def __init__(self, iou_thresh=0.5, neg_thresh=0.5, negative_mining_ratio=3, stds=(0.1, 0.1, 0.2, 0.2), **kwargs): super(SSDTargetGenerator, self).__init__(**kwargs) self._matcher = CompositeMatcher( [BipartiteMatcher(share_max=False), MaximumMatcher(iou_thresh)]) if negative_mining_ratio > 0: self._sampler = OHEMSampler(negative_mining_ratio, thresh=neg_thresh) self._use_negative_sampling = True else: self._sampler = NaiveSampler() self._use_negative_sampling = False self._cls_encoder = MultiClassEncoder() self._box_encoder = NormalizedBoxCenterEncoder(stds=stds) self._center_to_corner = BBoxCenterToCorner(split=False)