def train_step(batch_images, batch_labels):
with tf.GradientTape() as tape:
pred = ssd(batch_images, training=True)
output = ssd_prediction(feature_maps=pred, num_classes=NUM_CLASSES + 1)
gt = MakeGT(batch_labels, pred)
gt_boxes = gt.generate_gt_boxes()
loss_value = loss(y_true=gt_boxes, y_pred=output)
gradients = tape.gradient(loss_value, ssd.trainable_variables)
optimizer.apply_gradients(grads_and_vars=zip(gradients, ssd.trainable_variables))
loss_metric.update_state(values=loss_value)
def train_step(batch_images, batch_labels):
with tf.GradientTape() as tape:
pred = ssd(batch_images, training=True)#调用call函数得到最初的各个层的feature map，每一个feature Map为[ 1 19 19 150]
print("pred",tf.shape(pred[1]),"\n")
#print("prediction finished")
output = ssd_prediction(feature_maps=pred, num_classes=NUM_CLASSES + 1)#将featureMap的预测值经行一定得排列，shape:[1,8732,25]
#print("out",tf.shape(output))
gt = MakeGT(batch_labels, pred)#计算ground Truth
gt_boxes = gt.generate_gt_boxes()#产生gt_box
loss_value, cls_loss, reg_loss = loss(y_true=gt_boxes, y_pred=output)
gradients = tape.gradient(loss_value, ssd.trainable_variables)
optimizer.apply_gradients(grads_and_vars=zip(gradients, ssd.trainable_variables))
loss_metric.update_state(values=loss_value)
cls_loss_metric.update_state(values=cls_loss)
reg_loss_metric.update_state(values=reg_loss)