The Challenges of 3D Conversion
By Tony Baldridge
Issue: Volume 37 Issue 5: (Sep/Oct 2014)

The Challenges of 3D Conversion

While stereo 3D movies were making a comeback in 2005, the initial going was slow. The 3D industry didn't really officially begin until the release of Avatar in December 2009.  Since that time, the industry has grown exponentially. Today, there are tens of thousands of 3D theaters around the world, and a vast majority of the highest-grossing films in 2013 were 3D. Of those movies, the majority were converted from 2D to 3D, rather than captured natively with dual camera rigs.

What is so special about conversion? It's a more precise way to create 3D, and it's the most efficient way to handle VFX-heavy films. In a 3D conversion, every pixel in the film is considered a visual effect. 

There have been many challenges and lessons learned since the industry's inception in 2009. In this article, we'll take a close look at today's 3D industry, while dissecting 3D conversion hurdles and ways to overcome the inherent obstacles.

At Legend3D (L3D), we received our early training under the fire of production with some of the best stereographic talent in Hollywood. Corey Turner, previously from Sony Pictures Imageworks and now at Paramount, gave us our first opportunity to test the stereo conversion waters in 2009 on Alice in Wonderland and then another more rigorous project with Transformers: Dark of the Moon. 

Legend3d has converted a number of films to stereo 3d, including Life of pi and hugo.

Alongside Turner was Rob Engle, mentoring us on such films as Pirates of the Caribbean: On Stranger Tides and the Smurfs franchise, to name a few. Working with Phil McNally, formerly at DreamWorks, gave us all the volumes of experience needed when we were contracted to convert three Shrek films back-to-back in eight months. McNally's book, 3D Storytelling, is mandatory reading for each of our stereographers and is still heavily referenced today.

Turner, Engle, McNally, and other skilled stereographers who came along after them, contributed to the mentorship of our creative team, demanded the best, and expected us to deliver. Stereoscopic knowledge alone is not sufficient to achieve the best in 3D; it also takes a considerable amount of experience and practical training.

Truths and Misconceptions

At an International 3D Society Awards ceremony last year, Avatar Producer John Landau preached, "No more subtle 3D, guys; we need to wow audiences." The challenge was to continually create a 3D experience that envelops viewers and leaves them awestruck.

Realistic 3D is sometimes synonymous with native 3D, which, in my opinion, is false.  Realistic 3D is playing it safe -most of the time, too safe, and runs the risk of producing a non-immersive experience for an audience. Stereoscopic lenses used to shoot a scene -whether real lenses, as in native capture, or virtual lenses, as in conversion - will yield its own feel of depth and volume. The separation between those lenses typically offers a range of disparity within which a stereographer can design. However, that range of disparity should never constrain a stereographer.  

The concept of "realistic 3D" isn't exclusive to native capture, but also pertains to conversion, where the same "safe" rules are often imposed. In the early days, several films were poorly orchestrated and converted too fast, with little love, and the damage still plagues the 3D film industry. 

One lingering misconception is there are shots that are impossible to convert, and, consequently, the conversion process is inferior to native capture. Bear in mind that both native capture and conversion are nothing more than visual illusions. Whether it's native capture or conversion, knowledge, experience, and talent are essential ingredients in the creation of high-quality stereo experiences.

Over time, conversion as a means to synthesize 3D has redeemed itself and has demonstrated success with proper resources and time. Neither native stereo capture nor conversion is exempt from the realistic 3D pitfall, just as both methods can create spectacular, immersive 3D. 

Although it has been challenging to change the perception of 3D conversion, the hard work hasn't gone unnoticed. Most conversion vendors have taken their quality of work up a few notches and have renewed confidence in filmmakers and audiences. More and more clients understand that native and conversion can blend beautifully and enhance a film with top-quality 3D. And, more and more films are being told with stereo 3D, without being gimmicky. Old ideas, like "realistic is flat," are going out the window, and audiences are getting what they pay for in this genre.  

