File duration versus distance between keys
Counting frames and counting intervals answer different questions. Inclusive output from A through B contains B − A + 1 images. Range 1–96 contains 96 images and lasts four seconds at 24 fps. The distance between keys 1 and 97 is 97 − 1 = 96 intervals. That distance distributes the 360° change.
The linear curve is angle(f) = 360 × (f − 1) / 96 degrees. Thus frame 1=0°, 25=90°, 49=180°, 73=270° and 96=356.25°. Frame 97 returns to frame 1’s spatial orientation. The native file was reopened to check midpoint and endpoint transform matrices; the MP4 contains 96 frames at 24 fps. These checks establish temporal structure, while aesthetic evaluation still requires watching the sequence.
Why “0 and 360 are equivalent” is insufficient
The values represent the same orientation but different interpolation information. Two keys both at 0° describe no linear turn. Continuous Euler values at 0° and 360° define this example’s revolution. Other rotation modes, constraints or conversions may choose different paths; do not change rotation type without reassessing the curve.
Constant angular velocity does not mean constant velocity for every pixel. A side feature moves toward and away from the viewer, and its projection travels differently across the screen. This still occurs with orthographic projection because geometry rotates. The intent is constant rotation in space, not every detail moving across the screen along a straight line.
Adjust rhythm while preserving the seam
For an “arrive, stop, leave” action, Bézier and its handles can control acceleration. For a continuous rotating display, Linear avoids automatic deceleration each cycle. Other smoothly periodic curves are possible, but velocities at the seam must agree; matching position alone does not ensure continuous motion.
To double duration to eight seconds, use 192 images and a closing key at 193. That halves angular speed while retaining one turn. For two turns in four seconds, keeping 96 images and using 720° doubles speed, which may be harder to read. Render a small preview and choose for the purpose rather than the larger number.
If the loop seems to flicker, inspect animated materials/lights, frame-to-frame noise and encoding. If it pauses, check interpolation and duplicate frames. If it jumps, check range, sequence order and the match between last and first steps. This diagnosis combines mathematics, file structure and visual observation.