Release KITTI-C2L v1.0.0: documented self-contained benchmark, loader and baselines
db613b6 verified | # KITTI-C2L and sequence calibration assessment | |
| Assessment, 2026-10-17. The planned three-seed dataset, implementation and mean | |
| sequence comparisons are complete, including the longer unchanged-main controls. | |
| These experiments assess an optimized training recipe, not a reproduction of the | |
| published UniCal recipe. | |
| ## Decision | |
| **KITTI-C2L supports useful calibration with unchanged main.** With longer | |
| training, it improves both metrics versus usual KITTI and identity correction on | |
| both common held-out protocols across seeds42/43/44, including each test drive. | |
| However, the reproduced usual-KITTI baseline remains weak, so this does not | |
| establish parity with advertised UniCal accuracy. | |
| **Sequence inference improves accuracy modestly.** Three-frame feature averaging | |
| improves both metrics using the same frame-trained checkpoint across three seeds | |
| on both training corpora. Dedicated three-frame mean training does not establish | |
| an accuracy gain and uses three times the encoder exposure. | |
| **Broad parity for the frozen perturbation policy is unsupported.** With the | |
| improved branch under the matched short recipe, frozen C2L performs better on | |
| native targets but worse beyond the 10% margin on usual-relative targets. | |
| Regenerating usual-style perturbations on the same C2L frames meets the 10% | |
| noninferiority screen under both protocols. This supports the frame/ground-truth | |
| content under that policy, rather than parity of the frozen targets. These | |
| results do not justify advertising the frozen dataset as a validated reference | |
| benchmark matching published UniCal accuracy. | |
| ## Design and limits | |
| - Unchanged baseline: main commit `7c16fd81e4889d6f16076b1ec5b58835d876807b`. | |
| - Three paired training seeds: 42, 43, 44. Checkpoints selected by validation loss. | |
| - All configured usual-KITTI training drives versus full C2L stage 5, with C2L | |
| sequence 07 held out for validation. Shared test sequences are 09 and 10: | |
| 2,792 frame anchors, or 2,604 valid window anchors for temporal comparisons. | |
| - Frame training uses 256px inputs, 8,192 loss points sampled after dense depth-map | |
| construction, BF16 mixed precision, batch 8, four spawned workers, pinned | |
| memory, uniform learning rate 3e-5 and one warmup epoch. | |
| - Short frame runs process 185,070 encoder frames on C2L and 198,978 on usual | |
| KITTI. Whole-epoch rounding gives usual training approximately 7.5% more | |
| exposure. Dedicated window T1/T3 runs have equal updates and 3x encoder | |
| exposure for T3. | |
| - Native C2L targets use frozen dual-rig errors. Relative targets use usual-style | |
| camera-relative errors. Their distributions differ; report both separately. | |
| - Intervals use 5,000 paired bootstrap draws over training seeds and shared | |
| temporal blocks/windows. Conclusions are conditional on the held-out drives. | |
| Noninferiority requires the paired upper bound for candidate minus 1.10 times | |
| reference to be below zero for each metric. | |
| - Report translation MAE in centimetres and geodesic rotation error in degrees. | |
| Geodesic rotation is not interchangeable with the paper's Euler rotation MAE. | |
| - C2L training sequence 08 overlaps the usual paper-alpha test drive. It cannot | |
| be used as an unseen test for models trained on full C2L. | |
| ## Matched short-recipe dataset comparisons across three seeds | |
| Means are translation cm / geodesic degrees. Lower is better. | |
| | Implementation and targets | Usual KITTI | Frozen C2L | Finding | | |
| | --- | ---: | ---: | --- | | |
| | Unchanged main, native | 6.8449 / 1.3298 | 6.9364 / 1.3269 | Both within 10%; weak identity-level baselines | | |
| | Unchanged main, relative | 5.2190 / 0.9556 | 5.3051 / 0.9587 | Both within 10%; weak identity-level baselines | | |
| | Improved branch, native | 4.4919 / 0.6524 | 4.2528 / 0.6148 | C2L improves both metrics | | |
| | Improved branch, relative | 3.2897 / 0.4555 | 3.7726 / 0.5199 | C2L worsens both beyond the 10% margin | | |
| The improved branch's frozen-C2L relative deficit is 14.68% in translation and | |
| 14.14% in rotation. Both deficits exceed the tolerance with paired uncertainty, | |
| and repeat separately on drives 09 and 10. Main's identity reference is | |
| 6.6925 / 1.3287 on native targets and 5.0536 / 0.9542 on relative targets; | |
| matching those weak baselines does not establish useful calibration parity. | |
| With usual-style online perturbations regenerated on C2L, the improved branch | |
| reaches 4.4169 / 0.6436 on native targets and 3.2632 / 0.4368 on relative targets. | |
| Both metrics meet 10% noninferiority versus usual KITTI under both protocols, | |
| overall and on each held-out drive. No overall improvement versus usual KITTI is | |
| established. Training and validation perturbation policies change together, so | |
| this does not isolate training perturbations as the sole cause. | |
| ## Implementation and temporal effects | |
