{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T01:46:19Z","timestamp":1760233579758,"version":"build-2065373602"},"reference-count":34,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2021,1,26]],"date-time":"2021-01-26T00:00:00Z","timestamp":1611619200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000038","name":"NSERC","doi-asserted-by":"publisher","award":["50503-10925"],"award-info":[{"award-number":["50503-10925"]}],"id":[{"id":"10.13039\/501100000038","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Robotics"],"abstract":"<jats:p>In this paper, we present a novel method for visual-inertial odometry for land vehicles. Our technique is robust to unintended, but unavoidable bumps, encountered when an off-road land vehicle traverses over potholes, speed-bumps or general change in terrain. In contrast to tightly-coupled methods for visual-inertial odometry, we split the joint visual and inertial residuals into two separate steps and perform the inertial optimization after the direct-visual alignment step. We utilize all visual and geometric information encoded in a keyframe by including the inverse-depth variances in our optimization objective, making our method a direct approach. The primary contribution of our work is the use of epipolar constraints, computed from a direct-image alignment, to correct pose prediction obtained by integrating IMU measurements, while simultaneously building a semi-dense map of the environment in real-time. Through experiments, both indoor and outdoor, we show that our method is robust to sudden spikes in inertial measurements while achieving better accuracy than the state-of-the art direct, tightly-coupled visual-inertial fusion method.<\/jats:p>","DOI":"10.3390\/robotics10010023","type":"journal-article","created":{"date-parts":[[2021,1,26]],"date-time":"2021-01-26T08:29:16Z","timestamp":1611649756000},"page":"23","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Monocular Visual Inertial Direct SLAM with Robust Scale Estimation for Ground Robots\/Vehicles"],"prefix":"10.3390","volume":"10","author":[{"given":"Bismaya","family":"Sahoo","sequence":"first","affiliation":[{"name":"Mechanical &amp; Mechatronincs Engineering Department, University of Waterloo, Waterloo, ON N2L 3G1, Canada"}]},{"given":"Mohammad","family":"Biglarbegian","sequence":"additional","affiliation":[{"name":"School of Engineering, University of Guelph, Guelph, ON N1G 2W1, Canada"}]},{"given":"William","family":"Melek","sequence":"additional","affiliation":[{"name":"Mechanical &amp; Mechatronincs Engineering Department, University of Waterloo, Waterloo, ON N2L 3G1, Canada"}]}],"member":"1968","published-online":{"date-parts":[[2021,1,26]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"389","DOI":"10.1007\/s10846-018-0829-1","article-title":"Multiple Maps for the Feature-based Monocular SLAM System","volume":"94","author":"Hu","year":"2019","journal-title":"J. Intell. Robot. Syst."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"203","DOI":"10.1007\/s10846-018-0775-y","article-title":"Monocular SLAM System for MAVs Aided with Altitude and Range Measurements: A GPS-free Approach","volume":"94","author":"Urzua","year":"2019","journal-title":"J. Intell. Robot. Syst."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"287","DOI":"10.1007\/s10846-010-9490-z","article-title":"Fusion of IMU and Vision for Absolute Scale Estimation in Monocular SLAM","volume":"61","author":"Weiss","year":"2011","journal-title":"J. Intell. Robot. Syst."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1088","DOI":"10.1109\/TRO.2008.2004521","article-title":"Visual SLAM for Flying Vehicles","volume":"24","author":"Steder","year":"2008","journal-title":"IEEE Trans. Robot."},{"key":"ref_5","unstructured":"Zhou, F., Duh, H.B.L., and Billinghurst, M. (2008, January 15\u201318). Trends in Augmented Reality Tracking, Interaction and Display: A Review of Ten Years of ISMAR. Proceedings of the 7th IEEE\/ACM International Symposium on Mixed and Augmented Reality, ISMAR \u201908, Cambridge, UK."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1052","DOI":"10.1109\/TPAMI.2007.1049","article-title":"MonoSLAM: Real-Time Single Camera SLAM","volume":"29","author":"Davison","year":"2007","journal-title":"IEEE Trans. Pattern Anal. Mach. Intell."