Jakob J. Engel

EDBT 2026 Demo / reviewers in the wild / expert

dblp:243/3258 · also Jakob Julian Engel · DBLP profile ↗

← Back

23ranked-venue papers

5as first author

14since 2021 · last 2026

0000-0002-2799-5808ORCID · reported

Domains — the database's venue-derived domains; a paper can count in several

Artificial intelligence and machine learning · 20 · 5 first-author · 13 since 2021Graphics, computer vision, multimedia, augmented reality and games · 14 · 2 first-author · 10 since 2021Systems, architecture and hardware · 7 · 2 first-author · 3 since 2021Human-computer interaction and ubiquitous computing · 1

Year	Publication	Venue	Position
2026	Ego-EXTRA: video-language Egocentric Dataset for EXpert-TRAinee assistance abstract We present Ego-EXTRA, a video-language Egocentric Dataset for EXpert-TRAinee assistance. Ego-EXTRA features 50 hours of unscripted egocentric videos of subjects performing procedural activities (the trainees) while guided by real-world experts who provide guidance and answer specific questions using natural language. Following a ``Wizard of OZ'' data collection paradigm, the expert enacts a wearable intelligent assistant, looking at the activities performed by the trainee exclusively from their egocentric point of view, answering questions when asked by the trainee, or proactively interacting with suggestions during the procedures. This unique data collection protocol enables Ego-EXTRA to capture a high-quality dialogue in which expert-level feedback is provided to the trainee. Two-way dialogues between experts and trainees are recorded, transcribed, and used to create a novel benchmark comprising more than 15k high-quality Visual Question Answer sets, which we use to evaluate Multimodal Large Language Models. The results show that Ego-EXTRA is challenging and highlight the limitations of current models when used to provide expert-level assistance to the user. The Ego-EXTRA dataset is publicly available to support the benchmark of egocentric video-language assistants: https://fpv-iplab.github.io/Ego-EXTRA/. Francesco Ragusa, Michele Mazzamuto, Rosario Forte, Irene D'Ambra, James Fort, Jakob J. Engel, Antonino Furnari, Giovanni Maria Farinella	WACV	6
2025	Sonata: Self-Supervised Learning of Reliable Point Representations abstract In this paper, we question whether we have a reliable self-supervised point cloud model that can be used for diverse 3D tasks via simple linear probing, even with limited data and minimal computation. We find that existing 3D self-supervised learning approaches fall short when evaluated on representation quality through linear probing. We hypothesize that this is due to what we term the "geometric shortcut", which causes representations to collapse to low-level spatial features. This challenge is unique to 3D and arises from the sparse nature of point cloud data. We address it through two key strategies: obscuring spatial information and enhancing the reliance on input features, ultimately composing a Sonata of 140k point clouds through self-distillation. Sonata is simple and intuitive, yet its learned representations are strong and reliable: zero-shot visualizations demonstrate semantic grouping, alongside strong spatial reasoning through nearest-neighbor relationships. Sonata demonstrates exceptional parameter and data efficiency, tripling linear probing accuracy (from 21.8% to 72.5%) on ScanNet and nearly doubling performance with only 1% of the data compared to previous approaches. Full fine-tuning further advances SOTA across both 3D indoor and outdoor perception tasks. Xiaoyang Wu 0002, Daniel DeTone, Duncan P. Frost, Tianwei Shen, Christopher Xie, Jakob J. Engel, Richard A. Newcombe, Hengshuang Zhao, Julian Straub	CVPR	7
