CO-Calib
Multi-fisheye calibration observations with checkerboard targets across stereo and hex camera rigs.

Robust Multi-Fisheye Calibration

CO-Calib

Observation Quality Matters: Robust Multi-Fisheye Calibration via Failure-Oriented Analysis

Peize Liu1 Zhe Tong1 Chen Feng1,† Shaojie Shen1

1 Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology

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99.3%
Synthetic SR
3.69mm / 0.111°
Synthetic ATE
25/25
Real-world stereo SR
10/10
Real-world Hex-Fisheye SR

Failure-Oriented Analysis

Observations should guide optimization, not merely fill the image.

CO-Calib shows that multi-fisheye calibration failures are governed by whether observations make intrinsic initialization well conditioned. Limited radial span couples focal scale with fisheye projection-shape parameters, producing ambiguous updates. Our detector and error-analysis-guided selector construct frames that provide stable, separable constraints for the existing optimization backend.

Synthetic Dataset

1,600 sequences of synthetic fisheye stereo data

The benchmark spans wide lens distortion and stereo arrangement diversity by combining multiple fields of view and yaw rotations, yielding controlled calibration sequences for failure-oriented analysis.

4FoVs 180 / 200 / 220 / 240 deg
4yaw rotations 0 / 60 / 90 / 120 deg
16configurations 100 sequences x 480 stereo frames
Looping synthetic fisheye stereo dataset visualization.
Representative synthetic fisheye stereo observations across FoV and yaw configurations.

Results

Higher Success Rate on Synthetic Stereo Fisheye Benchmark

Across the 4 FoV x 4 yaw synthetic stereo benchmark, CO-Calib keeps calibration success high in wide-FoV regimes where Kalibr degrades, raising overall success from 68.1% to 99.3%.

CO-Calib
99.3%
Kalibr
68.1%
Random subset
30.9%
BA-only
13.5%
Synthetic stereo fisheye benchmark success rate comparison between Kalibr and CO-Calib across FoV and yaw configurations.
Synthetic stereo fisheye benchmark success rates across FoV and yaw configurations.

Real-world experiments

Two rig-level views for comparing calibration outcomes

CO-Calib achieves higher calibration success rates and more consistent extrinsic estimates on both real-world Hex-Fisheye and stereo fisheye rigs, producing stable results where standard pipelines become unreliable.

Hex-Fisheye real-world camera system.
Hex-Fisheye real-world rig used in the experiments.
Stereo fisheye real-world camera system.
Stereo fisheye real-world rig used in the experiments.

Citation

BibTeX

@article{liu2026observation,
  title={Observation Quality Matters: Robust Multi-Fisheye Calibration via Failure-Oriented Analysis},
  author={Liu, Peize and Tong, Zhe and Feng, Chen and Shen, Shaojie},
  journal={arXiv preprint arXiv:2607.05777},
  year={2026}
}