Building a 3D World in After Effects
COW Library : Adobe After Effects Tutorials : Bill O'Neil : Building a 3D World in After Effects
When a project requires a photo-realistic 3D world, After Effects isn't usually the first program that comes to mind. Typically a 3D modeling/animation program is necessary to create virtual 3D worlds. Since my comprehension in 3D programs is limited, I attempted to push the boundaries of After Effects to create a 3D world for a TV spot I was hired to direct and post for the Big Ten Basketball Conference.
The spot called for hip hop star, Talib Kweli to rap about Big Ten basketball on a "big stage". Originally the agency, Teamworks Media suggested shooting the spot in an arena full of fans with big screens playing the Big Ten's basketball clips. I convinced them that I could create a more interesting world in the computer with more athletic camera moves, less shooting headaches and minimal crowd control. Gulp.
I would shoot Talib Kweli's performance and his DJ separately on green screen as well as a row of fans that I could use to populate the arena.
I have become familiar with the AE 3D world to know its limitations, but I was also thinking about how to work within those limitations to create a believable concert arena.
Before I explain the process, take a look at the spot to see the final result. The only thing real is Talib Kweli, the DJ, and the fans. All the other pieces were created in Photoshop.
For the green screen shoot, I shot Talib lip-syncing to his track from high, low and front angles on a rotating turntable. (We used the Panasonic Varicam capturing at 30fps.) We were even able to fit the DJ and his gear on the rotating platform.
I have discussed this turntable technique in my "Shooting for 3D Post" tutorial. Basically, I like to have the artist slightly rotating so that I can match my 3D camera rotation in post. I didn't rotate the talent for the medium and close-up shots- just the wide shots where we see his feet.
The camera was locked off and in some cases rotated 90 degrees so that the talent fills the frame fully. This allows for some higher resolution scaling opportunities later in AE.
I shot 10 dancers from front, side and back so that I would have some flexibility in populating the audience from any angle. I also had lights panning on and off the actors in a ballyhoo fashion to lend some excitement to the scenes.
There have been enough tutorials and discussion on shooting green screen that I won't go into the process here. Just make sure the green is even and your subject has no spill. Back lighting will help this. I had to do some cleanup on my low angle shot that had seams in the green backing but it was no big deal.
In AE, 3D elements have to be flat layers that can be positioned in 3D space. The stage and set pieces could have no curves. The entire world would have to be constructed with flat art pieces. We had a storyboard artist sketch out a design for the big stage and I used that as a start point.
It was important to the Big Ten Conference to see their Basketball clips behind the artist and from all angles so I positioned big screens in the center of the stage behind Talib and on both sides of the stage in the audience.
I created a master comp for the basketball clips that would be referenced from all 3 screens. This way I could easily swap out footage and have it appear on all screens including the main screen which is actually 4 vertical panels that arch behind the stage.
Most of the set building took place in Photoshop. I started with the main stage which is tiered in two levels. Then I created the face panels, front edges, tall speakers, a truss, a beam, and animated light panels and light beams.
The illustration shows just a few of the set pieces. More pieces and detailing always add to the realism. I designed the main stage to have an overhang into the crowd with support posts. More edges and separation between objects allow for nice depth and parallax when the camera roams past. This principal also applies to the tall speakers which are two parts- the front grill and the cones behind it.
You'll note that all the pieces have shadows built in. I have written a few tutorials on shadows and how they will enhance the realism of a scene. In this concert arena the darkness is helpful in forgiving the unpopulated regions. I shadowed the beams and trusses to fall to black at top and bottom. Light that falls off from the center was all that was needed to sell the illusion.
I kept all the pieces small to save on render times. They only need to be as big as they will appear onscreen which is actually quite small.
I built a balcony with my dancers to flesh out the sides of the arena. I made the railing and back pieces in Photoshop and then in After Effects, I sandwiched the clip of my dancers facing us in between. I layered the clips using different start times so they wouldn't be in sync with each other. Note that I darkened and de-saturated the dancers to match the ambience of the arena.
I multiplied them across the screen so there were several balcony sections. It was too bright by itself so I roamed a few lights across the scene in a ballyhoo fashion so that it mostly falls into darkness. I rendered out about 10 seconds to use as wallpaper for the sides of the arena.
I took all the pieces into After Effects and started building. Assembling this virtual world is no less laborious than constructing a house. Every nail is pounded one at a time. There are no shortcuts aside from copy/pasting some duplicate set pieces. However, all the time spent on constructing the set will pay off immensely when it comes time to fly the camera around.
I started with the main stage piece and built everything on top of that. You will be switching to front, top and side views to get everything in the correct position. Most of the set pieces in this arena are at 90 degree angles on the x and z axes so it's just a matter of getting their relative positions correct. After Effects doesn't have a snap feature that I am aware of so you'll have to nudge the pieces together until there are no visible seams.
Since After Effects works with flat layers, some of the pieces will always have to be facing camera. In my "Shooting for 3D post" tutorial I explained a technique that uses a simple expression and a 3D null object to orient a layer toward the camera on the Y axis. This rotational expression was needed for the talent layers (Talib and the DJ), support posts, stage light beams, and the many crowd layers. The camera needs to be parented to the null object with the point of interest locked at the null object. The null object's location should be the same as the talent's position. When I rotate the null object, the camera will follow as well as all the layers that have the expression. This will make it easier when it comes time to animate.
It was difficult to populate the audience with the 10 dancers shot from front, side and rear. I peppered the front area of the stage with the rear angles of the dancer clips and the sides with front facing. I started them at different points as I did with the balcony section so it didn't look like a repeating pattern. I often had to shift their locations based on the position of the camera so that they wouldn't intersect with each other during the rotation. Most of the crowd would be in darkness thanks to some roving spot lights I animated.
I edited a rough cut to the music using the raw green screen shots. I also had to do a cut of the basketball footage that would appear in the screens.
I used this rough cut to determine my camera positions and motion in my AE 3D world. For all the shots of Talib that didn't show his feet, I left it as a 2D layer in front of the arena. I positioned my camera to match the angle and gave it a slight rotation even when Talib wasn't moving on the turntable.
The wide shots were fun to animate. I love flying the camera around the world at different angles. For the rotation, I had to match the angles of Talib on the turntable. For a 3 second shot I just key-framed my rotational null at the beginning of the shot to move the camera into the first position and then scrolled ahead to the last frame and adjusted the roation to match Talib's position. Since the turntable is moving at a constant speed, your camera motion in the AE world should match perfectly.
With rotation slaved to the null layer, I only animated the camera's x, y and z positions. While moving the camera you have to press the Ctrl key to maintain the point of interest's position at the 3D null layer.
To finish the world, I used Trapcode's Lux to create a couple of volumetric lights that work in 3D space. I could have done this for all the lights in the arena but it would have been a severe render hit. My Photoshop light beams worked just fine for most of the stage.
There are many other pieces I created to flesh out the rest of the world. Most notably, I added fluorescent ceiling lights as well as some light beams facing down.
I should point out that this was the second spot I created for the Big Ten Conference. Take a look at the first spot which has more of a grungy warehouse arena feel. The vintage TV's were shot live on the turntable. The rest of the world was created in Photoshop.
I have created a lot of 3D worlds since the Big Ten spots. You can find more samples on my website. The "Smithe Puppets" spot as well as the "Chicago Home Fitness" spot are green screen elements placed in an After Effects 3D world.
When I have time, I would like to dive into a 3D modeling/animation program but for now, After Effects has allowed me to create some cool 3D environments. Let me know if you have any specific questions about this tutorial. I'm always happy to help and also to see what others have created in After Effects.