Recording Actor's Performance
Recommended layout of an action video
- Enter the actor.
- Strike a T-pose.
It is preferable to have actor strike a “T-pose” before the actual action. The software will need T-pose for building actor appearance model during tracking. If you make several takes of one actor you do not need to re-record T-pose before each take.
When using the depth sensors, it is recommended to face the palms down, as it corresponds to the default orientation of the model's hand bones. When using color cameras, it is recommended to face the palms forward, as it helps the software in determining the right color for the model's hands.
Take is a concept originating from cinematography. In a nutshell, take is a single continuous recorded performance.
Usually it is a good idea to record multiple takes of the same motion, because a lot of things can go wrong for purely artistic reasons.
A common problem with motion capture is “clipping” in resulting 3D character animation. For example, arms entering the body of animated computer-generated character. Many CG characters have various items and attachments like a bullet-proof vest, a fantasy armor or a helmet. It can be easy for an actor to forget about the shape of the CG model.
For this reason, you may need to schedule more than one motion capture session for the same motions. Recommended approach is:
- Record the videos
- Process the videos in iPi Mocap Studio
- Import your target character into iPi Mocap Studio and review the resulting animation
- Give feedback to the actor
- Schedule another motion capture session if needed
Ian Chisholm's hints on motion capture
Ian Chisholm is a machinima director and actor and the creator of critically acclaimed Clear Skies machinima series. Below are some hints from his motion capture guide based on his experience with motion capture for Clear Skies III.
Three handy hints for acting out mocap:
- Don’t weave and bob around like you’re in a normal conversation – it looks terrible when finally onscreen. You need to be fairly (but not completely) static when acting.
- If you are recording several lines in one go, make sure you have lead in and lead out between each one, i.e. stand still! Otherwise, the motions blend into each other and it’s hard to pick a start and end point for each take.
- Stand a bit like a gorilla – have your arms out from your sides:
Well, obviously not quite that much. But anyway, if you don’t, you’ll find the arms clip slightly into the models and they look daft.
If you have a lot of capture to do, you need to strike a balance between short and long recordings. Aim for 30 seconds to 2 minutes. Too long is a pain to work on later due to the fiddlyness of setting up takes, and too short means you are forever setting up T-poses.
Because motion capture is not a perfect art, and neither is acting, it’s best to perform multiple takes. I found that three was the best amount for most motion capture. Take less if it’s a basic move, take more if it’s complex and needs to be more accurate. It will make life easier for you in the processing stage if you signal the break between takes – I did this by reaching out one arm and holding up fingers to show which take it was.
As it’s the same actor looking exactly the same each and every time, and there is no sound, and the capture is in lowres 320*200, you really need to name the files very clearly so that you later know which act, scene, character, and line(s) the capture is for.
My naming convention was based on act, scene, character, page number of the scene, line number, and take number. You end up with something unpleasant to read like A3S1_JR_P2_L41_t3 but it’s essential when you’ve got 1500 actions to record.