On-Manifold Preintegration for Real-Time Visual--Inertial Odometry
Christian ForsterLuca CarloneFrank DellaertDavide Scaramuzza
Develops an inertial measurement preintegration formulation on the rotation group with closed-form bias updates, allowing real-time visual-inertial odometry to achieve high accuracy within factor graph optimization frameworks.
Autonomous navigation and motion tracking in environments without GPS rely heavily on combining monocular cameras with inertial measurement units (IMUs), a technique known as visual-inertial odometry (VIO). However, existing systems face an ongoing trade-off between estimation accuracy and real-time computation: traditional filtering methods are fast but suffer from accumulated linearization errors, while full optimization methods are highly accurate but computationally overwhelmed by the high rate of IMU data and the growing trajectory history.
The main objective of the article is to demonstrate an efficient and accurate VIO framework that achieves real-time, maximum a posteriori motion estimation. It evaluates a mathematical formulation for preintegrating high-rate inertial measurements directly on the rotation manifold and combining them with landmark-free visual factors in an incremental optimization pipeline.
The researchers developed a theoretical model that combines multiple IMU measurements between keyframes into single relative motion constraints on the 3D rotation manifold, avoiding repeated integrations when sensor biases are updated. They integrated this preintegrated IMU model into a factor graph using a structureless vision approach—which analytically eliminates 3D landmark points—and solved the resulting optimization incrementally using the iSAM2 algorithm. The system was validated using Monte Carlo simulations over 50 runs alongside real-world evaluations on a 430-meter indoor trajectory with motion-capture ground truth and multi-floor outdoor datasets, benchmarking against established methods such as OKVIS, MSCKF, and Google Tango.
The findings confirm substantial performance and accuracy gains over existing approaches. First, in real-world indoor testing, the proposed method accumulated only 0.3 meters of average drift over 360 meters of traveled distance, outperforming both OKVIS and MSCKF, which each accumulated roughly 0.7 meters (a drift reduction of more than 50%). Second, the framework achieved steady real-time execution on standard hardware, taking roughly 10 milliseconds for backend state updates and 3 milliseconds for visual feature tracking. Third, outdoor trials showed superior end-to-end accuracy, recording 1.0 meter and 0.5 meter drift on respective paths compared to 2.2 meters and 1.4 meters for Google Tango. Finally, statistical consistency evaluations demonstrated that the estimator properly tracks sensor biases and avoids overconfidence along unobservable degrees of freedom, completely removing the mathematical singularities and coordinate-dependent errors inherent to older Euler-angle preintegration methods.
These results show that engineering teams do not need to sacrifice trajectory accuracy to achieve real-time tracking on computationally constrained mobile platforms, such as drones or augmented reality devices. By avoiding redundant recalculations and landmark state explosion, the approach lowers computing overhead and minimizes risk of catastrophic tracking drift in GPS-denied environments.
Decision-makers and engineering leads should consider adopting on-manifold IMU preintegration and structureless vision factors for future autonomous navigation stacks, leveraging the authors' open-source implementation within the GTSAM toolbox. Future deployment planning should evaluate integrating loop-closure detection to eliminate long-term residual drift and explore higher-order integration schemes if deploying with lower-frequency IMUs.
Confidence in the system's performance is high based on the consistency of simulated Monte Carlo tests and physical validation against ground truth. Key operational considerations include sensitivity to initial sensor calibration (such as camera-IMU extrinsic alignment and time synchronization) and the assumption of sufficient visual feature tracking from the front-end pipeline, which may degrade in textureless or highly dynamic environments.
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