two-stage: use region proposal network (RPN) to generate proposals
one-stage: remove RPN and use anchors with associated fixed proposals based on predefined scales/aspect-ratios.
Corner Points: remove anchors and directly predict corner points
No anchor: actually use aach cell as an anchor
RPDet: use object centers as positive cells; paired with deformable CNN
FoveaBox: use the cells in fovea area (object bounding box) as positive cells
Guided Anchoring: use deformable CNN to obtain adapted feature map