Colin (who has written some excellent posts on our blog) brought up an interesting question in the comments of my NAB report regarding storage requirements for 3D workflows. I found my response growing to blog post proportions, so here it is….

3D (stereoscopic) video does not always double the capture data for a couple of reasons, most notably because there are different capture methods, different post-production methods for processing the data, and different ways to project the data, all which can affect the data requirements at different points in the production, post-production, or delivery process.

Data requirements will be double at worst because there are (sometimes) two stereo video tracks, but since the cameras are capturing very similar information, one of the accepted standards for delivery is 2D+Delta compression for the MPEG format. Using this compression the image data is processed with an algorithm that removes redundant pixel data from the two video tracks. The amount of data is equal to one image plus whatever is different in the other image (the Delta). Using this compression, 3D video is usually roughly 40% larger than a single stream of HD video.

Some cameras, like Pace’s Fusion camera (above) which James Cameron used for Avatar, do shoot with two cameras side-by side, thus creating stereo video tracks and double the data for post (plus metadata). In this workflow, the two tracks are used to focus differently on objects in 3D space, dynamically changing the space between the cameras, and effectively using different z-depth focus to achieve the effect. This actually is not a new methodology, but using software algorithms to help determine focal length and automating what previously was manual can bring faster and more repeatable results. Another company, 3ality, is also providing similar functionality with different toolsets, including hardware that retrofits into 2D workflows. Interestingly enough, one of the major differences between them as 3D forerunners is that Pace is only a rentable technology solution, and 3ality cameras can be purchased. Two different positions.

When post is complete, there are some tricks that can be employed to reduce data for delivery including the 2D+Delta for transmission. For viewing the 3D data, there are a few different methods all which require different hardware (projectors, screens and potentially different methods of decoding).  Instead of using two projectors, some 3D can be projected using interleaved frames at a higher frequency through a polarized filter, i.e. one frame for the left eye, followed by one for the right. This is employed by RealD 3D and has by far the widest adoption in US theaters. Further, some theaters are equipped with active glasses technology, meaning that the glasses themselves ‘shutter’ either mechanically or using an LCD shutter linked wirelessly to the projection system for timing. I have heard these glasses are bulkier and heavier but better for certain situations.

3D workflow is particularly interesting to Control Group as an opportunity to help our clients design lean, optimized pipelines. This will impact our data stores, but why double data if it can be avoided? I think this is an opportunity for integrators like us to help productions, as well as the post-house, in evaluating these technologies and coming up with an appropriate blend of supporting technologies and workflows. Our goal is to build workflows that suit the business model and subject matter, as well as figure out how data is managed, archived, and stored. This is not the time to spend unnecessarily, but it is time to consider when and how this will affect our clients, and help them begin readiness preparations. We want to help our clients avoid turning down work because they haven’t put thought into these issues.

In conclusion, there are a variety of methods that a broadcaster or strategic consultant can invoke – some new, some old – to solve the technical issues. I think a lot of real challenges lie in the production of 3D content, such as the creative process of capturing a scene and the framing of the shots to take advantage of the magic of 3D. These are new processes and they involve re-educating producers, directors, cinematographers, camera operators, actors, and production designers.

The technology? No problem.

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