Maximum Classifier Discrepancy for Unsupervised Domain Adaptation

In this work, we present a method for unsupervised domain adaptation. Many adversarial learning methods train domain classifier networks to distinguish the features as either a source or target and train a feature generator network to mimic the discriminator. Two problems exist with these methods. First, the domain classifier only tries to distinguish the features as a source or target and thus does not consider task-specific decision boundaries between classes. Therefore, a trained generator can generate ambiguous features near class boundaries. Second, these methods aim to completely match the feature distributions between different domains, which is difficult because of each domain's characteristics. To solve these problems, we introduce a new approach that attempts to align distributions of source and target by utilizing the task-specific decision boundaries. We propose to maximize the discrepancy between two classifiers' outputs to detect target samples that are far from the support of the source. A feature generator learns to generate target features near the support to minimize the discrepancy. Our method outperforms other methods on several datasets of image classification and semantic segmentation. The codes are available at \url{https://github.com/mil-tokyo/MCD_DA}Comment: Accepted to CVPR2018 Oral, Code is available at https://github.com/mil-tokyo/MCD_D

Interaction-aware Kalman Neural Networks for Trajectory Prediction

Forecasting the motion of surrounding obstacles (vehicles, bicycles, pedestrians and etc.) benefits the on-road motion planning for intelligent and autonomous vehicles. Complex scenes always yield great challenges in modeling the patterns of surrounding traffic. For example, one main challenge comes from the intractable interaction effects in a complex traffic system. In this paper, we propose a multi-layer architecture Interaction-aware Kalman Neural Networks (IaKNN) which involves an interaction layer for resolving high-dimensional traffic environmental observations as interaction-aware accelerations, a motion layer for transforming the accelerations to interaction aware trajectories, and a filter layer for estimating future trajectories with a Kalman filter network. Attributed to the multiple traffic data sources, our end-to-end trainable approach technically fuses dynamic and interaction-aware trajectories boosting the prediction performance. Experiments on the NGSIM dataset demonstrate that IaKNN outperforms the state-of-the-art methods in terms of effectiveness for traffic trajectory prediction.Comment: 8 pages, 4 figures, Accepted for IEEE Intelligent Vehicles Symposium (IV) 202

Probabilistic, Variable and Interaction-aware Situation Recognition

Future advanced driver assistance systems (ADAS) as well as autonomous driving functions will extend their applicability to more complex highway scenarios and inner-city traffic. For these systems it is a prerequisite to know how an encountered traffic scene is most likely going to evolve. Situation recognition aims to predict the high level behavior patterns traffic participants pursue. Thus, it provides valuable information that helps to predict the next few seconds of a traffic scene. The extension of ADAS and autonomous driving functions to more complex scenarios poses a problem to state-of-the-art situation recognition systems due to the variability of the encountered scene layouts, the presence of multiple interacting traffic participants and the concomitant large number of possible situation classes. This thesis proposes and discusses approaches that tackle these challenges. A novel discriminative maneuver estimation framework provides the possibility to assess traffic scenes with varying layout. It is based on reusable, partial classifiers that are combined online using a technique called pairwise probability coupling. The real-world evaluations indicate that the assembled probabilistic maneuver estimation is able to provide superior classification results. A novel interaction-aware situation recognition framework constructs a probabilistic situation assessment over multiple traffic participants without relying on independence assumptions. It allows to assess each traffic participant individually by using maneuver estimation systems that determine complete conditional distributions. A real-world evaluation outlines its applicability and shows its benefits. The challenges associated with the increasing number of possible situation classes are addressed in two ways. Both frameworks allow to reuse classifiers in different contexts. This reduces the number of models required to cope with a large variety of traffic scenes. Moreover, a situation hypotheses selection scheme provides an efficient way for reducing the number of situation hypotheses. This lowers the computational demands and eases the load on subsequent systems