2025	HOT3D: Hand and Object Tracking in 3D from Egocentric Multi-View Videos abstract We introduce HOT3D, a publicly available dataset for egocentric hand and object tracking in 3D. The dataset offers over 833 minutes (3.7M+ images) of recordings that feature 19 subjects interacting with 33 diverse rigid objects. In addition to simple pickup, observe, and put-down actions, the subjects perform actions typical for a kitchen, office, and living room environment. The recordings include multiple synchronized data streams containing egocentric multi-view RGB/monochrome images, eye gaze signal, scene point clouds, and 3D poses of cameras, hands, and objects. The dataset is recorded with two headsets from Meta: Project Aria, which is a research prototype of AI glasses, and Quest 3, a virtual-reality headset that has shipped millions of units. Ground-truth poses were obtained by a motion-capture system using small optical markers attached to hands and objects. Hand annotations are provided in the UmeTrack and MANO formats, and objects are represented by 3D meshes with PBR materials obtained by an in-house scanner. In our experiments, we demonstrate the effectiveness of multi-view egocentric data for three popular tasks: 3D hand tracking, model-based 6DoF object pose estimation, and 3D lifting of unknown in-hand objects. The evaluated multi-view methods, whose benchmarking is uniquely enabled by HOT3D, significantly outperform their single-view counterparts. Prithviraj Banerjee, Sindi Shkodrani, Pierre Moulon, Shreyas Hampali, Shangchen Han, Linguang Zhang, Jade Fountain, Edward Miller 0001, Selen Basol, Richard A. Newcombe, Robert Wang 0002, Jakob J. Engel, Tomas Hodan	CVPR	13
2025	Benchmarking Egocentric Visual-Inertial SLAM at City Scale Anusha Krishnan, Shaohui Liu, Paul-Edouard Sarlin, Oscar Gentilhomme, David Caruso, Maurizio Monge, Richard Newcombe, Jakob J. Engel, Marc Pollefeys	ICCV	8
2025	Human-in-the-Loop Local Corrections of 3D Scene Layouts via Infilling abstract We present a novel human-in-the-loop approach to estimate 3D scene layout that uses human feedback from an egocentric standpoint. We study this approach through introduction of a novel local correction task, where users identify local errors and prompt a model to automatically correct them. Building on SceneScript, a state-of-the-art framework for 3D scene layout estimation that leverages structured language, we propose a solution that structures this problem as "infilling", a task studied in natural language processing. We train a multi-task version of SceneScript that maintains performance on global predictions while significantly improving its local correction ability. We integrate this into a human-in-the-loop system, enabling a user to iteratively refine scene layout estimates via a low-friction "one-click fix'' workflow. Our system enables the final refined layout to diverge from the training distribution, allowing for more accurate modelling of complex layouts. Christopher Xie, Armen Avetisyan, Henry Howard-Jenkins, Yawar Siddiqui, Julian Straub, Richard A. Newcombe, Vassileios Balntas, Jakob J. Engel	ICCV	8
2025	VertexRegen: Mesh Generation with Continuous Level of Detail abstract We introduce VertexRegen, a novel mesh generation framework that enables generation at a continuous level of detail. Existing autoregressive methods generate meshes in a partial-to-complete manner and thus intermediate steps of generation represent incomplete structures. VertexRegen takes inspiration from progressive meshes and reformulates the process as the reversal of edge collapse, i.e. vertex split, learned through a generative model. Experimental results demonstrate that VertexRegen produces meshes of comparable quality to state-of-the-art methods while uniquely offering anytime generation with the flexibility to halt at any step to yield valid meshes with varying levels of detail. Yawar Siddiqui, Armen Avetisyan, Christopher Xie, Jakob J. Engel, Henry Howard-Jenkins	ICCV	5
