text: _base_ = './fcos_hrnetv2p_w32_gn-head_mstrain_640-800_4x4_2x_coco.py'
  model = dict(
      backbone=dict(
          extra=dict(
              stage2=dict(num_channels=(18, 36)),
              stage3=dict(num_channels=(18, 36, 72)),
              stage4=dict(num_channels=(18, 36, 72, 144))),
          init_cfg=dict(
              type='Pretrained', checkpoint='open-mmlab://msra/hrnetv2_w18')),
      neck=dict(type='HRFPN', in_channels=[18, 36, 72, 144], out_channels=256))
  