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"932","DOI":"10.1109\/TRO.2008.2003276","article-title":"Inverse Depth Parametrization for Monocular SLAM","volume":"24","author":"Civera","year":"2008","journal-title":"IEEE Trans. Robot."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Klein, G., and Murray, D. (2007, January 13\u201316). Parallel Tracking and Mapping for Small AR Workspaces. Proceedings of the Sixth IEEE and ACM International Symposium on Mixed and Augmented Reality (ISMAR\u201907), Nara, Japan.","DOI":"10.1109\/ISMAR.2007.4538852"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Newcombe, R.A., Lovegrove, S.J., and Davison, A.J. (2011, January 6\u201313). DTAM: Dense tracking and mapping in real-time. Proceedings of the IEEE International Conference on Computer Vision, Barcelona, Spain.","DOI":"10.1109\/ICCV.2011.6126513"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Newcombe, R.A., Izadi, S., Hilliges, O., Molyneaux, D., Kim, D., Davison, A.J., Kohi, P., Shotton, J., Hodges, S., and Fitzgibbon, A. (2011, January 26\u201329). KinectFusion: Real-time dense surface mapping and tracking. Proceedings of the 2011 10th IEEE International Symposium on Mixed and Augmented Reality, Basel, Switzerland.","DOI":"10.1109\/ISMAR.2011.6092378"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1697","DOI":"10.1177\/0278364916669237","article-title":"ElasticFusion: Real-time dense SLAM and light source estimation","volume":"35","author":"Whelan","year":"2016","journal-title":"Int. J. Robot. Res."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"598","DOI":"10.1177\/0278364914551008","article-title":"Real-time Large Scale Dense RGB-D SLAM with Volumetric Fusion","volume":"34","author":"Whelan","year":"2014","journal-title":"Intl. J. Robot. Res."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1053","DOI":"10.1177\/0278364917728574","article-title":"Iterated extended Kalman filter based visual-inertial odometry using direct photometric feedback","volume":"36","author":"Bloesch","year":"2017","journal-title":"Int. J. Robot. Res."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1147","DOI":"10.1109\/TRO.2015.2463671","article-title":"ORB-SLAM: A Versatile and Accurate Monocular SLAM System","volume":"31","author":"Montiel","year":"2015","journal-title":"IEEE Trans. Robot."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1255","DOI":"10.1109\/TRO.2017.2705103","article-title":"ORB-SLAM2: An Open-Source SLAM System for Monocular, Stereo and RGB-D Cameras","volume":"33","year":"2017","journal-title":"IEEE Trans. Robot."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Engel, J., Sturm, J., and Cremers, D. (2013, January 1\u20138). Semi-Dense Visual Odometry for a Monocular Camera. Proceedings of the IEEE International Conference on Computer Vision (ICCV), Sydney, Australia.","DOI":"10.1109\/ICCV.2013.183"},{"key":"ref_17","unstructured":"Caruso, D., Engel, J., and Cremers, D. (October, January 28). Large-Scale Direct SLAM for Omnidirectional Cameras. Proceedings of the International Conference on Intelligent Robots and Systems (IROS), Hamburg, Germany."},{"key":"ref_18","unstructured":"Engel, J., Stueckler, J., and Cremers, D. (October, January 28). Large-Scale Direct SLAM with Stereo Cameras. Proceedings of the International Conference on Intelligent Robots and Systems (IROS), Hamburg, Germany."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Engel, J., Sch\u00f6ps, T., and Cremers, D. (2014, January 6\u201312). LSD-SLAM: Large-Scale Direct Monocular SLAM. Proceedings of the European Conference on Computer Vision (ECCV), Zurich, Switzerland.","DOI":"10.1007\/978-3-319-10605-2_54"},{"key":"ref_20","unstructured":"K\u00fcmmerle, R., Grisetti, G., Strasdat, H., Konolige, K., and Burgard, W. (2011, January 9\u201313). g2o: A General Framework for Graph Optimization. Proceedings of the 2011 IEEE International Conference on Robotics and Automation, Shanghai, China."