Denoising diffusion models show remarkable performances in generative tasks, and their potential applications in perception tasks are gaining interest. In this paper, we introduce a novel framework named DiffRef3D which adopts the diffusion process on 3D object detection with point clouds for the first time. Specifically, we formulate the proposal refinement stage of two-stage 3D object detectors as a conditional diffusion process. During training, DiffRef3D gradually adds noise to the residuals between proposals and target objects, then applies the noisy residuals to proposals to generate hypotheses. The refinement module utilizes these hypotheses to denoise the noisy residuals and generate accurate box predictions. In the inference phase, DiffRef3D generates initial hypotheses by sampling noise from a Gaussian distribution as residuals and refines the hypotheses through iterative steps. DiffRef3D is a versatile proposal refinement framework that consistently improves the performance of existing 3D object detection models. We demonstrate the significance of DiffRef3D through extensive experiments on the KITTI benchmark. Code will be available.

DiffRef3D是一种新颖的框架，采用了首次将扩散流程应用于使用点云的三维物体检测，通过将噪声逐渐添加到提案和目标物体之间的残差，并将噪声残差应用于提案以生成假设，然后通过迭代步骤对假设进行精确的盒子预测，从而在现有的三维物体检测模型中持续改进性能。

DiffRef3D：一种基于扩散的三维物体检测提案细化框架