Three papers accepted at ISMAR 2021

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We are happy to announce that three papers from our department have been accepted at the ISMAR 2021 conference.

ISMAR, the International Symposium on Mixed and Augmented Reality, is the leading international academic conference in the field of Augmented Reality and Mixed Reality. The symposium will be held as a hybrid conference from October 4th to 8th, 2021, with its main location in the city of Bari, Italy.

The accepted papers of our department are the following:

Visual SLAM with Graph-Cut Optimized Multi-Plane Reconstruction
Fangwen Shu, Yaxu Xie, Jason Raphael Rambach, Alain Pagani, Didier Stricker

Comparing Head and AR Glasses Pose Estimation
Ahmet Firintepe, Oussema Dhaouadi, Alain Pagani, Didier Stricker

A Study of Human-Machine Teaming For Single Pilot Operation with Augmented Reality
Nareg Minaskan Karabid, Alain Pagani, Charles-Alban Dormoy, Jean-Marc Andre, Didier Stricker

We congratulate all authors for their publication!

Contact: Dr. Alain Pagani



XR for nature and environment survey

On July 29th, 2021, Dr. Jason Rambach presented the survey paper “A Survey on Applications of Augmented, Mixed and Virtual Reality for Nature and Environment” at the 23rd Human Computer Interaction Conference HCI International. The article is the result of a collaboration between DFKI, the Worms University of Applied Sciences and the University of Kaiserslautern.

Abstract: Augmented, virtual and mixed reality (AR/VR/MR) are technologies of great potential due to the engaging and enriching experiences they are capable of providing. However, the possibilities that AR/VR/MR offer in the area of environmental applications are not yet widely explored. In this paper, we present the outcome of a survey meant to discover and classify existing AR/VR/MR applications that can benefit the environment or increase awareness on environmental issues. We performed an exhaustive search over several online publication access platforms and past proceedings of major conferences in the fields of AR/VR/MR. Identified relevant papers were filtered based on novelty, technical soundness, impact and topic relevance, and classified into different categories. Referring to the selected papers, we discuss how the applications of each category are contributing to environmental protection and awareness. We further analyze these approaches as well as possible future directions in the scope of existing and upcoming AR/VR/MR enabling technologies.

Authors: Jason Rambach, Gergana Lilligreen, Alexander Schäfer, Ramya Bankanal, Alexander Wiebel, Didier Stricker

Paper: https://av.dfki.de/publications/a-survey-on-applications-of-augmented-mixed-and-virtual-reality-for-nature-and-environment/

Contact: Jason.Rambach@dfki.de

Presseberichte zu unserem Projekt “KI-Rebschnitt”
Advancing sports analytics to coach athletes through Deep Learning research

The recent advancements in Deep learning has lead to new interesting applications such as analyzing human motion and activities in recorded videos. The analysis covers from simple motion of humans walking, performing exercises to complex motions such as playing sports.

The athlete’s performance can be easily captured with a fixed camera for sports like tennis, badminton, diving, etc. The large availability of low cost cameras in handheld devices has further led to common place solution to record videos and analyze an athletes performance. Although the sports trainers can provide visual feedback by playing recorded videos, it is still hard to measure and monitor the performance improvement of the athlete.  Also, the manual analysis of the obtained footage is a time-consuming task which involves isolating actions of interest and categorizing them using domain-specific knowledge. Thus, the automatic interpretation of performance parameters in sports has gained a keen interest.

Competitive diving is one of the well recognized aquatic sport in Olympics in which a person dives from a platform or a springboard and performs different classes of acrobatics before descending into the water. These classes are standardized by international organization Fédération Internationale de Natation (FINA). The differences in the acrobatics performed in various classes of diving are very subtle. The difference arises in the duration which starts with the diver standing on a diving platform or a springboard and ends at the moment he/she dives into the water. This is a challenging task to model especially due to involvement of rapid changes and requires understanding of long-term human dynamics. Further, the model must be sensitive to subtle changes in body pose over a large number of frames to determine the correct classification.

In order to automate this kind of task, three challenging sub-problems are often encountered:  1) temporally cropping events/actions of interest from continuous video;  2) tracking the person of interest even though other divers and bystanders may be in view; and 3) classifying the events/actions of interest.