2025	Ego-Exo4D: Understanding Skilled Human Activity from First- and Third-Person Perspectives abstract We present Ego-Exo4D, a diverse, large-scale multimodal multiview video dataset and benchmark challenge. Ego-Exo4D centers around simultaneously-captured egocentric and exocentric video of skilled human activities (e.g., sports, music, dance, bike repair). 740 participants from 13 cities worldwide performed these activities in 123 different natural scene contexts, yielding long-form captures from 1 to 42 minutes each and 1,286 hours of video combined. The multimodal nature of the dataset is unprecedented: the video is accompanied by multichannel audio, eye gaze, 3D point clouds, camera poses, IMU, and multiple paired language descriptions—including a novel “expert commentary” done by coaches and teachers and tailored to the skilled-activity domain. To push the frontier of first-person video understanding of skilled human activity, we also present a suite of benchmark tasks and their annotations, including fine-grained activity understanding, proficiency estimation, cross-view translation, and 3D hand/body pose. All resources are open sourced to fuel new research in the community. https://ego-exo4d-data.org/ Kristen Grauman, Andrew Westbury, Lorenzo Torresani, Kris Makoto Kitani, Jitendra Malik, Triantafyllos Afouras, Kumar Ashutosh, Vijay Baiyya, Siddhant Bansal, Bikram Boote, Eugene Byrne, Zachary Chavis, Joya Chen, Fu-Jen Chu, Sean Crane, Avijit Dasgupta, Jing Dong 0002, María Escobar, Cristhian Forigua, Abrham Gebreselasie, Sanjay Haresh, Jing Huang 0020, Md Mohaiminul Islam, Suyog Dutt Jain, Rawal Khirodkar, Devansh Kukreja, Kevin J. Liang, Jia-Wei Liu, Sagnik Majumder, Yongsen Mao, Effrosyni Mavroudi, Tushar Nagarajan, Francesco Ragusa, Santhosh K. Ramakrishnan, Luigi Seminara, Arjun Somayazulu, Yale Song, Shan Su, Zihui Xue, Jinxu Zhang, Angela Castillo, Changan Chen, Xinzhu Fu, Ryosuke Furuta, Cristina González, Prince Gupta, Jiabo Hu, Yifei Huang 0002, Yiming Huang 0011, Weslie Khoo, Anush Kumar, Robert Kuo, Sach Lakhavani, Miao Liu 0007, Mi Luo, Zhengyi Luo 0002, Brighid Meredith, Austin Miller, Oluwatumininu Oguntola, Xiaqing Pan, Penny Peng, Shraman Pramanick, Merey Ramazanova, Fiona Ryan, Kiran K. Somasundaram, Chenan Song, Audrey Southerland, Masatoshi Tateno, Takuma Yagi, Mingfei Yan, Xitong Yang, Zecheng Yu, Shengxin Cindy Zha, Chen Zhao 0002, Ziwei Zhao 0003, Zhifan Zhu 0001, Jeff Zhuo, Pablo Andrés Arbeláez, Gedas Bertasius, David Crandall, Dima Damen, Jakob J. Engel, Giovanni Maria Farinella, Antonino Furnari, Bernard Ghanem, Judy Hoffman, C. V. Jawahar, Richard A. Newcombe, Hyun Soo Park, James M. Rehg, Yoichi Sato 0001, Manolis Savva, Jianbo Shi, Mike Zheng Shout, Michael Wray	Int. J. Comput. Vis.	88
2024	Ego-Exo4D: Understanding Skilled Human Activity from First- and Third-Person Perspectives abstract We present Ego-Exo4D, a diverse, large-scale multi-modal multiview video dataset and benchmark challenge. Ego-Exo4D centers around simultaneously-captured ego-centric and exocentric video of skilled human activities (e.g., sports, music, dance, bike repair). 740 participants from 13 cities worldwide performed these activities in 123 different natural scene contexts, yielding long-form captures from 1 to 42 minutes each and 1,286 hours of video combined. The multimodal nature of the dataset is un-precedented: the video is accompanied by multichannel audio, eye gaze, 3D point clouds, camera poses, IMU, and multiple paired language descriptions-including a novel “expert commentary” done by coaches and teachers and tailored to the skilled-activity domain. To push the frontier of first-person video understanding of skilled human activity, we also present a suite of benchmark tasks and their annotations, including fine-grained activity understanding, proficiency estimation, cross-view translation, and 3D hand/body pose. All resources are open sourced to fuel new research in the community. Kristen Grauman, Andrew Westbury, Lorenzo Torresani, Kris Makoto Kitani, Jitendra Malik, Triantafyllos Afouras, Kumar Ashutosh, Vijay Baiyya, Siddhant Bansal, Bikram Boote, Eugene Byrne, Zachary Chavis, Joya Chen, Fu-Jen Chu, Sean Crane, Avijit Dasgupta, Jing Dong 0002, María Escobar, Cristhian Forigua, Abrham Gebreselasie, Sanjay Haresh, Jing Huang 0020, Md Mohaiminul Islam, Suyog Dutt Jain, Rawal Khirodkar, Devansh Kukreja, Kevin J. Liang, Jia-Wei Liu, Sagnik Majumder, Yongsen