Multiple-level Point Embedding for Solving Human Trajectory Imputation with Prediction
This work addresses the issue of sparse trajectory data for applications in human mobility analysis, presenting an incremental improvement by integrating imputation and prediction tasks.
The paper tackles the problem of sparse human trajectory data by proposing a model that simultaneously performs imputation and prediction, leveraging their mutual benefits to improve outcomes, with experimental results showing significant advantages in accuracy and stability over baselines on three real-world datasets.
Sparsity is a common issue in many trajectory datasets, including human mobility data. This issue frequently brings more difficulty to relevant learning tasks, such as trajectory imputation and prediction. Nowadays, little existing work simultaneously deals with imputation and prediction on human trajectories. This work plans to explore whether the learning process of imputation and prediction could benefit from each other to achieve better outcomes. And the question will be answered by studying the coexistence patterns between missing points and observed ones in incomplete trajectories. More specifically, the proposed model develops an imputation component based on the self-attention mechanism to capture the coexistence patterns between observations and missing points among encoder-decoder layers. Meanwhile, a recurrent unit is integrated to extract the sequential embeddings from newly imputed sequences for predicting the following location. Furthermore, a new implementation called Imputation Cycle is introduced to enable gradual imputation with prediction enhancement at multiple levels, which helps to accelerate the speed of convergence. The experimental results on three different real-world mobility datasets show that the proposed approach has significant advantages over the competitive baselines across both imputation and prediction tasks in terms of accuracy and stability.