no code implementations • 18 May 2024 • Jay Patrikar, Sushant Veer, Apoorva Sharma, Marco Pavone, Sebastian Scherer
Modern neural trajectory predictors in autonomous driving are developed using imitation learning (IL) from driving logs.
no code implementations • 8 May 2024 • Conner Pulling, Je Hon Tan, Yaoyu Hu, Sebastian Scherer
Multi-view stereo omnidirectional distance estimation usually needs to build a cost volume with many hypothetical distance candidates.
1 code implementation • 8 May 2024 • Peng Yin, Jianhao Jiao, Shiqi Zhao, Lingyun Xu, Guoquan Huang, Howie Choset, Sebastian Scherer, Jianda Han
We conclude with a discussion on PR's future directions, accompanied by a summary of the literature covered and access to our open-source library, available to the robotics community at: https://github. com/MetaSLAM/GPRS.
2 code implementations • 7 Apr 2024 • Zihan Wang, Bowen Li, Chen Wang, Sebastian Scherer
Few-shot object detection has drawn increasing attention in the field of robotic exploration, where robots are required to find unseen objects with a few online provided examples.
no code implementations • 18 Mar 2024 • Shubhra Aich, Wenshan Wang, Parv Maheshwari, Matthew Sivaprakasam, Samuel Triest, Cherie Ho, Jason M. Gregory, John G. Rogers III, Sebastian Scherer
The limited sensing resolution of resource-constrained off-road vehicles poses significant challenges towards reliable off-road autonomy.
no code implementations • 12 Mar 2024 • Ri-Zhao Qiu, Yafei Hu, Ge Yang, Yuchen Song, Yang Fu, Jianglong Ye, Jiteng Mu, Ruihan Yang, Nikolay Atanasov, Sebastian Scherer, Xiaolong Wang
An open problem in mobile manipulation is how to represent objects and scenes in a unified manner, so that robots can use it both for navigating in the environment and manipulating objects.
1 code implementation • 5 Mar 2024 • Jay Patrikar, Joao Dantas, Brady Moon, Milad Hamidi, Sourish Ghosh, Nikhil Keetha, Ian Higgins, Atharva Chandak, Takashi Yoneyama, Sebastian Scherer
In total, TartanAviation provides 3. 1M images, 3374 hours of Air Traffic Control speech data, and 661 days of ADS-B trajectory data.
no code implementations • 12 Feb 2024 • Qizhao Chen, Ziqi Hu, Junyi Geng, Dongwei Bai, Mohammad Mousaei, Sebastian Scherer
This paper introduces a unified MPC-based control strategy for a customized tiltrotor VTOL Unmanned Aerial Vehicle (UAV), which does not require mode-switching and can perform the control allocation in a consistent way.
no code implementations • 14 Dec 2023 • Yafei Hu, Quanting Xie, Vidhi Jain, Jonathan Francis, Jay Patrikar, Nikhil Keetha, Seungchan Kim, Yaqi Xie, Tianyi Zhang, Shibo Zhao, Yu Quan Chong, Chen Wang, Katia Sycara, Matthew Johnson-Roberson, Dhruv Batra, Xiaolong Wang, Sebastian Scherer, Zsolt Kira, Fei Xia, Yonatan Bisk
Motivated by the impressive open-set performance and content generation capabilities of web-scale, large-capacity pre-trained models (i. e., foundation models) in research fields such as Natural Language Processing (NLP) and Computer Vision (CV), we devote this survey to exploring (i) how these existing foundation models from NLP and CV can be applied to the field of robotics, and also exploring (ii) what a robotics-specific foundation model would look like.
1 code implementation • 14 Dec 2023 • Andrew Jong, Mukai Yu, Devansh Dhrafani, Siva Kailas, Brady Moon, Katia Sycara, Sebastian Scherer
We present the Wildland-fire Infrared Thermal (WIT-UAS) dataset for long-wave infrared sensing of crew and vehicle assets amidst prescribed wildland fire environments.
1 code implementation • 4 Dec 2023 • Nikhil Keetha, Jay Karhade, Krishna Murthy Jatavallabhula, Gengshan Yang, Sebastian Scherer, Deva Ramanan, Jonathon Luiten
Dense simultaneous localization and mapping (SLAM) is crucial for robotics and augmented reality applications.
no code implementations • 16 Oct 2023 • Krishna Suresh, Aditya Rauniyar, Micah Corah, Sebastian Scherer
To coordinate teams of aerial robots in filming groups of people in dense environments, a more general view-planning approach is required.
