Why I got the nan loss_bbox when i train and eval?

[shuangli59]

Why I got the nan loss_bbox when i train and eval?

[Cysu]

Did you modify the code? For the first training iteration, it should be something like

I1113 15:51:24.800622 32170 solver.cpp:240] Iteration 0, loss = 6.22973
I1113 15:51:24.800657 32170 solver.cpp:255]     Train net output #0: det_accuracy = 0.078125
I1113 15:51:24.800668 32170 solver.cpp:255]     Train net output #1: det_loss = 0.706399 (* 1 = 0.706399 loss)
I1113 15:51:24.800671 32170 solver.cpp:255]     Train net output #2: id_accuracy = 0
I1113 15:51:24.800676 32170 solver.cpp:255]     Train net output #3: id_loss = 9.26615 (* 1 = 9.26615 loss)
I1113 15:51:24.800681 32170 solver.cpp:255]     Train net output #4: loss_bbox = 1.04062e-05 (* 1 = 1.04062e-05 loss)
I1113 15:51:24.800685 32170 solver.cpp:255]     Train net output #5: rpn_bbox_loss = 0.188907 (* 1 = 0.188907 loss)
I1113 15:51:24.800689 32170 solver.cpp:255]     Train net output #6: rpn_cls_loss = 0.693245 (* 1 = 0.693245 loss)
I1113 15:51:24.800700 32170 solver.cpp:640] Iteration 0, lr = 0.001

[andongchen]

I have not modify the code! Could I modify the code?

[Cysu]

No. That won't be necessary. Directly running the training script should be fine. Could you please provide a full training log (by uploading to BaiduYun / GoogleDrive / Dropbox) for me to have further analysis?

Also could you please evaluate our trained model by following the instructions in the README, to see if it works properly?

[andongchen]

Yes, I can evaluate by your trained model,and there is no error.
The train log is here：https://drive.google.com/file/d/0Bz7UoqmY26NkeWphcnZYckNKUU0/view?usp=sharing

[Cysu]

That's quite weird. Could you please

1. Remove this line of randomness
2. Run the training script with specified random seed

experiments/scripts/train.sh 0 --set EXP_DIR resnet50 RNG_SEED 1

On my machine, this will lead to the same loss as follows for iteration 0

I0412 10:00:41.251739 29112 solver.cpp:240] Iteration 0, loss = 11.4016
I0412 10:00:41.251796 29112 solver.cpp:255]     Train net output #0: det_accuracy = 0.804688
I0412 10:00:41.251809 29112 solver.cpp:255]     Train net output #1: det_loss = 0.681872 (* 1 = 0.681872 loss)
I0412 10:00:41.251818 29112 solver.cpp:255]     Train net output #2: id_accuracy = 0
I0412 10:00:41.251827 29112 solver.cpp:255]     Train net output #3: id_loss = 9.40343 (* 1 = 9.40343 loss)
I0412 10:00:41.251835 29112 solver.cpp:255]     Train net output #4: loss_bbox = 0.522466 (* 1 = 0.522466 loss)
I0412 10:00:41.251844 29112 solver.cpp:255]     Train net output #5: rpn_bbox_loss = 0.123584 (* 1 = 0.123584 loss)
I0412 10:00:41.251876 29112 solver.cpp:255]     Train net output #6: rpn_cls_loss = 0.693231 (* 1 = 0.693231 loss)
I0412 10:00:41.251895 29112 solver.cpp:640] Iteration 0, lr = 0.001

[andongchen]

Sorry,when I first run the training script with no modify!There are one error!
experiments/scripts/train.sh 0 --set EXP_DIR resnet50`

Normalizing targets
done
Traceback (most recent call last):
  File "tools/train_net.py", line 130, in <module>
    max_iters=args.max_iters)
  File "/home/cy/PycharmProjects/person_search-master/tools/../lib/fast_rcnn/train.py", line 121, in train_net
    pretrained_model=pretrained_model)
  File "/home/cy/PycharmProjects/person_search-master/tools/../lib/fast_rcnn/train.py", line 50, in __init__
    pb2.text_format.Merge(f.read(), self.solver_param)
AttributeError: 'module' object has no attribute 'text_format'

And then I google solved by adding import google.protobuf.text_format in /lib/fast_rcnn/train.py!
and then got the nan_loss error!