We are developing a solution in co-operation with Institut für Angewandte Trainingswissenshaft in Leipzig (IAT) to tackle the three subproblems. We work towards a complete parameter tracking solution based on monocular markerless human body motion tracking using only a mobile device (tablet or mobile phone) as training support tool to the overall diving action analysis. The techniques proposed, can be generalized to video footage recorded from other sports.

Contact person: Dr. Bertram Taetz, Pramod Murthy

Three Papers Accepted at CAIP 2021

We are happy to announce that three papers with respect to our structured light 3D reconstruction pipeline have been accepted for publication at the CAIP 2021. The International Conference on Computer Analysis of Images and Patterns will take place from September 28th to 30th, 2021 as a virtual conference.

The three accepted papers are entitled ”Fast Projector-Driven Structured Light Matching in Sub-Pixel Accuracy using Bilinear Interpolation Assumption”, ”Simultaneous Bi-Directional Structured Light Encoding for Practical Uncalibrated Profilometry” and ”Joint Global ICP for Improved Automatic Alignment of Full Turn Object Scans” and will be available right after the conference.

Authors: Torben Fetzer, Gerd Reis and Didier Stricker

VIZTA Project 24M Review and public summary

DFKI participates in the VIZTA project, coordinated by ST Micrelectronics, aiming  at developing innovative technologies in the field of optical sensors and laser sources for short to long-range 3D-imaging and to demonstrate their value in several key applications including automotive, security, smart buildings, mobile robotics for smart cities, and industry 4.0. The 24-month review by the EU-commission was completed and a public summary of the project was released, including updates from DFKI Augmented Vision on time-of-flight camera dataset recording and deep learning algorithm development for car in-cabin monitoring and smart building person counting and anomaly detection applications.

Please click here to check out the complete summary: https://www.vizta-ecsel.eu/newsletter-april-2021/

Contact: Dr. Jason Rambach, Dr. Bruno Mirbach

Paper accepted at ICIP 2021

We are happy to announce that our paper “SEMANTIC SEGMENTATION IN DEPTH DATA : A COMPARATIVE EVALUATION OF IMAGE AND POINT CLOUD BASED METHODS” has been accepted for publication at the ICIP 2021 IEEE International Conference on Image Processing which will take place from September 19th to 22nd, 2021 at Anchorage, Alaska, USA.

Abstract: The problem of semantic segmentation from depth images can be addressed by segmenting directly in the image domain or at 3D point cloud level. In this paper, we attempt for the first time to provide a study and experimental comparison of the two approaches. Through experiments on three datasets, namely SUN RGB-D, NYUdV2 and TICaM, we extensively compare various semantic segmentation algorithms, the input to which includes images and point clouds derived from them. Based on this, we offer analysis of the performance and computational cost of these algorithms that can provide guidelines on when each method should be preferred.

Authors: Jigyasa Katrolia, Lars Krämer, Jason Rambach, Bruno Mirbach, Didier Stricker

Paper: https://av.dfki.de/publications/semantic-segmentation-in-depth-data-a-comparative-evaluation-ofimage-and-point-cloud-based-methods/

Contact: Jigyasa_Singh.Katrolia@dfki.de, Jason.Rambach@dfki.de

Paper Accepted at CVPR 2021 Conference!

We are proud that our paper “RPSRNet: End-to-End Trainable Rigid Point Set Registration Network using Barnes-Hut 2^D-Tree Representation” has been accepted for publication at the Computer Vision Pattern Recognition (CVPR) 2021 Conference, which will take place virtually online from June 19th to 25th. CVPR is the premier annual computer vision conference. Our paper was accepted from ~12000 submissions as one of 23.4% (acceptance rate: 23.4%).

Abstract: We propose RPSRNet – a novel end-to-end trainable deep neural network for rigid point set registration. For this task, we use a novel 2^D-tree representation for the input point sets and a hierarchical deep feature embedding in the neural network. An iterative transformation refinement module of our network boosts the feature matching accuracy in the intermediate stages. We achieve an inference speed of ~12-15$\,$ms to register a pair of input point clouds as large as ~250K. Extensive evaluations on (i) KITTI LiDAR-odometry and (ii) ModelNet-40 datasets show that our method outperforms prior state-of-the-art methods – e.g., on the KITTI dataset, DCP-v2 by 1.3 and 1.5 times, and PointNetLK by 1.8 and 1.9 times better rotational and translational accuracy respectively. Evaluation on ModelNet40 shows that RPSRNet is more robust than other benchmark methods when the samples contain a significant amount of noise and disturbance. RPSRNet accurately registers point clouds with non-uniform sampling densities, e.g., LiDAR data, which cannot be processed by many existing deep-learning-based registration methods.