1 code implementation • 7 Oct 2023 • Yuheng Qiu, Chen Wang, Can Xu, Yutian Chen, Xunfei Zhou, Youjie Xia, Sebastian Scherer
In contrast, data-driven IO methods struggle to accurately model the sensor motions, often leading to generalizability and interoperability issues.
1 code implementation • 1 Aug 2023 • Nikhil Keetha, Avneesh Mishra, Jay Karhade, Krishna Murthy Jatavallabhula, Sebastian Scherer, Madhava Krishna, Sourav Garg
In this work, we develop a universal solution to VPR -- a technique that works across a broad range of structured and unstructured environments (urban, outdoors, indoors, aerial, underwater, and subterranean environments) without any re-training or fine-tuning.
Ranked #1 on Visual Place Recognition on Nardo-Air R
no code implementations • 4 Apr 2023 • Ingrid Navarro, Jay Patrikar, Joao P. A. Dantas, Rohan Baijal, Ian Higgins, Sebastian Scherer, Jean Oh
In this work, we propose Social Robot Tree Search (SoRTS), an algorithm for the safe navigation of mobile robots in social domains.
1 code implementation • 3 Apr 2023 • Aryan, Bowen Li, Sebastian Scherer, Yun-Jou Lin, Chen Wang
This results in a robust, accurate, and portable indoor relocalization system, which outperforms the state-of-the-art methods in room-level relocalization by 9. 5% of PR-AUC and 7% of accuracy.
no code implementations • 6 Dec 2022 • Zhipeng Zhao, Huai Yu, Chenwei Lyv, Wen Yang, Sebastian Scherer
To overcome this limitation, we focus on correlating the information of 360 equirectangular images to point clouds, proposing an end-to-end learnable network to conduct cross-modal visual localization by establishing similarity in high-dimensional feature space.
1 code implementation • ICCV 2023 • Bowen Li, Ziyuan Huang, Junjie Ye, Yiming Li, Sebastian Scherer, Hang Zhao, Changhong Fu
Visual object tracking is essential to intelligent robots.
1 code implementation • 19 Oct 2022 • Sebastian Scherer, Robin Schön, Rainer Lienhart
Current SSL approaches use an initially supervised trained model to generate predictions for unlabelled images, called pseudo-labels, which are subsequently used for training a new model from scratch.
no code implementations • 5 Oct 2022 • Bardienus P Duisterhof, Yaoyu Hu, Si Heng Teng, Michael Kaess, Sebastian Scherer
An accurate calibration of the intrinsics and extrinsics is a critical pre-requisite for using the edge of a wide-angle lens for depth perception and odometry.
1 code implementation • 28 Sep 2022 • Shreyas Kulkarni, Peng Yin, Sebastian Scherer
Additionally, we introduce a semantic consistency loss that encourages realistic renderings of novel views.
no code implementations • 26 Sep 2022 • Sourish Ghosh, Jay Patrikar, Brady Moon, Milad Moghassem Hamidi, Sebastian Scherer
Detect-and-Avoid (DAA) capabilities are critical for safe operations of unmanned aircraft systems (UAS).
no code implementations • 22 Sep 2022 • Mateo Guaman Castro, Samuel Triest, Wenshan Wang, Jason M. Gregory, Felix Sanchez, John G. Rogers III, Sebastian Scherer
Our short-scale navigation results show that using our learned costmaps leads to overall smoother navigation, and provides the robot with a more fine-grained understanding of the robot-terrain interactions.
no code implementations • 22 Sep 2022 • Jingtian Yan, Xingqiao Lin, Zhongqiang Ren, Shiqi Zhao, Jieqiong Yu, Chao Cao, Peng Yin, Ji Zhang, Sebastian Scherer
To intelligently balance the robustness of sub-map merging and exploration efficiency, we develop a new approach for lidar-based multi-agent exploration, which can direct one agent to repeat another agent's trajectory in an \emph{adaptive} manner based on the quality indicator of the sub-map merging process.
