02 Shooting the plate¶
Status: Established practice. Most problems later in the pipeline start here, and are cheaper to fix on set than in post.
Phone or camera settings¶
| Setting | Use | Why |
|---|---|---|
| Frame rate | Fixed 24 or 25 fps (30 if the platform needs it) | Phones default to variable frame rate, which breaks tracking and sync |
| Shutter | About 1/100 s at 24–25 fps, faster for action | Less motion blur gives cleaner mattes and more trackable frames |
| Exposure, focus, white balance | All locked | Auto changes flicker the key and confuse the tracker |
| Stabilisation | Off for tracked shots | Digital stabilisation warps the image, so the solve won't match |
| Lens | One lens, no zoom during the take | A changing focal length is much harder to solve |
| HDR, night mode, beauty filters | Off | They change frame to frame |
| Codec | Highest bitrate the device allows, ProRes or 10-bit HEVC if available | Compression blocks ruin hair edges |
On phones, a manual camera app (for example the free Blackmagic Camera app on iOS and Android) gives you these locks.
Run probe on every clip as soon as it comes off the device. It warns about variable frame rate and rotation flags.
Screen and lighting¶
- Light the screen and the performer separately. Even light on the screen; the performer lit to match the virtual set's key direction.
- Distance. Keep the performer 2–3 m in front of the screen to cut green spill on costumes and hair.
- Colour. Green suits most costumes. Use blue for green costumes, wigs or props.
- Rim light behind the performer helps separate hair and lace from the background.
- No screen? AI matting (doc 03) works on ordinary backgrounds, but a plain, uncluttered wall still gives cleaner edges.
Make it trackable¶
- Put tracking markers (tape crosses, 10–20 cm apart) on the screen and floor, away from the performer's outline.
- Shoot with parallax: a slight move left or right or forward. A camera that only pans on a tripod can't be solved in 3D; that needs a nodal solve.
- Avoid fast whip pans on phones. Rolling shutter skews the frame.
Shoot extra¶
| Extra | Why |
|---|---|
| Clean plate: 3–5 s of the empty set, same camera move if possible | Prop removal, matte repair, light reference |
| Grey ball and colour chart in frame for a second | Match light direction and colour in Unreal |
| Measure one real distance (floor marker to marker) | Sets the scale of the camera solve |
| Phone gyro/IMU log if your app records it | A fallback when the visual solve fails |
Shot sheet (one per shot)¶
Shot: S03 "ultimate" cut-in
Character: [owned or licensed by: ______ ]
Performer: [name] consent form: [yes] under 18: [no / guardian form]
Moment: turn to camera, raise weapon, freeze 4 frames, flash
Duration: 4 s
Camera: handheld push-in 50 cm, eye height, 24 fps, 1/100, ISO locked
Screen / BG: green, markers on floor
Virtual set: [scene name], key light from camera left
Extras: clean plate, grey ball, distance A–B = 2.00 m