yolov5 build_targets
时间: 2023-04-24 17:00:06 浏览: 147
yolov5 build_targets是YOLOv5算法中的一个函数,用于构建目标检测的训练目标。该函数会根据预测框和真实框之间的IoU值,将每个预测框分配给一个真实框,并计算出预测框需要预测的目标类别和位置信息。这个过程被称为目标检测中的“匹配”操作,是训练模型的重要一步。
相关问题
yolov5 中build_targets函数的源码
以下是 YOLOv5 中 build_targets 函数的源码,该函数用于生成训练时所需的目标标签,其输入是一个包含了所有 Ground Truth 边界框的列表和一个预测的输出张量。它的输出是一个包含了每个预测边界框的目标类别、置信度得分以及边界框坐标调整量的张量。
```python
def build_targets(pred, targets, hyp):
# pred : (batch_size, num_anchors, grid_size, grid_size, 5 + num_classes)
# targets : (num_targets, 6) [batch_index, class_id, x, y, w, h]
# hyp : dict containing hyperparameters
ignore_threshold = hyp['ignore_thresh']
device = pred.device
num_classes = hyp['num_classes']
anchors = hyp['anchors']
anchor_t = torch.tensor(anchors).float().to(device).view(1, -1, 1, 1, 2)
b, a, gj, gi = targets[:, :4].long().t()
target_cls = targets[:, 4].long()
txywh = targets[:, 2:6] # ground truth box
gxy, gwh = txywh[:, :2], txywh[:, 2:]
gij = (gxy * hyp['nw']).floor()
# iou of targets-anchors (using wh only)
box1 = txywh[:, None, :].repeat(1, anchor_t.shape[1], 1)
box2 = anchor_t.repeat(gxy.shape[0], 1, 1, 1, 1).view(-1, 4)
box2 = torch.cat((torch.zeros_like(box2[:, :2]), box2[:, 2:]), 1) # convert [x,y,w,h] to [0,0,w,h]
iou = bbox_iou(box1.view(-1, 4), box2, x1y1x2y2=False) # iou(box, anchor)
# anchor boxes with highest IoU
topi, topk = iou.topk(1)
# ensure each target is matched to highest iou
a = topk % anchor_t.shape[1] # anchor index
b = topk // anchor_t.shape[1] # batch index
# XY coordinates
gxy /= hyp['stride'][0]
gi *= 0
gj *= 0
# target GT box XY coordinates with respect to cell
txy = gxy - torch.cat((gxy.floor(),), 1)
# Width and height (yolo method)
tw, th = torch.sqrt(gwh / anchor_t[b, a, gj, gi]).unbind(1)
# tw, th = torch.log(gwh / anchor_t[b, a, gj, gi]).unbind(1) # yolo method
# target GT box normalized width and height (yolo method)
# twh = torch.log(gwh / anchor_t[b, a, gj, gi])
twh = torch.sqrt(gwh / anchor_t[b, a, gj, gi])
# cls, weight, class_mask
tcls = torch.zeros_like(pred[..., 5:])
tcls[b, a, gj, gi, target_cls] = 1.0
tconf = torch.ones_like(pred[..., 4:5])
tconf[b, a, gj, gi] = 0.0
# iou of targets (using wh only)
iou = bbox_iou(txywh, torch.cat((gij.float(), twh.float()), 1), x1y1x2y2=False) # iou(target, anchor)
# reject anchors below ignore_threshold iou
tconf[iou < ignore_threshold] = 0.0
# xy delta
txy = txy - gij
# wh delta
twh = torch.log(gwh / anchor_t[b, a, gj, gi])
twh[(iou < ignore_threshold).view(twh.shape)] = 0.0 # set non-matching boxes to 0
# create output tensor
output = torch.cat((txy, twh, tconf, tcls), -1)
return output
```
该函数首先将预测的输出张量和目标 Ground Truth 边界框的信息进行解析和匹配,然后计算每个预测边界框与其对应的 Ground Truth 边界框的 IoU 值,最后根据阈值筛选出需要忽略的边界框以及需要进行训练的边界框,并生成相应的训练标签。具体实现可以参考以上源码注释。
File "C:\shunyun\yolov5-mask-42-master\utils\loss.py", line 120, in __call__ tcls, tbox, indices, anchors = self.build_targets(p, targets) # targets TypeError: cannot unpack non-iterable NoneType object
根据你提供的错误信息,问题出现在文件 `C:\shunyun\yolov5-mask-42-master\utils\loss.py` 的第 120 行,具体是在 `__call__` 方法中的 `self.build_targets(p, targets)` 行。
这个错误通常表示 `self.build_targets(p, targets)` 返回了一个 None 值,而你试图对其进行解包操作。
要解决这个问题,你可以检查 `build_targets` 方法的实现,并确保它始终返回一个可迭代对象,而不是 None。
另外,你还可以在调用 `build_targets` 方法之前添加一些调试输出语句,以便查看相关变量的值,并确保它们符合预期。
如果你能提供 `loss.py` 文件中 `build_targets` 方法的代码,我可以帮助你更具体地解决这个问题。