Cross-Domain Tracker Adaptation Without Target-Domain Labels via Vision-Language Agents
Organizations: Cisco Systems, Inc. San Jose, CA
Abstract
We present a system that uses a Vision-Language Model (VLM) as a diagnostic agent for adapting a detect-to-track pipeline to a new target domain without access to target-domain labels. Rather than optimizing against annotated metrics, the VLM directly inspects rendered tracking outputs, identifies visual failure modes, and recommends parameter updates through an iterative tuning loop. We first demonstrate that ground-truth-supervised hyperparameter transfer can be brittle. On MOT17->MOT20, applying a source-derived oracle configuration reduces mean HOTA by 0.090, from a target-domain ceiling of 0.357, to 0.267. Without using any target-domain labels, our VLM-based tuner recovers 67.8% of this lost headroom, finishing within 0.029 HOTA of the target ceiling; on the highest-density target sequence, it recovers up to 86.7%. We further show that label-free Bayesian optimization with handcrafted proxy objectives struggles under large domain shifts and can degrade configurations that are already strong. In contrast, the VLM tuner acts selectively: when its visual diagnosis reveals no clear failure mode, it declines to modify the configuration, preserving performance on easy transfers while improving hard ones. Finally, we characterize the conditions under which this approach succeeds, namely, when domain shift manifests through exposed detection-level parameters, versus where it is less effective, such as MOT17->DanceTrack, where the source oracle is already near-optimal.
Figures & tables
| Failure mode | Primary parameter response |
|---|---|
| id_switch | match_thresh |
| ghost_tracks | min_hits , spawn_thresh |
| fragmented_tracks | max_lost_age ; then velocity_decay |
| frequent_id_switches | match_thresh , max_lost_age |
| track_drift | adjust velocity_decay |
| Oracle Source | Target | Target Oracle | Oracle xfer | BO-proxy | VLM (ours) |
|---|---|---|---|---|---|
| MOT17 | MOT20 | 0.357 | 0.267 | 0.305 | 0.328 |
| MOT20 | MOT20 | 0.357 | 0.338 | 0.322 | 0.349 |
| DT | MOT20 | 0.357 | 0.312 | 0.305 | 0.326 |
| MOT17 | DT | 0.501 | 0.467 | 0.431 | 0.452 |
| MOT20 | DT | 0.501 | 0.428 | 0.412 | 0.441 |
| DT | DT | 0.501 | 0.460 | 0.402 | 0.477 |
| Source | Condition | 01 | 02 | 03 | 05 | Mean |
|---|---|---|---|---|---|---|
| MOT17 | Oracle transfer | 0.427 | 0.356 | 0.190 | 0.095 | 0.267 |
| MOT20 | Oracle transfer | 0.446 | 0.388 | 0.312 | 0.206 | 0.338 |
| DanceTrack | Oracle transfer | 0.424 | 0.374 | 0.289 | 0.160 | 0.312 |
| MOT17 | VLM from oracle | 0.429 | 0.360 | 0.327 | 0.195 | 0.328 |
| MOT20 | VLM from oracle | 0.446 | 0.393 | 0.312 | 0.247 | 0.349 |
| DanceTrack | VLM from oracle | 0.407 | 0.369 | 0.333 | 0.195 | 0.326 |
| M17 M20 | 01 | 02 | 03 | 05 | Mean |
|---|---|---|---|---|---|
| Oracle xfer | .427 | .356 | .190 | .095 | .267 |
| VLM (m ) | .406 .006 | .346 .006 | .320 .017 | .192 .002 | .316 .005 |
| Condition | 01 | 02 | 03 | 05 | Mean |
|---|---|---|---|---|---|
| Transfer from MOT17 Oracle | 0.427 | 0.356 | 0.190 | 0.095 | 0.267 |
| + Detection agent only | 0.398 | 0.335 | 0.312 | 0.190 | 0.309 |
| + Tracking agent only | 0.402 | 0.346 | 0.230 | 0.131 | 0.277 |
| + Both agents | 0.429 | 0.360 | 0.327 | 0.195 | 0.328 |
| Target per-sequence oracle | 0.459 | 0.372 | 0.348 | 0.248 | 0.357 |
| Condition | 01 | 02 | 03 | 05 | Mean |
|---|---|---|---|---|---|
| Oracle transfer | 0.427 | 0.356 | 0.190 | 0.095 | 0.267 |
| VLM text-only | 0.407 | 0.348 | 0.235 | 0.131 | 0.281 |
| VLM visual-only | 0.449 | 0.340 | 0.312 | 0.219 | 0.330 |
| VLM text+vision | 0.429 | 0.360 | 0.327 | 0.195 | 0.328 |
| Target oracle (ceiling) | 0.459 | 0.372 | 0.348 | 0.248 | 0.357 |
| Condition | 04 | 05 | 07 | 10 | 19 | 34 | 47 | 58 | Mean |
|---|---|---|---|---|---|---|---|---|---|
| MOT17 Oracle | 0.51 | 0.48 | 0.51 | 0.61 | 0.32 | 0.38 | 0.33 | 0.59 | 0.47 |
| + Det agent | 0.34 | 0.56 | 0.50 | 0.47 | 0.27 | 0.38 | 0.30 | 0.55 | 0.42 |
| + Tracking agent | 0.39 | 0.56 | 0.49 | 0.47 | 0.28 | 0.36 | 0.37 | 0.44 | 0.42 |
| + Both agents | 0.35 | 0.43 | 0.50 | 0.61 | 0.34 | 0.39 | 0.40 | 0.59 | 0.45 |
Multi-Object Tracking
Multi-object tracking (MOT) links detections across video frames to maintain object identities through motion, occlusion, and changing viewpoints.
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