* Update pytorch2onnx.py which using new logic to convert pytorch to ONNX

* use standard API to check whether in ONNX convert process

* only compare the score value while verifying results between ONNX and pytorch

* move import onnx before import torch, or something weird will happen

* use real images for input

* modifying the way of calling nms

* modify docstring for bbox2result, and remove unnecessary part for onnx exporting

* modify the 'Convert to ONNX' part in docs

* replace or to | in docstring

* update according to the latest mmcv

* add normalize part

* raise error while using low version mmcv

* minor update

* minor update

Co-authored-by: Jiarui XU <xvjiarui0826@gmail.com>

* update docstring formats

* fix :func:

* minor update

* add gfocal losses

* add gfl head, its related code, configs

* fix 2x config bug

* add most model and log in gfl README

* update gfl model and log

* Update transforms.py

modify variables  L, T, R, B   to  left, top, right, bottom

* Update gfocal_loss.py

modify variables into meaningful names:
* pt -> scale_factor
* a -> pos   b -> pos_label
* disl -> dis_left  disr -> dis_right
* wl -> weight_left  wr -> weight_right

* Update gfocal_loss.py

update formats

* remove duplicated get_bboxes/IoU calculation, make QFL consistent

* add all docstring in gfl_head.py and gfocal_loss.py

* Add docstrings of core modules and methods

* Update docs and fix comments

* Complete docstrings

* Resolve comments

* reformat docstrings

* resolve comments

* fixed vertical flip TTA

* fixed test

* add doc and one more check

* fixed docs

* add coder registry

* add coder for single stage

* rename to bbox_coder

* add doc string

* add doc string

* change default

* Refactor (all): all category -1 in anchor/bbox head and anchor/bbox target assign

* Fix (datasets): remove label + 1 in datasets

* Fix (bbox_head): fix bug of fc_cls that forget + 1

* Fix (atss_head & free_anchor): fix cat -1 bugs

* Fix (mask_head): remove label + 1 in mask heads

* fix atss

* Fix (rpn): fix cross_entropy_loss bug of RPN

* Fix (anchor_head): fix typo

* Refactor (anchor_head): use background_label rather than num_classes to indicate background class

* Refactor (docstring): add and reformat docstrings

* fix mask iou head

* Fix (mask_head): fix cat -1 bug

* Fix (mask_head): fix bug in mask inference

* Add (tests): add tests for mask rcnn and mask heads

* Refactor (unittest): refactor test_forward

* Refactor (new_empty): use new_full rather than new_empty

* Refactor (background_label): check background_label

* Add TODO

* Refactor (unittest): allow BP in unittest

Co-authored-by: Cao Yuhang <yhcao6@gmail.com>

* Refactor (all): change coordinate system

* Fix (mask_head): fix cat -1 bug in mask_paste

* Fix (unittest)
: modify unittest and pass CI

* reformat to pass CI

* Fix round coordinates bugs

* clean file

* Fix (test): use cpu version of aligned roi_align in tests

* Refactor (mask): clean np.stack

* Refactor (head): reformat code and fix missing -1

* Reformat: reformat and add doc strings

* Refactor (mask_head): more clea docstring

* fix (scale_factor): use new_tensor(scale_factor) in case it is numpy array

* reformat (models): reformat with flake8, yapf, and isort to pass CI

* fix (bbox_mapping): fix scale_factor bug in bbox_mapping

* fix img_meta bug

Co-authored-by: beansi <zhangwenwei@sensetime.com>

* Doctests for AnchorHead and related code

* Fix flake8 error

* resolve review on transforms.py

* Resolve comments

* resolve commend about foreground classes

* Add reference about bounding box delta encoding

* add fcos

* use P5 instead of C5

* add relu before extra convs in FPN

* add singleclass_nms, use caffe2 lr

* fix log interval

* use caffe2init and relu in extra layers

* fix scale layer, use p5 instead of c5

* fix focs target

* refactor code

* delete useless file

* clean

* refactor code

* change num_classes to cls_out_channels

* fix bug of in get_bboxes

* fix bug in test

* add r101 2x cfg

* ms use value mode, add x101-64x4d cfg

* add more comment and rename some variable

* rename centers to points, modify doc string of distance2bbox

* add fcos detector, replace frozen with requires_grad

* add README.md

* add r101-1x performance, rename cfg, add detector FCOS

* update fcos r50 2x performance, remove fpn caffe2 initialize

* fix flake8 error

* rename cfg

* fix grammar error of some comments

* minor fix comment

* change work_dir to be consistent with config name

* add FCOS support in README