single Action that is the accumulation 
of all the other animation.

You've saved a ton of time, because you used Offset Bone and curves to 
generate the basic walk animation, but were able to tweak it on a 
step-by-step basis afterward, also finely adjusting the transitions 
between the walking and stooping.

One of the comments slikdigit made to me about using NLA is that it's 
not super-useful for "hero-quality" animation because of that. You can't 
finely adjust the output in an intuitive way.

Now, if there were a new blending type for NLA, one that would let you 
add such tweaks as a new live Action, that would be great, but I'm not 
sure of the feasability of such a thing. Like you said, it would require 
a rethink of the entire system.

In short, baking allows you to use Blender's animation tools as 
"construction" tools -- steps on the road to a final, fully tweakable 
high-quality animation. Right now, they are frozen at their point of 
output, and you can take their results no further.
> Lastly, the proposal doesn't mention animation systems (dozens of  
> related objects). How to "bake" that, and again whatfor precisely?
I don't know that you'd want to bake entire systems of objects. Although 
you could, it wouldn't be that useful, as far as I can tell. This stuff 
is needed for character animation, mostly.
> In my idea, we need a really thorough design session once on the  
> Blender (character) animation system. It has severe weak parts that  
> block me from adding improvements or new features. I also lost the big  
> picture or design direction here... :)
Without a doubt, it does need to be thought over. But I'd be willing to 
bet that people are currently changing the scope and/or shots in their 
projects because "this" or "that" is simply too time consuming to 
accomplish. Allowing more flexibitily in the character animation via 
conversion and baking would help that.

Roland Hess -- harkyman


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