**UPDATE III: Oct 15th: Got an email from a Weta employee (who is very serious about their NDA btw) who very clearly pointed out that they do not use Giant's services for any of their in-house stuff like LOTRs or KING KONG (one would imagine this continuing for THE HOBBIT) unless they are collaborating with Giant outside of New Zealand. Giant provides them with software updates so that they can continue to do this on NZ for themselves. In fact if you go here and scroll down to "Post Production Diary - 31 Weeks To Go" (King Kong), you can view their mocap system (which is now their old one) in action, with Giant software running the system for the motion captured body. Obviously a lot of collaboration taking place.
**UPDATE II: Oct 10th: Got a reply from my source. Again - this is ONLY TO CLARIFY, not start/expand a rift. He insists that while Weta does have a mocap department, the software they use is Giant's. And he is quite certain that you cannot "purchase" that software, but must use Giant's services team that happens to come with the technology. The "headrigs" are another matter entirely though - not Giant's tech. So in the end, Weta does do their own mocap (100% end to end) for facials, but for full body work, the technology and service team is predominantly Giant. Not to say that Weta is not collaborating with them! They are. And together is where the magic is. From what the world has seen, there is no need to change anything - you make damn good products.
**SAME DAY UPDATE - *sigh* Could it be that I have hammered out a post too quickly again all in the same week? Yep. I trusted a source that I had who definitely seemed to know what he is talking about, but obviously who is VERY wrong. RETRACTION: WETA was and is responsible for working with mocap LOTRs and KING KONG. The only research that was done on those couple of statements in the opening paragraphs about WETA was simply from one of my sources that has not let me down before. We now he has. Regardless, the true nature of what I wanted to get across with this post was not inflamatory, but rather of collaboration. FAIL. So, in an effort to polish this the way it is intended for the new readers coming to view: Weta and Giant work together as a team to produce their work. There is a lot of magic there obviously. The aim for the post is to introduce readers to Giant, not alienate WETA. Damn poor week for me. Oh and I WOULD HAVE fact checked with WETA themselves if they would ever return my emails. But they don't. One too many exclusive inside sources contacting me I guess. Frankly, I don't give a shit about the PR people for WETA. I do love their technical work though, and thus this retraction.
Jim here. I thought I would clear up a lot of misconception of who is doing most of the big time motion capture work for the studios, and it is NOT Peter Jackson's WETA.
Meet Giant Studios. Giant are specialists in motion capture and boy are they focused. In fact, they are the folks responsible for the major motion capture scenes for IRON MAN, THE HULK, PIRATES OF THE CARIBBEAN, I AM LEGEND, PRINCE CASPIAN and THE MUMMY. And more recently, they are working on James Cameron's AVATAR and the Spielberg / Jackson trilogy TINTIN.
Furthermore, Giant are the ones who did the motion capture work for the LOTRs trilogy and KING KONG - many believe that WETA was responsible for that work. Yes WETA is a large VFX house and are damn good at what they do - effects. But they have not done mocap and have always called on Giant to do so.
There work has evolved and has taken us on a cinematic journey that just keeps getting better. For example, they have built a 70 by 36 foot grid-marked space (or Volume) for performance capture (same as motion capture but also captures the actor's facial performances) on AVATAR. Lightstorm and Giant further augment the larger, truss based, near infrared lighting system of the Volume with a single camera solution that they call "Headrigs" for capturing facial performances.
There are other players. A case in point is Imagemovers. From Post Magazine: "Imagemovers Digital's mocap stage, which was built for A Christmas Carol, also uses near infrared lighting, but had a separate truss system built for wirework so the mocap cameras wouldn't be effected by truss movement. Instead of upping the camera count, they relied on 100 cameras, using the HMCs for facial motion capture.
As it stands, in the world of mocap there is always a tug of war between increased accuracy and realtime performance. The greater the resolution and number of cameras, the more points can be captured with greater the accuracy of the points and the reduced incidents of occlusion. Unfortunately, this comes at the cost of realtime preview. The flexibility of shooting anywhere, especially outside of a soundstage or volume restricts the normal flexibility of 3D motion capture in that it often solves only the mocap from certain perspectives, which is fine when you are mixing with a traditional camera since its perspective is determined at the time of recording.
As processing gets faster and the tools, which combine multiple technologies, are developed, we can expect higher resolution while still providing realtime playback. There will also be a larger number of tools, and a larger pool of talent. The systems will be more flexible, quicker to set up, provide more accurate data, and provide more integrated workflows."
So as you can deduce, Cameron is going for better storytelling and then amping up the photo-realism in post production. I firmly believe this is the best tact to take with today's technology but as reported by POST, eventual higher resolutions in real time will serve to enhance the director's real time look at what he is shooting and speed up post production - saving money.
With experts in their field like Giant Studios, Hollywood is truly empowered to go places they have never dreamed possible before. How lucky are we to have the best minds in the business for both directing and for delivering the direction. 2009 can't come soon enough!
The photo on the left with the two horses and human being "mocapped" is from the performance capture volume of Cameron's AVATAR - Take a look at the first ever, super high resolution image of the AVATAR set here.
Here is an interesting thought: Who owns the rights to the actor's performances and the subsequent data that has been generated from it? Can a studio re-purpose that data at a later date on an entirely different project? Or is it the actor who has the right to assign where this data goes? How will you be able to trace the performance's origins if it has been "Image Metric'ified"?
Seeing this shirt brings up a question - how is facial capture being handled on Avatar? As we reported back in August, Image Metrics has some kind of working relationship with the Avatar team, as demonstrated by the following quote from Jon Landau, which, up until recently, was featured under "What Our Clients Say" on the Image Metrics website:
What, then, to make of all the dots on this t-shirt, when Image Metrics' claim to fame is their system's ability to capture facial movements without the use of dots and markers? 
