“…Ongoing development of various applications such as autonomous driving [5,11,32] and robotics [41] has led to the increasing demand for 3D object detectors that predict the class label, 3D bounding box and detection confidence score for each instance in a given 3D scene. In recent years, the 2D object detection methods have made great breakthroughs [6,15,22,49,55,59], far ahead of the 3D object detection methods, in particular, the anchor-free detection methods.…”