• CGSociety :: Production Focus
    7 April 2011, by Renee Dunlop

     

    At $30 million for an entire film, there was nothing limitless about the budget for Limitless. LOOK's VFX Supervisor Daniel Schrecker, 3D Artist and Generalist Shawn Lipowski, and compositor Daniel Molina had to use their entire brains to portray how lead character Eddie Morra used his.

    Director Neil Burger presented a hyperworld of speed, perception and creativity. "Neil had all these ideas about how as the addiction to the drug grows, they start to feel some of the side effects and their reality starts to fracture," said Schrecker. "It's all playing with the way Eddie sees the world when he is on the drug."
     
    Dan Schrecker.
    Shawn Lipowski.
    Dan Molina.


    Burger felt using the visuals of an infinite zoom would help show how Eddie's character would process information at an accelerated speed. Based on references like the White Stripe videos for Seven Nation Army, he envisioned a fractal type image that never lost resolution.

    To accomplish this, VFX Supervisor Schrecker worked with the cameraman and came up with a rig using three Red cameras with different lenses. Shot at 4K instead of the usual 2K, using a tripod and starting at the Metropolitan Museum of Art and traveling across town to Harlem, "we shot the same thing, wider, tighter, tightest and embedded those in each other so you had an image where you could zoom into the center and the resolution didn't fall apart because you were going into the next lens."


    "The reason for the three plates was to have enough coverage and not have to make extensive matte paintings to fill in holes. The director wanted the separate plates to appear as a seamless infinite zoom but at the same time have the option to make the camera speed ramp up and down in order to sell the hyperactivity lead character Eddie Morra (played by Bradley Cooper) was experiencing.

    "We controlled the speed of this infinite zoom just by scaling the image."



    Daniel Molina was in charge of compositing the plates together into a coherent camera zoom with one scene fitting seamlessly into the next. “In order to get rid of the obvious rectangle shape of the plate we would mask out sections of the wide view and keep only what we needed. This would allow us to omit any scaling up to the nested pre-comped plates.



    Molina chose After Affects to utilize the tool Continuous Rasterization which allows the image to be scaled up or down but keep the full 4K resolution of the image, "which is what we needed to do for this to work. That way when the smaller images were scaled to 0.001, obviously very small ?like a pixel small? up to 100, it would keep the resolution and still appear untouched.

    " However, there were still technical bugs in wrangling the motion to be a constant linear flow without unwanted changes in speed. By using the After Effects Exponential Scaling tool, Molina was able to layer the images together at a steady rate.

    The next issue was how to assemble all the images in line to appear like one seamless zoom. As an example, a zoom would start as a generic New York street scene with a camera move that heads towards a distant billboard.
    Once the billboard becomes full frame another scene nested inside the billboard image picks up the camera move towards a new focus, and the process is continued. Getting the scene to zoom forwards without unwanted artifacts required the edges to be warped and feathered to line up properly, and the inevitable varying focuses required a good amount of grunt work to correct.

    And though the alignment was usually close, small offsets caused problems as they propagated through the sequence. Anything moving in the shot would cause parallax issues.

    Cars or people sometimes had to be roto'd out from one plate and inserted into the next plate(s) or holes had to be cut through previous plates so those elements showed through in order to continue the elements' movement across the screen and not simply appear or disappear at random.



    Because of how these zoom shots were strung together from a series of plates, and each plate in the zoom depended on the details in plate before, a modification to one plate would propagate changes throughout the stack of plates and the entire post-production process would have to be repeated to accommodate those changes. "Sometimes this would be done from scratch, which is why we would try to get the timing first and then go back and fix all the other stuff. Once we got the timing, it was just a lot of fixing seams, fixing roto, adding stuff."



    The infinite mirror shot was a combination of five shots as Eddie transforms from the 'down on his luck' writer to the image of success.

    All five plates were shot using motion control then were slap-comped in Avid before they were handed to Molina for the final steps. "The reference I got consisted of 20 plates, the intro plate of him walking, six salon shots, six workouts, six wardrobe plates and the last one of him at his desk." Molina used Nuke to take advantage of it's built-in camera tracker and 3D capabilities. "I had to implement pretty much every type of technique to get it done. We had six months or so to pull it off and I used pretty much all six months to complete it."


    Molina began by recreating the references, then keyed and garbage matted out the three center scenes, placing them on to image cards and lined them up using Nuke's 3D system.

    He recreated the camera move flying from the first camera push through the center cards and easing into the last push in. Gaps at the edge of the image cards were filled in with set extensions. "One of the main technical problems was that these plates were shot on a motion control rig.
    The further I spaced out the cards, the more I had to fill in [with set extensions]. They kept asking to space the cards further apart so you could read his reflection better, but at the same time, have the camera move past him at a fast pace. I had to set up a rig that would give me the 4K card with the set filled in, but also another 8K card that would fill in any extra dead space in order to fill in any wiggle room due to the spacing changes."