Proper Tech/Talent Blend

Technology is the backbone of the conversion industry. With that comes the talent that embraces it and moves it forward. All conversion vendors are faced with the task of building software and workflows that can provide them with the edge needed to execute the highest quality projects in a time-efficient and cost-effective manner.

Tentpole feature films will always push the conversion envelope in every way.

Landing a job is often decided by filmmakers and studios, and the only way to win those contracts is to have both the technological advancements and talent necessary to successfully execute the work. Maintaining a technical and creative edge by constantly staying ahead of the competitive curve remains one of the biggest challenges in conversion.

From a purely technological perspective, working from the GPU is very common now, but wasn't not too long ago. The very first drop of Legend3D's proprietary conversion software was built leveraging the GPU, where nearly all the math was crunched. While it's not fun coding within a GPU environment, it allows for innovation that makes working through shots and rendering them very fast. By necessity, conversion software has become more robust so it can deal with more complicated visual effects and, recently, handle larger formats (4k, 6k). This has made the complexity of coding within the GPU more daunting. 

Tentpole films will always push the conversion envelope. Handling many VFX layers efficiently without slowing down the artist or stunting the creative process becomes a perpetual challenge. Such challenges can put a vendor out of business if a company remains technologically stagnant.

Real-time, Interactive Depth Grading

Currently, there is an arms race to give directors a DI-like depth-grading experience, much like the final touches in a color-grading session. Instead of tuning the color, there is a desire to tune depth in real time exactly the way they want it. 

For a hefty price tag, there are systems available that allow clients to achieve a limited amount of control over the stereo output. The systems allow filmmakers to reconverge and add floating windows, but they don't offer much more. To truly dial in shots, the most demanding filmmakers will require a deeper level of control. They will want to adjust the volume of a character's head and extend the nose out half a pixel, while pulling the background in, so the overall shot's parallax sits comfortably in 2.5 percent.

This level of control and type of session is what conversion vendors are racing to provide -some vendors are close, and some are already there. 

Converting films to 3D is very labor-intensive. It literally requires small armies of artists working frame by frame, often specializing in one aspect or another, such as rotoscoping, clean plate generation, inpainting, stereo painting, depth design, and so on. There was a time when doing this type of work locally (in the US) was feasible, and we saw many Hollywood job opportunities flourish in 3D conversion. But, times are changing (and have been for quite a while now).

All bets are off when entering a bidding war with vendors outside the US. Tax incentives in various international locations have changed the playing field considerably, and the only resolution has been to join them or find competent talent in countries such as India and China, where labor costs are far less than in the US.

When the world is the client's playground, international production pipelines become a necessity for survival. Achieving efficient production logistics around the world is one of many challenges that have to be mastered to compete in today's competitive conversion playing field.

Although conversion had a rocky start, the art of stereo synthesis has come a long way. Today, both filmmakers and conversion vendors have expanded their 3D knowledge, experience, and confidence in conversion to drive the stereo renaissance forward and deliver the highest form of 3D. Conversion technology - particularly in production management, image processing, the handling of complex VFX and real-time DI-type depth grading -has advanced the art to a new level. Ultimately, conversion is another tool in the creative toolbox designed to serve the story and the director's vision.

Like any evolving industry, especially those driven by technology and talent, 3D conversion has its challenges. But, they are surmountable with good teachers, commitment to R&D and innovation, and a cost-effective pipeline that integrates international talent and next-generation technology.

Tony Baldridge joined Legend3D in 2003 and was instrumental in the evolution of the company's proprietary software, holding inventorship on several Legend3D patents. As a stereoscopic visual effects supervisor, he has steered the helm on many blockbuster conversion titles, such as Transformers: Dark of the Moon, Life of Pi, Top Gun 3D, Alice in Wonderland, Ghost Rider: Spirit of Vengeance, Enchanted Kingdom, The Smurfs 2, and others.