Abstract
LiDAR-inertial odometry (LIO) systems differ in whether they continue estimating gravity after initialization. We compare four gravity-bias state configurations in each of FAST-LIO2 and LIO-SAM, then separately test a gravity-direction factor. Across 12 dataset sequences evaluated with FAST-LIO2, fixing gravity under continuous LiDAR correction produces mean paired changes in vertical and 3D position errors with 90% confidence intervals within $\pm 2\%$. Tests on 4 sequences with LIO-SAM likewise show no consistent benefit from online gravity. Multi-second LiDAR outages, unlike reduced range or field of view, reveal trajectory-dependent costs of fixing gravity. A history-matched 23D-to-21D switch places the repeatable 3D error increase after LiDAR updates resume. Under 5-s outages, a direction factor from the same IMU used for preintegration improves accuracy on Hall05 but worsens both errors with online gravity on TUHH. Dynamic-start tests also show fixed-bias failures at particular starting phases. We recommend keeping gravity and accelerometer bias online for robustness; use a direction factor only after verifying vertical and 3D accuracy gains under the intended operating conditions.
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Cite this article
APA 7
Xu, J., Jin, Z., Yu, K., Jiang, C., Huang, H., Jin, T., Luo, H., & Xia, Z. (2026). Does Online Gravity Estimation Matter? Revisiting a Silent Design Split in LiDAR-Inertial Odometry. https://omanscience.com/en/articles/does-online-gravity-estimation-matter-revisiting-a-silent-design-split-in-lidar-inertial-odometry
MLA 9
Xu, Jie, et al. "Does Online Gravity Estimation Matter? Revisiting a Silent Design Split in LiDAR-Inertial Odometry." https://omanscience.com/en/articles/does-online-gravity-estimation-matter-revisiting-a-silent-design-split-in-lidar-inertial-odometry.
Chicago (author–date)
Xu, Jie, Ziyi Jin, Kangjin Yu, Can Jiang, Hongjun Huang, Tongxing Jin, Hongkun Luo, and Zhongpu Xia. 2026. "Does Online Gravity Estimation Matter? Revisiting a Silent Design Split in LiDAR-Inertial Odometry." https://omanscience.com/en/articles/does-online-gravity-estimation-matter-revisiting-a-silent-design-split-in-lidar-inertial-odometry.
Harvard
Xu, J., Jin, Z., Yu, K., Jiang, C., Huang, H., Jin, T., Luo, H. and Xia, Z. (2026) 'Does Online Gravity Estimation Matter? Revisiting a Silent Design Split in LiDAR-Inertial Odometry', Available at: https://omanscience.com/en/articles/does-online-gravity-estimation-matter-revisiting-a-silent-design-split-in-lidar-inertial-odometry.
Vancouver
Xu J, Jin Z, Yu K, Jiang C, Huang H, Jin T, et al. Does Online Gravity Estimation Matter? Revisiting a Silent Design Split in LiDAR-Inertial Odometry. https://omanscience.com/en/articles/does-online-gravity-estimation-matter-revisiting-a-silent-design-split-in-lidar-inertial-odometry
IEEE
J. Xu, Z. Jin, K. Yu, C. Jiang, H. Huang, T. Jin, H. Luo, and Z. Xia, "Does Online Gravity Estimation Matter? Revisiting a Silent Design Split in LiDAR-Inertial Odometry," https://omanscience.com/en/articles/does-online-gravity-estimation-matter-revisiting-a-silent-design-split-in-lidar-inertial-odometry.