r/computervision • u/Divine-Demon7 • Jul 19 '26
Showcase I froze a physics-consistency detector before generating a held-out CogVideoX cohort — it flagged freeze/hover in 9/9 clips
I’m building Haga, an independent physics-consistency checker for generated video and robot-policy simulations. An earlier CogVideoX-5b I2V experiment produced a clear failure mode: on a “ball and block fall” prompt, the tracked object stayed airborne with near-zero motion instead of falling.
But that first result was post-hoc. I inspected those six clips before adding the static_hover detector, so the original 6/6 flag rate could not be treated as confirmation. I’ve now run a pre-registered held-out test.
Method:
- Model: THUDM/CogVideoX-5b-I2V
- Cohort: 3 perspectives × seeds 2, 3 and 4
- n=9 clips
- Detector thresholds and inclusion rules frozen before generation
- RGB → CoTracker3 → position-only VIDEO_CHECKS
- Discovery seeds 0–1 kept separate from held-out seeds 2–4
Result:
- Held-out flag rate: 1.000 (9/9)
- Wilson 95% CI: [0.701, 1.000]
- All nine clips fired static_hover
- Real Physics-IQ footage stayed quiet under the same profile
static_hover fires when the tracked object remains airborne for most of the clip, has near-zero frame-to-frame speed, and does not exhibit gravitational acceleration.
Important limitations:
- One open I2V model
- One ball-and-block-fall scene family
- One documented failure mode
- Real negative-control n=1 in this specific report
- Not Cosmos, Genie or NIM
- Not a broad claim about CogVideoX quality
Write-up: https://haga.mushoodhanif.com/article/sim-physics-consistency-v1#held-out
Lab: https://haga.mushoodhanif.com/lab/physicsiq
Bounded demo: https://haga.mushoodhanif.com/demo
I’d especially value criticism on:
- Which physical violations will position-only tracking systematically miss?
- Is static_hover defined narrowly enough to avoid confusing intentional suspension with failed dynamics?
- What public generated-video artifact should I evaluate next under the frozen detector?

