King Arthur and his Bytes of the Round Table

A 13TB storage epic

Exclusive Does anyone still say "The camera never lies?" Well, maybe it doesn't - but the film projector certainly does, which is why London post-production house Cinesite needed 14TB of top-of-the-line storage from Network Appliance for its work on King Arthur, the latest Hollywood historical epic.

It's fascinating to see the sort of digital effects that companies such as Cinesite can now do. One of the film's highpoints is a battle on a frozen lake, though as the photos below show, this was really filmed in a dry valley, with the grassy banks being digitally subtracted and replaced.

There was a snag though: Arthur's dark hair blended too well with the hillside, so it too got subtracted. The hair therefore had to be re-shot subsequently and digitally added back in, alongside the icy cliffs:

Before and after: digital wizardry from Cinesite

Digital video means that the film industry now consumes storage at a rate that even the largest business might find daunting, and it keeps on growing as directors demand bigger and better effects.

"As the cost of workstations and render-farms has come down, the goalposts have moved - they get more for their money," says Peter Robertshaw, Cinesite's technical services manager. "We realised last year that the game had changed, and that where we had 40 artists we'd need 120."

The problem was the back-end, he says, and was actually two different problems: "The 2D artists require lots of different files quickly, whereas the 3D artists need lots of similar files repetitively, such as surface textures."

The Linux and SGI servers used in the past simply couldn't keep up, so after exploring a number of options Robertshaw chose a NetApp FAS940 fileserver, along with a Netcache DNFS, also from NetApp, to handle the 3D images.

"We scan the 2D frames at up to 6k or more, but usually 2k [2000 pixels across] which takes 12.5MB per frame. Then we record the finished digital intermediates back out to film - it took nine days writing to two recorders to produce the 35mm film stock."

There are 24 frames per second so each minute of 2k-scanned film is 18GB, and the data cannot be compressed because compression usually means some video information is lost. Then there are all the extra 2D and 3D elements to add, such as digital paintings for the backgrounds and textures for the CGI'd surfaces.

"We've got about 13TB of data associated with King Arthur, not including local copies on the workstations, and we reckon we've done about 25 minutes of footage," he says.

"We also did a similar number of shots for Harry Potter, hundreds for Troy, and others for Around the World in 80 Days and Alien vs Predator. All that data has to go somewhere - currently it goes to DTF2 tape but that will change soon, probably to SuperAIT or LTO2."

He adds that the NetApp kit has quadrupled throughput and reduced latency. The artists say that 3D rendering still takes too long, but Robertshaw says that at least the storage is no longer the main bottleneck.

A particular benefit of the FAS940 was that it could be upgraded without downtime - Cinesite started out with 4TB but quickly realised it needed much more. "That would be terrifying with a different filesystem, such as Linux," Robertshaw says.

But what you really want to know is whether the film's any good, yes? On the plus side, some of the cinematography is excellent, the battle scenes are stirring, and the CGI is cutting edge and mostly superb. OK, so the young Lancelot can't act, but fortunately the older version is Ioan Gruffudd, who can - most of the eye-candy here is male, by the way.

What will annoy some is that, having got some of the history right - the Roman politics, say, and Arthur and his knights as Romano-British cavalry fighting the Saxon invaders - they got so much dreadfully wrong. Fifth century Saxons with crossbows? I think not. Those same Saxons attacking Hadrian's Wall? Ahem.

Add to all that a confused script that merely leads us from one set-piece to another, with little rationale or character development, and you get a film that is fun in parts, but probably best to borrow on DVD. If you do want to see it in the cinema though, it opens in the UK on Friday 30 July. ®

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