Caffe implementation of FAIR paper "Focal Loss for Dense Object Detection" for SSD.
layer {
name: "mbox_loss"
type: "MultiBoxFocalLoss" #change the type
bottom: "mbox_loc"
bottom: "mbox_conf"
bottom: "mbox_priorbox"
bottom: "label"
top: "mbox_loss"
include {
phase: TRAIN
}
propagate_down: true
propagate_down: true
propagate_down: false
propagate_down: false
loss_param {
normalization: VALID
}
focal_loss_param { #set the alpha and gamma, default is alpha=0.25, gamma=2.0
alpha: 0.25
gamma: 2.0
}
multibox_loss_param {
loc_loss_type: SMOOTH_L1
conf_loss_type: SOFTMAX
loc_weight: 1.0
num_classes: 21
share_location: true
match_type: PER_PREDICTION
overlap_threshold: 0.5
use_prior_for_matching: true
background_label_id: 0
use_difficult_gt: true
neg_pos_ratio: 3.0
neg_overlap: 0.5
code_type: CENTER_SIZE
ignore_cross_boundary_bbox: false
mining_type: NONE #do not use OHEM
}
}