Trax Blending, finally the Tech Preview is out

At last, Cory's just posted the Trax Blending tech preview up here, something I've been working with the Maya dev team on for the last 6 months or so.

http://area.autodesk.com/blogs/cory/maya_trax_blending_technology_preview

I might follow this up with a few more examples over the next few weeks. Basically it allows you to properly redirect animation data and complex rigs in the Trax, lining motion up using the ghosts, kind of taken tech from MotionBuilder. We've been testing this on raw MoCap data and Rigged data, only been begging for the guys to do this for 7years! :)  Theres also an automated match function, you select the offset node from the data and hit the match, it'll take the first and last frames from 2 clips and line the general motion up based on those.

Maya Audio Offset in 2012

 In a previous post I mentioned that since Maya2011 they'd changed the way the offset attribute on sound nodes worked:

"So, 2 sets of attrs work together. Offset and EndFrame, SourceStart and SourceEnd. The Offset is no longer what it used to be, this is the start of the clip nothing more. If like us you have tons of sound code designed to offset audio then it's all stuffed! you need to manage both Offset and EndFrame at the same time now in order to shift a sound node along time."

I'd just like to to point out that this looks to have been reverted back to the previous behaviour inb the latest 2012 builds where the offset attribute controls the clip offset as you'd always have expected it to do.

Mark

Hidden Audio functionality in Maya2011

New Audio Handling in Maya2011

I wanted to point out a couple of hidden features for Audio handling that aren't in the docs and that kind of slipped into Maya2011 via the CameraSequencer upgrades. The audio node in Maya used to just have 2 main attrs, path and offset, that was all you could do, point it to a wav and set the start time. If you now look at an audio node in 2011 there's a ton of new attributes to control the behaviour of the audio. Unfortunately most of this is hidden unless you're using the AttributeEditor or CameraSequencer, in which case RMB on a sound you'll get access to Mute, that's about it. In the Trax sound is still just a simple, poorly supported add-on..... or is it?

Firstly there's now a Mute attr, so you can mute out those audio's you don't want, this displays in both Sequencer and Trax, but for Trax you have to set the attr direct.  Now for the more complex stuff. If you're used to editing in Trax you're used to sliding the start and end times, trimming the clip etc. There's no UI support for Sound for any of this, BUT you can still do it via the attr's directly.

So, 2 sets of attrs work together. Offset and EndFrame, SourceStart and SourceEnd. The Offset is no longer what it used to be, this is the start of the clip nothing more. If like us you have tons of sound code designed to offset audio then it's all stuffed! you need to manage both Offset and EndFrame at the same time now in order to shift a sound node along time.

However, using the Source attrs you can now trim the audio, directly in Maya..... there's not a lot been mentioned about this and we only found it by accident.

 The 2 sound nodes here are the same bit of audio, but the lower has been offset to start at frm 120, because the source start has also been moved to frm120 the audio is still in sync with the original one, just trimmed to start later on. The end source has been moved in, trimming the audio to stop earlier. You can also add silence to the start of the sound if needed.

Thought I'd share that as it's actually going to be really useful, think I'll push for the UI  integration from Autodesk so that the sound node is treated like the clips are, about to be trimmed directly rather than having to set the attrs up manually.

Mark

Trax, Character Sets and Referencing

Whilst this stuff is fresh in my mind I wanted to put it down, more for my reference but who knows, it may be useful to others.

How Does Referencing work with Character Sets?
As per previous posts, referencing is nothing more than an import of data from one scene into your current, followed by an edit list applied afterwards. The thing is that the refEdits are all based on full Dag node paths, so if you change the name of a node in the master file, or reparent it, your referencing for that edit fails. Namespaces go some way to eliviate clash issues but other than that, it's all name based. In fact, you really need to think of Maya's scene hieracrhy not as a nested scene graph, but as a flat, dag name based database.

So How Do CharacterSets help?
Unlike normal referencing, all connections to objects that are members of a CharacterSet are based NOT on name, but on the membership index of that set. This means that as long as you carefully maintain the internal order of the chSet, you can rename and regroup at will, the connections for your animations will be maintained.

A Little Deaper:
The CharacterSet in Maya is actually mapped in a totally different way internally to that which the users sees. Rather than using names to pass animations to channels it uses characterMapping and characterAlias's. It's actually split down into 3 main internal arrays,

• Map 0 : unitlessValues : animCurveTU - attrs like user defined and scales
  
• Map 1 : linearValues : animCurveTL - transform data
  
• Map 2 : angularValues : animCurveTA- rotational data
  

in your Master Rig file (.ma) that contains the characterSet you see a block that looks something like this:

setAttr ".rm" -type "characterMapping" 206 "RIG:Shoulders_Ctr.SpineBias"
0 1 "RIG:Shoulders_Ctr.rotateZ" 2 1 "RIG:Shoulders_Ctr.rotateY"
2 2 "RIG:Shoulders_Ctr.rotateX" 2 3 "RIG:Shoulders_Ctr.translateZ"
1 1 "RIG:Shoulders_Ctr.translateY" 1 2 "RIG:Shoulders_Ctr.translateX"
1 3 "RIG:Hips_Ctr.rotateZ" 2 4 "RIG:Hips_Ctr.rotateY"

Here the characterSet has 206 members (channels), "RIG:Shoulders_Ctr.SpineBias 0 1" indictates that this is a unitlessValue (Map 0) and it's unitlessValue[1]. "RIG:Hips_Ctr.rotateZ" 2 4 indicates it's an angularValue (Map 2) and angularValue[4].... and so on....

The channels within the ChSet are mapped to these arrays in the order they're found within the ChSet, but going from bottom to top. It's this mapping thats then used to reConnect channels and animCurves when you load or reference the scene.
In the referenceEdits you'll see the connections from animCurves to these lists, which will give you an idea of just how the data is mapped internally on a real scene.

The key thing here is that because it's all based on order, should you switch your reference to a rig whos chSet mapping is different the whole thing falls apart. Say you had a refEdit :

connectAttr animCurveTL4545 LinearValue[4] 

that connected the translateX of the Wrist to it's animCurve, this edit would still just blindly go and remake this connection, even though LinearValue[4] may now be a completely different object. Now in Maya2011 they try and resolve this issue in a post load script that runs after file load, but's it's better to know about than rely on it.

So the key is, maintain the chSets, order is king.

Maya Animation Layers

I've just spend the last few days moaning at the Animation Layer setups and how poor the merge functionality is in Maya. We had a cutscene here that was 4000frms of baked MoCap, 3 animLayers, which took 40 minutes to merge on a 64bit beast of a machine. I can't understand why Autodesk are running the standard Bake command when it's so slow over large timelines.

Answer, by-pass it and use Trax. Ended up writing a function that would take all the nodes in each layer and generate a clip with the animData in it. So for the above case we end up with 3 clips. Now the Trax merge is FAST. The results meant that the same bake process going via this method went from 40 minutes, to 20 secs :)

And people diss Trax! It may be a little excentric, and lacking in features, but at least it's fast and clean.