| Under matched short recipes, the improved single-frame implementation beats | |
| unchanged main on both datasets | |
| and both protocols across three seeds. On C2L, native translation/rotation errors | |
| fall by 38.7% / 53.7%, and relative errors by 28.9% / 45.8%. This is an | |
| implementation bundle, including input normalization, projection geometry and | |
| encoder training-mode fixes; it is not an isolated temporal effect. | |
| Inference-only feature averaging uses the same frame-trained checkpoint for T1 | |
| and T3 within each seed, CPU FP32, and identical window anchors and targets: | |
| | Training corpus | T1 | T3 mean | Finding | | |
| | --- | ---: | ---: | --- | | |
| | C2L | 4.3470 / 0.6343 | 4.1036 / 0.5944 | Both improve, including each drive | | |
| | Usual KITTI | 4.4792 / 0.6347 | 4.3875 / 0.6110 | Both improve, including each drive | | |
| Dedicated mean training instead gives T1 5.9607 / 0.9667 versus T3 | |
| 5.9956 / 0.9378. Neither metric establishes improvement across three seeds. | |
| Both meet the 10% tolerance, but T3 consumes three times the encoder exposure. | |
| The capacity-matched Transformer pilot also failed to establish a useful gain; | |
| that pilot is single-seed evidence. | |
| ## Longer unchanged-main controls across three seeds | |
| Every C2L arm completed 50 epochs, 925,350 encoder frames and 115,700 optimizer | |
| updates. Every usual-KITTI arm completed 61 epochs, 933,666 encoder frames and | |
| 116,754 updates. Whole-epoch rounding gives usual training approximately 0.9% | |
| more exposure. Both update count and cosine-schedule horizon change versus the | |
| short runs; this does not isolate training duration alone. | |
| | Held-out targets | Usual KITTI | Frozen C2L | C2L minus usual paired 95% intervals | | |
| | --- | ---: | ---: | --- | | |
| | Native | 7.2228 / 1.3284 | 4.0628 / 0.7746 | [-4.1324, -2.3403] cm / [-0.5986, -0.5135] degrees | | |
| | Relative | 5.6084 / 0.9543 | 3.5458 / 0.6061 | [-3.1650, -1.1924] cm / [-0.3870, -0.3095] degrees | | |
| C2L improves both metrics versus longer usual training, short C2L training and | |
| identity under both protocols, overall and separately on drives09/10. This | |
| resolves the weak-learning concern from short unchanged-main C2L runs: the | |
| frozen data supports useful calibration with this implementation and schedule. | |
| Longer usual-KITTI training establishes no improvement versus short training or | |
| identity for either metric under either protocol. Relative translation is worse | |
| than identity, with an increase interval of [0.0047, 1.8244] cm. Translation | |
| noninferiority within 10% versus short training or identity is not established | |
| under either protocol. The usual baseline remains a weak comparator. | |
| The audit loaded all six best and final recovery checkpoints on CPU, verified | |
| optimizer/scheduler state and completed updates, checked every validation epoch, | |
| matched initial weights within seeds and against short controls, and recomputed | |
| controller aggregates independently. Numeric reductions agree within 1e-12; | |
| report structure and metadata match exactly. Validation selected C2L epochs | |
| 45/34/40 and usual epochs60/53/25 for seeds42/43/44, respectively (one-based). | |
| Validation curves were non-monotonic, especially C2L seed43; these are results of | |
| validation-selected checkpoints, not proof of stable end-of-schedule convergence. | |
| The implementation improvements reported above use matched short recipes. | |
| Comparing them directly with these longer main runs would confound implementation | |
| with training budget. The temporal inference comparison isolates fusion by | |
| using the same checkpoint and anchors within each paired seed. | |
| ## Evidence and reproduction | |
| The tracked `assessment_results.json` provides a compact numeric evidence summary | |
| with source-report hashes. `comparison_protocol.json`, `run_comparison.py`, | |
| `evaluate_comparison.py` and `paired_analysis.py` define the training, evaluation | |
| and comparison machinery. Local experiment outputs are intentionally ignored by | |
| Git. `logs/comparison/current-assessment-index.json` indexes report paths and | |
| SHA-256 hashes; reports retain prediction-source hashes, paired intervals, | |
| per-drive results and control audits. Reproduction requires KITTI data and the | |
| frozen C2L snapshot; no private producer package is required at runtime. | |
| Primary local reports are `main-dataset-assessment-seeds42-44.json`, | |
| `strong-dataset-assessment-uniformlr-seeds42-44.json`, | |
| `aligned-perturbation-assessment-seeds42-44.json`, | |
| `implementation-{c2l,usual}-assessment-seeds42-44.json`, | |
| `cpu-window-inference-{c2l,usual}-assessment-seeds42-44.json`, | |
| `temporal-mean-uniformlr-assessment-seeds42-44.json` and | |
| `long-main-assessment-seeds42-44.json`, under `logs/comparison`. | |
| Source: mirrored from `mcocheteux/unical-plus` commit | |
| `2550c6dbab40d48f64bc260f03bf5e69d5bc5452`, `experiments/ASSESSMENT.md`. | |
| Retains CC BY-NC 4.0; see `release/v1/UNICAL-LICENSE.txt` in the metadata package | |
| or `LICENSE` in the separate baseline package. | |