Mao, Effrosyni Mavroudi, Tushar Nagarajan, Francesco Ragusa, Santhosh K. Ramakrishnan, Luigi Seminara, Arjun Somayazulu, Yale Song, Shan Su, Zihui Xue, Jinxu Zhang, Angela Castillo, Changan Chen, Xinzhu Fu, Ryosuke Furuta, Cristina González, Prince Gupta, Jiabo Hu, Yifei Huang 0002, Yiming Huang 0011, Weslie Khoo, Anush Kumar, Robert Kuo, Sach Lakhavani, Miao Liu 0007, Mi Luo, Zhengyi Luo 0002, Brighid Meredith, Austin Miller, Oluwatumininu Oguntola, Xiaqing Pan, Penny Peng, Shraman Pramanick, Merey Ramazanova, Fiona Ryan, Kiran K. Somasundaram, Chenan Song, Audrey Southerland, Masatoshi Tateno, Takuma Yagi, Mingfei Yan, Xitong Yang, Zecheng Yu, Shengxin Cindy Zha, Chen Zhao 0002, Ziwei Zhao 0003, Zhifan Zhu 0001, Jeff Zhuo, Pablo Andrés Arbeláez, Gedas Bertasius, Dima Damen, Jakob J. Engel, Giovanni Maria Farinella, Antonino Furnari, Bernard Ghanem, Judy Hoffman, C. V. Jawahar, Richard A. Newcombe, Hyun Soo Park, James M. Rehg, Yoichi Sato 0001, Manolis Savva, Jianbo Shi, Mike Zheng Shout, Michael Wray	CVPR	87
2024	SceneScript: Reconstructing Scenes with an Autoregressive Structured Language Model Armen Avetisyan, Christopher Xie, Henry Howard-Jenkins, Tsun-Yi Yang, Samir Aroudj, Suvam Patra, Fuyang Zhang, Duncan P. Frost, Luke Holland, Campbell Orme, Jakob J. Engel, Edward Miller 0001, Richard A. Newcombe, Vassileios Balntas	ECCV (61)	11
2024	Nymeria: A Massive Collection of Multimodal Egocentric Daily Motion in the Wild Lingni Ma, Yuting Ye, Fangzhou Hong, Vladimir Guzov, Yifeng Jiang 0002, Rowan Postyeni, Luis Pesqueira, Alexander Gamino, Vijay Baiyya, Hyo Jin Kim 0004, Kevin Bailey, David Soriano Fosas, C. Karen Liu, Ziwei Liu 0002, Jakob J. Engel, Renzo De Nardi, Richard A. Newcombe	ECCV (24)	15
2024	Robust Indoor Localization with Ranging-IMU Fusion abstract Indoor wireless ranging localization is a promising approach for low-power and high-accuracy localization of wearable devices. A primary challenge in this domain stems from non-line of sight propagation of radio waves. This study tackles a fundamental issue in wireless ranging: the unpredictability of real-time multipath determination, especially in challenging conditions such as when there is no direct line of sight. We achieve this by fusing range measurements with inertial measurements obtained from a low cost Inertial Measurement Unit (IMU). For this purpose, we introduce a novel asymmetric noise model crafted specifically for non-Gaussian multipath disturbances. Additionally, we present a novel Levenberg-Marquardt (LM)-family trust-region adaptation of the iSAM2 fusion algorithm, which is optimized for robust performance for our ranging-IMU fusion problem. We evaluate our solution in a densely occupied real office environment. Our proposed solution can achieve temporally consistent localization with an average absolute accuracy of ∼0.3m in real-world settings. Furthermore, our results indicate that we can achieve comparable accuracy even with infrequent range measurements down to 1Hz. David Caruso, Ashutosh Dhekne, Qi Qu, Jakob J. Engel, Jing Dong 0002	ICRA	5
2022	Long-term Visual Map Sparsification with Heterogeneous GNN abstract We address the problem of map sparsification for long-term visual localization. For map sparsification, a commonly employed assumption is that the pre-build map and the later captured localization query are consistent. However, this assumption can be easily violated in the dynamic world. Additionally, the map size grows as new data accumulate through time, causing large data overhead in the long term. In this paper, we aim to overcome the environmental changes and reduce the map size at the same time by selecting points that are valuable to future localization. Inspired by the recent progress in Graph Neural Network (GNN), we propose the first work that models SfM maps as heterogeneous graphs and predicts 3D point importance scores with a GNN, which enables us to directly exploit the rich information in the SfM map graph. Two novel supervisions are proposed: 1) a data-fitting term for selecting valuable points to future localization based on training queries; 2) a K-Cover term for selecting sparse points with full-map coverage. The experiments show that our method selected map points on stable and widely visible structures and out-performed baselines in localization performance Ming-Fang Chang, Yipu Zhao, Rajvi Shah, Jakob J. Engel, Michael Kaess, Simon Lucey	CVPR	4