Now I do as you say the step 1 and 2! also got the nan loss

I0412 11:58:24.734537 15281 solver.cpp:240] Iteration 0, loss = 45.384
I0412 11:58:24.734563 15281 solver.cpp:255]     Train net output #0: det_accuracy = 0.03125
I0412 11:58:24.734571 15281 solver.cpp:255]     Train net output #1: det_loss = 0.693147 (* 1 = 0.693147 loss)
I0412 11:58:24.734575 15281 solver.cpp:255]     Train net output #2: id_accuracy = -nan
I0412 11:58:24.734578 15281 solver.cpp:255]     Train net output #3: id_loss = 0 (* 1 = 0 loss)
I0412 11:58:24.734582 15281 solver.cpp:255]     Train net output #4: loss_bbox = 0.0592934 (* 1 = 0.0592934 loss)
I0412 11:58:24.734586 15281 solver.cpp:255]     Train net output #5: rpn_bbox_loss = 0.00123454 (* 1 = 0.00123454 loss)
I0412 11:58:24.734591 15281 solver.cpp:255]     Train net output #6: rpn_cls_loss = 0.693147 (* 1 = 0.693147 loss)
I0412 11:58:24.734596 15281 solver.cpp:640] Iteration 0, lr = 0.001
I0412 11:58:48.375877 15281 solver.cpp:240] Iteration 20, loss = nan
I0412 11:58:48.376101 15281 solver.cpp:255]     Train net output #0: det_accuracy = 0.929688
I0412 11:58:48.376142 15281 solver.cpp:255]     Train net output #1: det_loss = 0.620077 (* 1 = 0.620077 loss)
I0412 11:58:48.376157 15281 solver.cpp:255]     Train net output #2: id_accuracy = -nan
I0412 11:58:48.376165 15281 solver.cpp:255]     Train net output #3: id_loss = 0 (* 1 = 0 loss)
I0412 11:58:48.376170 15281 solver.cpp:255]     Train net output #4: loss_bbox = nan (* 1 = nan loss)
I0412 11:58:48.376176 15281 solver.cpp:255]     Train net output #5: rpn_bbox_loss = 0.185238 (* 1 = 0.185238 loss)
I0412 11:58:48.376183 15281 solver.cpp:255]     Train net output #6: rpn_cls_loss = 0.680902 (* 1 = 0.680902 loss)
I0412 11:58:48.376190 15281 solver.cpp:640] Iteration 20, lr = 0.001

[andongchen]

@Cysu First ,very thanks for your perfect job.There is no issue,but I have a question, have you try YOLO9000 for pedestrain detection,YOLO v2 for object detection is more faster and precision than faster rcnn.At your current work have the detection accuracy influence the person_search‘s mAP.

[Cysu]

Thank you very much for the suggestion. I really appreciate recent advances in object detection, e.g., YOLO v2, FPN, etc., and would like to give it a try if I have some time in the future. But currently I may not have enough spare time for it, and YOLO v2 seems to be implemented only in darknet, which is not that popular, compared with caffe / tf / pytorch.

By the way, do you still suffer from nan loss? If not, how did you solve it?

[andongchen]

Now, there are tensorflow verson YOLO:https://github.com/thtrieu/darkflow
I still suffer from the nan loss,i think it's machine environment's error ,but i not sure.

[Cysu]

Thank you very much for the link. I will check about it.

It's quite weird about the nan problem. Sorry but currently I have no idea about why it happens.

[duanLH]

@andongchen @Cysu When training ,I got "id_accuracy = -nan", Is normal ?

[Cysu]

@duanLH, id_accuracy = -nan is possible, because there are cases that the proposals do not contain any ground truth person, especially at the beginning stage of training.