“Rigid Point Set Registration using Barnes-Hut (BH) 2^D-tree
Representation — The center-of-masses (CoMs) and point-densities of
non-empty tree-nodes are computed for the respective BH-trees of the
source and target. These two attributes are input to our RPSRNet which
predicts rigid transformation from the global feature-embedding of the
tree-nodes.”

Authors: Sk Aziz Ali, Kerem Kahraman, Gerd ReisDidier Stricker

To view the paper, please click here.

Paper Accepted in IEEE Access Journal!

We are happy to announce that our paper “Fast Gravitational Approach for Rigid Point Set Registration With Ordinary Differential Equations” has been accepted for publication in the IEEE Access Journal (Impact Factor: 3.745).

Abstract: This article introduces a new physics-based method for rigid point set alignment called Fast Gravitational Approach (FGA). In FGA, the source and target point sets are interpreted as rigid particle swarms with masses interacting in a globally multiply-linked manner while moving in a simulated gravitational force field. The optimal alignment is obtained by explicit modeling of forces acting on the particles as well as their velocities and displacements with second-order ordinary differential equations of n-body motion. Additional alignment cues can be integrated into FGA through particle masses. We propose a smooth-particle mass function for point mass initialization, which improves robustness to noise and structural discontinuities. To avoid the quadratic complexity of all-to-all point interactions, we adapt a Barnes-Hut tree for accelerated force computation and achieve quasilinear complexity. We show that the new method class has characteristics not found in previous alignment methods such as efficient handling of partial overlaps, inhomogeneous sampling densities, and coping with large point clouds with reduced runtime compared to the state of the art. Experiments show that our method performs on par with or outperforms all compared competing deep-learning-based and general-purpose techniques (which do not take training data) in resolving transformations for LiDAR data and gains state-of-the-art accuracy and speed when coping with different data.

Authors: Sk Aziz Ali, Kerem Kahraman, Christian Theobalt, Didier StrickerVladislav Golyanik

Link to the paper: https://ieeexplore.ieee.org/document/9442679

DFKI-BMW joint research on Augmented Reality for automotive use cases

In the frame of a research cooperation, DFKI’s Augmented Vision Department and BMW are working jointly on Augmented Reality for In-Car applications. Ahmet Firintepe, a BMW research PhD under the supervision of Dr. Alain Pagani and Prof. Didier Stricker has recently published two papers on outside-in head and glass pose estimation:

Ahmet Firintepe, Alain Pagani and Didier Stricker:
“A Comparison of Single and Multi-View IR image-based AR Glasses Pose Estimation Approaches”
Proc. of the IEEE Virtual Reality conference – Posters. IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW) (IEEEVR-2021)

In this paper, we present a study on single and multi-view image-based AR glasses pose estimation with two novel methods. The first approach is named GlassPose and is a VGG-based network. The second approach GlassPoseRN is based on ResNet18. We train and evaluate the two custom developed glasses pose estimation networks with one, two and three input images on the HMDPose dataset. We achieve errors as low as 0.10 degrees and 0.90 mm on average on all axes for orientation and translation. For both networks, we observe minimal improvements in position estimation with more input views.

Ahmet Firintepe, Carolin Vey, Stylianos Asteriadis, Alain Pagani, Didier Stricker:
From IR Images to Point Clouds to Pose: Point Cloud-Based AR Glasses Pose Estimation
In: Journal of Imaging 7 80 Seiten 1-18 MDPI 4/2021.

In this paper, we propose two novel AR glasses pose estimation algorithms from single infrared images by using 3D point clouds as an intermediate representation. Our first approach “PointsToRotation” is based on a Deep Neural Network alone, whereas our second approach “PointsToPose” is a hybrid model combining Deep Learning and a voting-based mechanism. Our methods utilize a point cloud estimator, which we trained on multi-view infrared images in a semisupervised manner, generating point clouds based on one image only. We generate a point cloud dataset with our point cloud estimator using the HMDPose dataset, consisting of multi-view infrared images of various AR glasses with the corresponding 6-DoF poses. In comparison to another point cloud-based 6-DoF pose estimation named CloudPose, we achieve an error reduction of around 50%. Compared to a state-of-the-art image-based method, we reduce the pose estimation error by around 96%.