2021	Distributed Client-Server Optimization for SLAM with Limited On-Device Resources abstract Simultaneous localization and mapping (SLAM) is a crucial functionality for exploration robots and virtual/augmented reality (VR/AR) devices. However, some of such devices with limited resources cannot afford the computational or memory cost to run full SLAM algorithms. We propose a general client-server SLAM optimization framework that achieves accurate real-time state estimation on the device with low requirements of on-board resources. The resource-limited device (the client) only works on a small part of the map, and the rest of the map is processed by the server. By sending the summarized information of the rest of map to the client, the on-device state estimation is more accurate. Further improvement of accuracy is achieved in the presence of on-device early loop closures, which enables reloading useful variables from the server to the client. Experimental results from both synthetic and real-world datasets demonstrate that the proposed optimization framework achieves accurate estimation in real-time with limited computation and memory budget of the device. Yetong Zhang, Ming Hsiao, Yipu Zhao, Jing Dong 0002, Jakob J. Engel	ICRA	5
2021	MR-iSAM2: Incremental Smoothing and Mapping with Multi-Root Bayes Tree for Multi-Robot SLAM abstract We present multi-robot iSAM2 (MR-iSAM2), an efficient incremental smoothing and mapping (iSAM) algorithm to solve multi-robot simultaneous localization and mapping (SLAM) inference problems. MR-iSAM2 is based on a novel data structure multi-root Bayes tree (MRBT), which packs multiple Bayes trees with the same undirected clique structure. In multi-robot scenarios, the MRBT enables new measurements from different robots to be updated in different root branches, while all updates are performed around the single root of the Bayes tree in the original iSAM2 algorithm. As a result, the MRBT better reveals the underlying sparsity and information flow in multi-robot SLAM inference problems than the Bayes tree. Based on this insight, we further develop MR-iSAM2 to incrementally update and maintain the sparsity structure of the MRBT and enable efficient information propagation among the roots for inter-robot inference. We analyze the properties of the MR-iSAM2 algorithm, and show with both synthetic and real world datasets that it significantly outperforms iSAM2 in efficiency when solving multi-robot SLAM problems. Yetong Zhang, Ming Hsiao, Jing Dong 0002, Jakob J. Engel, Frank Dellaert	IROS	4
2018	Direct Sparse Odometry abstract Direct Sparse Odometry (DSO) is a visual odometry method based on a novel, highly accurate sparse and direct structure and motion formulation. It combines a fully direct probabilistic model (minimizing a photometric error) with consistent, joint optimization of all model parameters, including geometry-represented as inverse depth in a reference frame-and camera motion. This is achieved in real time by omitting the smoothness prior used in other direct methods and instead sampling pixels evenly throughout the images. Since our method does not depend on keypoint detectors or descriptors, it can naturally sample pixels from across all image regions that have intensity gradient, including edges or smooth intensity variations on essentially featureless walls. The proposed model integrates a full photometric calibration, accounting for exposure time, lens vignetting, and non-linear response functions. We thoroughly evaluate our method on three different datasets comprising several hours of video. The experiments show that the presented approach significantly outperforms state-of-the-art direct and indirect methods in a variety of real-world settings, both in terms of tracking accuracy and robustness. Jakob J. Engel, Vladlen Koltun, Daniel Cremers	IEEE Trans. Pattern Anal. Mach. Intell.	1
