If you’re an Autodesk Maya user, and have never dabbled with its “AnimationLayer” features, the next few paragraphs might help point out their uses.

If you’re not an Autodesk Maya user I strongly recommend you don’t read this –I can only imagine how tedious this must sound to you all.  Honestly, move on – get a coffee, sleep –anything else, just go.

Right, they’re all gone so I’ll continue…

This is based on cobbled together findings so far and the Maya Help, so by all means yellif you spot a mistake or have improvements/suggestions/freshly baked cake.

Maya Animation Layers…

…what are they?
Ways to organise (or ‘organize’, if you’re into that) your animation,specifically your keys.

…why bother?

• You want to see what a change might look liketo your animation – and then decide to keep it, or ditch the whole change, andstrop-off about how much time you’ve wasted, and tell yourself you’ll nevermake anything of this anyway.
• Or you want to add the finer tweaks to an existing animation without having towork out “What did I add that keyfor?”
• Or to try alternative takes/versions of an animation, without having to savemultiple scenes for each, losing track of which version does what.
• Or to re-do part of your animation, without removing the original just in case.

…where do I find Animation Layers?
The Layer Editor lives in the bottom half of the Channel Box, we’re after the thirdtab along (called “Anim”) – it’s the same location that you’ll find the Displayand Render Layers living in peace together.

…so what do I do?
Let’s say you’ve already got a lovely animation, a rocket taking off vertically,and now we want to make it turn as it takes off.  All the existing keys are perfect, but theycan lead to confusion when adding finer touches.  Or maybe we’re not allowed to change them, orwe’re just wondering “…what if I changed it…”.

Well you could:

• Select the rocket control
• In the Layer Editor, switch to the “Anim” tab, then hit the last icon in therow of 4 (the diamond with the circle, “Create Layer from Selected”).  Similar to how you’d create a new Display orRender Layer for an object.
• That’s all there is to it.

You’ve now got:
The lovely rocket animation you’ve done so far living in the BaseAnimation layer that shows up in thelist, and we’ve also a lovely empty new layer (named along the lines of AnimLayer1) to get cracking on/for ourchanges.

If you click on the BaseAnimationlayer (you’ll get the green icon to show it’s selected), and those existing keysare available as usual in the Graph Editor/Time Slider etc.  

Now select the new AnimLayer1 layer, to see….well, nothing.  But what you can now do is add keys whilethis new layer is selected, and the animation you’ll get playing back will bethe two sets of keys/two animations combined. Adding keys to the layer as and when you want.

Want the rocket to turn once it’s up?  Just add rotation keys to this new layer. Want to see how it’d look if it sped up abit, add keys in AnimLayer1 applying a little to the take-off and tweak/amend away, knowing that whatyou had to start with is still safe in the BaseAnimationlayer.

So, by default for Animation Layers, what you get on playback will be the
animation/keys from all the layers being added for each attribute, at each point in time.

What if I wanted the rocket to not just take off vertically, but get so farthen crash?  It’s OK – it’s not mannedand they stopped sending monkeys up ages ago.

Do the same as above (select the control and create an Animation Layerfor it), but right-click on the new empty AnimLayer1and under Layer Mode switch to “Override” (rather than “Additive”).  
Now, key away with the layer and do yourrocket crash animation.  What you’ll getplaying back this time is just the crash, not the original take-off, and not the twoanimations combined.  Reason being, asthe name implies, keys on an Override layer override all others.
Using Override layers you can now decide which version you prefer, the original take-offor the crash, since both animations exist on different layers.  You can obviously apply this to any timespan, doing alternative versions for as much or little of your scene as youwant.

Hopefully the above gives an inkling of whatAnimation Layers in Maya are, and how they might help you out at some point.  The “Maya Help” is stuffed with the finer points, butsome key bits I’ve picked up so far would be:

• Mute and solo – icons against each layer, allowing you to switch each layer on/off, picking/choosing what you see on playback.
• Adding objects to/removing objects from layers – done much the same as Displayand Render Layers.
• Layer Weight – the two main types of Animation Layer (explained above) areAdditive (applying animation ‘in addition’ to other layers) and Override (applyanimation ‘instead of’ other layers).  Aweight can also be applied to each layer, to control the degree of impact they have onthe final result.
• Layer sequence – is important, especially for override layers (where thetop-down priority means the top-most layer gets priority).
• Splitting attributes/channels across layers – you can pick/choose which attributesare assigned to which layers (so you could have a layer with only Translate Xon, for example).
• Naming layers – same as Display/Render layers – double tap the name to changethem.
• Grouping layers – you can parent Animation Layers up in the same way as youwould in the Outliner (middle-drag), to help with organising. Nothing stops you having a parent layer that’san Override type and it’s children are all Additive.
• Merging layers – to merge animation/keys from different layers, select/shift-selectthe layers, and right click/look for the Merge options. Alternatively use the Bake Animation option.
• Layer types/attributes – right click on a layer to see/change it’s options.

Final bit on Rotation and Scale across multiple Animation Layers:

Should you end up with Rotation and/or Scalekeys spread across multiple layers they’re handled in a default way, with analternative for each….

Scale Accumulation
Say you’ve an animation where an object is scaled to grow to 1.5x its start size – andyou add a new layer to do the same again to see how it looks.
By default, the cube will end up 2.25x it’s start size, not the 3x which youmay expect.
Reason being, since Multiply is the default setting for Scale Accumluation, you’re getting 1.5 x 1.5 =2.25

Rotation Accumulation
Rotation is, by default, at a “By Component level”:
If you’ve an object with rotation applied to it in more than onelayer, the default setting is to sum therotational values you have for the X, Y and Z attributes individually to get thefinal rotation that you see.  Thealternative setting (“By Layer”) appears to (from experiments so far!) take the resultant object from the top-most layer, and applythe rotation specified in the next layer to that.

Right-click on a layer to access the above Accumulation settings.

In real-world terms I’m not sure what/where you’d need to amend these, but ifyou do have unexpected rotate or scale results, and have values across multipleAnimation Layers, then this may be worth looking into further.

And finally…
I’ve had Maya occasionally lag and/or crash when I’m down to having just the BaseAnimation layer.  You can’t do a right-click and pick Delete as you can for other layers, but you can enter Delete BaseAnimation; as a MEL command to remove it.  Keys wont be removed, but so far it has stopped the lags/crashes.

Like I say yell if feel the above is madness or you can add toit.

Cheers,
Lee

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