caffe源码分析---IoU计算

IoU计算

$$IoU=\frac{predict检测框与ground\_truth检测框的交集}{predict检测框与ground\_truth检测框的的并集}$$

源码

IoU就是caffe.ssd中的JaccardOverlap。

计算IoU
来自caffe.ssd/src/caffe/util/bbox_util.cpp

template 
Dtype JaccardOverlap(const Dtype* bbox1, const Dtype* bbox2) {
// 若不重叠，返回0
  if (bbox2[0] > bbox1[2] || bbox2[2] < bbox1[0] ||
      bbox2[1] > bbox1[3] || bbox2[3] < bbox1[1]) {
    return Dtype(0.);
  } else {
    const Dtype inter_xmin = std::max(bbox1[0], bbox2[0]);
    const Dtype inter_ymin = std::max(bbox1[1], bbox2[1]);
    const Dtype inter_xmax = std::min(bbox1[2], bbox2[2]);
    const Dtype inter_ymax = std::min(bbox1[3], bbox2[3]);

    const Dtype inter_width = inter_xmax - inter_xmin;
    const Dtype inter_height = inter_ymax - inter_ymin;
    const Dtype inter_size = inter_width * inter_height;
	
	// 求bbox的面积
    const Dtype bbox1_size = BBoxSize(bbox1);
    const Dtype bbox2_size = BBoxSize(bbox2);

    return inter_size / (bbox1_size + bbox2_size - inter_size);
  }
}

求bbox面积
来自caffe.ssd/src/caffe/util/bbox_util.cpp

template 
Dtype BBoxSize(const Dtype* bbox, const bool normalized = true);

template 
Dtype BBoxSize(const Dtype* bbox, const bool normalized) {
  if (bbox[2] < bbox[0] || bbox[3] < bbox[1]) {
    // If bbox is invalid (e.g. xmax < xmin or ymax < ymin), return 0.
    return Dtype(0.);
  } else {
    const Dtype width = bbox[2] - bbox[0];
    const Dtype height = bbox[3] - bbox[1];
    if (normalized) {
      return width * height;
    } else {
      // If bbox is not within range [0, 1].
      return (width + 1) * (height + 1);
    }
  }
}