2016	Direct visual-inertial odometry with stereo cameras abstract We propose a novel direct visual-inertial odometry method for stereo cameras. Camera pose, velocity and IMU biases are simultaneously estimated by minimizing a combined photometric and inertial energy functional. This allows us to exploit the complementary nature of vision and inertial data. At the same time, and in contrast to all existing visual-inertial methods, our approach is fully direct: geometry is estimated in the form of semi-dense depth maps instead of manually designed sparse keypoints. Depth information is obtained both from static stereo - relating the fixed-baseline images of the stereo camera - and temporal stereo - relating images from the same camera, taken at different points in time. We show that our method outperforms not only vision-only or loosely coupled approaches, but also can achieve more accurate results than state-of-the-art keypoint-based methods on different datasets, including rapid motion and significant illumination changes. In addition, our method provides high-fidelity semi-dense, metric reconstructions of the environment, and runs in real-time on a CPU. Vladyslav Usenko, Jakob J. Engel, Jörg Stückler, Daniel Cremers	ICRA	2
2015	Reconstructing Street-Scenes in Real-Time from a Driving Car abstract Most current approaches to street-scene 3D reconstruction from a driving car to date rely on 3D laser scanning or tedious offline computation from visual images. In this paper, we compare a real-time capable 3D reconstruction method using a stereo extension of large-scale direct SLAM (LSD-SLAM) with laser-based maps and traditional stereo reconstructions based on processing individual stereo frames. In our reconstructions, small-baseline comparison over several subsequent frames are fused with fixed-baseline disparity from the stereo camera setup. These results demonstrate that our direct SLAM technique provides an excellent compromise between speed and accuracy, generating visually pleasing and globally consistent semi-dense reconstructions of the environment in real-time on a single CPU. Vladyslav Usenko, Jakob J. Engel, Jörg Stückler, Daniel Cremers	3DV	2
2015	Large-scale direct SLAM for omnidirectional cameras abstract We propose a real-time, direct monocular SLAM method for omnidirectional or wide field-of-view fisheye cameras. Both tracking (direct image alignment) and mapping (pixel-wise distance filtering) are directly formulated for the unified omnidirectional model, which can model central imaging devices with a field of view above 180°. This is in contrast to existing direct mono-SLAM approaches like DTAM or LSD-SLAM, which operate on rectified images, in practice limiting the field of view to around 130° diagonally. Not only does this allows to observe - and reconstruct - a larger portion of the surrounding environment, but it also makes the system more robust to degenerate (rotation-only) movement. The two main contribution are (1) the formulation of direct image alignment for the unified omnidirectional model, and (2) a fast yet accurate approach to incremental stereo directly on distorted images. We evaluated our framework on real-world sequences taken with a 185° fisheye lens, and compare it to a rectified and a piecewise rectified approach. David Caruso, Jakob J. Engel, Daniel Cremers	IROS	2