1 code implementation • 17 Sep 2022 • Shihao Shen, Yilin Cai, Wenshan Wang, Sebastian Scherer
Learning-based visual odometry (VO) algorithms achieve remarkable performance on common static scenes, benefiting from high-capacity models and massive annotated data, but tend to fail in dynamic, populated environments.
no code implementations • 14 Sep 2022 • Peng Yin, Ivan Cisneros, Ji Zhang, Howie Choset, Sebastian Scherer
The visual camera is an attractive device in beyond visual line of sight (B-VLOS) drone operation, since they are low in size, weight, power, and cost, and can provide redundant modality to GPS failures.
1 code implementation • 9 Sep 2022 • Peng Yin, Shiqi Zhao, Ivan Cisneros, Abulikemu Abuduweili, Guoquan Huang, Micheal Milford, Changliu Liu, Howie Choset, Sebastian Scherer
A summary of this work and our datasets and evaluation API is publicly available to the robotics community at: https://github. com/MetaSLAM/GPRS.
Loop Closure Detection Simultaneous Localization and Mapping
no code implementations • 30 Aug 2022 • Peng Yin, Abulikemu Abuduweili, Shiqi Zhao, Changliu Liu, Sebastian Scherer
We present BioSLAM, a lifelong SLAM framework for learning various new appearances incrementally and maintaining accurate place recognition for previously visited areas.
1 code implementation • 19 Jul 2022 • Ivan Cisneros, Peng Yin, Ji Zhang, Howie Choset, Sebastian Scherer
We present the ALTO dataset, a vision-focused dataset for the development and benchmarking of Visual Place Recognition and Localization methods for Unmanned Aerial Vehicles.
no code implementations • 14 Jul 2022 • Peng Yin, Haowen Lai, Shiqi Zhao, Ruohai Ge, Ji Zhang, Howie Choset, Sebastian Scherer
We present AutoMerge, a LiDAR data processing framework for assembling a large number of map segments into a complete map.
no code implementations • 6 Jul 2022 • Shiqi Zhao, Peng Yin, Ge Yi, Sebastian Scherer
Our previous work provides a viewpoint-invariant descriptor to deal with viewpoint differences; however, the global descriptor suffers from a low signal-noise ratio in unsupervised clustering, reducing the distinguishable feature extraction ability.
no code implementations • 17 May 2022 • Azarakhsh Keipour, Mohammadreza Mousaei, Maryam Bandari, Stefan Schaal, Sebastian Scherer
On the other hand, while physical interaction with these objects has been done with ground manipulators, there have not been any studies on physical interaction and manipulation of the deformable linear object with aerial robots.
no code implementations • 7 Apr 2022 • Yafei Hu, Junyi Geng, Chen Wang, John Keller, Sebastian Scherer
To the best of our knowledge, this work for the first time demonstrates value function prediction on real-world dataset for robot exploration in challenging subterranean and urban environments.
1 code implementation • 3 Dec 2021 • Bowen Li, Chen Wang, Pranay Reddy, Seungchan Kim, Sebastian Scherer
Few-shot object detection has attracted increasing attention and rapidly progressed in recent years.
1 code implementation • CVPR 2022 • Nikhil Varma Keetha, Chen Wang, Yuheng Qiu, Kuan Xu, Sebastian Scherer
In this context, we propose a novel temporal 3D object encoding approach, dubbed AirObject, to obtain global keypoint graph-based embeddings of objects.
no code implementations • 23 Nov 2021 • Haowen Lai, Peng Yin, Sebastian Scherer
Recent years have witnessed the increasing application of place recognition in various environments, such as city roads, large buildings, and a mix of indoor and outdoor places.
no code implementations • 22 Nov 2021 • Thiago A. Rodrigues, Jay Patrikar, Natalia L. Oliveira, H. Scott Matthews, Sebastian Scherer, Constantine Samaras
The adoption of Uncrewed Aerial Vehicles (UAVs) for last-mile deliveries will affect the energy productivity of package delivery and require new methods to understand the associated energy consumption and greenhouse gas (GHG) emissions.
1 code implementation • 18 Nov 2021 • Chen Wang, Yuheng Qiu, Wenshan Wang, Yafei Hu, Seungchan Kim, Sebastian Scherer
Instead, we propose to develop a method that automatically adapts online to the environment to report interesting scenes quickly.
no code implementations • 5 Nov 2021 • Stephan Brehm, Sebastian Scherer, Rainer Lienhart
Unsupervised Domain Adaptation (UDA) aims to adapt models trained on a source domain to a new target domain where no labelled data is available.
