Measuring the dose on the sample batch

Measure what Seedance delivered against what you wrote, per kind of move, from the sample takes you made anyway.

On the sample batch (decided), at no credit cost. The sample batch is the first batch of a film: one sample shot per scene, made as two 480p drafts (see Planning, budgets and takes → The generation rhythm). For each kind of move (push, arc, truck, handheld) you note what was delivered against what was written, and the drift on named locks. Speaking shots' pushes are measured the same way. The same reading works on the window of any take you review (see Video with Seedance → Take selection and review).

How to measure (the tool steps are in Do it yourself below):

1. Restate the written dose in frame terms. A push as a scale factor: a face that grows by a fifth is 1.2. A pan as a share of the frame width. A roll in degrees.

2. Track the window you will use (the stretch of the take that goes into the edit) with a motion tracker, on two detailed features at the same depth, and read its values every half second. The scale is the push or zoom, the sideways position against the frame width is the pan, and the rotation is the roll.

3. Without a tracker, measure one feature in pixels on frames taken every half second: a face's width, a doorframe's height. The ratio between two frames is the scale; the feature's sideways shift against the frame width is the pan. A tracker that draws the move as curves shows a stall or a drift by the curve's shape; take your figures from tracked values or the frames.

4. Compare. A face meant to grow by a fifth (1.2) that grows by a tenth (1.1) got half its dose. A pan meant to cross half the frame that crosses a sixth got a third.

5. On a named lock, read the largest drift from the first frame. Any visible push-in or zoom on a lock fails at camera level; the drift figure itself is not a pass mark.

6. On a truck, arc or crane, track two points separately, position only: one on the near layer and one on the far layer. If both move by the same amount, the background is a flat card.

7. Inside a move, a curve that goes flat for half a second or more is a stall. Check whether the camera still moves in the last half second when the plan's cut is in motion.

8. Plain areas can't be tracked: a seamless backdrop, open sky, a smooth wall. Judge those stretches by eye.

What the figure is for. It is this project's measured floor: how much of each kind of written move arrived. You decide whether to write bigger. It is never a pass mark, and never a new default on its own.

Do it yourself

Track the move (After Effects)

1. Open the Tracker panel, choose Track Motion and tick Position, Rotation and Scale; this gives two track points.

2. Place both on detailed features at the same depth and track.

3. Add a null object (Layer → New → Null Object), choose it under Edit Target, and click Apply.

4. Read the null's values every half second: Scale is the push or zoom (120% is 1.2), Position against the frame width is the pan, Rotation is the roll.

5. For the parallax check on a truck, arc or crane, run two separate tracks, position only: one on the near layer and one on the far layer.

Export frames every 0.5 s (ffmpeg and an image viewer)

1. Export a frame every half second, or use any editor's still export:

ffmpeg -i take.mp4 -vf fps=2 f_%03d.png

1. Open two frames in an image viewer and measure the same feature in pixels on each.

Read the curves for a stall or a drift (DaVinci Resolve)

1. Use the free tracker on the Color page: it draws pan, tilt, zoom and rotation as curves.

2. Read the curve's shape to spot a stall or a drift, and take your figures from After Effects or the frame exports.

Sources

• Higgsfield's katana workflow (the remix figure this measurement replaces with your own).