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Zero mAP without mask #11
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@dereyly I met the same problem. I see your train log. The loss becomes very large at 500 iters and finally the loss_rpn_cls is still about 0.3. It means the model is not trained correctly. The case is similar to me. Do you know the reason? |
Sorry for the late reply As mentioned in #1 (comment), the SyncBN has some stability issues. You are suggested to train the SyncBN model with batch size a least 16. Also, it is not the trivial solution in my opinion. You are suggested to train a model without GC first to see if the mAP with drops. |
Hi, thanks for your work. I'm dealing with this issue too, can GN be used to replace SyncBN? |
Hi, we haven't try it. We may try it in the future. You are welcome to try it by yourself. |
Because I only have access to one GPU (P40), I can't use SyncBN. I have tried GN with a batch size of 1 and 10241024 image input and default normalization setting with a batch size of 6 and 512512 image input (small input due to memory limitation), the later worked fine, but the first just gave no bbox prediction. Then by print, I found that when using GN, the feature map after the backbone net will become with the same pixels (like [-3.1547, -3.1547, -3.1547 .....]) after some training. |
By the way the model is cascade_mask_rcnn_r16_gcb_dconv_c3-c5_x101_32x4d_fpn_syncbn_1x |
I want to train a SyncBN model in a single P40, any suggestion is welcome. Thank you. |
There is no need for SyncBN when only one GPU is available. You could use BN instead. Linear scale up strategy should be adopted according to your effective batch size. I don't think non SyncBN would have Zero mAP issue. The fixBN results could be found in the updated readme. |
It turns out that the batch size of 1 works if I use a smaller learning rate with longer time consumed. So I think this issue may have two causes, one is a too large learning rate, the other is some data input error (as mentioned in tensorflow/models#6273). |
In my machine learning course, I have learned that small learning rates may lead to local optima, but is no prediction a local optimum for object detection tasts like this? |
By the way, the batch size of 1 didn't work very well in the first 1/3 period of training. I'm still finding better settings. |
Hello.
Thank you for nice work, I try to use non local nets (GCNet) on practice
This config DCN + GCNet r4 + scale_augmentation and without mask -- faster RCNN (cascade)
mAP =0
I read the log and its strange acc = 97.6621 from begining to end -- maybe it is trivial solution always 0
20190514_202710.log
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