Motion control is the use of robotic camera equipment to create programmable, precise and repeatable camera moves. Many professional motion control service providers use custom rigs, some use commercially produced rigs such and the Milo. Lately, companies such as Bot & Dolly, The Marmalade and Mark Roberts Motion Control have adapted robotic arms normally used in manufacturing.
You can use motion control data as a seed or guide path for your virtual camera solve. The data from motion control rigs is the instructions, not a record of the actual movement. Therefore, the bumps and jitter present in the plate are not present in the data. This means that footage shot with a motion control system must still be tracked. Lightcraft Technology’s Previzion records the actual movement so it’s data has the potential to be more accurate than a rig’s.
Motion control data is primarily distributed as an ASCII table. Each row represents a frame and each column represents an axis of motion. The motion control system should be genlocked with the camera. After importing into a 3D package the motion control data will need to be conformed. The first step is synchronizing with the plate. This is usually done by using a bloop light recorded in the plate. The bloop frame should be noted in your delivered data. The path will then need to be oriented and scaled to match the virtual set. Some motion control systems have tools to assist with this. Some do not. The two most common motion control data formats are Kuper and Flair.
Motion control data can come from the following sources:
- Traditional motion control rig with a crane and dolly
- Motion control head
- Lightcraft Technology’s Previzion and Airtrack
- Lens Data System (LDS)