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 } }