SF3D: SlowFast Temporal 3D Object Detection

Leveraging inputs over multiple consecutive frames has been shown to benefit 3D object detection. However, existing approaches often demonstrate unsatisfactory scaling with increasing temporal histories. In this work, we propose SF3D, a late fusion module which addresses this issue by better modeling temporal relationships via a two-stream factorization. Concretely, SF3D operates on an input sequence of consecutive bird's-eye view (BEV) features, which is partitioned into "short-term" and "long-term" frames. A more heavily parameterized short-term branch using adapters and deformable attention aggregates features closer to the current timestep. In parallel, a long-term branch composed of efficiently implemented global convolution layers aggregates a larger window of temporally distant historical features. This two-stream paradigm allows SF3D to effectively consume near-term information, while scaling to efficiently leverage longer historical windows. We show that SF3D works with arbitrary upstream BEV encoders and downstream detectors, achieving improvements over recent state-of-the-art on the Waymo Open and nuScenes benchmarks.