IKinema’s popular IK solver is back with a fresh name and a smattering of new features. Gary Marshall gets in on the Action
PRICE: £890 Upgrade
PLATFORM: Windows / Mac / Linux
MAIN FEATURES:
DEVELOPER: IKinema
Having reviewed the first version of IKinema back when it was the debutante at the solvers’ ball (Reviews, 3D World 142), it’s refreshing to have seen the plug-in gain widespread adoption and generally make a good name for itself.
For those unaware of the previous release, IKinema offered Maya users a package of animation tools based upon a revolutionary IK solver. Distilled from research into control armatures, the key selling points were the ability to quickly set up characters for animation with a few clicks in a tidy interface.
New stretchy IK capabilities added to IKinema Action 2 for Maya mean things like tails and tentacles are simple to rig and animate
Physical properties such as momentum and centre of mass could be dialled in for realism and, best of all, it didn’t assume that the user had major technical rigging expertise.
Once up and running, the results were pleasing for an offering at a modest price point. Since those early days the tool has been reworked and reborn under its new Action moniker, but is there more punch for your pennies under the hood?
The fundamentals remain largely the same for setup – an instance of the solver is created at the root of the hierarchy in question and IKinema populates each segment with its attributes. Upon completion, a user would simply add tasks (constraints) at key solving points on the skeleton then manipulate these tasks, either directly or through control objects.
A teach frame the solver does its best to create the most believable pose while satisfying said tasks.
Tasks are tuneable in a multitude of ways, like specifying how far back up the chain its influence should extend or how much weight the solver should bias towards it. Each segment (joint) also has dynamic properties to tweak, with transform limits being the most used feature.
Creation is a little quicker now if you’re setting up multiple solvers in one hierarchy – for example, one for the body and another two for each hand. Previously this required un-parenting each chain, creating the solver and then re-parenting, whereas now simply [Shift]-selecting joints excludes them from that particular solver instance.
Retargetting feels slicker in this release, with more tools to deal with characters or differing proportions
While superficially these processes all feel unchanged, there’s a key difference to note. When testing the original version, a frustration came to light – the solver characteristics were based on a non-deterministic model, which meant that a pose at any given frame was solved based on the previous pose in a kind of layered accumulation.
This was all well and good unless you made mistakes during setting up your tasks, or scrubbed the timeline forward to see your tasks in action and decided to change something – simply hitting [Ctrl]+[Z] for a crafty undo wouldn’t do the trick.
Instead, you were likely to see your rig suddenly jump to an awkward pose having gained an amalgamated rotation from somewhere, a gripe noted in my original review.
Now there’s a neat little checkbox on the Global Solver instance – Continuously Solving. Unticking this forces the solver to provide a deterministic solution, so poses are always built based on knowledge of the initial bind pose. In the real world this means you get the same result for the entire range of your motion no matter if you scrub, playback or undo. Even if you forget, unticking the box snaps the pose into the non-continuous state and you’re free to carry on working, sanity intact.
When it’s time to finally bake your motion, the ‘continuous’ solve provides the most fluid-looking motion as an end result. This is a huge change and adds great value to the tool, while also proving that some developers really do listen to the concerns of their end-users!
As IKinema gained industry momentum, it quickly became clear that there was potential in the area of marker solving. At Framestore, we saw the opportunity to bring mocap solving into Maya – and to retire MotionBuilder’s notoriously ‘droopy shouldered’ offering. In the original version this was not possible – at least, not in a practical, production-ready state.
In IKinema Action 2 you’re now offered a solution – position tasks with offsets. The solve-enabled rig is posed within your point cloud, and clusters of markers are linked to joints.
In IKinema Action 2 you can position tasks with offsets. The solve-enabled rig is posed within your point cloud, and clusters of markers are linked to joints.
One slightly tedious element is that you have to link markers one by one and disable solving on individual segments before hookup, but any scripter worth their salt should be able to automate this process with the supplied MEL SDK. The resulting motion is fluid, nuanced and, most importantly, authentic to what was captured on stage.
This workflow is a genuine go-to for high-end character-driven VFX shows – indeed, it seems that IKinema itself is focused more on this particular distinction in the toolset than those that might appeal to keyframers or people wanting to build more traditional rigs.
That said, ‘stretchy’ IK is offered in this release as a tickable attribute on joints. Emulating this with Maya’s standard tools has always been a hassle, first needing a splineIK solver based on a curve, then setting up connections to dynamically scale bones on their twist axis. Here, no additional setup steps are required – you get the stretch attribute for free. Simply ticking it allows your joints to stretch and shrink, with limits respected if you choose to enforce them.
The motion produced for something like a whippy tail, for example, is comparable to an infinitely more complex hand-built setup. Even more interesting is the potential to simulate subtle spine stretch and compression in the marker solve pipeline, adding a further dimension to achievable realism.
On the retargeting side, IKinema claims refinement in the internals of the retargeting engine. While there are no new offerings in how or what can be retargeted, the whole thing feels more polished. In the early version it seemed that good results could only really come from working with hierarchies of identical size and skeletal topology, or risk obvious foot slide and other motion defects.
Now scaling tasks to compensate for proportional differences works much better, while ‘reach’ tools help to maintain your limb contacts – tools that packages such as MotionBuilder have had for some time, and done a good job of.
Future releases might go even further, implementing advanced motion edit tools such as ghosting, time-warping and pose libraries. Finally, backwards compatibility doesn’t appear to be a problem, with a test scene built in version 1.1 loading without issue in version 2.
PROS
CONS
IKinema Action 2 addresses the major drawbacks of the first release and adds new features to keep this plug-in going from strength to strength. While it’s not a one-stop shop for all things animation, it deserves a key place in your pipeline
ABOUT THE AUTHOR
Gary Marshall is senior motion capture TD at Framestore London, and is currently working on Alfonso Cuaron’s Gravity. He’s spent the last seven years working on motion-capture projects around the world for VFX, feature animation and games, from capturing and editing data to writing tools and building pipelines
framestore.com
Posted on Thursday, May 24th, 2012 at 11:49 am under Applications, Reviews. You can subscribe to comments. You can leave a comment, or trackback from your own site.
Tags: 3D review, 3D software, IK solver, ikinema, Ikinema Action 2 for Maya, review
The world's leading magazine for CG artists Subscribe Now
