architecture: FCOS
pretrain_weights: https://paddledet.bj.bcebos.com/models/pretrained/ResNet50_cos_pretrained.pdparams

FCOS:
  backbone: ResNet
  neck: FPN
  fcos_head: FCOSHead

ResNet:
  depth: 50
  variant: 'b'
  norm_type: bn
  freeze_at: 0 # res2
  return_idx: [1, 2, 3]
  num_stages: 4

FPN:
  out_channel: 256
  spatial_scales: [0.125, 0.0625, 0.03125]
  extra_stage: 2
  has_extra_convs: True
  use_c5: False

FCOSHead:
  fcos_feat:
    name: FCOSFeat
    feat_in: 256
    feat_out: 256
    num_convs: 4
    norm_type: "gn"
    use_dcn: False
  fpn_stride: [8, 16, 32, 64, 128]
  prior_prob: 0.01
  norm_reg_targets: True
  centerness_on_reg: True
  num_shift: 0.5
  fcos_loss:
    name: FCOSLoss
    loss_alpha: 0.25
    loss_gamma: 2.0
    iou_loss_type: "giou"
    reg_weights: 1.0
  nms:
    name: MultiClassNMS
    nms_top_k: 1000
    keep_top_k: 100
    score_threshold: 0.025
    nms_threshold: 0.6