1 code implementation • 21 Sep 2021 • Yuheng Qiu, Chen Wang, Wenshan Wang, Mina Henein, Sebastian Scherer
To the best of our knowledge, AirDOS is the first dynamic object-aware SLAM system demonstrating that camera pose estimation can be improved by incorporating dynamic articulated objects.
1 code implementation • 18 Sep 2021 • Dasong Gao, Chen Wang, Sebastian Scherer
Nevertheless, simply finetuning the model on new data is infeasible since it may cause the model's performance on previously learned data to degrade over time, which is also known as the problem of catastrophic forgetting.
no code implementations • 20 Aug 2021 • Weikun Zhen, Huai Yu, Yaoyu Hu, Sebastian Scherer
We first present a unified representation based on quadrics, leading to a consistent and concise formulation.
no code implementations • 12 Aug 2021 • Zheng Fang, Sifan Zhou, Yubo Cui, Sebastian Scherer
Then, to fuse the information of features in the two branches and obtain their similarity, we propose two cross correlation modules, named Pointcloud-wise and Point-wise respectively.
no code implementations • 9 Aug 2021 • Cherie Ho, Andrew Jong, Harry Freeman, Rohan Rao, Rogerio Bonatti, Sebastian Scherer
Aerial vehicles are revolutionizing applications that require capturing the 3D structure of dynamic targets in the wild, such as sports, medicine, and entertainment.
1 code implementation • 31 May 2021 • Arnav Choudhry, Brady Moon, Jay Patrikar, Constantine Samaras, Sebastian Scherer
Computing the CVaR on the risk-space distribution provides a metric that can evaluate the overall risk of a flight before take-off.
no code implementations • 27 May 2021 • Peng Yin, Lingyun Xu, Jianmin Ji, Sebastian Scherer, Howie Choset
One of the main obstacles to 3D semantic segmentation is the significant amount of endeavor required to generate expensive point-wise annotations for fully supervised training.
no code implementations • 27 May 2021 • Peng Yin, Lingyun Xu, Ji Zhang, Howie Choset, Sebastian Scherer
Based on such features, we further design a spherical convolution network to learn viewpoint-invariant symmetric place descriptors.
no code implementations • 13 Mar 2021 • Yaoyu Hu, Wenshan Wang, Huai Yu, Weikun Zhen, Sebastian Scherer
Stereo reconstruction models trained on small images do not generalize well to high-resolution data.
no code implementations • 25 Feb 2021 • Azarakhsh Keipour, Guilherme A. S. Pereira, Sebastian Scherer
We propose a new algorithm for real-time detection and tracking of elliptic patterns suitable for real-world robotics applications.
no code implementations • 1 Jan 2021 • Chen Wang, Yuheng Qiu, Sebastian Scherer
In this paper, we aim to bridge GNN to lifelong learning, which is to overcome the effect of ``catastrophic forgetting" for continuously learning a sequence of graph-structured tasks.
no code implementations • 19 Nov 2020 • Rogerio Bonatti, Arthur Bucker, Sebastian Scherer, Mustafa Mukadam, Jessica Hodgins
First, we generate a database of video clips with a diverse range of shots in a photo-realistic simulator, and use hundreds of participants in a crowd-sourcing framework to obtain scores for a set of semantic descriptors for each clip.
no code implementations • 12 Nov 2020 • Azarakhsh Keipour, Mohammadreza Mousaei, Andrew T Ashley, Sebastian Scherer
The strategies are lightweight, simple, and allow rapid integration of the available tools with these new vehicles for the fast development of new real-world applications.
no code implementations • 10 Nov 2020 • Arthur Bucker, Rogerio Bonatti, Sebastian Scherer
We validate our approach in multiple cluttered environments of a photo-realistic simulator, and deploy the system using two UAVs in real-world experiments.
2 code implementations • 6 Nov 2020 • Hao Li, Huai Yu, Wen Yang, Lei Yu, Sebastian Scherer
Targeting at the unified line segment detection (ULSD) for both distorted and undistorted images, we propose to represent line segments with the Bezier curve model.
