Just before the holiday break I was pulled off of a very cool project (temporarily) to supervise a commercial for "Call of Duty." At the time I was pulled off I was knee deep in modeling and texturing Optimus Prime for the latest trailer for Transformers: Fall of Cybertron. I was bummed to get pulled off of Transformers, but I knew I'd be coming back to it later. The Call of Duty spot was really cool though so it worked out that I got to be on both projects. :)
When Call of Duty ended I went immediately back onto Transformers right as lighting was about to begin. Some lighting had be started by the show's CG sup but I was asked to help develop the look of all the shots on the "lower level" where Megatron first appears through to the end of the trailer. I started with the first shot of Megatron as he stands above an autobot he has just destroyed. This was an important shot and it would help to set the look of the following shots on the lower level of the environment. These characters were particularly difficult to light. For the most part the models themselves did not have small bevels on their sharp edges (although some of the hero characters did). Because of that it was hard to get highlights and shapes to read. It was also a bit difficult in that everything in the scene was reflective metal with a lot of flat surfaces. It took some experimentation and I also went back into the original published textures for Megatron and reworked them to bring a little more diffuse back into his metal shaders so that we would see a little more direction to the lighting. We ended up with a nice balance between lighting with diffuse light and also with reflections.
The hardest shot I worked on was the 360 degree spin around Bruticus as all his parts come together and transform into the complete character. The environment used in other shots was not designed for this shot. Which meant this shot needed to have a completely custom environment built for it. Originally, I started off by taking a bunch of the existing environments parts and duplicating and positioning them around a central platform that Bruticus is on. The shot was over 1000 frames long and done in super slo motion because we were applying a bunch of speed ramps in the edit. So i was rendering every 50th frame at first just to get some feedback for how the environment was coming together. My first attempt was ok, but the environment was just too vast and open. So I went back in and started moving all the buildings and pieces closer to the center so that everything was much more closed in and we were seeing up to these large building tops instead of to just the sky. The environment was fairly easy to light, but felt like I was lighting 4 shots in one because it had to look good from every angle. When it came to lighting Bruticus though, things got really complicated. Unfortunately, Bruticus's model really needed more work done to it, but there just wasn't time. So his character was missing all the micro bevels that would help catch highlights. To start we picked some key moments of his animation and decided we wanted to use the lighting to help show off these key poses. So as the camera spins around I placed buildings that were going to be exploding as well as lights that would rim light Bruticus when then went off. This was good for interactive lighting, but he also needed a base light rig that would look good from all angles as well. So to keep him rim lit I started by creating a light rig that would spin exactly opposite to the cameras motion so that he was always rim lit. This worked ok, but because it was constant it felt like a cheat. It just never changed at all. So I came up with a different trick that felt more natural and interesting (even though it was also a cheat). What I did was place some large area lights in roughly the places where the environment was brightest. Then I put a sphere around Bruticus that had him completely enclosed inside, but the area lights were outside of it. I then linked this spheres rotation to exactly match the camera's rotation. Then I deleted the faces of the sphere that the camera could see. What this ended up doing was hiding all the area lights from being able to light the front faces of Bruticus, but as we spun around it would reveal those lights only when they would be rim lighting him. This trick worked nicely because the large area lights were slowly revealed and would appear to get brighter and dimmer as the sphere rotated revealing and then concealing them.
I have to give much respect to our compositors who really knocked it out of the park on this project in a very short amount of time. They did a fantastic job of integrating all of our cg lighting with real smoke and fire elements, adding lens effects and overall just balancing out all the lighting and FX to make the shots look as real as they do.