  Motion forecasting plays a pivotal role in autonomous driving systems,
enabling vehicles to execute collision warnings and rational local-path
planning based on predictions of the surrounding vehicles. However, prevalent
methods often assume complete observed trajectories, neglecting the potential
impact of missing values induced by object occlusion, scope limitation, and
sensor failures. Such oversights inevitably compromise the accuracy of
trajectory predictions. To tackle this challenge, we propose an end-to-end
framework, termed Multiscale Transformer (MSTF), meticulously crafted for
incomplete trajectory prediction. MSTF integrates a Multiscale Attention Head
(MAH) and an Information Increment-based Pattern Adaptive (IIPA) module.
Specifically, the MAH component concurrently captures multiscale motion
representation of trajectory sequence from various temporal granularities,
utilizing a multi-head attention mechanism. This approach facilitates the
modeling of global dependencies in motion across different scales, thereby
mitigating the adverse effects of missing values. Additionally, the IIPA module
adaptively extracts continuity representation of motion across time steps by
analyzing missing patterns in the data. The continuity representation
delineates motion trend at a higher level, guiding MSTF to generate predictions
consistent with motion continuity. We evaluate our proposed MSTF model using
two large-scale real-world datasets. Experimental results demonstrate that MSTF
surpasses state-of-the-art (SOTA) models in the task of incomplete trajectory
prediction, showcasing its efficacy in addressing the challenges posed by
missing values in motion forecasting for autonomous driving systems.