Ranked #5 on Line Segment Detection on wireframe dataset (sAP10 metric)
2 code implementations • 31 Oct 2020 • Wenshan Wang, Yaoyu Hu, Sebastian Scherer
We present the first learning-based visual odometry (VO) model, which generalizes to multiple datasets and real-world scenarios and outperforms geometry-based methods in challenging scenes.
2 code implementations • CVPR 2022 • Chen Wang, Yuheng Qiu, Dasong Gao, Sebastian Scherer
In this paper, we bridge GNN and lifelong learning by converting a continual graph learning problem to a regular graph learning problem so GNN can inherit the lifelong learning techniques developed for convolutional neural networks (CNN).
3 code implementations • ECCV 2020 • Chen Wang, Wenshan Wang, Yuheng Qiu, Yafei Hu, Sebastian Scherer
In this paper, we explore the problem of interesting scene prediction for mobile robots.
1 code implementation • 1 Apr 2020 • Huai Yu, Weikun Zhen, Wen Yang, Ji Zhang, Sebastian Scherer
With the pose prediction from VIO, we can efficiently obtain coarse 2D-3D line correspondences.
1 code implementation • 31 Mar 2020 • Wenshan Wang, Delong Zhu, Xiangwei Wang, Yaoyu Hu, Yuheng Qiu, Chen Wang, Yafei Hu, Ashish Kapoor, Sebastian Scherer
We present a challenging dataset, the TartanAir, for robot navigation task and more.
Robotics
no code implementations • 23 Nov 2019 • Huai Yu, Weikun Zhen, Wen Yang, Sebastian Scherer
In this paper, we propose a new 2D-3D registration method to estimate 2D-3D line feature correspondences and the camera pose in untextured point clouds of structured environments.
no code implementations • 23 Nov 2019 • Yaoyu Hu, Weikun Zhen, Sebastian Scherer
The proposed deep-learning assisted method is evaluated on the Middlebury dataset and high-resolution stereo images collected by our customized binocular stereo camera.
no code implementations • 15 Oct 2019 • Rogerio Bonatti, Wenshan Wang, Cherie Ho, Aayush Ahuja, Mirko Gschwindt, Efe Camci, Erdal Kayacan, Sanjiban Choudhury, Sebastian Scherer
In this work, we address the problem in its entirety and propose a complete system for real-time aerial cinematography that for the first time combines: (1) vision-based target estimation; (2) 3D signed-distance mapping for occlusion estimation; (3) efficient trajectory optimization for long time-horizon camera motion; and (4) learning-based artistic shot selection.
no code implementations • 3 Oct 2019 • John Keller, Sebastian Scherer
We present a hierarchical disparity algorithm that reduces noise, separately identify wires using semantic object triangulation in three images, and use information about the polarization of light to estimate the disparity of reflective objects.
no code implementations • 25 Sep 2019 • Wenshan Wang, Yaoyu Hu, Sebastian Scherer
A visualization of the latent space demonstrates that our algorithm learns an effective abstraction of the long action sequences.
Hierarchical Reinforcement Learning reinforcement-learning +1
2 code implementations • 16 Sep 2019 • Rogerio Bonatti, Ratnesh Madaan, Vibhav Vineet, Sebastian Scherer, Ashish Kapoor
We analyze the rich latent spaces learned with our proposed representations, and show that the use of our cross-modal architecture significantly improves control policy performance as compared to end-to-end learning or purely unsupervised feature extractors.
2 code implementations • 14 Jul 2019 • Azarakhsh Keipour, Mohammadreza Mousaei, Sebastian Scherer
We have also provided the helper tools in several programming languages to load and work with the data and to help the evaluation of a detection method using the dataset.
2 code implementations • 1 Jul 2019 • Azarakhsh Keipour, Mohammadreza Mousaei, Sebastian Scherer
The result is an easy-to-deploy anomaly detection method that does not assume a specific aircraft model and can detect many types of faults and anomalies in a wide range of autonomous aircraft.
