Extend a single deterministic prediction trajectory

[ceresshadows]

Description: The current implementation in Apollo's prediction module exhibits a significant issue due to its reliance on a single deterministic prediction trajectory for Non-Player Characters (NPCs). This approach lacks flexibility and can lead to potential collision risks, as illustrated in the provided examples.

In the specific scenario described, the NPC (highlighted in a red box) is predicted to move straight ahead. However, the actual behavior (ground truth) of the NPC is to abruptly turn left. This discrepancy between the prediction and the actual behavior leads to a faulty planning trajectory that keeps accelerating and risks a collision with the NPC. The issue is exacerbated by the planning module's complete dependence on this singular predictive outcome.

Screenshots demonstrating the issue:

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Issue Reference: Apollo GitHub Issue #12715

Proposed Solution: A potential solution to this issue is for Apollo to enhance its prediction module to output multiple potential trajectories for each NPC, each associated with a certain level of confidence. This multi-trajectory predictive approach would allow the planning module to make more informed decisions. For instance, it could choose to slow down or maintain a cautious approach until there's a higher confidence in selecting the most probable action, based on the comprehensive outputs from the prediction module.