2015	Large-scale direct SLAM with stereo cameras abstract We propose a novel Large-Scale Direct SLAM algorithm for stereo cameras (Stereo LSD-SLAM) that runs in real-time at high frame rate on standard CPUs. In contrast to sparse interest-point based methods, our approach aligns images directly based on the photoconsistency of all high-contrast pixels, including corners, edges and high texture areas. It concurrently estimates the depth at these pixels from two types of stereo cues: Static stereo through the fixed-baseline stereo camera setup as well as temporal multi-view stereo exploiting the camera motion. By incorporating both disparity sources, our algorithm can even estimate depth of pixels that are under-constrained when only using fixed-baseline stereo. Using a fixed baseline, on the other hand, avoids scale-drift that typically occurs in pure monocular SLAM.We furthermore propose a robust approach to enforce illumination invariance, capable of handling aggressive brightness changes between frames - greatly improving the performance in realistic settings. In experiments, we demonstrate state-of-the-art results on stereo SLAM benchmarks such as Kitti or challenging datasets from the EuRoC Challenge 3 for micro aerial vehicles. Jakob J. Engel, Jörg Stückler, Daniel Cremers	IROS	1
2014	LSD-SLAM: Large-Scale Direct Monocular SLAM Jakob J. Engel, Thomas Schöps, Daniel Cremers	ECCV (2)	1
2014	Semi-dense visual odometry for AR on a smartphone abstract We present a direct monocular visual odometry system which runs in real-time on a smartphone. Being a direct method, it tracks and maps on the images themselves instead of extracted features such as keypoints. New images are tracked using direct image alignment, while geometry is represented in the form of a semi-dense depth map. Depth is estimated by filtering over many small-baseline, pixel-wise stereo comparisons. This leads to significantly less outliers and allows to map and use all image regions with sufficient gradient, including edges. We show how a simple world model for AR applications can be derived from semi-dense depth maps, and demonstrate the practical applicability in the context of an AR application in which simulated objects can collide with real geometry. Thomas Schöps, Jakob J. Engel, Daniel Cremers	ISMAR	2
2013	Semi-dense Visual Odometry for a Monocular Camera abstract We propose a fundamentally novel approach to real-time visual odometry for a monocular camera. It allows to benefit from the simplicity and accuracy of dense tracking - which does not depend on visual features - while running in real-time on a CPU. The key idea is to continuously estimate a semi-dense inverse depth map for the current frame, which in turn is used to track the motion of the camera using dense image alignment. More specifically, we estimate the depth of all pixels which have a non-negligible image gradient. Each estimate is represented as a Gaussian probability distribution over the inverse depth. We propagate this information over time, and update it with new measurements as new images arrive. In terms of tracking accuracy and computational speed, the proposed method compares favorably to both state-of-the-art dense and feature-based visual odometry and SLAM algorithms. As our method runs in real-time on a CPU, it is of large practical value for robotics and augmented reality applications. Jakob J. Engel, Jürgen Sturm, Daniel Cremers	ICCV	1
2012	Camera-based navigation of a low-cost quadrocopter abstract In this paper, we describe a system that enables a low-cost quadrocopter coupled with a ground-based laptop to navigate autonomously in previously unknown and GPS-denied environments. Our system consists of three components: a monocular SLAM system, an extended Kalman filter for data fusion and state estimation and a PID controller to generate steering commands. Next to a working system, the main contribution of this paper is a novel, closed-form solution to estimate the absolute scale of the generated visual map from inertial and altitude measurements. In an extensive set of experiments, we demonstrate that our system is able to navigate in previously unknown environments at absolute scale without requiring artificial markers or external sensors. Furthermore, we show (1) its robustness to temporary loss of visual tracking and significant delays in the communication process, (2) the elimination of odometry drift as a result of the visual SLAM system and (3) accurate, scale-aware pose estimation and navigation. Jakob J. Engel, Jürgen Sturm, Daniel Cremers	IROS	1