Adaptive 3D Perception for Small Aerial Targets Under Sparse Sampling via Reinforcement Learning

Detecting small aerial targets (SATs) in long-range LiDAR is challenging because motion causes extreme variations in point density, breaking fixed-voxel and static-threshold assumptions in standard 3D detection and tracking. To address the challenges, we introduce A3PRL, an RL-driven adaptive perception framework that closes the loop between LiDAR sensing and tracking. A3PRL uses a sparsityaware proposal stage with Temporal Dispersion Signatures and velocity-change cues, and a lightweight 5D policy that jointly adjusts voxel resolution, detection sensitivity, and association gating from label-free statistics of sparsity, foreground acceptance, and track stability. The policy is trained with privileged ground-truth trajectories to optimize a reward balancing geometric accuracy, temporal stability, and regularized acceptance, but runs fully label-free at test time. On the public MMAUD benchmark, training on V1 and evaluating on unseen V2/V3, A3PRL reduces 3D localization error by about 19% over its non-RL counterpart and consistently outperforms LiDAR-only and multimodal baselines under both day and night conditions. The same policy is able to transfer to other SAT datasets with heterogeneous scan patterns, maintaining accurate and stable trajectories.