Author name cluster

Johan Vertens

Possible papers associated with this exact author name in Arrow. This page groups case-insensitive exact name matches and is not a full identity disambiguation profile.

7 papers

1 author row

IROS Conference 2023 Conference Paper

Improving Deep Dynamics Models for Autonomous Vehicles with Multimodal Latent Mapping of Surfaces

Johan Vertens
Nicolai Dorka
Tim Welschehold
Michael Thompson
Wolfram Burgard

The safe deployment of autonomous vehicles relies on their ability to effectively react to environmental changes. This can require maneuvering on varying surfaces which is still a difficult problem, especially for slippery terrains. To address this issue we propose a new approach that learns a surface-aware dynamics model by conditioning it on a latent variable vector storing surface information about the current location. A latent mapper is trained to update these latent variables during inference from multiple modalities on every traversal of the corresponding locations and stores them in a map. By training everything end-to-end with the loss of the dynamics model, we enforce the latent mapper to learn an update rule for the latent map that is useful for the subsequent dynamics model. We implement and evaluate our approach on a real miniature electric car. The results show that the latent map is updated to allow more accurate predictions of the dynamics model compared to a model without this information. We further show that by using this model, the driving performance can be improved on varying and challenging surfaces.

Details

IROS Conference 2022 Conference Paper

Realistic Real-Time Simulation of RGB and Depth Sensors for Dynamic Scenarios using Augmented Image Based Rendering

Johan Vertens
Wolfram Burgard

Simulation remains one of the key methods for testing and validation of robotic perception systems and it also becomes increasingly important for training visuomotor policies for autonomous driving or manipulation. Further, as perception pipelines tend to leverage increasing amounts of modalities, it appears vital to simulate additional cues such as depth maps aside from RGB images. To align simulation with real-world observations, it is key to achieve realistic renderings of these maps, which includes the capability of rendering other dynamic objects in the scene. In this work, we propose an approach to real-time simulation of photo-realistic RGB images and sensor-realistic depth maps, that can contain dynamic objects at user-defined locations. Our method employs a selection of static samples of a pre-recorded database and multimodal cues from CAD models that are fused and warped to synthesize new imagery for a target camera pose. We show the efficacy of our method on newly proposed datasets recorded in a variety of different setups.

Details

IROS Conference 2020 Conference Paper

HeatNet: Bridging the Day-Night Domain Gap in Semantic Segmentation with Thermal Images

Johan Vertens
Jannik Zürn
Wolfram Burgard

The majority of learning-based semantic segmentation methods are optimized for daytime scenarios and favorable lighting conditions. Real-world driving scenarios, however, entail adverse environmental conditions such as nighttime illumination or glare which remain a challenge for existing approaches. In this work, we propose a multimodal semantic segmentation model that can be applied during daytime and nighttime. To this end, besides RGB images, we leverage thermal images, making our network significantly more robust. We avoid the expensive annotation of nighttime images by leveraging an existing daytime RGB-dataset and propose a teacher-student training approach that transfers the dataset's knowledge to the nighttime domain. We further adopt a domain adaptation method to align the learned feature spaces across the domains and propose a novel two-stage training scheme. Furthermore, due to a lack of thermal data for autonomous driving, we present a new dataset comprising over 20, 000 time-synchronized and aligned RGB-thermal image pairs. In this context, we also present a novel target-less calibration method that allows for automatic robust extrinsic and intrinsic thermal camera calibration. Among others, we use our new dataset to show state-of-the-art results for nighttime semantic segmentation.

Details

ICRA Conference 2020 Conference Paper

Learning Object Placements For Relational Instructions by Hallucinating Scene Representations

Oier Mees
Alp Emek
Johan Vertens
Wolfram Burgard

Robots coexisting with humans in their environment and performing services for them need the ability to interact with them. One particular requirement for such robots is that they are able to understand spatial relations and can place objects in accordance with the spatial relations expressed by their user. In this work, we present a convolutional neural network for estimating pixelwise object placement probabilities for a set of spatial relations from a single input image. During training, our network receives the learning signal by classifying hallucinated high-level scene representations as an auxiliary task. Unlike previous approaches, our method does not require ground truth data for the pixelwise relational probabilities or 3D models of the objects, which significantly expands the applicability in practical applications. Our results obtained using real-world data and human-robot experiments demonstrate the effectiveness of our method in reasoning about the best way to place objects to reproduce a spatial relation. Videos of our experiments can be found at https://youtu.be/zaZkHTWFMKM.

Details

ICRA Conference 2019 Conference Paper

A Maximum Likelihood Approach to Extract Finite Planes from 3-D Laser Scans

Alexander Schaefer
Johan Vertens
Daniel Büscher
Wolfram Burgard

Whether it is object detection, model reconstruction, laser odometry, or point cloud registration: Plane extraction is a vital component of many robotic systems. In this paper, we propose a strictly probabilistic method to detect finite planes in organized 3-D laser range scans. An agglomerative hierarchical clustering technique, our algorithm builds planes from bottom up, always extending a plane by the point that decreases the measurement likelihood of the scan the least. In contrast to most related methods, which rely on heuristics like orthogonal point-to-plane distance, we leverage the ray path information to compute the measurement likelihood. We evaluate our approach not only on the popular SegComp benchmark, but also provide a challenging synthetic dataset that overcomes SegComp's deficiencies. Both our implementation and the suggested dataset are available at [1].

Details

ICRA Conference 2017 Conference Paper

AdapNet: Adaptive semantic segmentation in adverse environmental conditions

Abhinav Valada
Johan Vertens
Ankit Dhall
Wolfram Burgard

Robust scene understanding of outdoor environments using passive optical sensors is a onerous and essential task for autonomous navigation. The problem is heavily characterized by changing environmental conditions throughout the day and across seasons. Robots should be equipped with models that are impervious to these factors in order to be operable and more importantly to ensure safety in the real-world. In this paper, we propose a novel semantic segmentation architecture and the convoluted mixture of deep experts (CMoDE) fusion technique that enables a multi-stream deep neural network to learn features from complementary modalities and spectra, each of which are specialized in a subset of the input space. Our model adaptively weighs class-specific features of expert networks based on the scene condition and further learns fused representations to yield robust segmentation. We present results from experimentation on three publicly available datasets that contain diverse conditions including rain, summer, winter, dusk, fall, night and sunset, and show that our approach exceeds the state-of-the-art. In addition, we evaluate the performance of autonomously traversing several kilometres of a forested environment using only the segmentation for perception.

Details

IROS Conference 2017 Conference Paper

SMSnet: Semantic motion segmentation using deep convolutional neural networks

Johan Vertens
Abhinav Valada
Wolfram Burgard

Interpreting the semantics and motion of objects are prerequisites for autonomous robots that enable them to reason and operate in dynamic real-world environments. Existing approaches that tackle the problem of semantic motion segmentation consist of long multistage pipelines and typically require several seconds to process each frame. In this paper, we present a novel convolutional neural network architecture that learns to predict both the object label and motion status of each pixel in an image. Given a pair of consecutive images, the network learns to fuse features from self-generated optical flow maps and semantic segmentation kernels to yield pixel-wise semantic motion labels. We also introduce the Cityscapes-Motion dataset which contains over 2, 900 manually annotated semantic motion labels, which is the largest dataset of its kind so far. We demonstrate that our network outperforms existing approaches achieving state-of-the-art performance on the KITTI dataset, as well as in the more challenging Cityscapes-Motion dataset while being substantially faster than existing techniques.

Details