Another aspect of an action you will need to consider is how you’re actually going to capture it. Thinking about this now can help save valuable time during the capture session and minimise the amount of editing work required afterwards. You may not have the answers to all the following questions at this early stage but it is worth beginning to consider it and make a note of any actions that will require further investigation. Also, don’t be afraid to rule out motion capture for actions you feel may be achieved more simply using hand animation.
Hardware – Can the motion capture system capture the action? All motion capture systems have some kind of limitation that can restrict what they can capture, where they can capture it and the quality of the data they produce. If you are unsure of a systems limitations try to arrange a test shoot or discuss the actions with a motion capture company to highlight any potential problems.
Facilities – Does the action require specialist facilities or location? Motion capture stages are generally large empty spaces with a designated performance area surrounded by cameras. Some actions may require the use of a specialist facility or location in order to be performed correctly. This is something you will need to discuss with the motion capture company as their system will need to be portable and capable of capturing at the alternative location.
Space – How much space does the action require? Try to estimate the amount of space required to performa an action, especially if it looks like it is going to cover more than a couple of meters in a single direction (Don’t forget to include vertical as well as horizontal directions). The capture volume is defined by the space in which the motion capture system can detect the movements of the performer. If the amount of space required to perform an action is larger than the space within the capture volume, the system won’t be able to capture it. It may be possible to change the configuration of the capture volume to accommodate different actions, but this can be very time consuming. Another option, which would require careful planning, could involve breaking the action down in to separate takes that fit inside the volume, and then recombining them at the editing stage.
Equipment – Does the action require specialist equipment? Beside the standard props and scenery requirements, an action may also require more specialised equipment for safety or performance reasons. This kind of equipment may have specific requirements in order to be set-up and used, and may also require qualified people to operate it. These kind of actions should be discussed with the motion capture company to ensure their facilities can accommodate the equipment and that it won’t compromise their ability to capture the action.
Abilities – What skills are required to perform the action? Some actions may require specific skills or abilities to perform them, either to the level you want or for safety reasons. Understanding what skills are required to perform the actions will help you hire the right performers and may also require you to cast multiple performers to play the same role.
Proportions – What are the proportional differences between the performer and the character? Ideally the skeletal proportions of the performer and the character they will be playing should be the same. The closer the skeletons match, the better the mocap data will transfer and the less editing the actions will require. If there are any scale differences between the skeletons, these will need to be factored in to the measurements of everything the performer will interact with on set.
Contact – Is contact in the action necessary? Careful planning and understanding of all interactions can help reduce the amount of editing an action will require. Contact with themselves, other performers, props and the environment can all increase the amount of editing an action may require, especially if the performers and character have differing proportions. Actions with very close proximity between performers can also affect a motion capture system’s ability to capture the action; these types of actions will need to be discussed with the motion capture company to make sure they are able to capture them or provide an alternative solution.