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Concha, A., and Civera, J. (October, January 28). DPPTAM: Dense piecewise planar tracking and mapping from a monocular sequence. Proceedings of the 2015 IEEE\/RSJ International Conference on Intelligent Robots and Systems (IROS), Hamburg, Germany.","DOI":"10.1109\/IROS.2015.7354184"},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Concha, A., and Civera, J. (June, January 31). Using superpixels in monocular SLAM. Proceedings of the 2014 IEEE International Conference on Robotics and Automation (ICRA), Hong Kong, China.","DOI":"10.1109\/ICRA.2014.6906883"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Greene, W.N., Ok, K., Lommel, P., and Roy, N. (2016, January 16\u201321). Multi-level mapping: Real-time dense monocular SLAM. Proceedings of the 2016 IEEE International Conference on Robotics and Automation (ICRA), Stockholm, Sweden.","DOI":"10.1109\/ICRA.2016.7487213"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"249","DOI":"10.1109\/TRO.2016.2623335","article-title":"SVO: Semidirect Visual Odometry for Monocular and Multicamera Systems","volume":"33","author":"Forster","year":"2017","journal-title":"IEEE Trans. Robot."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Mourikis, A.I., and Roumeliotis, S.I. (2007, January 10\u201314). A Multi-State Constraint Kalman Filter for Vision-aided Inertial Navigation. Proceedings of the 2007 IEEE International Conference on Robotics and Automation, Roma, Italy.","DOI":"10.1109\/ROBOT.2007.364024"},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Wu, K., Ahmed, A., Georgiou, G., and Roumeliotis, S. (2015, January 13\u201317). A Square Root Inverse Filter for Efficient Vision-aided Inertial Navigation on Mobile Devices. Proceedings of the Robotics: Science and Systems, Rome, Italy.","DOI":"10.15607\/RSS.2015.XI.008"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Qin, T., and Shen, S. (2017, January 24\u201328). Robust initialization of monocular visual-inertial estimation on aerial robots. Proceedings of the 2017 IEEE\/RSJ International Conference on Intelligent Robots and Systems (IROS), Vancouver, BC, Canada.","DOI":"10.1109\/IROS.2017.8206284"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1109\/TRO.2016.2597321","article-title":"On-Manifold Preintegration for Real-Time Visual\u2013Inertial Odometry","volume":"33","author":"Forster","year":"2017","journal-title":"IEEE Trans. Robot."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"498","DOI":"10.1109\/18.910572","article-title":"Factor graphs and the sum-product algorithm","volume":"47","author":"Kschischang","year":"2001","journal-title":"IEEE Trans. Inf. Theory"},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Concha, A., Loianno, G., Kumar, V., and Civera, J. (2016, January 16\u201321). Visual-inertial direct SLAM. Proceedings of the 2016 IEEE International Conference on Robotics and Automation (ICRA), Stockholm, Sweden.","DOI":"10.1109\/ICRA.2016.7487266"},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Bradler, H., Ochs, M., Fanani, N., and Mester, R. (2017, January 24\u201331). Joint Epipolar Tracking (JET): Simultaneous Optimization of Epipolar Geometry and Feature Correspondences. Proceedings of the 2017 IEEE Winter Conference on Applications of Computer Vision (WACV), Santa Rosa, CA, USA.","DOI":"10.1109\/WACV.2017.56"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"221","DOI":"10.1023\/B:VISI.0000011205.11775.fd","article-title":"Lucas-Kanade 20 Years On: A Unifying Framework","volume":"56","author":"Baker","year":"2004","journal-title":"Int. J. Comput. Vis."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1214\/aoms\/1177703732","article-title":"Robust Estimation of a Location Parameter","volume":"35","author":"Huber","year":"1964","journal-title":"Ann. Math. Statist."},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Furgale, P., Rehder, J., and Siegwart, R. (2013, January 3\u20137). Unified temporal and spatial calibration for multi-sensor systems. Proceedings of the 2013 IEEE\/RSJ International Conference on Intelligent Robots and Systems, Tokyo, Japan.","DOI":"10.1109\/IROS.2013.6696514"}],"container-title":["Robotics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2218-6581\/10\/1\/23\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T05:15:23Z","timestamp":1760159723000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2218-6581\/10\/1\/23"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,1,26]]},"references-count":34,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2021,3]]}},"alternative-id":["robotics10010023"],"URL":"https:\/\/doi.org\/10.3390\/robotics10010023","relation":{},"ISSN":["2218-6581"],"issn-type":[{"type":"electronic","value":"2218-6581"}],"subject":[],"published":{"date-parts":[[2021,1,26]]}}}