detectron2/configs/COCO-InstanceSegmentation/mask_rcnn_R_50_FPN_1x.yaml

_BASE_: "../Base-RCNN-FPN.yaml"
MODEL:
  WEIGHTS: "detectron2://ImageNetPretrained/MSRA/R-50.pkl"
  MASK_ON: True
  RESNETS:
    DEPTH: 50