Self-critical Learning of Influencing Factors for Trajectory Prediction using Gated Graph Convolutional Network

Forecasting future trajectories of multiple pedestrians in a crowded environment is a challenging problem due to the complex interactions among the pedestrians. The interactions can be asymmetric and their influences may vary over time. Moreover, each pedestrian can exhibit different behavior at any given time and context and thus they may have multiple future possible trajectories. In this work, we present a Gated Graph Convolutional Network (GatedGCN) based trajectory prediction model that explicitly deal with the asymmetric influences among the adjacent pedestrians through edge-wise gating mechanism. Through GatedGCN only, an overall average improvement of 16% and 18% was achieved on the two performance metrics over the state-of-the-art trajectory forecasting methods. Next, we tackle the problem of learning multi-modal distributions of each pedestrian trajectory using variational auto-encoders (VAEs). However, trajectories sampled from the learned distribution usually ignore the factors affecting the pedestrian motion such as collision avoidance and the target destination. While many of the existing approaches focus on learning such factors during the trajectory encoding process, we proposed a novel self-critical learning approach based on Actor-Critic framework to learn such factors during the trajectory generation process. We empirically show that our method creates fewer number of collisions than the existing methods on popular trajectory forecasting benchmarks.