  Learning-based approaches to autonomous vehicle planners have the potential
to scale to many complicated real-world driving scenarios by leveraging huge
amounts of driver demonstrations. However, prior work only learns to estimate a
single planning trajectory, while there may be multiple acceptable plans in
real-world scenarios. To solve the problem, we propose an interpretable neural
planner to regress a heatmap, which effectively represents multiple potential
goals in the bird's-eye view of an autonomous vehicle. The planner employs an
adaptive Gaussian kernel and relaxed hourglass loss to better capture the
uncertainty of planning problems. We also use a negative Gaussian kernel to add
supervision to the heatmap regression, enabling the model to learn collision
avoidance effectively. Our systematic evaluation on the Lyft Open Dataset
across a diverse range of real-world driving scenarios shows that our model
achieves a safer and more flexible driving performance than prior works.