Systems and Control Robotics Systems and Control
no code implementations • 4 Apr 2019 • Rogerio Bonatti, Cherie Ho, Wenshan Wang, Sanjiban Choudhury, Sebastian Scherer
In this work, we overcome such limitations and propose a complete system for aerial cinematography that combines: (1) a vision-based algorithm for target localization; (2) a real-time incremental 3D signed-distance map algorithm for occlusion and safety computation; and (3) a real-time camera motion planner that optimizes smoothness, collisions, occlusions and artistic guidelines.
no code implementations • 4 Apr 2019 • Mirko Gschwindt, Efe Camci, Rogerio Bonatti, Wenshan Wang, Erdal Kayacan, Sebastian Scherer
Aerial filming is constantly gaining importance due to the recent advances in drone technology.
no code implementations • 26 Mar 2019 • Wenshan Wang, Aayush Ahuja, Yanfu Zhang, Rogerio Bonatti, Sebastian Scherer
We show that by leveraging unlabeled sequences, the amount of labeled data required can be significantly reduced.
no code implementations • 8 Nov 2018 • Weichen Dai, Yu Zhang, Ping Li, Zheng Fang, Sebastian Scherer
This method utilizes the correlation between map points to separate points that are part of the static scene and points that are part of different moving objects into different groups.
1 code implementation • 5 Nov 2018 • Manash Pratim Das, Zhen Dong, Sebastian Scherer
While external pose estimation and fiducial marker based localization would require setup, maintenance, and manual calibration; marker-free self-localization can be achieved using the onboard depth sensor and camera.
Robotics
1 code implementation • 16 Oct 2018 • Yanfu Zhang, Wenshan Wang, Rogerio Bonatti, Daniel Maturana, Sebastian Scherer
The first-stage network learns feature representations of the environment using low-level LiDAR statistics and the second-stage network combines those learned features with kinematics data.
no code implementations • 10 Sep 2018 • Shichao Yang, Sebastian Scherer
In this paper, we present a monocular Simultaneous Localization and Mapping (SLAM) algorithm using high-level object and plane landmarks.
no code implementations • 28 Aug 2018 • Rogerio Bonatti, yanfu Zhang, Sanjiban Choudhury, Wenshan Wang, Sebastian Scherer
Autonomous aerial cinematography has the potential to enable automatic capture of aesthetically pleasing videos without requiring human intervention, empowering individuals with the capability of high-end film studios.
5 code implementations • 1 Jun 2018 • Shichao Yang, Sebastian Scherer
Objects can provide long-range geometric and scale constraints to improve camera pose estimation and reduce monocular drift.
no code implementations • 7 Apr 2018 • Sankalp Arora, Sanjiban Choudhury, Sebastian Scherer
The contribution of the paper helps identify the properties of a POMDP problem for which the use of MDP based POMDP solvers is inappropriate, enabling better design choices.
no code implementations • 20 Nov 2017 • Sanjiban Choudhury, Siddhartha Srinivasa, Sebastian Scherer
We are interested in planning algorithms that actively infer the underlying structure of the valid configuration space during planning in order to find solutions with minimal effort.
no code implementations • ICML 2017 • Po-Wei Chou, Daniel Maturana, Sebastian Scherer
Recently, reinforcement learning with deep neural networks has achieved great success in challenging continuous control problems such as 3D locomotion and robotic manipulation.
no code implementations • 24 Jul 2017 • Shichao Yang, Yulan Huang, Sebastian Scherer
In the paper, we propose an incremental and (near) real-time semantic mapping system.
1 code implementation • 10 Jul 2017 • Mohak Bhardwaj, Sanjiban Choudhury, Sebastian Scherer
In this paper, we do so by training a heuristic policy that maps the partial information from the search to decide which node of the search tree to expand.
1 code implementation • NeurIPS 2017 • Sanjiban Choudhury, Shervin Javdani, Siddhartha Srinivasa, Sebastian Scherer
By leveraging this property, we are able to significantly reduce computational complexity from exponential to linear in the number of edges.
Robotics
no code implementations • 27 Apr 2017 • Shichao Yang, Sandeep Konam, Chen Ma, Stephanie Rosenthal, Manuela Veloso, Sebastian Scherer
Second, predict the trajectory from the depth and normal.
no code implementations • 21 Mar 2017 • Shichao Yang, Yu Song, Michael Kaess, Sebastian Scherer
In this paper, we propose real-time monocular plane SLAM to demonstrate that scene understanding could improve both state estimation and dense mapping especially in low-texture environments.
no code implementations • 19 Mar 2017 • Shichao Yang, Sebastian Scherer
Most visual odometry algorithm for a monocular camera focuses on points, either by feature matching, or direct alignment of pixel intensity, while ignoring a common but important geometry entity: edges.