Today I was reading an article in Cinefex magazine on The force Awakens, and found some impressive details regarding the way they handled the lightsabers, which was different from any of the previous films. The whole article is great, as Cinefex articles generally tend to be, but here are some interesting quotes about the lightsabers in particular.
- "We made blades out of acetal. That is a very tough material, like solid nylon, that we managed to bore out to a 36-inch length. We then built a special core that held 3,000 LEDs, and programmed each LED to a board inside the lightsaber handle, where we also hid the batteries. Everything was radio controlled. When we wanted the blade to switch on, the lights illuminated progressively up the blade, the way a lightsaber behaves, and we also programmed LEDs to pulse We installed a motion sensor so when the blade hit an object, it sensed vibration through the handle and flashed the lights to white. You couldn't have done any of that ten years ago because LED technology has progressed, thanks to the mobile phone industry" - Manufacturing Supervisor James Enright
- "On Episode III, we cheated on-set lighting to create lightsaber interactions. The trouble was, the interactive light was never emanating from the saber. This time, we discussed with cinematographer Dan Mindel how we could more effectively create interactive lightsaber effects. We did tests using LED lights, and the prop department built features into props that allowed us to change the value of the light depending on how quickly the blades were moving. We could remotely control their color temperature, and when the lightsabers clashed, they even flashed." - Visual Effects Supervisor Roger Guyett
- "We took lightsaber effects to the next level. It was so much more sophisticated than the roto shapes and glows in the earlier films. Both sabers were matchmoved, lit, and textured 3D objects with a huge amount of effects passes and 2.5D setups inside the composites." - Compositing Supervisor Jay Cooper
So not only did the use hugely complex radio-controlled LED props, to create authentic interactive lighting on the set, ILM then tracked the blades, replaced them with 3D blade effects, and then added shimmers, sparks, and steam as they interacted with weather and the environment. Fascinating, eh?