    Molina worked on the roto, Photoshopped matte paintings and textures, camera tracked, stabilized plates, fixed any edging issues, added a soft defocus and hazed out the back image cards. The salon and gym were complete recreations minus the actors.



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    3D Artist/Generalist Shawn Lipowski, the same artist who did the wing work on Black Swan, also helped Eddie to crack the stock market. Lipowski was the tracking artist, 3D artist, and compositor.

    Burger was looking for an effect like a split-flap display, the old style information board still seen in some train stations.
    The process required "a surprising amount of Nuke work just because I had to do the 2D animation first and then feed that to 3D. There were probably ways I could have done it in Maya but I could see it as a 2D sequence so I did it in Nuke and just let the expressions read the images sequence and drive the tiles.

    I just thought that was a little bit simpler and gave me more control for the expanding rows flipping effect."



    The first issue was lens distortion since the shot used a very round lens, not quite fish-eye but round enough to cause a lot of distortion. Also working with 4K plates, Lipowski removed the distortion using Nukes' lens distortion tool, then tracked it in boujou, took the 3D track to Maya and began building out the room.

    The ceiling was entirely replaced with polygonal modeling. "I built the ceiling based on the undistorted plate, rendered it undistorted then when I brought it back into Nuke I reintroduced that barrel distortion.

    "Everything lined up really nicely. No textures or lighting were projected from the original plate, it was all with Maya lights, HDR for reflections, and Final Gather and mental ray for global illumination.
    The motion used Maya expressions that were driven by a 2D animation that Lipowski set up in Nuke. "I had a 20 by 22 grid and the various rows of the grid had gradients. Some would go from black to white from left or right, and sometimes would start in the middle. I brought that into Maya and the expressions would read into the image sequence that I generated in Nuke with all the gradients.

    When the tiles would pass 50% grey the expressions would flip that tile with a random delay, sometimes eight frames or so, with ease-in and ease-out." All the texturing was done in Photoshop, there were no projections, just a lot of painting and grunge maps. There was a baked ambient occlusion pass to get some of the edges of the tiles to pop, and a texture for the wood boards behind the ceiling tiles.





    As the drug works its magic on Eddie's mind, he conquers his first big obstacle, finishing his novel. Furiously working at his laptop as letters, words, and finally entire phrases fall around him. Burger gave a list of phrases, such as "The power to achieve"; "A dream of perfectibility"; "Eventful centuries rapidly succeeding" and "We are particles in our own whole," one Lipowski made sure to add since the whole rig is driven by particles. The falling letters were also 4K scans.

    Burger wanted the letters to interact with the environment so Lipowski built simple occlusion geometry for the entire room and geometry for the ceiling to use as the emission geometry. The falling letters were instanced from the alphabet to particles, but phrases became more complicated.




    For example, if you were to just instance a word to a particle, then that whole word is not going to collide. The word "perfectibility" is rather long, and if it falls on the desk some of those letters might graze past and continue towards the floor. "You want it to wrap around objects and be interactive. If you were to instance a word to a single particle you wouldn't get that interaction. Wherever the particle stops the whole word stops." Again the solution was expressions and Python comman

    Each frame of the animation rig has an emission rate. There is a controller with a keyed emission rate because the number of falling letters, words and phrases increases throughout the scene. The script, based on the emission rate, randomly selects a phrase from the list and will pick a random polygon on the emission geometry, and within that triangle it will select a random point. Depending on how long the word is and how it's going to do the kerning, it figures out where the first particle needs to be to center the phrase.

    Using the phrase "The power to achieve" it will start by offsetting to the left and find the position of the first particle which in this case will represent the letter "T". It will set up various particle attributes when it emits the "T" then will continue to the "h". The letters include random vertical offsets so when they leave the emitter they fell more like rope or string.
    The letters that are lower have less mass and the ones that are higher have more. The final product used Nuke for compositing, was rendered in mental ray, using Final Gather, a couple passes for shadows, an ambient occlusion contact pass, a cast shadow pass, depth pass, glow pass, and lighting was set up based on the light and lamps in the room. The shot was in flux to the end, facing constant style changes, finally ended up being 350 frames by the time Lipowski completed.

    When I asked Lipowski if he has been sneaking some of Eddie's drug to help keep up with the demands of his schedule, he laughed and said no but admitted "my two drugs of choice are caffeine and cortisol, the stress hormone." Stress LOOKs pretty good on these guys.







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