How to change backbone

[gonghaotian]

I'd like to change the backbone to another architecture
but I did not find the code of this part
how to change the architecture of backbone?
thanks~
@heilaw

[heilaw]

The network architecture is defined here.

[gonghaotian]

@heilaw thank u for ur reply
i have another problem when i test my model
the model can be tested on coco val2014 with 38mAP and i think the result is acceptable because some of my training details
but when i test on coco test2017，mAP are all -1，i dont know the meaning of -1 ，i googled this but find nothing
thanks a lot!

[gonghaotian]

btw，issue#120 meet the same problem like mine